AN ABSTRACT OF THE THESIS OF
Kathleen M. Ronan for the degree of MASTER OF SCIENCE in Food Science and Technology presented on June 4. 1981
Title: THE EFFECTS OF PROCESSING ON SODIUM-POTASSIUM AND CALCIUM-
PHOSPHORUS RATIOS IN FOODS . S 'I Abstract approved: ~ ^ ~~ Dr. pf Jane Wyatt
The objective of this study was to determine the effects of processing on sodium - potassium and calcium - phosphorus ratios in tuna canned in oil and in water, peanut butter, white and whole wheat flours. Mineral levels were determined by atomic absorption spectrophotometry in food samples at various stages in the production of these finished products.
The average sodium - potassium ratios of the tuna samples were: 1.37 raw, 1.24 precooked, 1.87 canned in oil and 1.61 canned in water.
Processing did not significantly effect sodium and potassium ratios in canned tuna. The average calcium - phosphorus ratios of the tuna samples were: 0.034 raw, 0.024 precooked, 0.034 canned in oil and 0.065 canned in water. The ratio of the canned in water meat was significantly effected by processing.
The average sodium - potassium ratios of the peanut samples were:
0.034 raw, 0.043 roasted, 0.031 blanched and 0.781 peanut butter. The ratio of peanut butter was significantly greater than the ratios of the other peanut samples. The average calcium - phosphorus ratios of the peanut samples were: 0.148 raw, 0.121 roasted, 0.141 blanched and
0.128 peanut butter. These ratios were not significantly effected by processing. The average sodium - potassium ratio was 0.16 in white flours,
0.84 in whole wheat flour and 0.89 in the kernel. The average calcium - phosphorus ratio was 0.14 in white flours, 0.07 in whole wheat flour and 0.07 in the kernel. The ratios of the kernel and whole wheat flour were not significantly different. Processing significantly effected the ratios of the white flour.
The preferred concentration of sodium chloride and a 1:1 sodium - potassium chloride mixture in white and whole wheat breads was also studied. Bread samples were made with 1.0%, 0.75% and 0.5% levels of both salt treatments. They were evaluated by an untrained flavor panel for overall desirability with a nine point hedonic scale. The judges preferred a sodium chloride white bread with a 7.0 sodium - potassium ratio, and a sodium chloride whole wheat bread with a 3.29 ratio. These ratios were both lower than those found in commercial products. White and whole wheat breads made with 0.75% sodium chloride were as accept- able as breads made with 1.0% 1:1 sodium - potassium chloride mixture.
The sodium - potassium ratio of the salt mixture white bread was 1.20 and the ratio of the whole wheat bread was 0.91.
The addition of salt to finished products for flavor had an effect on the sodium - potassium ratio of the foods studied. Also, reducing the amount of added salt to commercial breads and replacing some sodium chloride with potassium chloride were acceptable means of lowering the sodium - potassium ratios of white and whole wheat breads. The Effects of Processing on Sodium - Potassium and
Calcium - Phosphorus Ratios in Foods
by Kathleen M. Ronan
A THESIS
submitted to
Oregon State University
in partial fullfiliment of the requirements for the degree of
Master of Science
June 1982 APPROVED:
Associat^Professor offtood Science and Technology in charge of major
Head of Department ofjTFo'ocT Science and Technology
Dean of Gradu/tfe Scho ^T
Date thesis is presented June 4, 1981
Typed by Jill Nowac for Kathleen Ronan ACKNOWLEDGEMENT
I would like to express my gratitude to Dr. Wyatt for her guidance throughout this project. I also wish to thank Betsi Timm for her analytical work as well as her encouragement and support. TABLE OF CONTENTS
Page
INTRODUCTION 1
REVIEW OF LITERATURE 5 The Effects of Unit Operations on the Mineral Content of Food 5 Peanut Processing and its Effects on Minerals 8 Tuna Processing and its Effects on Minerals 10 Milling of Grain and its Effects on Minerals 12 Calcium - Phosphorus Ratios in Foods 15 Role of Sodium and Potassium in Body Metabolism 17 Sodium Requirement in Humans 18 Dietary Sodium and Hypertension 19 Dietary Potassium and Hypertension 21 Salt Substitutes and Potassium Chloride 22 Use of Sodium Chloride - Potassium Chloride Mixtures in Food 26 The Role of Salt in Breadmaking 29
MATERIALS AND METHODS 31 Peanuts 31 Tuna Fish 31 Flour 32 Sample Preparation 32 Moisture Determination 33 Fat Determination 33 Dry Ashing Procedure 33 Sodium, Potassium and Calcium Determinations 34 Phosphorus Determination 34 Preliminary Bread Study 35 Bread Preparation 36 Mineral Analyses 36 Flavor Panel Evaluation 37 Statistical Analysis of Flour, Tuna and Peanuts 37 Statistical Analysis of Bread Flavor Panel Evaluation 38
RESULTS AND DISCUSSION 39 The Effects of Processing on Sodium - Potassium and Calcium - Phosphorus Ratios in Tuna Fish 39 Moisture and Fat Content of Tuna Samples 39 Sodium in Raw Tuna 39 Potassium in Raw Tuna 41 The Effect of Precooking on Sodium, Potassium, Calcium and Phosphorus levels in Tuna 44 Sodium, Potassium, Calcium and Phosphorus Levels in Tuna Canned in Oil 45 Sodium, Potassium, Calcium and Phosphorus Levels in Tuna Canned in Water 45 Sodium - Potassium and Calcium - Phosphorus Ratios in Canned Tuna 47 Summary of the Effects of Processing on Tuna 49 Page
RESULTS AND DISCUSSION (continued) The Effects of Processing on Sodium - Potassium and Calcium - Phosphorus Ratios in Peanuts 51 Moisture and Fat Content of Peanut Samples 52 Mineral Levels in Raw Peanuts 52 Effect of Roasting on Mineral Levels in Peanuts 52 Effect of Blanching on Mineral Levels in Peanuts 56 The Mineral Content of Peanut Butter 56 The Sodium - Potassium and Calcium - Phosphorus Ratios in Peanut Butter 57 Summary of the Effects of Processing on Peanut Butter 59 The Effects of Processing on Sodium - Potassium and Calcium - Phosphorus Ratios in Wheat Products 61 Moisture and Fat Content of Wheat Products 61 Mineral Composition of Bran 63 Mineral Composition of Wheat Germ 63 Mineral Composition of the Whole Wheat Kernel 65 Mineral Composition of Flours 66 The Sodium - Potassium and Calcium - Phosphorus Ratios in Flours 68 Composition of High Selenium Wheat 69 Summary of the Effects of Processing on the Sodium - Potassium and Calcium - Phosphorus Ratios in White and Whole Wheat Flour 72 Overall Desirability of White and Whole Wheat Breads Made with Sodium Chloride or a 1:1 Sodium - Potassium Chloride Mixture 75 Difference Test 78 The Sodium and Potassium Content of White and Whole Wheat Breads 78 The Sodium - Potassium Ratios of White and Whole Wheat Breads 80 Conclusions from the Overall Desirability Flavor Tests 80 Conclusions from the Triangle Tests 81
SUMMARY 84
BIBLIOGRAPHY 86 LIST OF FIGURES
Figure Page
1. Mean sodium, potassium, calcium and phosphorus levels in tuna fish as effected by processing. 50
2. Mean sodium, potassium, calcium and phosphorus levels in peanuts as effected by processing. 60
3. Mean, sodium, potassium, calcium and phosphorus levels in wheat products as effected by processing. 73 4. Sodium (Na) and Potassium (K) levels in white and whole wheat breads. 82 LIST OF TABLES
Table Page
1. Moisture and fat content of tuna fish during processing. 40
2. The Sodium, Potassium, Calcium and Phosphorus content of tuna fish during processing. 42 3. Percent retention of minerals in precooked, canned in oil and canned in water tuna fish. 43 4. The sodium - potassium and calcium - phosphorus ratios of tuna fish during processing. 48 5. Moisture and fat content of peanuts during processing. 53
6. Sodium, potassium, calcium and phosphorus levels in peanuts during processing. 54 7. Percent retention of minerals in blanched peanuts and peanut butter. 55 8. Sodium - potassium and calcium - phosphorus ratios of peanuts during processing. 58
9. Sodium, potassium, calcium and phosphorus levels in wheat as effected by processing. 62 10. Sodium, potassium, calcium and phosphorus levels in wheat as effected by processing. 64 11. Percent retention of sodium, potassium, calcium and phosphorus in flour. 67
12. Sodium - potassium and calcium - phosphorus ratios in wheat as effected by processing. 70 13. Sodium, potassium, calcium and phosphorus levels in high selenium wheat. 71 14. Overall desirability of experimental white and whole wheat breads. 76 15. Sodium, potassium and sodium - potassium ratios of white and whole wheat breads. 79 THE EFFECTS OF PROCESSING ON SODIUM-POTASSIUM AND CALCIUM-
PHOSPHORUS RATIOS IN FOODS
INTRODUCTION
The major purpose of processing foods is to free man from total dependence on geography and climate in providing for his nutritional needs and wants (Harris and von Loesecke, 1960). Consumers, being generally removed from agriculture, have little understanding of what is involved in creating food products. The advent of nutritional labeling has helped to make them both aware and concerned about the nutrient content of processed foods. This awareness emphasizes the importance of obtaining information concerning losses or increases in nutrients due to processing to provide optimal nutritional quality in the processed product (Meredith and Dull, 1979). The effect of pro- cessing on the nutritional value of some foods and some nutrients has been well researched. It is important however to update and add to this information due to the changes in varieties of plants and growing conditions, changes in the methods of processing, improved methods of assay and the lack of information concerning several nutrients (Bender,
1978). Processing in general is expected to affect all classes of nutrients
Yet vitamins are by far the most widely studied group. Ascorbic acid, thiamine and vitamin A have received most of the research effort as they are used as indices of retention when evaluating processing technology
(Lund, 1979). Very little research has been done concerning the effects of processing on minerals in foods. In light of todays consumer concerns 2 and the prevalence of processed foods, it is important that this infor- mation be obtained and its significance evaluated.
Some minerals found in foods seem to be more important than others in terms of their health implications. Individually, both calcium and phosphorus play important roles in the body, yet research indicates it is the relationship of calcium to phosphorus in the diet that is of critical importance for optimum nutrition and health (Linkswiler and Zemel, 1979;
Anonymous, 1973).
The ideal ratio of calcium to phosphorus in the adult diet is 1:1
(National Academy of Sciences, 1974) however most American diets are much richer in phosphorus than calcium (Linkswiler and Zemel, 1979). It has long been believed a high dietary phosphorus intake results in decreased calcium absorption (Linkswiler and Zemel, 1979). There also is evidence from studies with lower animals which suggests low calcium - phosphorus dietary ratios cause bone demineralization or osteoporosis which is a disease commonly seen in the elderly (Anonymous, 1973; Schaafsma and
Visser, 1980). Human studies have yielded conflicting data concerning the relationship between dietary calcium - phosphorus ratios and the bone (Linkswiler and Zemel, 1979; Bell et. al_., 1977). However, the research supporting the theory that a low calcium - phosphorus dietary ratio promotes bone demineralization is sufficient to cause concern about the effects of processing on this ratio in foods.
Excessive intake of sodium chloride has been suspected of playing a role in the onset of essential hypertension for some time. Essential hyper- tension is a chronic elevation of blood pressure due to either or both an increase in peripheral resistance and effective blood volume expansion
(Goodhart and Shils, 1980). It is the most prevalent precipitating factor 3 in the genesis of cardiovascular diseases, which are the leading causes of death in the United States (Kaplan, 1980).
A hypothesis has been proposed that a diet high in sodium chloride coupled with a diminishing intake of potassium can bring on the onset of hypertension. It appears that potassium may have a protective effect against excess sodium and that the ratio of sodium to potassium in the diet is most important when controlling hypertension (Goodhart and Shils,
1980; Frank and Mickelsen, 1969; Weinsier, 1976; Meneely, 1973).
The Senate Select Committee on Nutrition and Human Needs in 1977 recommended that Americans reduce their consumption of sodium to help promote optimum health (Institute of Food Technologists' Expert Panel on
Food Safety and Nutrition, 1980). In 1979 the Select Committee on GRAS
Substances stated the amount of salt in processed foods should be restricted (National Food Processors Association Information Letter, 1978).
It is clear that much concern exists regarding the influence a diet high
in sodium has on general health. This concern along with the prevalence of hypertension in our society indicate a need for research to determine
how processing effects sodium - potassium ratios in foods. The result of
reduced sodium levels in processed foods on their taste and overall accept- ability should also be investigated.
Efforts have been made by the food industry to develop salt substitutes
to help consumers decrease their sodium intakes. These commonly contain
potassium chloride which tends to have an unpleasant bitter after taste.
Spices are therefore often added to these substitutes to help mask their
bitterness. Consequently they do not have a characteristic salty flavor
and have not been generally accepted (Frank and Mickelsen, 1969). Mix-
tures of sodium and potassium chloride have been successful in experimental 4
settings as a salt substitute (Mickelsen et_. al_., 1977; Frank and Mickelsen,
1969). The sodium chloride seems to mask the bitter aftertaste of the
potassium chloride. These mixtures have been shown to be a successful means of reducing dietary sodium, increasing dietary potassium and impart-
ing a salty flavor to foods. They have also been studied for their use
in commercially processed foods. Data indicates few problems in substi-
tuting sodium - potassium chloride mixtures for pure sodium chloride in
such products (Frank and Mickelsen, 1969; Seman et. al_., 1980; Bell et.
al_., 1972; Wyatt, 1981).
The major objective of this study was to determine the effects of
processing on sodium - potassium and calcium - phosphorus ratios in tuna
fish, peanut butter and flour. The preferred concentration of sodium
chloride and a 1:1 sodium - potassium chloride mixture in white and whole
wheat breads were also studied. REVIEW OF LITERATURE
The Effects of Unit Operations on the Mineral Content of Foods
The major reason that food is processed is to increase its shelf life. Other reasons may be to improve palatability and texture, create new products, remove inedible parts from fruits and vegetables and elim- inate microorganisms (Bender, 1978). Processing is a compromise situa- tion however as it leads to an inevitable loss in certain nutrients from foods (Harris and von Loesecke, 1960).
General commercial processes which may result in mineral losses in- clude peeling, blanching and cooking (Tannenbaum, 1976). Research con- cerning the effects of peeling or trimming fruits and vegetables on their mineral concentrations is limited. It is indicated that any losses which accompany this process are due to the unequal distribution of minerals in the food (Harris and von Loesecke, 1960). Increases in the sodium content of the peeled product occur when sodium hydroxide, which is frequently used to soften and peel the skins of produce, is inadequately removed during final rinsing procedures (Bender, 1973).
Blanching involves the application of some type of heat to a food, usually either steam or boiling water (Harris and von Loesecke, 1960).
The time and temperature used depend upon the final process to be employed and the nature of the food being considered (Lee, 1958). The general functions of blanching are:
1. To remove foreign materials which may influence flavor.
2. To wilt bulky vegetables so that a proper uniform fill of
container can be achieved. 6
3. To expel air and other gases which might create excessive pressure
in the sealed container.
4. To produce the desired appearance of the finished product by
"fixing color" or removing materials which impart an undesirable
appearance to the liquid medium.
5. To inactivate enzymes.
6. To decrease the bacterial load (Harris and von Loesecke,
1960). Horner (1936-1937) studied the effects of water blanching on mineral
losses in several vegetables. He observed that peas blanched for 3 min at
100 C lost 39% K20 and 20% P^. Beans blanched for 3 min at 82 C lost
40% K20. Carrots blanched for 7 min at 100 C lost 16% K20 and 15% P^. Calcium was found to be generally absorbed by the vegetables during
blanching. The extent of absorption was dependent on the hardness of the water employed, the time of blanching and the nature of the vegetable. The
analytical techniques used in this study were not fully developed however
and results must be interpreted with caution.
Lee and Whitcombe in 1945 studied the effect of duration, temperature,
and type of blanching on the mineral composition of peas, green beans,
lima beans and spinach. Steam blanching did not cause significant changes
in the composition of any of the vegetables except spinach where moderate losses in ash and phosphorus and a slight gain in calcium were noted.
In 1969 Bengtsson studied the effects of water blanching on mineral
concentrations in spinach. The calcium content increased after blanching.
The retention of magnesium and phosphorus was greater than that of
potassium and sodium. This was not suprising as magnesium is a component 7 of chlorophyl and phosphorus of phospholipids; both water insoluble com- pounds.
Augustin and Swanson in 1979 studied mineral retention in potatoes during water blanching. Greater losses of potassium and magnesium were seen than of zinc, copper, iron and manganese. Also, washing and cutting had a greater effect on mineral losses than blanching.
In 1979 Lopez and Williams looked at various minerals in both fresh and canned onions. They found significantly higher levels of chloride, copper, iron and sodium in canned onions than in fresh onions, and signif- icantly higher levels of magnesium, potassium and phosphorus in fresh onions than in canned. Sodium increase was seen because the onions were canned in a 2% citric acid/sodium chloride brine. It was speculated that losses in potassium, phosphorus and magnesium were due to leaching during blanching and in the canning brine.
In 1979 Elkin studied the mineral levels in canned and raw green beans, peaches and sweet potatoes. In canned green beans, decreases in calcium, phosphorus, magnesium, and potassium and an increase in sodium was observed compared to the raw product. It was concluded that these results were due to an interchange of minerals in the beans with those in the blanching water and in the sodium containing canning brine. The canned peaches did not retain 100% of the mineral concentrations found in the raw product. The losses were so small however that they were attributed to experimental error. Canned sweet potatoes showed complete retention of calcium, phosphorus and magnesium. Rather large deviations from 100% retention were seen for potassium, manganese, copper and zinc, but it was unclear to the author if these differences were due to experi- mental error or if actual losses occurred due to processing. 8
A few studies have been done recently concerning the effects of cooking on mineral levels in legumes. Meiners et^. a]_. in 1976 studied mineral levels in ten different kinds of raw and cooked legumes. Legumes were cooked by first boiling one cup portions for 2 min in about 950 g of water and then simmering for 20 - 140 min, depending on the kind of legume, until determined done. Minerals in the cooked legumes were about one third to one half of the values in the raw product. This was mainly due to the increased weight of the cooked legumes because of water absorption. Some loss of minerals from the legumes was noted however after analyzing the cooking water. Relatively large amounts of magnesium, phosphorus and potassium were lost.
Kumar et. al_. , in 1978 studied the effect of cooking on minerals in germinated legumes. Germinated greengram, cowpea and chickpea were cooked in six times their weight of distilled water until determined done by a panel of judges. No appreciable change was seen in phosphorus and magnesium levels due to this cooking procedure but a loss of calcium was noted.
Augustin et_. al_. in 1980 also studied mineral retention in ten kinds of cooked legumes. Legume samples were cooked to doneness in water as determined by a taste panel. The percent retention was greatest with calcium, then phosphorus, potassium and lastly sodium.
Peanut Processing and its Effects on Minerals
The manufacture of peanut butter consists of shelling, dry roasting and blanching the peanuts followed by fine grinding. Salt is usually added to improve flavor. Small quantities of hydrogenated fat, dextrose, corn syrup solids, glycerin, lecithin and other flavor ingredients may 9 also be added (Woodruff, 1966).
Peanuts are dry roasted by either a batch or continuous method. In the batch method, peanuts are roasted in a revolving 800 F oven where they are heated to 320 F and held for 40 to 60 min. The trend among large manufacturers is towards continuous roasting. In this procedure the peanuts are roasted in counter current hot air and continuously agi- tated. Both methods result in a reduction in moisture content and a release of free oil from the cytoplasm (Woodruff, 1966).
After roasting, the hot peanuts pass to a cooler box where air is passed by them to help reduce their temperature. They are then dry or water blanched to remove the skins. Peanuts pass through the dry blancher in a continuous stream and are subjected to heat (280 F) and gentle rubbing between brushes. Water blanched peanuts are first rolled between station- ary blades then subjected to hot water sprays and lastly run under canvas covered pads. These procedures split, loosen and remove the peanut skins. Blanched peanuts are inspected to remove those over roasted or otherwise unsuitable nuts. Nuts are then ground and desirable additives are mixed with the ground nuts at this time (Woodruff, 1966).
Watt and Merril in 1963 reported the mineral levels in raw and roasted peanuts and peanut butter. They reported lower levels of calcium, phosphorus and potassium in peanut butter than in both raw and roasted peanuts. No theory was proposed as to why these lower levels were seen. Peanut butter also contained more sodium than the other two foods because salt was added during processing for flavor. Raw and roasted peanuts contained
70 mg calcium/100 g, 405 mg phosphorus/100 g, 5 mg sodium/100 g, and 680 mg potassium/100 g. Peanut butter contained 59 mg calcium/100 g, 380 mg phosphorus/100 g, 605 mg sodium/100 g and 627 mg potassium/100 g. 10
In 1976 the mineral levels in both raw peanuts and peanut butter were determined by Galvao ert. a]_. Data showed a statistically significant difference in calcium, potassium, phosphorus and sodium levels between the two foods. Increases in sodium and phosphorus and decreases in
potassium and calcium were noted in the peanut butter as compared to the raw peanut. The levels reported in raw peanuts were 48 mg calcium/100 g,
137 mg phosphorus/100 g, 8.4 mg sodium/100 g and 187 mg potassium/100 g.
The peanut butter contained 46.7 mg calcium/100 g, 188 mg phosphorus/100 g,
388 mg sodium/100 g and 682 mg potassium/100 g.
Tuna Processing and its Effects on Minerals
Freshly caught tuna can be held on board the fishing vessel in
several ways. One of the oldest methods is to place crushed ice on the
bottom of a bin, lay the whole fish over it and then cover the fish with more crushed ice. Refrigerator coils line the hold where the bins are
stored to reduce the rate of melting ice (Jarvis, 1943).
Another method is to fill the hold with refrigerated sea water into which the fish are placed. The sea water, cooled by a refrigeration system
to about 28 F, is circulated continuously through the hold thus providing
an efficient means of heat exchange (Jarvis, 1943). A new system in-
volves precooling the fish in the same manner, disposing of the sea water
and then using a precooled salt brine to lower the fish temperatures to
9-10 F. After the fish are frozen, the brine is drained from the hold
and a refrigeration system is used to keep the fish in a frozen state and
to prevent large uptakes of sodium by the fish from the brine (Jarvis, 1943; Doust, 1975; Delmas, 1975). 11
Whole, frozen fish are delivered to the processing plant. They are thawed either at room temperature or placed in tanks of running water.
The thawed fish are butchered and precooked on racks in a steam chest at about 216 F and held at that temperature until an internal temperature of 150 F is reached. They are then cleaned, cut, graded and packed into cans. Salt in either a vegetable oil or water and vegetable broth may be added prior to retorting (Jarvis, 1943).
An experiment was done in 1954 by Holston and Pottinger to determine if freezing of fish by immersion in cold sodium chloride brine resulted in excessive penetration of sodium into the fish meat. Scrod haddock was used as the experimental fish. The effect of brine (23% sodium chloride by weight) and temperature of salt penetration showed a graded increase in salt content in the first 1/4 inch of meat with increases in brine temperature from -6 to 15 F. Once the fish were frozen, salt was ab- sorbed very slowly. It was concluded, to minimize the rate of salt pene- tration during the initial stages of freezing, the brine temperature should be held as low as possible.
The effect of brine concentration on salt penetration was also studied. Fish held 60 min in a 23% brine at 15 F contained 1.2% salt in the first 1/4 inch of meat. A similar sample, held under the same condi- tions, in 15% brine contained only 0.72% sodium in the corresponding section of meat.
A study in 1959 by Peters looked at sodium uptake in haddock immersed in a 23% sodium chloride brine for 180 min at 5, 10 and 15 F. Core samples taken from the neck of the fish showed the colder the holding temperature the lower the sodium concentration. This relationship also held true after the fish were thawed. Fish frozen at 5 F had an average 12 salt concentration of 1.23%. After thawing this was reduced to 0.31%.
The salt threshold in haddock was determined to be 0.5 to 0.6% and the optimum salt concentration for palatability was 0.9 to 1.2%. Samples frozen at all three temperatures contained salt well above this optimum palatability level. The same fish after thawing contained salt in excess of the salt threshold but not the salt optimum.
Thurston in 1958 reported 34 mg/100 g of sodium and 293 mg/100 g of potassium in fresh frozen tuna received from a fishing vessel. Gordon and Roberts in 1977 reported canned albacore tuna with added salt contained
221 mg phosphorus/100 g, 257 mg potassium/100 g,. 2.1 mg calcium/100 g and 370.4 mg sodium/100 g.
Milling of Grain and its Effects on Minerals
Variations in the milling process are seen in different mills but general procedures can be summarized. Cleaning and possible blending of wheat usually precedes the actual milling process. Cleaning involves several steps, including screening, air aspiration, scouring and washing
(Paul and Palmer, 1972).
Tempering of wheat after cleaning expedites separation of the starchy endosperm from the outer parts of the kernel. This involves the addition of water in several steps to a 14 - 19% moisture content. This treatment causes the bran to become tough and the endosperm more friable. The application of heat (46 - 48 C) may be used during the water treatment and this procedure is referred to as conditioning (Paul and Palmer, 1972;
Jones, 1958).
The milling of wheat is by rollers, and the process is divided into two sections. In the first, called breaking, the bran is broken open 13 and the endosperm milled away in successive and gradual steps. This
system often involves four or more sets of rollers and after each break
the resulting mixture is sifted. Rollers in the second section are called reduction rollers and they receive the free endosperm from the
siftings in the first section. These rollers exert pressure which acts
to reduce the size of the endosperm particle thus producing white flour
(Matz, 1959).
The term extraction is defined as the number of parts by weight of
flour obtained from a hundred parts of wheat. The degree of separation or
refinement of endosperm material is reflected in this extraction rate.
A decrease in ash content is seen as the percent extraction is increased.
The concentration of the individual mineral elements also decreases upon milling and extraction. Potassium is the major mineral found in wheat.
It decreases in concentration proportional to the decrease in ash. There-
fore the mineral levels in white flour depend primarily on the efficiency
of the endosperm separation, the percent extraction employed and uncon-
trollable variations which occur due to the variety of wheat and its
growing conditions (Jones, 1958).
Several studies have been done to determine the mineral content of the
different products of the wheat kernel as well as the whole kernel. In
1945 concentrations of the bran, endosperm and whole kernel of three
varieties of red winter wheat were determined by Morris et. &]_. The bran contained higher levels of phosphorus, potassium, and calcium than did
the endosperm and the whole kernel. Sodium levels were approximately
the same in all samples. Slight variation was seen between all species
for all minerals. However, this work was done at a time when analytical
techniques were not fully developed and an accurate report of the mineral 14 concentrations was not obtained.
A study in 1964 by Czerniejewski et_. al_. compared the mineral levels
in the whole wheat kernel and white flour of ten different species of wheat. Variations in individual minerals existed among the ten species
but this variation did not appear to be related to growing area or total ash. The mean values found in the wheat were 0.454% potassium, 0.433%
phosphorus, 0.045% calcium and 45 ppm sodium. Mean values in the white
flour made from the corresponding wheats were 0.105% potassium, 0.126%
phosphorus, 0.18% calcium and 9.8 ppm sodium.
Waggle et. a]_. in 1967 compared the mineral content of the whole wheat kernel, bran, germ, shorts, red dog and white flour of hard red
winter, hard red spring, soft red winter and white wheat. Bran was found
to contain the highest percentage of calcium, phosphorus, potassium,
sodium and magnesium. The germ also contained high levels of these minerals compared to the whole kernel and white flour. Shorts and red
dog had intermediate levels of those minerals observed.
The mean values found in the wheat were 0.032% calcium, 0.36% phos-
phorus, 0.38% potassium and 0.008% sodium. The mean values found in the
bran were 0.086% calcium, 1.3% phosphorus, 1.5% potassium and 0.02% sodium.
The mean values found in the germ were 0.049% calcium, 0.86% phosphorus,
0.98% potassium and 0.021% sodium. The mean values found in the shorts
were 0.075% calcium, 0.79% phosphorus, 0.92% potassium and 0.016% sodium.
The mean values found in the white flour were 0.025% calcium, 0.067%
phosphorus, 0.08% potassium and 0.005% sodium.
A 1977 study by Lorenz and Loewe compared the mineral content of
eight species of hard wheat to six species of soft wheat from different
parts of the United States and Canada. Significant differences were seen 15 between most of the species for all minerals in both hard and soft wheats.
Significant differences were also seen between the hard and soft wheats for iron, zinc and potassium. The mean values in soft wheat were 0.347% potassium, 0.025% calcium and 21.2 ppm sodium. The mean values in hard wheat were 0.308% potassium, 0.025% calcium and 22.41 ppm sodium.
Calcium - Phosphorus Ratios in Foods
According to the Recommended Dietary Allowances (National Academy of
Sciences, 1974), the ideal ratio of calcium to phosphorus in the adult diet is 1:1. Most Americans consume diets much higher in phosphorus than cal- cium however because phosphorus is naturally more plentiful in most foods.
In addition, phosphate additives are used increasingly in processed foods.
They are commonly found in meats, cheeses, soft drinks and modified food starches. It was estimated that additional sources of phosphorus from processed foods may increase intakes by 0.5 to 1.0 g per day (Linkswiler and Zemel, 1979).
It has long been believed a diet high in phosphorus results in the formation of insoluble salts in the gut and consequently decreased calcium absorption (Linkswiler and Zemel, 1979). One study showed that increasing the phosphorus intake from 900 to 2411 mg/day for young men did not affect apparent absorption of calcium when calcium intake was 800 mg. Calcium absorption was depressed slightly however when calcium intake was 2400 mg.
(Linkswiler and Zemel, 1979). Bell et^. al_. in 1977 studied the response of adult humans to phosphate food additives. He found a depression of serum calcium concentration in all subjects.
There is evidence from studies with lower animals which suggests low calcium - phosphorus ratios are detrimental in that they cause bone demineralization (Linkswiler and Zemel, 1979; Anonymous, 1973; Draper 16 et. al., 1972; Schaafsma and Visser, 1980). Schaafsma and Visser in 1980
fed experimental rats two high phosphorus diets (1.3%) with either a
normal (0.6%) or a low (0.2%) calcium content. Both high phosphorus diets resulted in decreased plasma phosphorus throughout the study,
nephrocalcinosis, depressed urinary calcium and reduced femur density.
Draper et. al_. in 1972 fed rats diets containing 1.2% calcium and
either 0.6% or 1.2% phosphorus. Those fed the 1.2% phosphorus diet
exhibited a greater loss of calcium from the skeleton and a loss of cal-
cium, phosphorus and organic matter from the femur than those fed the
0.6% phosphorus diet. These effects were not seen in parathyroidectomized
rats also studied.
Laflamme and Jowsey in 1972 fed dogs phosphorus supplements of about
1.8 g for four months and then 2.1 g for six months in addition to their
basal diets. An increase in parathyroid hormone was seen in these dogs
as well as a decrease in bone mineral content, a distinct bone porosity
and deposition of calcium in the kidney and heart. These data indicated
that excess dietary phosphorus accelerated the rate of bone resorption in
lower animals. This may be due to secondary hyperparathyroidism induced
by the flux of excess phosphorus through the blood (Draper et a]_., 1972;
Bell et. al., 1977).
In striking contrast to the above findings in rats and dogs were
those reported for monkeys by Anderson e_t. al_. in 1977. No evidence of
bone demineralization was seen with animals fed high phosphorus diets
for seven years.
The fact that high phosphorus diets have been demonstrated to cause
bone demineralization in animals raises the possibility that low calcium -
phosphorus dietary ratios may be a contributing factor in bone mineral 17 loss in man. However, studies which looked at the effects of low calcium phosphorus dietary ratios in man were inconclusive (Linkswiler and
Zemel, 1979; Anonymous, 1973; Draper et. al_., 1972; Bell et. al_., 1977;
Spencer et. al_., 1978). Additional research is needed to clearly under-
stand the effects in humans of diets with low calcium - phosphorus ratios.
Role of Sodium and Potassium in Body Metabolism
Sodium, potassium and chloride ions are essential for many body processes including water balance, nerve impulse conduction, heart action and certain enzyme systems. Normally, the body will maintain a proper balance of these ions even over a wide range of dietary intakes
(Federation of American Societies of Experimental Biology, 1979).
Sodium is the most abundant and important extracellular cation in osmotic pressure maintenance and body fluid balance. Potassium as well as calcium, manganese, phosphate, chloride, and proteins are the major contributors to the osmotic pressure of the intracellular environment.
The effective osmotic pressure of the inside and outside cellular envir- onments are normally equal because the cell membrane is freely permeable
to water (Battarbee and Meneely, 1978).
The concentration gradient typically observed for sodium and potassium
ions across cell membranes can be explained in terms of an active trans-
port system. Normally this system transfers intracellular sodium to
the external environment and extracellular potassium to the internal
environment at the expense of ATP. This mechanism of exchange is not
fully understood but is thought to occur in a loosely coupled manner. 18
It is sensitive to the concentrations of both intracellular sodium and extracellular potassium. Increases in either or both concentrations will increase the rate of exchange. Thus this mechanism has its own system of feedback control directly related to the concentration of the transported substances (Battarbee and Meneely, 1978).
The regulation of total sodium ion concentration in the body is controlled primarily by the kidneys and the hormones of the adrenal cortex which act upon the kidneys. Other organs and hormonal factors are known to influence this regulation but the mechanisms of the inter- action are not well defined. Regulation takes place mainly in the distal portion of the renal tubules. Potassium and hydrogen ions inside the tubule cells are exchanged for sodium ions present in the lumen of the tubules. Thus the amount of sodium reabsorbed and not excreted in urine is dependent on the potassium ion concentration in the tubular cells. This mechanism is not fully understood yet it is known that water intake, kidney efficiency and the ratio of sodium and potassium
in the diet are interrelated factors which can influence sodium excre- tion (Federations of American Societies for Experimental Biology, 1979)..
Sodium Requirement in Humans
Most human beings have a taste for salt but this is not synonymous with a need for sodium (Weinsier, 1976). Dahl found that persons whose daily intake was continuously restricted to well below 0.5 g per day for months demonstrated no salt cravings. The addition of 1.0 g of
salt to their diets was noticed. On the other hand, patients who con-
sumed long term diets containing up to 250 meq/day of sodium chloride did not notice the addition of 5.0 to 10.0 g of salt to their diets. 19
He concluded salt appetite in man was largely conditioned (Weinsier,
1976).
The exact human sodium requirement has been very difficult to assess.
The most frequent estimate of the minimum adult daily requirement is about 200 mg of sodium or 0.5 g of salt. The average American diet is currently estimated to include about 3.0 g of salt occurring naturally
in foods, 3.0 g added by the cook and at the table, plus some 4 - 6 g added during commercial processing. Thus the total daily intake for the . average consumer is estimated to be in the range of 10 - 12 g of salt
(Institute of Food Technologists' Expert Panel on Food Safety and
Nutrition, 1980).
Dietary Sodium and Hypertension
Hypertension or high blood pressure is the result of either or
both increased peripheral resistance and effective blood volume expansion.
It is generally accepted that susceptibility to essential hypertension is
genetic in nature, but the method of transmission is unclear. Envir- onmental factors such as stress, overcrowding, psychosocial and psycho-
logical perturbations as well as dietary disturbances play a role in
the genesis of this disease (Goodhart and Shils, 1980).
Numerous studies have been done with rats to determine the rela-
tionship between high sodium intakes and hypertension (Goodhart and
Shils, 1980; Weinsier, 1975; Battarbee and Meneely, 1978; Dahl, 1972).
Dahl and Schackow in 1964 showed that nearly 80% of laboratory rats developed high blood pressure when large amounts of salt were included
in their diets. Meneely et al_. in 1955 and Meneely et^ al_. in 1957 fed rats 20 diets containing salt in very small, intermediate and large amounts. Each increment of salt in the diet resulted in a concomitant increase in blood pressure. It was concluded that a cause and effect relationship existed between excess dietary sodium and hypertension in the rat.
Many intrapopulation and epidemiological studies involving geo- graphical or ethnically isolated populations consuming various quanti- ties of salt, have been done to determine if salt intakes relate to the prevalence of hypertension in humans (Altschul and Grommet, 1980).
Results from these studies are often difficult to interpret. There is general agreement however that among populations the incidence of hypertension can be predicted from the average daily sodium intake
(Altschul and Grommet, 1980; Battarbee and Meneely, 1978). A conclu- sive study was done by Page et. aj_. in 1974 where different societies one who had daily sodium intakes of less than 30 meq, one that had an intake of 130 - 150 meq, and two others that had intermediate sodium intakes were monitored for the occurance of high blood pressure. The first society showed less than 1% of the subjects who were 20 years old or older had blood pressures exceeding 140 over 90 mm of Hg. The society with the highest salt intake had between 7 and 10% in the hyper- tensive category. The other two societies were intermediate in their blood pressures.
Clinical studies have produced decisive evidence that a diet high in sodium is related to the presence of hypertension in man. Ambard and Beaujard in 1904 were the first to record the observation that deprivation of salt may result in a decrease in blood pressure in persons essential hypertension. Allen and Sherril in 1922 21 also found that diets sharply restricted in salt were effective in lower- ing hypertensive patients blood pressures. Kempner in 1944 described results in the management of hypertension with a rice and fruit diet providing 0.2 g of sodium per day. A fall in blood pressure was observed and attributed to a reduced sodium intake. Many other investigators have studied the effects of salt intake on high blood pressure with humans and concluded there is a correlation between salt intake and hypertension (Dahl, 1972; Battarbee and Meneely, 1978).
It was speculated that increased salt intake leads to expansion of extracellular fluid and increased cardiac output. This in turn leads to higher peripheral vascular resistance and high blood pressure with normalization of cardiac output (Goodhart and Shils, 1980). Sustained hypertension cannot occur however without some change in renal perfor- mance; otherwise, the pressure diuresis that ensues would reduce the extracellular fluid volume and blood volume enough to bring the pressure back to near normal (Battarbee and Meneely, 1978).
Dietary Potassium and Hypertension
Although most attention has been devoted to the sodium ion in relation to hypertension, important studies have also been done concern- ing potassium.(Meneely, 1973). Addison claimed in 1928, that the pre- valence of hypertension in the United States was possibly related to our typically high sodium - low potassium diets. This conclusion followed his clinical studies which showed that potassium administration could lower elevated blood pressure. Priddle in 1962 also reported that high potassium intakes can lead to a decrease in blood pressure in hypertensive patients. 22
McQuarrie, et_. al_. in 1936 noticed that some diabetic children have intense salt cravings and subsequent high blood pressures.
These elevated pressures were completely prevented when potassium was substituted for approximately one third of the total dietary salt.
Animal experiments have corroborated these clinical findings.
Meneeiy in 1973 demonstrated the protective effects of potassium chloride on rats rendered hypertensive by diets high in sodium chloride. Potassium chloride, when added to their diets, reduced blood pressure in only the most severely hypertensive rats but the survival times for all rats were increased. He suggested that the dietary sodium - potassium ratio plays an important role in determining the severity if not the development of salt induced hypertension. Other investigators have reported similar results with rabbits, dogs and rats (Frank and
Mickelsen, 1969).
The average American diet has a sodium - potassium ratio of about
1.5 up to 6. In contrast, the ratio of Kempners rice - fruit diet which proved effective in reversing hypertension was 0.5. It was con- cluded that an effort to lower the sodium - potassium dietary ratio could result in a decrease in the prevalence and severity of hyperten-
sion in our society (Weinsier, 1976).
Salt Substitutes and Potassium Chloride
It was recommended as early as 1901 that patients with edematous
heart disease follow salt restricted diets. This treatment was later
extended to include those with congestive heart failure, hypertension
and renal diseases (Frank and Mickelsen, 1969). Today, a sodium 23 restricted diet is generally recommended to all people suffering from hypertension (Mitchel et. ail_., 1976). Most find it difficult however, to follow restrictions and do not comply with such a recommendation.
It was speculated that people have problems following a salt restricted diet because they have been accustomed to salty foods since infancy, low sodium diets are complex and usually prescribed unenthusiastically, and most people are unaware of the added sodium chloride in cheese and most processed foods (Dahl, 1972).
In 1977, the staff of the Senate Select Committee on Nutrition and
Human Needs developed Dietary Goals for the United States. One of the stated goals was that salt consumption be reduced to approximately 3.0 g per day. A task force of fourteen scientists from the Council for
Agricultural Science and Technology responded that while some general reduction in salt consumption might be desirable, "an arbitrary goal of only 3.0 g/day, however, would provide an unpalatable, therapeutic - type diet that would require exceedingly careful selection of foods from a limited list" (Institute of Food Technologists' Expert Panel on Food
Safety and Nutrition, 1980).
Later in 1977, the Senate Select Committee raised its recommendation to 5.0 g per day. This diet could be achieved by eliminating most highly salted processed foods, sodium containing condiments and salt at the table (Institute of Food Technologists' Expert Panel on Food Safety and Nutrition, 1980).
The Surgeon General of the United States and the American Heart
Association have also recommended that Americans decrease their salt intake to help promote optimum health (Anonymous, 1980). In 1979 the 24
Select Committee on GRAS Substances stated that the amount of salt in
processed foods should be restricted (National Food Processors Associa-
tion Information Letter, 1978).
The most commonly used salt substitutes contain potassium chloride. Lithium chloride, although palatable and salty, cannot be used because
of its toxicity (Frank and Mickelsen, 1969). Potassium chloride is a
safe food additive. The Select Committee on GRAS Substances concluded:
"there is no evidence in the available information on potassium chloride
that demonstrates or suggests reasonable grounds to suspect a hazard
to the public when it is used at levels that are now current or that might reasonably be expected in the future" (National Food Processors
Association Information Letter, 1978).
Potassium chloride can have a salty flavor as well as a rather
unpleasant bitter taste (Frank and Mickelsen, 1969). Von Skramlik
reported in 1965 that it produced a mixed sensation at various concen-
trations. Solutions of potassium chloride from .009 to 0.02 M tasted
sweet, 0.02 to 0.5 M bitter, 0.05 to 0.5 M salty and 0.2 to 0.5 M sour. Manufacturers have usually tried to mask the bitter taste by combining
it with citric or other acids, monopotassium glutamate, choline, ammonium
chloride or spices. These mixtures were not generally successful however
because they did not impart the agreeable, salty flavor of sodium chlor-
ide. Many felt they were little better than no seasoning at all (Frank
and Mickelsen, 1969).
Mixtures of sodium and potassium chlorides have been studied as
possible means of reducing dietary sodium without deprivation of a
palatable salty seasoning. These mixtures have the appeal of con-
currently reducing dietary sodium and augmenting potentially bene- 25 ficial dietary potassium (Frank and Mickelsen, 1969).
Ball and Meneely in 1957 found various mixtures of sodium and potassium chloride masked the disagreeable flavor of the latter. Frank and Mickelsen reported in 1969 that 72 panelists tasted a solution containing 0.164% potassium chloride and 67% reported it as tasting bitter. An additional concentration of 0.1% sodium chloride was added to the solution and the percentage reporting it bitter decreased to 11.
Only 24% of the panelists found a solution containing 0.4% potassium chloride with 0.1% sodium chloride as bitter tasting. This concentra- tion of potassium chloride alone was bitter to all panelists.
Frank and Mickelsen performed another study in 1969 to obtain an
evaluation of mixtures of sodium and potassium chlorides under actual eating and cooking conditions. Twelve subjects were provided with one meal a day for ten days. They received the same menu each day except
that one of five different salt mixtures was used in cooking and supplied at the table in a shaker. This salt ranged from pure sodium chloride
to mixtures of sodium with increasing concentrations of potassium chloride. Each subject had their own shaker and the weight of salt used was determined after each meal. It was concluded that mixtures con-
taining up to approximately one half potassium chloride appeared to be as salty as pure sodium chloride. The subjects did not notice any
bitterness or other objectionable qualities in the foods prepared or
seasoned with mixtures of sodium and potassium chloride.
Mickelsen j!t. a]_. conducted a study in 1977 with six subjects to compare the acceptability of a 1:1 mixture of sodium and potassium
chlorides to pure sodium chloride. The subjects did not detect a sig-
nificiant difference in potato chips or roasted peanuts seasoned with 26 either pure sodium chloride or the salt mixture.
In another study by Mickelsen et. al_. in 1977, 25 individuals used
the same amounts of both pure sodium chloride and the 1:1 salt mixture
in salting to taste cooked green beans, hard boiled eggs, and steak. In
the same study using ten men for 28 days, he again found that the
subjects salted their food with essentially the same amounts of regular
table salt as of the 1:1 mixture. These results were in contrast to
those reported by Kincaid et^. aK in 1975 however. They found that
a 1% aqueous solution of sodium chloride was equal in saltiness to a
1.2% solution of a 1:1 mixture of sodium and potassium chlorides.
Potassium chloride is not only a good compound for supplementing
the saltiness of sodium chloride, but its physical properties make it
technically an ideal substance for admixture with sodium chloride.
Mixtures of the two salts are essentially indistinguishable from pure
sodium chloride. They are both colorless and transparent cubic crystals
which can be obtained in any desired particle size. The specific gravity
of sodium chloride (2.16) is similar to that of potassium chloride
(1.99) so that mixtures will not segregate and both are water soluble
(Frank and Mickelsen, 1969).
Use of Sodium Chloride - Potassium Chloride Mixtures in Foods
Various sodium - potassium chloride mixtures have been experimented
with to replace the ordinary salt used in processed foods (Seman et.
al_., 1980; Bell et. al_., 1972; Rogers, 1973; Wyatt, 1981). Cucumber
pickles are currently on the list of foods not allowed on sodium restricted
diets. Therefore, fermented whole dill and whole sweet pickles were 27 made using three different treatments of sodium potassium chloride mix- tures to determine if acceptable low sodium fermented pickles could be manufactured. A panel of judges rated the 0.1% sodium chloride - 0.7% potassium chloride equilibrated brine treatment of whole sweet pickles as good and acceptable. Apparently, the low level of potassium chloride substituted well for sodium chloride, however, higher levels of pot- assium chloride and salt free treatments were rated low because of bitterness or flatness. In rating the whole dill pickles, the judges reduced the overall acceptability of the potassium chloride mixtures to fair and none were acceptable.
Sodium chloride is a principle ingredient in processed meats due to its flavor, preservation and protein solubilizing properties (Seman et. al., 1980). Work was done by Seman et. al_. in 1980 to determine the effects of partial replacement of sodium chloride on bologna character- istics and acceptability. Nine different combinations of sodium chloride, potassium chloride and magnesium chloride at high and low ionic strengths
(0.42 and 0.21) and low ionic strengths of 0.13% tripotassium phosphate were used. A consumer panel tested the flavor acceptability of the treatments and rated the high ionic strength sodium chloride and high ionic strength sodium chloride - potassium chloride in equal strengths mixture to be similar in acceptability. The low ionic strength sodium chloride - potassium chloride - phosphate treatment was liked signifi- cantly less than the other two. It was concluded that partial replace- ment of sodium chloride with potassium chloride would produce an acceptable commercial bologna product.
Rogers in 1973 experimented with using potassium chloride in pro- 28 cessed cured hams. He found that hams cured with pure potassium chloride were unpalatable but produced the same visible effects associated with hams made with pure sodium chloride. Hams cured with a 1:1 mixture of sodium and potassium chlorides were almost indistinguishable on the basis of both taste and appearance.
Wyatt in 1981 investigated the possibility of replacing sodium chloride with a 1:1 mixture of sodium and potassium chlorides in canned corn and green beans. The concentrations of the mixture used were
1.7% and 2.3%. These concentrations were compared to a reference of
1.5% pure sodium chloride for their overall desirability. The 1.5% sodium chloride reference and the 1.7% salt mixture samples were rated equally desirable when tested in green beans. The 2.3% salt mixture was rated less desirable as it was found to be too salty. Both salt mixture samples were rated less desirable than the reference pure sodium chloride in the corn treatments. The sodium - potassium ratio in processed green beans with no added salt was 0.16. The ratio was 1.41 when sodium chloride was added at 1.5%. The ratio found for the salt blend which was rated as desirable as the pure sodium chloride reference was 0.65. It was concluded that the use of 1:1 sodium - potassium chlorides salt mixtures in canned vegetables resulted in lower sodium - potassium ratio than was found in vegetables processed with pure sodium chloride. Unpublished work was done by private industry using a 1:1 sodium - potassium chloride mixture in bread. It produced a product very similar
in dough fermentation, carbon dioxide retention, loaf volume, texture, crust and toasting properties to bread made with pure sodium chloride.
Apparently potassium chloride substituted well for sodium chloride in 29 maintaining the physical characteristics of bread. It was unclear from this work however, if the bread was acceptable in terms of flavor (Frank and Mickelsen, 1969).
The Role of Salt in Breadmaking
Salt is added to bread primarily to enhance its flavor character- istics. In addition to its own saline taste, salt stimulates the capacity of the palate to recognize flavors of other substances as well.
Thus, small quantities of sugar are recognized in the presence of salt which in its absence would not be perceived (Paul and Palmer, 1972;
Strong, 1969; Jago, 1911).
Salt also provides a means of controlling fermentation in bread by its osmotic effect on yeast cells. It works to inhibit alcoholic, lactic, viscous and ropy ferments which would be injurious to the final bread product (Jago, 1911). Even though salt is present in bread in a relatively small quantity, its control of fermentation can be as effective as that of sucrose because salt has a greater effect per unit of weight
(Paul and Palmer, 1972). All levels of salt suppress yeast activity so that the ommission of salt entirely results in a very short dough development time (Strong, 1969) and a great production of gas and other byproducts of fermentation (Pyler, 1952).
A strengthening and tightening effect on the gluten of dough is attributed to salt .(Strong, 1969; Pyler, 1952; Cooper and Reed, 1968).
Gluten is the most abundant protein present in flour and it is made up of two fractions called gliadin and gluten. Hydrated separately, gliadin is very extensible and tacky, gluten is more elastic and strong. These fractions are hydrated together in bread to form a co- 30 hesive, elastic gluten network. These properties allow bubbles of gas liberated by yeast to expand this network without an undue amount of coalescence or leakage to the atmosphere (Paul and Palmer, 1972).
It is unclear how salt acts to tighten gluten in bread. Its action may be due to an inhibitory effect on proteolytic enzymes (Strong,
1969; Pyler, 1952; Cooper and Reed, 1968). Cooper and Reed in 1968 claimed that this proteolytic effect is more correctly called dough slackening and it is actually due to yeast reductases. These reductases act on thioctic acid from flour or glutathione from yeast. These reduced compounds then may cleave internal disulfide bonds in the gluten molecule, thus weakening the dough. It has been suggested that flour strength may be inversely related to its endogenous thioctic acid content. Black et. al_. in 1960 showed that yeast contains a thioctic acid reducing enzyme which would continuously replenish the reduced form of thioctic acid thus catalyzing the dough slackening reaction. This theory is speculative, yet it is certain that salt acts somehow to prevent this slackening or proteolytic effect in bread (Strong, 1969). 31
MATERIALS AND METHODS
Peanuts
Peanut samples were obtained from a commercial peanut butter manufacturer. Four different sample lots were procured at various stages in the production of peanut butter. Samples included raw,
roasted, blanched peanuts and the finished product. The lots sampled were: 100% runner peanuts; 100% Spanish style peanuts; a mixture of
50% Spanish style and 50% runner peanuts; and 100% runner peanuts.
The finished products from the different lots were: creamy style peanut butter; chunky style peanut butter; and old fashioned style peanut butter. The creamy and chunky style peanut butter contained
3% peanut oil, 6.75 - 7.5% corn syrup, 1% salt and 1.5% hudrogenated oil. Peanuts were blanched at room temperature and roasted at 300 -
310 F for 18 min prior to being ground into peanut butter. Samples were held at 0 F until analyzed.
Tuna Fish
Tuna samples were obtained from a commercial tuna processor.
Four lots, each of a different species of fish were procured at different stages in the production of canned tuna. The lot species were skip jack, extra small yellow fin, large yellow fin and albacore.
Samples from each lot were raw, precooked, canned in oil and canned in water tuna. The raw samples were taken from the top half of the tail end of the fish, behind the dorsal fin. The precooked samples consisted 32 of white loin meat. Skip jack and yellow fin were precooked at 175 F and albacore at 195 F. The canned in water samples contained 1.2% added salt. The canned in oil samples were filled with a 50 - 50 mixture of a vegetable broth and soybean oil and 1.2% salt. The veget- able broth was made from the water soluble broth of a mixture of freeze dried vegetables containing carrots, parsley, onions and potatoes.
Both types of canned tuna were retorted at 230 F for 75 - 80 min.
Samples were held at 0 F until analyzed.
Flour
Three lots of white flour were obtained from a flour mill. The samples from each lot were: whole wheat kernels, wheat germ, mill run
(bran), low grade flour (prior to finishing for white flour), unbleached unenriched flour, bleached - unenriched flour and bleached - enriched flour. Three lots of whole wheat kernels and whole wheat flour were also obtained. An additional lot of high selenium wheat was ground into flour by Western Quality Laboratory, Pullman, Washington. This lot included unground bran, ground shorts, white flour, whole wheat flour and whole wheat kernel samples. The kernels were 12.2% moisture, 11.6% protein and yielded 78.7% flour, 16.4% bran and 4.69% shorts upon milling. The bran and shorts were dried to 80 F overnight and ground with a Fritz hammer mill through a .024 inch screen. Samples were held at 0 F until analyzed.
Sample Preparation
Both the oil and water broths were separated from the tuna meat 33 by draining the mixture on a stainless steel strainer for 5 min. The raw, blanched and roasted peanuts and the whole wheat kernels were homogenized in a Waring blender prior to being analyzed.
Moisture Determination
Samples were weighed into 125 ml porcelain crucibles in triplicate and dried in a vacuum oven following AOAC time and temperature speci- fications (AOAC 1975). Dried samples were cooled in a dessicator and weight loss was reported as percent moisture. These dried samples were then used in the dry ashing procedure.
Fat Determination
Sample fat concentrations were determined using the Soxhlet pro- cedure outlined by AOAC in 1975. Analyses were done in triplicate.
Dry Ashing Procedure
The general ashing procedure outlined by Noller and Bloom (1978) was followed to prepare samples for mineral determinations. All dried samples were homogenized in a Waring blender and weighed in triplicate into 55 ml porcelain crucibles. The weight of sample used was dependent on the expected mineral concentrations in the particular food sample.
An attempt was made to char the sample with a bunsen burner to aid ashing. This resulted in too much variability in the final readings due to loss of sample. Therefore a hot plate was used to char the samples prior to ashing in a muffle oven at 550 C. The samples were removed after 24 hours and the mixture of ash and organic matter which had resulted was wetted with 5 ml of 20% nitric acid and slowly brought 34 to dryness on a hot plate. The crucibles were placed in the muffle oven for another 24 hours so that all organic matter was completely ashed.
Fifteen ml of 20% nitric acid was added to the cooled crucibles.
They were then gently heated on a hot plate for 20 min to aid in solubil- izing the ashed material. These solutions were filtered through acid rinsed Mo. 42 Whatman paper into 100 ml volumetric flasks. Flasks were brought to volume with a 1% (w/v) lanthanum oxide diluent for calcium determinations and 1500 ppm lithium chloride diluent for sodium and pot- assium determinations with the atomic absorption spectrophotometer. These diluents were necessary to help prevent interferences from other elements when analyzing samples. Reagents used were all Baker Reagent Grade.
Sodium, Potassium and Calcium Determinations
Tuna, peanut and flour samples, after suitable preparation, were analyzed for sodium, potassium and calcium concentrations using a Perkin
Elmer Model Number 303 atomic absorption spectrophotometer. Single element hollow cathode lamps were employed for these determinations.
Calcium, sodium and potassium absorptions were measured at 211.7 nm, 295.1 nm and 383.8 nm respectively. The microprocessor unit was employed so that all mineral concentrations could be read directly in ppm. Standards were prepared by suitable dilutions of stock solutions available from
VWR Scientific Products. Fifteen ml of 20% nitric acid was added to all
standards before being brought up to volume with the proper diluent.
Phosphorus Determination
Approximately 300 mg of dried, homogenized sample was weighed into a 50 ml erlenmeyer flask. Three ml of a 3:1 (v/v) mixture of nitric and 35 sulfuric acids was added to the flask and this mixture was heated until all material appeared to be dissolved. Then 0.5 ml of 70% perchloric acid was added and heat increased to about 225 - 250 C. After the perchloric acid fumes ceased to be evolved, the flask was removed from the heat and cooled to room temperature. About 1.0 ml of distilled water was used to wash down the sides of flask. The mixture was then transfered to a 100 ml volumetric flask.
A 4.0 ml aliquot of the ashed solution was placed in a colorimeter tube to which 1.0 ml of ammonium molybdate , 5 ml of distilled water and 2 0.4 ml of Fiske - Subbarrow solution was also added. After ten minutes the tube was read at 660 nm with a Bausch and Lomb Spectronic 20. Stan- dards were made by appropriate dilutions of monobasic potassium phosphate and contained 4.0 ml of 0.5% sulfuric acid. A blank was also prepared which contained 4.0 ml of 0.5% sulfuric acid. Phosphorus concentrations were read in ppm from a standard curve. All analyses were done in triplicate.
Preliminary Bread Study
Ten white bread samples were made following a standard white bread recipe. Five samples were made with a range of concentrations of sodium chloride (0.3%, 0.5%, 0.75%, 1.0% and 1.25%). The other five samples contained the same concentrations of a 1:1 sodium - potassium chloride salt mixture in replacement of the pure sodium chloride. Ten additional bread samples were made following the same recipe except that
Dissolve 50 grams of ammonium molybdate in 400 ml of 10 N sulfuric acid and dilute to one liter. 2 Grind 125 mg 1-4 amino naphthol sulfonic acid in a mortar and pestle. Add a few drops of 15% sodium bisulphite and transfer to a 50 ml volu- metric flask. Make to volume with 15% sodium sulphate, then add 1.25. ml of 20% sodium sulfite. Solution must be made every two weeks. 36 one half of the white flour was replaced with whole wheat flour. These samples contained the same concentrations of sodium chloride and salt mixture as the white bread samples. An informal taste test was done to evaluate the overall desirability of these different concentrations of sodium chloride and salt mixture in white and whole wheat bread. It was determined that 0.5%, 0.75%, and 1.0% were most suitable for further taste evaluation.
Bread Preparation
A local bakery in Corvallis, Oregon produced all bread samples used for flavor panel evaluation. A commercial bakery was used so that a sufficient quantity of each treatment for evaluation and analysis could be made in a given lot. Whole wheat and white bread samples were made following the recipe used in the preliminary study. These samples con- tained 0.5%, 0.75% and 1.0% concentrations of both pure sodium chloride and the salt mixture. All samples were held at 0 F until needed.
Two loaves of commercial white bread and commercial whole wheat bread were obtained at a local supermarket for analytical purposes only.
Mineral Analyses
Bread samples were torn into small pieces using plastic gloves and mixed in a plastic bag to yield a representative mixture for assay.
Moisture determinations were made and samples were dry ashed following the procedures previously outlined. All bread samples were analyzed for sodium and potassium concentrations using a Coleman flame photometer model number 21 and appropriate element filters. Deionized water was used as 37 a diluent in all analyses. Standards were prepared from stock solutions as previously described. A standard curve was used to determine sodium concentrations in ppm. Potassium concentrations were read directly from the flame photometer in meq/1. All analyses were done in triplicate.
Flavor Panel Evaluation
Bread samples were evaluated by an untrained panel comprised of students and staff from the Department of Food Science and Technology,
Oregon State University, Corvallis, Oregon. A nine point hedonic scale ranging from 1 "extremely undesirable" to 9 "extremely desirable" was used to evaluate the samples for overall desirability. Four different groups of samples were evaluated: white breads made with three concen- trations of sodium chloride, white breads made with three concentrations of the salt mixture, whole wheat breads made with three concentrations of sodium chloride and whole wheat breads made with three concentrations of the salt mixture.
Mean scores were determined for all samples. A triangle test was then done comparing the all sodium chloride sample with the highest mean score to the salt mixture sample which most closely matched it in degree of saltiness. The salt mixture samples were chosen by an informal taste test. The triangle test was done with both the all white and whole wheat sampl es.
Statistical Analysis of Flour, Tuna and Peanuts
An analysis of variance was done to determine the significance of differences among the mean values for the different treatments. A Newman-
Keuls test was then done to determine which means were significantly 38 different at the .05 level. Statistical computations were conducted at the Computer Center at Oregon State University, Corvallis, Oregon.
Statistical Analysis of Bread Flavor Panel Evaluation
The significance of differences among the mean scores for overall desirability was determined with an analysis of variance test. Least significant differences (LSD) at the .05 level were utilized in assessing which means were significantly different. To establish significance at the .05 level with the triangle test, 19 out of 40 judges had to respond correctly (Roessller et. al., 1978). 39
RESULTS AND DISCUSSION
The Effects of Processing on Sodium - Potassium and Calcium - Phosphorus
Ratios in Tuna Fish
Raw, precooked, canned in oil and canned in water tuna samples were analyzed to determine the effects of processing on sodium - potassium and calcium - phosphorus rations in tuna fish.
Moisture and Fat Content of Tuna Samples
The moisture and fat content of the tuna samples are presented in
Table 1. The moisture content decreased due to precooking and increased in the canned in water samples for all species. A large increase in the fat content of the canned in oil samples was observed. The other treat- ments did not have a significant effect on the fat content of the samples.
All albacore samples had a higher percentage of fat than the other species samp! es.
Sodium in Raw Tuna
The experimental sodium concentrations in raw tuna were converted to a wet weight basis for comparison with reported literature values. These experimental values were: 407.0 mg/100 g extra small yellow fin; 368.17 mg/100 g albacore; 219.59 mg/100 g large yellow fin and 574.62 mg/100 g skip jack. These values were all higher than 34.0 mg/100 g reported by
Thurston in 1958. It was speculated the experimental fish contained high levels of sodium because of the salt brine used for freezing on the fishing vessel. 40
Table 1. Moisture and Fat Content of Tuna Fish During Processing.
% Fat Species Treatment % Moisture (dry weight)
Extra Small Yeliowfin Raw 72.58 0.52 Precooked 67.86 0.48 Canned, oil 60.89 42.05 Canned, water 73.00 0.94
Albacore Raw 65.12 13.16 Precooked 61.16 21.00 Canned, oil 56.50 40.99 Canned, water 67.80 22.82
Large Yeliowfin Raw 73.04 0.70 Precooked 68.04 0.67 Canned, oil 61.48 34.55 Canned, water 74.50 0.42
Skip jack Raw 71.87 0.20 Precooked 66.90 0.79 Canned, oil 61.48 30.39 Canned, water 75.20 1.13 41
Studies by Holston and Pottinger in 1954 and Peters in 1959 demon- strated that fish meat absorbed sodium from the salt brine in which it was frozen. The sodium concentration and temperature of the brine were factors which influenced the amount of sodium uptake by the fish. Once the fish were frozen they absorbed further salt very slowly. Doust in
1975 concluded sodium uptake by fish could be excessive if left in the brine for a long period of time after freezing. Delmas in 1975 concluded when fish were destined for canneries the uptake of large amounts of sodium was not a great problem.
The experimental fish may have been frozen at a relatively high temperature (greater than 15 F) and in a very concentrated sodium chloride brine. Possibly, they were held in the brine for a long period of time after freezing. These conditions would be conducive for sodium absorption by the fish and account for the high levels in the raw samples analyzed.
The sodium concentrations in the raw fish were significantly different among all species. These differences were possibly due to a combination of natural species variation, size of fish, and to different conditions under which they were frozen on the fishing vessel. The species that contained low levels of sodium may have been frozen at a lower temperature than those that contained higher sodium levels. Extra small yellow fin and skip jack are small fish (Sharp and Dizon, 1978) with large surface to volume ratios. Therefore they would probably absorb more sodium from the freezing brine than larger fish. Extra small yellow fin and skip jack contained higher concentrations of sodium than large yellow fin and albacore,
Potassium in Raw Tuna
The experimental potassium concentrations in raw tuna were converted 4?
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CM o CM r-~ m to CTi CM «r o co to O CM «■ en o en •r- O 3 ^' in o o- in to to to in m m o m to P^ r-* 00 to to ^i •o ^ '- UD r— < o O -^ >, m m ^ <«■ tn ON d CM CO «r CM m en oi CM CM to Ol i*- t/i a» s- CO CM vo --J r~ vo CM r^ «»• Ol to Ol •a* «T en P*» r— P*« «*■ P- O c 3 o — -f- Ol ■o 4 Species Treatment Sodium Potassium Calcium Phosphorus Extra Small Yellowfin Precooked 69 75 100 100 Canned, oil 51 43 61 51 Canned, water 69 55 143 69 Albacore Precooked 69 78 52 86 Canned, oil 82 79 54 63 Canned, water 118 83 175 79 Large Yellowfin Precooked 57 78 100 100 Canned, oil 49 48 100 63 Canned, water 63 69 184 77 Skip jack Precooked 65 66 61 100 Canned, oil 38 19 85 100 Canned, water 50 54 111 70 CO 44 to a wet weight basis for comparison with reported literature values. These experimental values were: 298.26 mg/100 g extra small yellow fin; 204.0 mg/ 100 g albacore; 314.0 mg/100 g large yellow fin and 351.85 mg/lOOg. These values were in relative agreement with 293.0 mg/100 g reported by Thurston in 1958. All raw fish samples contained significantly different concentra- tions of potassium. These differences may have been due to natural species variation. The Effect of Precooking on Sodium, Potassium, Calcium and Phosphorus Levels in Tuna The mineral values of the different treatments and species of fish are presented on a dry weight basis in Table 2. Precooking resulted in significant losses of sodium and potassium in all species of fish, calcium losses in skip jack and albacore and a loss of phosphorus in skip jack only. The steam treatment used to precook the fish may have caused these losses by promoting leaching of the minerals from the fish. On the average, 65% of the sodium, 74% potassium, 78% calcium and 97% phosphorus found in the raw tuna samples were retained after precooking (Table 3). Sodium is found mainly extracellularly in fish. It was thought that this location would facilitate the leaching of sodium from the fish during precooking. This may explain why more sodium, than the other minerals studied, was lost during the steam treatment. Potassium, on the other hand, is found primarily intracellularly in fish. It was speculated that this location would prevent leaching of this mineral. However, potassium was lost during precooking in this study. Love reported in 1961 that freezing fish in a sodium chloride brine often causes cells to rupture. It seemed possible that if cells in the experimental fish were damaged in this manner during freezing, potassium would have been more readily lost during 45 precooking. Sodium, Potassium, Calcium, and Phosphorus Levels in Tuna Canned in Oil The canned in oil extra small yellow fin contained significantly lower levels of sodium, potassium calcium and phosphorus; albacore in oil contained less phosphorus; large yellow fin in oil less potassium and phosphorus and skip jack in oil less sodium and potassium than the pre- cooked and raw tuna samples (Table 2). The percent fat in the canned meat increased to an average of 37% from 3.6% in the precooked meat (Table 1). These lower mineral values in the canned in oil samples may not reflect actual losses from the precooked tuna meat. It was probable that the in- creased sample weight due to oil absorption resulted in the lower mineral levels. It was also possible that some of the minerals were absorbed by the oil in which they were packed and thus resulted in lower levels in the meat. The albacore in oil contained more sodium and the large yellow fin in oil the same amount of sodium as the precooked samples. The vegetable oil broth in which they were packed contained 1.2% added salt for flavor. Therefore these meats probably absorbed sodium from the oil after they were canned. The large yellow fin and albacore precooked samples con- tained less sodium than the other two species. This factor may have accounted for the albacore and large yellow fin meats absorbing sodium from the oil while the other species precooked samples did not. Sodium, Potassium, Calcium, and Phosphorus Levels in Tuna Canned in Water The canned in water extra small yellow fin, large yellow fin and skip jack contained less potassium and phosphorus than the raw and precooked samples (Table 2). The broths in which the meats were canned contained 46 significant amounts of these two elements. Some potassium and phosphorus leached from the tuna meat into the broths after canning. It was unclear why leaching did not occur with the albacore canned tuna also. The tuna meat samples contained significantly more calcium in all species of canned tuna than the raw and precooked samples. Possibly, the canning broth was made from relatively hard water and calcium was absorbed from the broth by the tuna meat. Albacore and skip jack canned tuna meats in water contained higher levels of sodium than the precooked samples (Table 2). These meat samples absorbed sodium from the salt containing water broth in which they were canned. The extra small and large yellow fin however did not absorb sodium from the broth as there was no significant difference in the sodium levels of the precooked and canned samples. The large yellow fin broth contained a lower level of sodium than the other broths. This may explain why the large yellow fin meat did not absorb a significant amount of sodium. It was unclear why the different species absorbed different quantities of sodium when all broths theoretically contained the same concentrations of added salt. The experimental mineral values for the canned in water meat were averaged over species and converted to a wet weight basis for comparison with literature values. The experimental average mineral values were: 265.27 mg sodium/100 g; 172.59 mg potassium/100 g; 10.8 mg calcium/100 g and 168.29 mg phosphorus/100 g. The experimental sodium, potassium and phosphorus levels were lower and the calcium level higher than those reported by Gordon and Roberts in 1977. It was possible that more leaching of potassium and phosphorus during precooking and into the canning broth occured with the experimental fish than those studied by Gordon and 47 Roberts. It was also possible that lower experimental sodium levels were seen because the tuna meat did not generally absorb a large quantity of sodium from the broth in which it was packed. It was unclear if Gordon and Roberts assayed a mixture of broth and meat or just the meat sample. The experimental water broths contained significant amounts of sodium, phosphorus and potassium. Therefore higher concentrations of these minerals would have been determined if the broth and meat were blended and then analyzed. Sodium - Potassium and Calcium - Phosphorus Ratios in Canned Tuna The sodium - potassium and calcium - phosphorus ratios of the different treatments and species of tuna fish are presented in Table 4. The sodium - potassium ratio increased from 1.63 in the raw to 3.28 in the canned in oil skip jack. No significant differences were seen between these treatments among the other species. The sodium - potassium ratios in the canned in water meats of the albacore and extra small yellow fin species (2.57 and 1.74 respectively) were significantly greater than the raw fish samples (1.8 and 1.35 respectively). The increased ratios were probably due to the loss of potassium during precooking and to the canning broths as well as the absorption of sodium from the broths by some meat samples. The calcium - phosphorus ratio increased from 0.18 in the raw to 0.32 in the canned in oil large yellow fin (Table 4). Possibly more phos- phorus than calcium was lost during precooking and to the vegetable oil. The calcium - phosphorus ratios of the raw and canned in oil samples among the other species were not significantly different. An increase in the canned in water calcium - phosphorus ratio compared to the raw was 48 Table 4. The Sodium-Potassium and Calcium-Phosphorus Ratios of Tuna Fish During Processing. Sodium- Calcium- Species Treatment Potassium Phosphorus Extra Small Yellowfin Raw 1.349A'C'1 0.028A'1 Precooked 1.244A 0.025A'2 Canned, oil 1.633B'C'4 0.033A'3 Canned, water 1.740B'5 0.0574 Broth 1.705B 0.028A'5 Albacore Raw 1.801A'2 0.029A,1 Precooked 1.602A'3 O.OIJ^'2 Canned, oil 1.854A'4 0.025A'3 Canned, water 2.572 0.0644 Broth 3.551 0.019A'5 1 Large Yellowfin Raw 0.699A'B o.oie^^' Precooked 0.513A 0.015A'2 Canned, oil 0.705B 0.032B'C'3 : Canned, water 0.634B 0.040C'5 Broth 0.812B 0.021B Skip jack Raw 1.634 A'1'2 0.058A Precooked ^.604A,3 0.039 Canned, oil 3.278 0.053A Canned, water 1.502A'5 0.092 Broth 2.525 0.052A A B ' Treatments which have the same letter ^,B) among the same lot and mineral are not statistically different at the 0.05% level. 1,2 Treatments with the same number (1,2) for one mineral among all lots are not statistically different at the 0.05% level. 49 noted for all species. This was due to the absorption of calcium by the meat from the water broth and the loss of phosphorus during pre- cooking. Summary of the Effects of Processing on Tuna Fish Mineral levels of the different treatments were averaged over the four species and are presented in Figure 1. These averaged values repre- sent the mineral content of the typical product consumed by the public. They are therefore more relevant than individual species values when discussing the nutritional implications of the mineral content of tuna fish. The general trends noted in the individual species among the different treatments were also noted-in the averaged values. Significant losses of sodium, potassium and calcium occured during precooking. The canned in oil product contained significantly lower concentrations of phosphorus and potassium due to oil absorption and subsequent increased sample weight. A significant increase in calcium was observed in the canned in water meat samples due to absorption from the broth. The average sodium - potassium ratios of the tuna samples were: 1.37 raw; 1.24 precooked; 1.87 canned in oil and 1.61 canned in water. The differences in these ratios were not significant because of the variation in sodium and potassium levels among the individual species. The sodium concentration of the raw fish immediately after capture was unknown. A significant increase in the sodium - potassium ratio of the canned samples would have been noted if the raw samples did not contain sodium absorbed from the brine in which they were frozen. The average Amercian diet has a sodium - potassium ratio of 1.5 to 6.0. The ratio of Kempners rice-fruit diet which proved effective in 50 1800 1600 - Sodium 1400 Potassium 1200 Phosphorus >» 1000 Q C* 800 - o o 600 E 400 200 Calcium -f-v- icfn. A B A,6 s a •a o Figure 1. Mean sodium, potassium, calcium and phosphorus levels in tuna fish as effected by processing. A,B, Samples with the same letter are not significantly different at the 0.5% level 51 reversing hypertension was 0.5 (Weinsier, 1976). The sodium - potassium ratio in both types of canned products was therefore on the low side of the range found in a typical diet. It has been speculated however that the sodium - potassium ratio in the American diet is too high and could be a contributing factor in the prevalence of hypertension in our society (Weinsier, 1976). An optimum or recommended dietary ratio has not been proposed. Therefore it was unclear if processing of tuna fish resulted in an "unhealthy" sodium - potassium ratio in the canned products. The average calcium - phosphorus ratios of the tuna samples were: 0.034 raw; 0.024 precooked; 0.034 canned in oil and 0.065 canned in water. The ratio of the canned in water meat was significantly greater than the ratio of other samples. The ideal ratio of calcium to phosphorus in the adult diet is 1:1 (National Academy of Sciences, 1974). It has been speculated that low calcium - phosphorus dietary ratios are a contributing factor in bone mineral loss in man (Linkswiler and Zemel, 1979). The calcium - phos- phorus ratios in the tuna products were all very low because calcium is found in a lower concentration than phosphorus in raw tuna. This ratio was actually improved in the canned in water tuna due to calcium absorp- tion from the water broth. The Effects of Processing on Sodium - Potassium and Calcium - Phosphorus Ratios in Peanuts Raw, roasted, precooked and peanut butter samples were analyzed to determine the effects of porcessing on sodium - potassium and calcium phosphorus ratios in peanuts. 52 Moisture and Fat Content of Peanut Samples The moisture and fat content of the peanut samples are presented in Table 5. The moisture content decreased from an average of 6.22% in the raw peanuts to 1.47% in the roasted product. The loss of moisture was probably due to the high heat used to roast the peanuts. The fat content of the peanuts was relatively uneffected by processing. The average fat content was 49.29%. Mineral Levels in Raw Peanuts The experimental mineral concentrations in raw peanuts were converted to a wet weight basis for comparison with reported literature values. These experimental values were: 19.38 mg sodium/100 g; 566.76 mg potass- ium/100 g; 51.73 mg calcium/100 g and 344.54 mg phosphorus/100 g. The experimental potassium, calcium and phosphorus levels were in relative agreement with the average of those reported by Galvao et^. al_. in 1976 and Watt and Merril in 1963. The experimental sodium values were higher however. The mineral concentrations of the different peanut products studied are presented in Table 6 on a dry weight basis. There were no significant differences in sodium levels of the raw peanuts from the four lots examined. There were significant differences in potassium, calcium and phosphorus among the different lots. Effect of Roasting on Mineral Levels in Peanuts The roasting process had no effect on the sodium, potassium, calcium 53 Table 5. Moisture and Fat Content of Peanuts During Processing, % Fat Content 1 Variety % Moisture Treatment (Dry) 50-50 Spanish Runner Raw 5.79 48.48 Roasted 1.38 49.32 Blanched 1.47 49.42 Peanut Butter 2.83 38.76 (Chunky Style) 100% Runner Raw 6.43 47.16 Roasted 1.64 49.31 Blanched 1.61 50.47 Peanut Butter 1.46 49.94 (Old Fashioned) 100% Spanish Raw 5.67 50.32 Roasted 1.48 50.97 Blanched 1.79 51.14 Peanut Butter 2.37 52.76 (Creamy Style) 100% Runner Raw 6.99 48.91 Roasted 1.39 50.59 Blanched 1.49 50.39 Peanut Butter 2.67 50.81 (Creamy Style) 54 in CM c\j m cn CM m O r^ in 0 ^■ ro p^ o> en UD 10 10 p*. in O m 10 m vo 10 vo m ro o m in" _; ro p^ ^ «3- r^ m ro CM' ro' r-s r-- p^ «3- ^■ CM 1— o o CM CM V) 3 Ol—. P~ «r en 10 P^ ro m ,_ «T u » «» ro CO ^• CO 10 o o « «t <. in 0 m 0 «■ «r "S- en OT 0 pv <7> O <3- CM p^ in co en 0 O 0 r*. ro P>. F» «• 10 CM m ro CN. ^ VO CM in ro r^ 01--^ «> » M s < co 0 IO CM CO in o< CO 00 CO 10 00 in CO CM r*s in ro m 0 0 r^. 0 a\ in m ro a\ CM on LO p^ *r co p^ 10 vo 0 10 10' CO in 10 in r^ r— ^ CO -0 ^ c £ en—. CM •3- ^■ n 10 .— 0 ■" CO CO < CO in «£ < •s ■4 CM et OJ ^m. "O ^■^ *—* .0 01 0) 01 01 S-r- 1. c 1- r— s- <— 4-1 01 >> 0) 0 0) >1 OJ >, c ■w *J *J ■•- 4-1 4-> 4-1 4-1 0) ■M m 4-1 .C 4-> 0) > Ui OJ 1/1 -o c .C OJ •U > *J o c s- m ^ 0 C OJ c >> 3 01 OJ OJ r— OJ -«-> 0 a. c c c T3 E E - 0) in c Percent Retention Variety Treatment Sodium Potassium Calcium Phosphorus 50-50 Blanched 100% 86% 100% 100% 1 Peanut Butter 2984% 83% 100% 88% 100% Runner Blanched 100% 91% 84% 100% Peanut Butter 665% 88% 77% 100% 100% Spanish Blanched 134% 95% 69% 100% Peanut Butter 2135% 89% 75% 96% 100% Runner Blanched 100% 96% 85% 100% Peanut Butter 2278% 92% 83% 96% 1 en 56 and phosphorus content of the peanuts studied. No significant differences were seen between the raw and roasted peanuts for any of the minerals. These results agreed with data published by Watt and Merril in 1963. Effect of Blanching on Mineral Levels in Peanuts Blanching caused significant losses of potassium and calcium but not of sodium and phosphorus from the peanuts studied. The blanched peanuts did not contain significantly different levels of sodium or phos- phorus than the raw samples. They did contain significantly lower levels of potassium in all lots and calcium in three lots. On the average 92% potassium and 84% calcium found in the raw peanuts was retained after blanching (Table 7). The blanching treatment promoted leaching of calcium and potassium from the peanuts. Blanching also removed the peanut skins which were reported to contain a greater concentration of calcium and the same concentration of potassium as the peanut (Watt and Merrill, 1963). Possibly some of the loss of calcium after blanching was due to the removal of the peanut skins. It was unclear why potassium and calcium were lost during blanching and phosphorus and sodium were not. These results were in agreement with those published by Lee and Whitcombe in 1945 with peas. They reported a large decrease in potassium and no effect on phosphorus levels due to blanching. The Mineral Content of Peanut Butter On the average, 88% of the potassium, 83% calcium and 95% phosphorus found in the raw peanuts was retained in the peanut butter (Table 7). The experimental peanut butters contained lower concentrations of 57 potassium than the raw nuts in all lots and calcium and phosphorus in three lots. Lower levels of potassium and calcium were expected in the peanut butter as significant losses occured during blanching. The sodium content of the peanut butter increased due to the addition of salt for flavor. There was no significant difference in the sodium level of peanut butters made from 50-50 Spanish - runner and 100% runner varieties. Peanut butter made from 100% Spanish contained significantly more sodium and peanut butter made from 100% runner peanuts less sodium, than the other two products. Old fashioned style peanut butter characteristically contains less added salt thus lower levels of sodium. It was unclear why the peanut butter made from 100% runner peanuts contained more sodium than the other two products as the same concentration of salt was added to the creamy and chunky style peanut butters. The higher concentration may have been due to product contam- ination or experimental error. The experimental mineral concentrations were averaged over lot and converted to a wet weight basis for comparison with reported literature values. These experimental values were: 411.62 mg/100 g sodium; 517.49 mg potassium/100 g; 42.57 mg calcium/100 g and 334.29 mg phosphorus/ 100 g. The sodium and phosphorus levels were higher and the potassium level lower than those reported by Galvao et^. al_. in 1976. The same differences in phosphorus and potassium concentration were found in the raw peanuts. The Sodium - Potassium and Calcium - Phosphorus Ratios in Peanut Butter The sodium - potassium and calcium - phosphorus ratios of the 58 Table 8. Sodium-Potassium and Calcium-Phosphorus Ratios of Peanuts During Processing. Sodiurn- Calcium- Variety Treatment Potassium Phosphorus 50-50 Raw 0.027A'1 0.127A'1 A C Roasted 0.025A'2 0.123A'D Blanched 0.039A'3 0.105A'3 A 7 9 Peanut Butter 0.973 o.n9 ' ' (Chunky Style) A 1 100% Runner Raw 0.030*'' 0.165A'2 Roasted 0.030A'2 0.172A'6 Blanched 0.037A'3 0.139B'4 Peanut Butter 0.222 0.135B'8'9 (Old Fashioned) 100% Spanish Raw 0.044A 0.122B'1 _ A,B,5 Roasted 0.039 0 112 Blanched 0.0643 0.088A'3 A r» "7 Peanut Butter 1.064 0.103A'B'7 (Creamy Style) A 2 100% Runner Raw 0.035A'1 0.178*^ 2 Roasted o.oso^ 0.159A'6 Blanched 0.034A'3 0.^42A,4 Peanut Butter 0.065 0.153A'8 (Creamy Style) A R 'Treatments which have the same letter ^,B) among the same lot and mineral are not statistically different at the 0.05% level. 1,2 Treatments with the same number (1,2) for one mineral among all lots are not statistically different at the 0.05% level. 59 different treatments and lots of peanuts are presented in Table 8. All finished products contained a significantly higher sodium - potassium ratio than the raw peanuts. This increase was due to the addition of salt to the peanut butter and the loss of potassium during blanching. No significant differences in the calcium - phosphorus ratios of the raw and finished products in three lots were seen. Summary of the Effects of Processing on Peanut Butter Mineral levels of the different treatments were averaged over the four lots and are presented in Figure 2. These averaged values represent the mineral content of the typical product consumed by the public. They are therefore more relevant than individual lot values when discussing the nutritional implications of the mineral content of peanut butter. The general trends noted in the individual lots among the different treat- ments were also noted in the averaged values. Sodium, potassium, calcium and phosphorus levels were not significantly effected by the roasting process. Blanching resulted in losses of potassium and calcium but not of sodium and phosphorus. Peanut butter contained a significantly higher concentration of sodium than the raw peanuts due to salt added for flavor. The average sodium - potassium ratios of the different treatments were: 0.034 raw, 0.043 roasted, 0.031 blanched and 0.781 peanut butter. The ratio of peanut butter was significantly greater than the other peanut products. The sodium - potassium ratios of the raw, roasted and blanched peanuts were very low. The ratio in peanut butter with added salt was less than the 1.5 to 6.0 ratio commonly found in the American diet. This low ratio was due to the high concentration of potassium in peanuts. 60 roo _ ,. Potassium Sodium 600 - - LT _ (U 500 $ Phosphorus 400 - r J_ .JT_ Q rh 1 1 +. a> 300 - O O 1 \ 200 o> E Calcium 100 _ T i. T r I n 1 ! i 1 * II 8 3 A A 8 8 8 -^ -^ 5 5 rr T) O o o S Q O O Figure 2. Mean sodium, potassium, calcium and phosphorus levels in peanuts as effected by processing. 'Samples with the same letter are not significantly different at the 0.5% level. 61 Despite the salt added to peanut butter, processing resulted in a product with a low sodium - potassium ratio. The average calcium - phosphorus ratios of the different treatments of peanuts were: 0.148 raw; 0.121 roasted; 0.141 blanched and 0.128 peanut butter. These ratios were not significantly different. They were all very low because peanuts naturally contain a much higher concen- tration of phosphorus than calcium. Consumption of peanuts and peanut butter could contribute to the low calcium - phosphorus ratio commonly found in the American diet. The Effects of Processing on Sodium-Potassium, Calcium-Phosphorus Ratios in Wheat Products Low grade, untreated, bleached not enriched, and bleached enriched white flours, whole wheat flour, bran, germ and the whole wheat kernel were analyzed to determine the effects of processing on sodium - potass- ium and calcium - phosphorus ratios in wheat products. Moisture and Fat Content of Wheat Products The moisture and fat content of the wheat samples are presented in Table 9. The moisture content was about 12% in all wheat products. The whole wheat kernel and whole wheat flour contained about 1.9% fat. The germ portion of the kernel contained the greatest concentration of fat as it v/as present at an average of 11.2%. The bran contained about 4.9% and the different white flours about 1.3% fat. The low grade flour contained a slightly higher concentration of fat than the other white flours (2.2%) because it characteristically contains fragments of the bran and germ por- tion of the kernel which contained relatively high concentrations of fat. 62 Table 9. Moisture and Fat Content of Wheat as Effected by Processing. Treatment Lot # % Moisture % Fat (dry wt ) Kernel 1 10.98 1.59 2 10.73 2.39 3 13.04 1.57 Bran 1 13.66 4.78 2 13.23 4.80 3 13.05 5.18 Germ 1 13.17 12.25 2 12.43 8.92 3 11.61 12.34 Low Grade 1 13.56 1.28 2 13.38 2.57 3 13.10 2.63 Untreated 1 12.25 1.20 2 12.07 1.31 3 12.01 1.26 Bleached Not Enriched 1 13.65 1.42 2 13.35 1.31 3 13.46 1.26 Bleached Enriched 1 13.81 1.25 2 13.24 1.29 3 13.51 1.31 Whole Wheat Kernel Sample 1 4 10.92 1.90 Sample 2 4 11.31 1.76 Sample 3 4 11.14 1.77 Whole Wheat Flour Sample 1 4 12.41 2.11 Sample 2 4 12.30 1.81 Sample 3 4 11.98 2.29 High Selinium Kernel 5 11.92 1.68 Bran 5 14.63 5.15 Shorts 5 6.64 4.16 Bleached-Enriched 5 13.77 1.07 Whole Wheat Flour 5 12.26 2.02 63 Mineral Composition of Bran Sodium, potassium, calcium and phosphorus concentrations of the wheat products studied are presented in Table 10. Bran makes up about 14% of the whole wheat kernel and usually includes the pericap, the seed coat, a thin layer of nucellar tissue which lies just inside the seed coat and the aleurone or outer layer of endosperm (Paul and Palmer, 1972). This portion of the whole wheat kernel contained the greatest concentra- tion of potassium, calcium, and phosphorus of the products studied. These averaged values were: 1172.05 mg potassium/100 g, 76.72 mg calcium/100 g and 1267.76 mg phosphorus/100 g. The calcium and sodium levels of the bran among the three lots studied were not significantly different. Potassium levels were significantly different in all lots and no signif- icant differences in the phosphorus concentrations in two lots were determined. Bran is removed from the whole wheat kernel in the production of white flour and in years past was often added to animal feed, however because of recent interest in whole grain foods, bran and wheat germ are now finding their way into a variety of human foods. It contains a high percentage of vitamins as well as minerals and cellulose material. Man is unable to digest this cellulose which therefore tends to speed the passage of food through the digestive tract preventing complete absorption of nutrients. Animals however are able to digest cellulose and efficient absorption of the bran nutrients is not a problem (Wheat Flour Institute, 1966). 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The sodium concentration of the germ was significantly greater than the concentration in bran. The averaged min- eral values in the germ were: 33.6 mg sodium/100 g; 955.2 mg potassium/ 100 g; 50.6 mg calcium/100 g and 1144.7 mg phosphorus/100 g. No significant differences were seen in the sodium and phosphorus levels of the germ among the three lots and the calcium concentrations among two lots. The potassium levels were significantly different in all three lots. Wheat germ makes up about 2.5% of the whole wheat kernel and is the embryo or sprouting section of the seed (Paul and Palmer, 1972). It also is removed from the kernel in the production of white flour as it contains a high percentage of fat which would limit the keeping quality of flour (Wheat Flour Institute, 1966). Mineral Composition of the Whole Wheat Kernel The whole wheat kernel contained significantly lower levels of calcium, phosphorus and potassium than the bran and germ samples (Table 10). The sodium concentration of the kernel was significantly lower than in germ. No significant differences were seen in the sodium levels of the kernel and bran. The average mineral values of the kernel were: 28.0 mg sodium/100 g; 314.5 mg potassium/100 g; 25.1 mg calcium/100 g and 390.1 mg phosphorus/100 g. The potassium and phosphorus levels in the kernels among two lots and the sodium and calcium levels among all three lots were not significantly different. The three lots of wheat products studies were obtained from the same mill on different days of production. Soil, fertilizers, variety, 66 weather and location are factors which effect the mineral content of wheat products (El Gindy et_ aj_., 1957). Differences in mineral levels in bran, germ and the kernel between lots were due to daily variations in growing conditions and variety of the milled wheat. Mineral Composition of Flours The sodium, potassium, calcium and phosphorus concentrations of the different flours studied are also presented in Table 10. White flour is made from the endosperm which comprises 83% of the whole wheat kernel. Untreated, bleached not enriched and bleached enriched white flours contained lower levels of all minerals than the kernel, germ and bran samples analyzed. On the average 45% of the sodium and 27% potassium, 75% calcium and 33% phosphorus found in the kernel was retained in the white flour (Table 11). The bran and germ contained the greatest concentration of minerals. These results were in agreement with those published by Waggle et_. al_. in 1967. Bleaching and enriching did not effect the mineral content of the experimental white flours. No significant differences were seen in the sodium, potassium, calcium and phosphorus levels of the untreated, bleached not enriched and bleached enriched flours. Most chemicals used for bleaching flour are oxidizing agents such as chlorine dioxide, acetone, peroxides, bromates, iodates and benzoyl peroxide. Calcium and phosphate compounds are sometimes used as carriers for these bleaching agents (Paul and Palmer, 1972). Such carriers were probably not used to bleach the experimental flours as the bleached products did not contain higher levels of these minerals than the unbleached products. Table 11. Percent Retention of Sodium, Potassium, Calcium, and Phosphorus in Flour. Percent Retention Treatment Lot # Sodium Potassium Calcium Phosphorus Low Grade 1 100 60 100 115 2 100 54 100 55 3 73 71 100 75 Untreated 1 30 23 69 35 2 100 24 100 26 3 43 23 100 75 Bleached Not Enriched 1 41 26 100 37 2 31 21 100 25 3 56 26 69 36 Bleached Enriched 1 41 31 100 34 2 36 27 100 26 3 59 24 73 36 Whole Wheat Flour Sample 1 4 100 108 100 100 Sample 2 4 100 100 100 in Sample 3 4 100 100 100 100 1 68 The standard for enriched flour includes the addition of thiamine, ribo- flavin, niacin and iron. Optional ingredients are calcium and Vitamin D (Paul and Palmer, 1972). No increase in calcium was seen in the exper- imental enriched flours therefore this nutrient was not included as an enrichment ingredient. The potassium and phosphorus levels in the low grade flour were significantly greater than those of the other white flours but lower than the kernel, germ and bran. Low grade flour characteristically contains fragments of bran and germ and a high percentage of ash. There- fore high levels of the individual minerals were expected (Jones, 1958). The calcium, phosphorus and potassium levels of the experimental whole kernel, bran, germ and white flour samples were lower than those reported by Czerniejewski et. aj_. in 1964. The sodium concen- trations of all experimental samples however were higher than those reported by these investigators. These higher levels were probably due to variations in growing conditions and variety of wheat. Whole wheat flour is characterized as containing the endosperm as well as the bran and germ of the kernel. Therefore the flour was expected to contain the same concentration of minerals as the kernel. No signi- ficant differences were seen in the sodium and calcium levels of both the kernel and whole wheat flour in all three lots and the potassium and phosphorus levels in two lots. The differences between the mineral concentrations of the whole wheat flour and kernel were probably due to unequal distribution of the minerals in the samples. The Sodium - Potassium and Calcium - Phosphorus Ratios in Flour The sodium - potassium and calcium - phosphorus ratios of the 69 different treatments and lots of wheat products are presented in Table 12. The whole wheat kernel had an average sodium - potassium ratio of 0.089. All experimental white flours had a sodium - potassium ratio significantly greater than the ratio of the whole kernel. The bran and wheat germ sections of the kernel contained the greatest concentrations of potassium. These products were not included however in white flour which consequently contained a lower level of potassium and a higher sodium - potassium ratio than the whole kernel. The sodium - potassium ratios of the whole kernel and the whole wheat flours were not signifi- cantly different. This was expected as the whole wheat flour contains all sections of the kernel. The whole wheat kernel had an avera'ge calcium - phosphorus ratio of 0.067. All experimental white flours contained a calcium - phosphorus ratio significantly greater then the ratio in the whole kernel. More calcium than phosphorus was removed during the separation of endosperm from bran and germ in the milling of white flour and resulted in this increased ratio. No significant differences in the calcium - phosphorus ratios of the whole kernel and the whole wheat flours were seen. This was again expected as the flour contains all sections of the whole kernel Composition of High Selenium Wheat High selenium wheat samples were collected for use in a human bio- availability study by another group of investigators. It was also analyzed for its sodium, potassium, calcium and phosphorus concentrations The data is presented in Table 13. The high selenium wheat products contained higher levels of sodium, potassium, calcium and phosphorus than the products from the other lots studied. The bran contained a 70 Table 12. Sodium-Potassium and Calcium-Phosphorus Ratios in Wheat as Effected by Processing. Sodium- Calcium- Treatment Lot # Potassium Phosphorus Kernel 1 0 094 0.071^'] - A'B 11 2 O.OSS^'T' 0.050?'' 3 0.089*'' 0.0751 Bran 1 0.025^ 0.062^'^ 2 0.021*'^ 0.0575' 3 0.018D^ o.oer Germ 1 0.031^ 0.0495'^ 2 0.038j», 0.037':^ 3 0.035^ 0.048•3 Low Grade 1 0 177 0.062?'^ - A B 5 b 2 0.122?'^'° 0.084^' 3 0.093A'b 0.104° Untreated 1 0.120?'5 0.138B'5 2 0.199?'; 0 137 3 0.168L'4 0.136- A4H'4 Bleached Not Enriched 1 0.187R 7 2 0.128?'"';' 0.151B'7 3 0.196l"u»/ B C 8 Bleached Enriched 1 0 •]22 '8'8 2 oil^S' ' 0.149?'° 3 0.222u 0.151*'° Whole Wheat Kernel Sample 1 4 o.m. , 0.071 1 Sample 2 4 0.089"' 0.089 Sample 3 4 0.087^'' 0.059 1 Whole Wheat Flour Sample 1 4 0.092^ 0.066?'1 Sample 2 4 0.087*'^ 0.072' M Sample 3 4 0.070 0.062*'' A B ' Treatments which have the same letter (A,B) among the same lot and mineral are not statistically different at the 0.05% level 1 2 ' Treatments with the same number (1,2) for one mineral among all lots are not statistically different at the 0.05% level. Table 13. Sodium, Potassium, Calcium and Phosphorus Levels in High Selinium Wheat. Sodium Potassium Calcium Phosphorus (mg/100 g (mg/100 g Sodium- (mg/100 g (mg/100 g Calcium- Variety dry wt.) SD dry wt.) SO Potassium dry wt. SO dry wt.) SO Phosphorus a Kernel 38.09 5.07 329.63 6.02 0.116 36.63A 1.96 477.47A 10.31 0.077A Bran 62.52 3.43 1364.31 8.47 0.046 98.14B 3.34 1958.30 63.53 0.050 Shorts 43.63A 3.53 849.03 5.27 0.051 83.12B 2.56 1206.80 53.45 0.069A Bleached Enriched 18.06 1.95 78.78 7.40 0.232 22.02 0.78 126.07 5.21 0.175 Whole Wheat Flour 25.96 2.73 305.72 9.04 0.083 34.87A 1.40 461.40A 18.09 0.076A Standard Deviation A,B. Treatments which have the same letter (A,n)among the same lot and mineral are not statistically different at the 0.05% level. 72 significantly higher concentration of minerals than the other wheat products as was seen in the lots previously analyzed. Shorts contained significantly more potassium, calcium, and phosphorus than the kernel, white and whole wheat flours. Shorts are a mixture of bran, germ, flour and other material remaining after milling (Wheat Flour Institute, 1966). They were therefore expected to contain a high concentration of the minerals studied. The whole wheat flour contained significantly lower levels of calcium and sodium and the same levels of potassium and phosphorus as the kernel. The lower levels were probably due to unequal distribution of calcium and sodium in the samples. It was interesting that the high selenium wheat also contained higher levels of sodium, potassium calcium and phosphorus than the other experimental lots of wheat samples. Summary of the Effects of Processing on the Sodium - Potassium and Calcium - Phosphorus Ratios in White and Whole Wheat Flours Mineral levels of the wheat products were averaged over the lots and are presented in Figure 3. The general trends noted in the individual lots among the different wheat products were also noted in the averaged values. The bran contained significantly greater levels of potassium, calcium and phosphorus than the other wheat products. The germ contained significantly greater levels of these minerals than the whole kernel. The sodium concentration was greatest in the germ and no significant differences in the bran and kernel concentrations were determined. All white flours contained significantly lower mineral levels than the kernel, bran and germ. The low grade flour had significantly greater levels of all minerals than the other white flours. The mineral levels 73 i*00 Phosphorus :300 Potassium I2C0 JZ i iCO - 'CCO >. Q 900 a> O O •IOC £ 200 -30 Sodium 4 A 343900 "■a-o c 3-tTCT- < » "" 3 (0 _ 3 3 o"* "^o o 3 —a — o — Figure 3. Mean sodium, potassium calcium and phosphorus levels in wheat products as effected by processing. A B 5 Samples with the same letter are not signi- ficantly different at the 0.5% level. bl= bleached en= enriched 74 of the kernel and whole wheat flour were not significantly different. The average sodium - potassium ratio was 0.16 in the experimental white flours, 0.084 in whole wheat flour and 0.089 in the kernel. Processing had no effect on the ratio of whole wheat flour as there were no significant differences in the ratios of the kernel and the flour. The ratio in white flour was significantly greater than the ratio in the kernel and the whole wheat flour. These ratios were all low compared to the range of 1.5 - 6.0 found in the average American diet. Commercial food products made from white flour account for the major consumption of wheat by the population. It is a common ingredient of foods such as bread, crackers, macaroni products and many snack foods (Wheat Flour Institute, 1966). Salt is usually added to these processed foods as a preservative and for flavor. Therefore the sodium - potassium ratio of these products are greater than the ratio in white flour. Kaplan, 1980 reported the ratio in white flour was 0.02 and this ratio was increased to 5.03 in commercial white bread. It was concluded a greater increase in the sodium - potassium ratio resulted from processing white flour into commercial food products than milling wheat into white flour. The average calcium - phosphorus ratio was 0.14 in the experimental white flours, 0.07 in whole wheat flour and 0.07 in the kernel. The ratios of the kernel and the whole wheat flour were not significantly different. The ratio of the white flour however was significantly greater than the ratios of the kernel and whole wheat flour. The calcium phosphorus ratios of all wheat products were low compared to the 1:1 recommended dietary ratio. These low ratios were due to the naturally high concentration of phosphorus and low concentration of calcium in 75 wheat. Milling wheat into white flour raised this ratio due to the removal of bran and germ which contained high concentrations of phosphorus. The consumption of wheat products could contribute to the low calcium - phosphorus ratio of the average American diet. Overall Desirability of White and Whole Wheat Breads Made With Sodium Chloride or a 1:1 Sodium - Potassium Chlorides Mixture The mean scores for overall desirability of the different bread samples are presented in Table 14. The 0.75% sodium chloride white bread received the highest mean score. This score was significantly higher than the 1.0% but not the 0.5% sodium chloride breads. The judges found the 0.75% bread more desirable than the 1.0%, but the 0.75% and 0.5% sodium chloride breads were equally desirable. The judges were encouraged to comment freely on the flavor of the different bread samples. These comments indicated the 1.0% bread was very salty and therefore received a low mean score. Also the judges could not disting- uish between the 0.5% and 0.75% sodium chloride treatments and conse- quently the mean scores for overall desirability were not significantly different. The 0.75% sodium chloride whole wheat bread received the highest mean score. This score was significantly higher than the 1.0% but not the 0.5% sodium chloride breads. These results were identical to those of the sodium chloride white breads. The judges found the 0.75% bread more desirable than the 1.0%, but the 0.5% and 0.75% sodium chloride breads were equally desirable. Comments again indicated the 1.0% was very salty and therefore received a low mean score. Also the judges 76 Table 14. Overall Desirability of Experimental White and Whole Wheat Breads. Bread Treatments Mean Score (40 Judgements) White Breads 1 .0 NaCl 5.48; 0.75 NaCl 5.25 0.50 NaCl 5.93 A,B I I Whole Wheat Breads A '1 .0 NaCl 5.87 0.75 NaCl 6.85 A,B !0.50 NaCl 6.48 'Salt Mixture White Breads A,B 1 .0 NaCl/KCl1 5.86 0.75 MaCl/KCl 6.33J 0.50 NaCl/KCl Salt Mixture Whole Wheat Breads 1 .0 NaCl/KCl 38 0.75 NaCl/KCl 85 0.50 NaCl/KCl 6.43r NaCl/KCl = a 1:1 mixture. A B ' Mean scores that have the same letter (A,B,) among the same test are not significantly different. Scores ranged from 1 "extremely undesirable" to 9 "extremely desirable". 77 could not distinguish between the 0.5% and 0.75% sodium chloride breads and consequently the mean scores for overall desirability were not significantly different. The 0.75% sodium - potassium chlorides mixture white bread received the highest mean score. This score was significantly higher than the 0.5% score. No significant differences were seen between the 0.75% and the 1.0% salt mixture bread mean scores. The judges found the 0.75% and 1.0% treatments equally desirable and more desirable than the 0.5% salt mixture bread. Comments indicated the 0.5% bread was bland and flat and therefore undesirable. Also many judges could not distinguish between the 0.75% and 1.0% salt mixture breads and consequently the mean scores for overall desirability were not significantly different. The judges apparently did not notice any objectionable flavor from the potassium chloride as the overall desirability mean scores were comparable to those of the sodium chloride white bread samples. The mean scores of the 1.0%, 0.75% and 0.5% sodium - potassium chlorides mixture whole wheat breads were not significantly different. The whole wheat flour contributed more flavor than white flour to the 0.5% salt mixture bread and therefore this bread was not considered bland or flat. The judges apparently did not notice any objectionable flavor from the potassium chloride as the mean scores were higher than the scores for the sodium chloride whole wheat breads. Sodium chloride masked the bitter flavor of potassium chloride in both white and whole wheat salt mixture breads. These results agreed with those reported by Ball and Meneely in 1957 and Frank and Mickelsen in 1969. These investigators found various mixtures of sodium and potassium chlorides 78 masked the disagreeable bitterness of the latter. Difference Test The 0.75% sodium chloride and 1.0% sodium - potassium chlorides mixture breads were tested by the triangle test to determine if a panel of untrained judges could distinguish between the two products. Seven- teen judges responded correctly in the white bread test and eighteen in the whole wheat bread test. Therefore the judges did not significantly distinguish between the 0.75% sodium chloride and the 1.0% sodium - potassium chlorides mixture breads. The Sodium and Potassium Content of White and Whole Wheat Breads The sodium and potassium content of the experimental breads and two different brands of commercial white and whole wheat breads are presented in Table 15. The experimental sodium chloride white bread samples contained an average of 61.5 mg/100 g potassium. The sodium content of these samples were: 578.4 mg/100 g 1.0% treatment, 415.0 mg/ 100 g 0.75% treatment, and 283.3 mg/100 g 0.5% treatment. The commercial white bread products contained an average of 62.0 mg potassium/100 g and 630.0 mg sodium/100 g. The experimental sodium chloride whole wheat bread samples contained an average of 132.2 mg/100 g potassium. The sodium content of these samples were: 590.8 mg/100 g 1.0% treatment, 422.5 mg/100 g 0.75% treat- ment, and 250.0 mg/100 g 0.5% treatment. The commercial whole wheat breads contained an average of 213.2 mg potassium/100 g and 617.9 mg 79 Table 15. Sodium, Potassium and Sodium-Potassium Ratios of White and Whole Wheat Breads. Sodium Potassium (mg/100 g (mg/100 g Sodium- wet wt.) SD1 wet wt.) SD Potassium White Breads 1.0 NaCl 578.40 10.05 60.41 9.84 9.78 0.75 NaCl 415.00 7.44 59.32 6.79 7.00 0.50 NaCl 283.31 3.51 64.70 4.26 4.38 Commercial A 644.70 10.46 63.91 5.69 10.09 Commercial B 615.31 8.63 60.22 5.31 10.22 Whole Wheat Breads 1.0 NaCl 590.81 13.74 124.00 3.42 4.76 0.75 NaCl 422.50 6.50 128.51 0.56 3.29 0.50 NaCl 250.00 2.42 144.10 7.43 1.73 Commercial A 585.65 6.36 220.42 3.96 2.66 Commercial B 650.31 10.41 205.91 4.01 3.16 Salt Mixture White Breads 1.0 NaCl/KCl2 240.91 4.56 200.02 5.81 1.20 0.75 NaCl/KCl 199.50 7.42 180.74 7.42 1.10 0.50 NaCl/KCl 129.22 2.95 157.30 3.49 0.82 Salt Mixture Whole Wheat Breads 1.0 NaCl/KCl 263.61 5.99 290.80 6.75 0.91 0.75 NaCl/KCl 250.00 7.62 270.00 3.84 0.92 1 0.50 NaCl/KCl 185.23 2.11 220.74 4.96 0.84 ' Standard Deviation ^NaCl/KCl - a 1:1 mixture 80 sodium/100 g. The commercial breads contained more potassium than the experimental breads which were made with one-half white and one-half whole wheat flours. The commercial products were probably made with more whole wheat flour which contains more potassium than white flour (Table 10). The 1.0% sodium chloride treatment approximates the sodium level of commercial whole wheat bread. The experimental sodium - potassium chlorides mixture white and whole wheat breads contained less sodium and more potassium than the experimental sodium chloride breads and commercial products. The whole wheat salt mixture breads contained more potassium than the white breads. The Sodium - Potassium Ratios of White and Whole Wheat Breads The sodium - potassium ratios of the experimental and commercial white and whole wheat breads are also presented in Table 15. The sodium ■ potassium ratios of the experimental salt mixture white and whole wheat breads were all lower than those of the experimental sodium chloride breads and commercial products. Conclusions From the Overall Desirability Flavor Tests The 0.75% sodium chloride white and whole wheat breads were rated significantly more desirable than the 1.0% breads in overall desirability. The judges in this study preferred breads with a lower concentration of sodium than commonly found in commercial products. The reduction of sodium levels in processed breads would probably not adversely effect 81 the overall desirability and acceptability of these products. Conclusions From the Triangle Tests The judges were not able to distinguish between white and whole wheat bread samples made with a 1:1 sodium - potassium chlorides mixture and those made with 100% sodium chloride. Therefore the breads made with a 1.0% level of the salt mixture were as acceptable as the products containing 0.75% sodium chloride. The sodium and potassium content of these breads are presented in Figure 4. The sodium - potassium ratios of the 1.0% salt mixture breads were 1.2 in white and 0.91 in whole wheat bread. The ratios of the 0.75% sodium chloride breads which were indistinguishable from the salt mixture samples, were 7.0 in white and 3.29 in whole wheat bread. It was concluded the use of a 1:1 sodium - potassium chloride mixture in both white and whole wheat breads was a successful means of lowering sodium - potassium ratios in bread while maintaining an acceptable product. The 1.0% salt mixture imparted the same degree of salty flavor as 0.75% sodium chloride. These results were in contrast to those reported by Mickelsen et. al_. in 1977. He concluded a 1:1 sodium - potassium chloride salt mixture on a weight basis was as salty as sodium chloride alone. The experimental results agreed rather well however with those reported by Kincaid £t. al_. in 1975. These authors reported a 1.2% aqueous solution of a 1:1 sodium - potassium chlorides mixture was equal in saltiness to a 1.0% sodium chloride aqueous solution. Von Skramlik reported in 1965 a 1.0 M solution of sodium chloride matched the saltiness of a 1.36 M solution of potassium chloride. Therefore potassium chloride 82 500 0.75% NaCI 1.0% Na-KCl 0.75% NaCI 1.0% Na-KCl mixture mixture White Bread Whole Wheat Bread Figure 4. Sodium (Na) and Potassium (K) levels in white and whole wheat breads. NaCI = pure sodium chloride Na-KCl = 1:1 sodium-potassium chloride mixture 83 was slightly less salty than sodium chloride. This relationship helps explain why judges prefered higher concentrations of the salt mixture than of sodium chloride in both white and whole wheat experimental breads. 84 SUMMARY Processing resulted in a general increase in the sodium - potassium ratio of tuna canned in oil and in water and an increase in the calcium - phosphorus ratio of tuna canned in water. The increases in the sodium - potassium ratios were due to freezing tuna in a salt brine, adding salt to the finished product and the loss of potassium during precooking. The increased calcium - phosphorus was due to the absorption of calcium from the water broth in which it was packed. Processing resulted in an increase in the sodium - potassium ratio of peanut butter due to the addition of salt to the finished product and the loss of potassium during precooking. The calcium - phosphorus ratio was uneffected by processing. The sodium - potassium and calcium - phosphorus ratios of whole wheat flour were uneffected by processing. White flour had a higher sodium - potassium and calcium - phosphorus ratio than the whole kernel. These increased ratios were due to the separation of bran and germ, which contained high levels of potassium and phosphorus, from the endosperm in the milling of white flour. The addition of salt to finished products for flavor had the greatest effect on the sodium - potassium ratios of the experimental foods. Yet, the judges in this study preferred white and whole wheat bread samples made with less salt than average commercial products. They also found breads made with a 1:1 sodium - potassium chlorides mixture as acceptable as those made with 100% sodium chloride. 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