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Handbook of Processed Meats and Poultry Analysis

Leo M.L. Nollet, Fidel Toldrá

Moisture and Water Activity

Publication details https://www.routledgehandbooks.com/doi/10.1201/9781420045338.ch3 Young W. Park Published online on: 12 Nov 2008

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The publisher does not give any warranty express or implied or make any representation that the contents will be complete or accurate or up to date. The publisher shall not be liable for an loss, actions, claims, proceedings, demand or costs or damages whatsoever or howsoever caused arising directly or indirectly in connection with or arising out of the use of this material. Downloaded By: 10.3.98.104 At: 22:17 27 Sep 2021; For: 9781420045338, chapter3, 10.1201/9781420045338.ch3 CRC_45318_Ch003.indd 35 © 2009byTaylor & FrancisGroup,LLC Chapter 3 . Mtoooiso osueDtriain...... 43 Determination of Moisture Methodologies ...... 3.7 42 Determination for Moisture ...... Methods Sampling 3.6 Determination toMoisture Related of Drying ...... 41 Mechanism 3.5 3.4 Water 38 Water Foods ...... Other and Meat in Activity 3.3 38 ...... of 37 Water Properties aFood System in ...... 3.2 3.1 Introduction ...... Contents Young W. Park Moisture and Water Activity 3.7.2 Indirect Methods ...... 59 3.7.1 Direct Methods ...... 45 3.7.2.6 Conductivity Method 3.7.2.5 63 Dielectric ...... Capacitance 3.7.2.4 Microwave 63 ...... Absorption 3.7.2.3 Near Method Spectroscopy Absorption Infrared ...... 61 Infrared–Refl 63 ...... 3.7.2.2 3.7.2.1 Refractometry ...... 59 Determination Moisture in Methods of Direct Application ...... 59 3.7.1.9 3.7.1.8 Gas Chromatography 3.7.1.7 Th 58 ...... 3.7.1.6 Chemical 56 Method Fischer Titration Karl ...... Desiccation 3.7.1.5 58 ...... 3.7.1.4 Distillation Methods 3.7.1.3 Freeze-Drying ...... 53 ...... 53 3.7.1.2 Vacuum-Oven Drying 3.7.1.1 Air-Oven ...... 51 Drying ...... 45 ermogravimetric ermogravimetric Method 58 ...... ectance Spectroscopy Spectroscopy ...... 61 ectance ... 36 ...... 35 9/8/2008 2:46:02 PM Downloaded By: 10.3.98.104 At: 22:17 27 Sep 2021; For: 9781420045338, chapter3, 10.1201/9781420045338.ch3 CRC_45318_Ch003.indd 36 © 2009byTaylor & FrancisGroup,LLC References ...... References 36 tively the most important component of the product, constituting up to75% component by weight. constituting product, of the important most the tively quantita- is or water moisture meat, consumer. In and processor food tothe economic importance great content content, has moisture moisture toits related inversely content is food matter in dry foodstuff of present in water amount the todesignate erature [1].foods Th testing and processing in indices used widely and content oneMoisture is important most of the 3.1 Introduction product [4]. product aff adversely can of moisture quantities small very some in cases, and materials food,industries paper, such as where plastics, and acceptable levels between of moisture vary tomany concern of great of quantity, its are determination the and of moisture, reactivity cal index of economic value, stability, of food products quality and [1,2]. Th by decomposition and loss in weight would aff would weight in loss by decomposition and decomposition[2]. product of the simultaneous Th withoutcausing sample ist. Th analysis of moisture is frequently one of the most diffi manufacturing. and consumption retail lowof of dependent water-holding with meat is both water-binding on purposes and the capacity [5]. water of tobind meat added ability the is water-binding Th capacity, which with together meat of the properties manufacturing tothe respect with important also is WHC quality. of meat determinant anegative is drip excessive consumer, and tothe unsightly is drip by weight, [5]. sold is meat Since structure its present water in tissue the of toretain meat ability It the meat. is of economic for value the parameter quality important an is water-binding capacity. WHC as well loss of volatile constituents from the food is another diffi industry applications. in especially sought, simultaneously are goals both if even or for accuracy, either rapidity selected usually are determination of moisture methods Analytical hazards. topresent no operational (f) precision, and good and (e) test, per accuracy low cost and tohavereasonable investment initial of low apparatus available (d) areadily touse brief training, with persons by nontechnical even be rapid, (b) to be applicable [8]. suggested Th been to has assay the for moisture method However, ideal an broadest arerequirements e (a) to range of materials, (c) tocontinuously be performable preferably sought,of other substances present although [6,7]. Th it may be doubtful that such a goal will ever be achieved [5]. e complexity of moisture assay will be dependent on the conditions of the food and the nature nature the and dependent be food of conditions on the the will assay of moisture ecomplexity

Th Th Although the determination of moisture content in foods is highly important, the accurate accurate the important, highly is content foods of in moisture determination the Although Accurate, rapid, and simple methods of moisture assay applicable to all types of foods are are of foods types toall applicable assay of moisture simple methods rapid, and Accurate, is is largely attributable to the diffi tothe attributable largely is is e amount of moisture is a measure of yield and quantity of food solids, and can be a direct adirect be can and ofsolids, food quantity and of yield ameasure is of eamount moisture e amount of water in food is also directly related to its water-holding capacity (WHC) as as (WHC) water-holding toits related capacity directly also is food of in eamount water Handbook of Processed Meats and Poultry Analysis Poultry and Meats ofProcessed Handbook Ⅲ e terms “water content” and “moisture content” have been used interchangeably in lit- in interchangeably “watercontent” content” “moisture eterms used and been have 3.7.2.10 Summary of Indirect Methods Methods of Indirect Summary ...... 65 3.7.2.10 64 Methods ...... Instrumental Indirect Other 3.7.2.9 3.7.2.8 Cryoscopic 64 Absorption Ultrasonic ...... and Sonic Methods 3.7.2.7 64 ...... culty of complete separation of all the water from a food afood from water the of of all complete separation culty ect the accuracy of the determination [2,6]. Th determination of the accuracy the ect cult tasks encountered by the food chem- food by encountered the tasks cult culty involved in moisture determination. s and other substances [2,3]. othersubstances Because s and e abundance and chemi- and eabundance e production of eproduction water ect the quality of quality the ect e desirability ...... 65 e 9/8/2008 2:46:03 PM Downloaded By: 10.3.98.104 At: 22:17 27 Sep 2021; For: 9781420045338, chapter3, 10.1201/9781420045338.ch3 CRC_45318_Ch003.indd 37 © 2009byTaylor & FrancisGroup,LLC diff the [10].of torecognize association more important it generally is However, analysis, for moisture degree in varying ice as solid forms several in and by bound bond hydrogen of forces, are water cules monomolecular state as gaseous water vapor, inliquid dihydrol, state as largely mole- inwhich two diff three present in be Physically, can water [9]. polarity due high toits reactive unusually is and nature Water in aubiquitous is substance Properties of Water in aFood System 3.2 from a few percent to approximately 12% toapproximately percent (wet component or afew from food food of basis) the [21]. BET monolayer the is BET monolayerrange [6]. water water bound the values For foods, most tightly [20]. data sorption isotherm Th moisture for modeling equations (GAB) Boer Anderson–de or Guggenheim– Brunauer–Emmett–Teller (BET) the using calculated commonly most are values water. Monolayer for surface except extent, toavariable water bound as considered be may water All to0.1–2.2 [14,19]. solids g/g corresponding present, 0.5 water total total toover of the than 30% less Th remainder. the than temperatures athigher for longer times retained is drying during asample in water of water. the Part not free the and water bound to the food to another. Th [14,19]. lower atconsiderably temperature frozen one from varies bound-water Such concentration [2]. − At drying or fi is water bound the which in of or proteins polysaccharides gels from observed clearly be can tion Water formhydrates. of hydra- also tartrate potassium as such salts monohydrates, and form stable lactose and maltose, dextrose, water.” as “bound such Carbohydrates ofwater hydration, so-called or forces hydrogenWaals bond formation. Th Th condensation. capillary or forces proteins) and by molecular cellulose, solid ofcomponents pectins, the (i.e.,faces starches, sur- or external internal on layer the mono- or polymolecular thin, avery as adsorbed of is water Th compounds. asolvent solutions, as or crystalline for and colloidal the molecular phenolics toform and gums, proteins, as such macromolecules for hydrophilic medium dispersing a as serves water Such material. of the pores the within and spaces intergranular the in water free as of frozen foods and food products [14]. products food and foods of frozen stability toimprove storage the believed is or of dehydration, addition sugar partial concentration, by freezing, content preserved tobe free-water of in foods decrease [22]. stability Likewise, storage Th storage. freezing and freezing during occur also of foods texture in changes Irreversible foods. (even at− by freezing readily not is separated for example, biocolloids, the present water in total proportion [2]. of the treatment heat Acertain toaparticular subjected is food when the unchanged [19].(c) water bound (e) and forces, osmotic water, chemically by bound physical water (d) colloidal water, (a) water, as occluded (b) exist capillary may material biological in found water that suggested been not It clear. has still ofare water bound nature the and systems colloidal of in water state the bonded [1,14,18]. chemically and adsorbed, of water—free, broad types involves three Th [3,11,15–17]. suggested been has aterm as use its minating classifi One alternative classifi be ever, can water rmly held [2,13–14]. by bonds hydrogen rmly us, removal of free water rather than bound water from dried foods has been known toimprove known been has foods dried from water bound than rather water of free removal us, erent types of interactions of water within a food rather than the physical state of [11]. water state physical the than rather afood of within water of interactions erent types Historically, water a in foodstuff Small changes in water content can exert a large infl alarge exert content water in can changes Small of defi of avariety Because Bound water has been defi been has water Bound remains formof that water the as of researchers majority ned by the e ultimate accuracy of an analytical method for moisture determination is related related is determination for moisture method analytical of an accuracy eultimate 125°C, all the free water is usually frozen, and the remaining bound water is not is water bound remaining the and frozen, usually is water free the 125°C, all ed in at least three forms [2,11–14]. forms three atleast in ed Th is water is closely associated with absorbing macromolecules by van der by van absorbingmacromolecules with associated closely is water is nitions, the concept of bound water is quite controversial, and ter- and quite is controversial, conceptof water bound the nitions, exists in two forms, known as “free” and “bound” [6]. How- [6]. “bound” and “free” as known forms, two in exists erent forms as gas, liquid, and solid state. It exists in the the in It solid state. exists and liquid, gas, erent as forms e third form of water is in chemical combination as as combination chemical in form of is water ethird uence on storage stability of low-moisture stability onuence storage Moisture and Water Activity Water Activity and Moisture e range of bound water in foods is is foods ofin water bound erange e fi rst form of water in foods exists exists foods form of in water rst e second form esecond cationscheme is is why e most 230°C) 230°C) Ⅲ 37 9/8/2008 2:46:03 PM Downloaded By: 10.3.98.104 At: 22:17 27 Sep 2021; For: 9781420045338, chapter3, 10.1201/9781420045338.ch3 CRC_45318_Ch003.indd 38 © 2009byTaylor & FrancisGroup,LLC moisture content in foods and other materials [2,13,23]. materials other and content foods moisture in of determination the in used have absorption been and scattering conductivity,light and thermal absorption), resonance conductivity,magnetic and constant, dielectric (high properties electrical [23].tion tendency Th aggrega- molecular own its ability, and ionization and dissolving constant, dielectric power, high sion, viscosity. and Th specifi including stants, specifi c heat, 38 various types of food with the same level of content level water signifi same exhibit the with of food types various However, food. of the perishability the of solutes decreases concentration the and increases turn in content water the of which reducing of afood, purpose for the performed ability. is Dehydration content water perish- its the ofand food between exists arelationship it not is perfect, Although 3.4 Water Activity [5]. of by anumber noncovalent forces surfaces slaughter. Th after immediately cut tissue from of occurs loss water little very and animal, living the in tissue the to [5]. structure agel proteins Muscle impart by animals protein content, young fected in except Th of binding. water mechanism role the in proteins have acentral and muscletissue, with Water associated is meat in Water in Meat andOther Foods 3.3 to a tightening of the myofi of the to atightening Th proteins. meat the in changes by caused are which of juice, release the and of tissue hardening and shrinkage including ucts, [5].volume and perishability [17]. perishability and of muscle fi the Th 50°C. and 30 between attemperature occurs WHC in decrease most and of tissue, rigidity and tenderness the in toalterations related closely are heating during WHC in whichaff offunction postmortem changes, mal, some loss as drip from freshly cut surfaces is inevitable. Th myofi thin and thick the between 85% Approximately bound of is water about 10% and more be would realistic. overestimate, an age, source, and growth season of the animal. Th animal. of the season growth and source, age, the with degree toalesser content fat on varies the and content primarily moisture depends their (Table origins plant 3.1) [17]. content fi of moisture and meat tothe respect with First, and dried eggs have approximately 74 haveapproximately 5% [1]. and eggs water, dried respectively and fresh to75% whereas chicken, geese in 50%in from contain of content. meats water tions Poultry from 50 to 70%, whereas some organs may contain up to 80% water. Sausages have wide varia-

Researchers have shown that water displays abnormally high values of certain physical con- physical of certain values high abnormally displays water have that shown Researchers Previously, up to 60% of water was thought to be bound by the myofi by the bound tobe thought Previously, of was water up to60% Drastic changes in WHC and tenderness in meat occur during heating of the meat prod- meat of the heating during occur meat in tenderness and WHC in changes Drastic Th ere are wide variations in moisture content of natural and processed foods of animal and and of animal foods processed and content moisture of in natural variations wide ereare Handbook of Processed Meats and Poultry Analysis Poultry and Meats ofProcessed Handbook Ⅲ is is attributed to the water molecule behaving as a dipole and binding strongly to strongly binding adipoleand as behaving molecule water tothe attributed is is bers of raw meat is closely connected with the tenderness of cooked meat [24]. meat of cooked tenderness the with connected closely is of meat raw bers e water content of meat is inversely related to fat content, whereas it unaf- content,is tofat whereas content ewater related inversely of is meat ese special constants may be derived from its remarkable and variable solvent variable and remarkable its from derived be may constants special ese e characteristics of water in chemical reactivity, volatility, solvent reactivity, power, chemical of in water echaracteristics brillar network by heat denaturation of the proteins [24]. Changes [24]. proteins of the by denaturation Changes heat network brillar is considerable decrease of WHC during heating is attributable attributable is heating during of WHC decrease considerable is brils [5]. Because this binding is looser than in the living ani- living the in than looser is binding [5]. this brils Because c gravity, heat of infusion, heat of evaporation, surface ten- ect the pH of the meat and the changes in myofi in changes the pHand meat of the the ect e range of moisture content in meat and fi content and meat of moisture in erange e amount of drip loss is mainly a cant diff brils, but this fi but this brils, e sarcomere length length esarcomere erences in stability stability in erences sh products, gure was brillar brillar sh is is sh 9/8/2008 2:46:03 PM Downloaded By: 10.3.98.104 At: 22:17 27 Sep 2021; For: 9781420045338, chapter3, 10.1201/9781420045338.ch3 CRC_45318_Ch003.indd 39 © 2009byTaylor & FrancisGroup,LLC include the growth of microorganisms and hydrolytic chemical reactions. a reactions. chemical hydrolytic and of microorganisms growth include the Th association. weaker in that than activities degradative support [17]. nonaqueous constituents to various ability with less has association strong Water in engaged be a useful indicator of product stability and microbial safety [17]. safety microbial and of stability product indicator auseful be suffi correlates it Th diff due tothe tially is about specifi 0.90,onis the depending a [25]. atan grow may c bacteria bacteria Some halophilic ronmental level. ronmental encounter, aff reactants chemical and enzymes, bacteria, grow well on foods having an a Molds can todryness. more resistant molds are bacteria, tomost Compared spoilage. food cause the range of 0.9–1.00. range Th the in activity awater require bacteria most growth, microbial permitting temperatures usual the At available to support biological and chemical reactions. a reactions. chemical and tosupportbiological available water activity equals RH/100. Quantitatively, a equals activity water conditions, equilibrium [25]. under humidity, and temperature torelative related is Water activity same ofatthe solution water of pure the of vapor vaporpressure pressure ratio tothe the is and of 0.75, and certain osmophilic yeasts can grow even atlower even a grow can yeasts osmophilic of 0.75, certain and the escaping tendency of a solvent from solution), and fo is the fugacity of the pure solvent. p/po is is p/po solvent. pure the of fugacity the a not equal does is sometimes and fo measured, term the and solution), from solvent a of tendency escaping the bility, safety, and other properties more reliably than water content can. Although a Although content water can. than more reliably properties other bility, and safety, e term “water activity” (a “wateractivity” eterm a par- is which products, of food Water of content perishability not indicator is alone areliable Th w e eff can be defi be can ect of a ect Fennema, O.R., MarcelDekker, inFood Chemistry New SourceYork,: Asparagus,beans(green),cabbage, caulifl Beets,broccoli,carrots, potatoes Avocado, bananas,peas(green) Vegetables Rhubarb,strawberries, tomatoes Apples,peaches,oranges, grapefruit Berries, cherries, pears Fruit Fish, muscleproteins Chicken, allclasses,rawmeatwithoutskin Beef, raw, retailcuts Pork, raw, compositeofleancuts Meat Food Water Contentsof Various Foods Table 3.1 lettuce ciently well with rates of microbial growth and many degradative reactions as to as reactions degradative many and growth of microbial rates with ciently well ned as a as ned w on microorganism growth is very important is very intermediate-moisture in on growth microorganism foods. erences in intensity of association of water with nonaqueous constituents. nonaqueous constituents. of with water of association intensity in erences 1996, 17–94. e minimum a w

p/po, where f is the fugacity of the solvent (fugacity means means = f/fo solvent of the (fugacity =p/po, fugacity the where fis w ) was developed to indicate the intensity with which water associates associates water which with intensity the toindicate developed ) was w of about 0.80, and can show slow growth at room temperature atroom temperature show slow growth can of about and 0.80, w below not which most important food bacteria grow will w is a measure of unbound, free water in a system w [17]. of solutions, aproperty is Water activity food at materials theecting microenvi- ower, Moisture and Water Activity Water Activity and Moisture w , not absolute content, water what is w , but these microorganisms seldom microorganisms , but these e degradative activities of water activities edegradative Water Content (%) 90–95 85–90 74–80 90–95 90–90 80–85 65–81 74 50–70 53–60 w can predict food sta- can w is not perfect, notis perfect, Ⅲ 39 9/8/2008 2:46:03 PM w

Downloaded By: 10.3.98.104 At: 22:17 27 Sep 2021; For: 9781420045338, chapter3, 10.1201/9781420045338.ch3 CRC_45318_Ch003.indd 40 © 2009byTaylor & FrancisGroup,LLC at a 40 ate-moisture foods, many of which have below 20% moisture [25]. moisture havebelow 20% of which many foods, ate-moisture a an months on with somefor foods several London, 1958.) in (Görling, P., temperatures. at various forpotatoes isotherms desorption Moisture 3.1Figure in Figure 3.1 [17,26]. Th Figure in shown as sorption water isotherms yield plots of data such [2,25]. Diagrammatic (ERH) humidity variety of food products.variety for awide established havebeen at 15% sorption water isotherms [2,25]. 100°C and Similar RH attained is equilibrium the to2% moisture, dries further product food the if Similarly, RH. 40% and at100°C at4% moisture into equilibrium comes product the [25]. that 3.1 Figure illustrates diff Th [2]. atmosphere the humidity, from it pick may up moisture above this whereas further, dried be can Fundamental Aspects oftheDehydration ofFoodstuffs Aspects Fundamental erent levels of humidity in bell jars and weighing the sample after several hours of exposure of hours exposure several after sample the weighing and jars bell in oferent humidity levels w Th below 0.65. However, such low a e humidity at which the product neither loses nor gains moisture is the equilibrium relative relative equilibrium the is moisture nor neither product gains loses the atwhich ehumidity Handbook of Processed Meats and Poultry Analysis Poultry and Meats ofProcessed Handbook Ⅲ e ERH atdiff eERH

Moisture content (g/g D.M.) 0.1 0.2 0.3 0.4 0.5 0 erent temperature can be measured by exposing the dried food sample to sample food dried the by exposing measured be can erent temperature e ERH diff eERH 0.2 er between foods. Below the atmospheric humidity level, food level, food atmospheric humidity the Below foods. er between w generally is not applicable in the fabrication of intermedi- fabrication the not in is applicable generally w 0.4 as low 0.70. as as Mold completely is growth inhibited p/po

0° 20° 40° 60° 80° 0.6 100° , Society of Chemical Industry, Industry, ofChemical , Society 0.8 1.0 9/8/2008 2:46:04 PM Downloaded By: 10.3.98.104 At: 22:17 27 Sep 2021; For: 9781420045338, chapter3, 10.1201/9781420045338.ch3 CRC_45318_Ch003.indd 41 © 2009byTaylor & FrancisGroup,LLC free liquid surface. Th the following. process, moisture loss from the sample occurs in two distinct stages or periods, which is detailed in drying the During of asample. determination moisture the in removal or moisture of drying nism aff drying of Th determination. moisture of the aspect acritical is sample ameat from of moisture Removal Mechanism of Drying Related to Moisture Determination 3.5 mentals of Food Engineering mentals ofFood S.E, (Charm, process. inafood-drying removal ofmoisture phases The 3.2 Figure water. Th food the [11,25].within Th diff due tomoisture dramatically, decreases rate drying where the period, end constant-rate of atthe the rate drying the in asuddendrop is there [2,11,25,27]. place takes stage, evaporation as this fast as After material of the surface the reaches constant-rate period [11,25,27,28]. drying Th infl indicates decomposition of fl indicates 3.3 Figure For example, high. too are that to temperatures when exposed decompose also can [1,11,14,18], illustrated commonly most be can decomposition of sugars Although products other decomposition. product causing temperatures higher toavoid using taken be However, must care employed be [11]. can conditions operating harsher and goal, not ultimate the high-quality dehydrated a toyield required conditions operating typical the under reached never food usually is water percent product [25]. During unspecifi under for carrots curve moisture determination, however, quality is fi tothe extends point and ection In the initial stage, the drying rate remains constant, and equals that of evaporation from a from of evaporation that equals and constant, remains rate drying the stage, initial the In Th More extreme time–temperature combinations may be used for the analysis of moisture. of moisture. analysis for the used be may combinations time–temperature More extreme e second stage of drying period, known as the falling-rate drying period, eperiod, at second begins the falling-rate of known as drying stage drying is infl ects ects the quantifi 100 50 0 ection point is frequently referred to as the critical moisture content moisture [2,11,25]. critical the toas referred pointfrequently is ection is stage of drying is controlled by surface evaporation, which is known as the the as known is which evaporation, by controlled surface is of drying stage is is sudden fall of drying rate is caused by the physicochemically bound cation of moisture in the food. It is desirable to understand the mecha- the to understand It food. desirable the is in of moisture cation Constant-rate dryingperiod our or other sugar-containing food products at temperatures above attemperatures products food or sugar-containing our other AVI Publishing, Westport, CT,, AVI Westport, 1971.) Publishing, ed drying conditions is shown in Figure 3.2 [25]. As shown, zero zero [25]. shown, 3.2 As Figure in shown is conditions drying ed Critical moisturecontent content [25,27,28]. moisture nal of adrying example An usion being reduced by physical or chemical interactions interactions or chemical by physical reduced usion being is phase of constant rate continues as long as water Dr Falling-rate dryingperiod y in g time Moisture and Water Activity Water Activity and Moisture The Funda- The e rate Ⅲ 41 9/8/2008 2:46:04 PM Downloaded By: 10.3.98.104 At: 22:17 27 Sep 2021; For: 9781420045338, chapter3, 10.1201/9781420045338.ch3 CRC_45318_Ch003.indd 42 © 2009byTaylor & FrancisGroup,LLC 42 Th sincelaboratory foodstuff analysis, diffi is absolutely sample representative Asingle value. of any is determination of nomoisture population, method sample of the representative are samples the Unless moisture analysis. before prepared be must food the of sample representative a that essential also is it sphere, moisture from toprevent opening before up toroom temperature towarm allowed should be container sample the condensing [11]. analysis tested, are samples chemical before appropriate on temperature refrigerated at an When the cold followed by storage labels, clear and closures tight with food. containers or glass plastic rigid dry in placed In addition [1,11,18]. toavoid exchange food, moisture to quickly should be they taken, are samples Once the avoiding abulk from taken or samples food, bulk for the atmosphere minimized should be tothe exposure sample exposure atmosphere [11]. and food the between gradients atmospheredue towater-activity to the Th to atmo- sample during moisture determination is important because [1,6,18,29]. batches larger from moisture ofsamples representative a handling the and selection Handling is easily gained from or lost Th Sampling Methods for Moisture Determination 3.6 low temperatures. relatively at decompose that for foods useful particularly is drying vacuum have shown that Researchers [29]. pressure reduced under by drying increased be can removal of rate moisture the peratures, tem- [29]. line high such of using straight the in Instead discontinuity depicted by the as 180°C, Bell, L.N. and offl Determination content. moisture the on oftemperature Effect 3.3 Figure us, sampling errors can sometimes be greater than the experimental error of analysis [6,7]. error of analysis experimental the than greater be sometimes can errors sampling us, e accuracy of moisture determination of a meat sample is largely dependent on the method of dependent method on the largely is of sample ameat determination of moisture eaccuracy

Handbook of Processed Meats and Poultry Analysis Poultry and Meats ofProcessed Handbook Ⅲ

Moisture lost by drying (%) Handbook of Food Analysis 10 11 12 13 14 15 16 17 100 Drying temperature/°C s and food ingredients are relatively heterogeneous materials. materials. heterogeneous relatively are ingredients food s and 150 , Marcel Dekker,, Marcel NewYork, 2002.) 200 250 moisture content extrapolated Theorical cult to obtain forobtain to cult our. (Park, Y.W. Y.W. (Park, our. erefore, erefore, 9/8/2008 2:46:04 PM Downloaded By: 10.3.98.104 At: 22:17 27 Sep 2021; For: 9781420045338, chapter3, 10.1201/9781420045338.ch3 CRC_45318_Ch003.indd 43 © 2009byTaylor & FrancisGroup,LLC Analysis of AOAC International summarized in Table in 3.1.summarized ucts [30]. Food-product conditions to be considered in sampling for moisture measurement are chemical, and physical methods [1]. methods physical and chemical, Th distillation, principles—drying, Tableshown in major One four by analytical wayis the 3.2. the sample should be carefully considered, depending on the food type. Th type. food on the depending considered, carefully should be sample the Th or blender processor food followed domestic by amodern mixing. using the Control and Determination ofMoisture Handbook one reviews, Pande published more of the extensive [1,3,14,18,29]. published havebeen determination of moisture on methodologies reviews Many Methodologies of Moisture Determination 3.7 Y.W. Bell, L.N. and (Park, sampling. forhomogeneous size reduction ofsample method Quartering 3.4 Figure repeated until a suitable sample size is obtained. Th obtained. is size sample asuitable until repeated the or Th mixed. thoroughly are glass, quarters two other the and Two paper, rejected, segments. are quarters glazed of sheet large a on pile top. bench Th laminated of aclean, uniform a surface into formed is food bulk the quartering, [7,29]. quartering as known In process the using reduced be can sample of apowdered bulk size infl can size particle in tions a sieve of suitable mesh size (18–40 mesh) to obtain a uniform particle size distribution [1]. Varia- [11]. samples wet of dry,and moist, homogenization for the of equipment pieces essential are grinders and powder mills, homogenizers, graters, mincers, ers, effi be can of samples mixing zation of depends food sample. on thorough thetype and Reduction of thesize in food particles as homogenous aspossible to have precise results analytical for moisture content. Th subdivided into groups may small that homogenous be treated as [6,29]. Food samples should be [7]. samples food heterogeneous For stratifi the stratifi whereas homogenous samples, food ate for relatively appropri- most concept [6,7].is sampling Random fundamental recommended most the is pling Generally, analytical methods of moisture determination can be classifi be can determination of moisture methods analytical Generally, Meat, fi Meat, diffi is types food applicable toall method sampling ageneral Finding Depending on the moisture determination technique, ground samples may be passed through through passed be may samples ground technique, determination moisture on the Depending Offi cial Methods of Analysis ofAOAC ofAnalysis International Methods cial , in four volumes four [7]., in for specifi methodologies Detailed sh products, and some vegetables having high moisture content are best homogenized homogenized content best moisture are high having some and vegetables sh products, Reject Accept Handbook of Food Analysis ofFood Handbook Accept Reject uence moisture values if too small a sample is analyzed [7]. Th analyzed is sample a small too if values moisture uence ciently accomplished using a number of mechanical devices. Blend- devices. of anumber mechanical using ciently accomplished describes minimum weight considerations for specifi considerations weight minimum describes quadrants and Mix accepted re divide e other is by direct and indirect procedures based on based procedures indirect and by direct is eother e pile is divided into four equal parts by separating quarter quarter by separating parts equal into four divided epile is , Marcel Dekker,, Marcel NewYork, 2002.) ed random sampling, the sample population is is population sample the sampling, random ed e quartering method is depicted in Figure 3.4. Figure in depicted is method equartering Accept Reject [30]. Accept Reject Moisture and Water Activity Water Activity and Moisture ed random sampling is employed for for employed is sampling random ed quadrants and Mix accepted if needed re divide bec found food products in can cult, but random sam- butrandom cult, e minimum weight of weight eminimum e ed in two ways, as as ways, two in ed Offi cial Methods of Methods cial e homogeni- c food prod- e process is is eprocess e aliquot Ⅲ 43 9/8/2008 2:46:05 PM Downloaded By: 10.3.98.104 At: 22:17 27 Sep 2021; For: 9781420045338, chapter3, 10.1201/9781420045338.ch3 CRC_45318_Ch003.indd 44 © 2009byTaylor & FrancisGroup,LLC 44 show the advantages and disadvantages of each individual method under the two classifi two the under method individual of each disadvantages and show advantages the classifi are determination of moisture methodologies [6]. of comparison, For purpose determination the off and nondestructive, rapid, are methods indirect [6]. However, time-consuming and manual, tedious, mostly are they although determination, calibrated. are they which against measurements of direct direct methods. Th against standard moisture values thatof have hydrogen been precisely determined of or water number amount on depend the either that food of the properties the atoms instead, usingdirectly; one or are more measured of the quantifi and not sample is removed the from moisture methods, However, indirect for the [6]. Th [6]. soforth and titration, by weighing, measured is quantity its and method, tion, or another extrac- distillation, by drying, solid-food the samples from water involves removing normally scientifi underlying the

It is known that direct methods usually give accurate and even absolute values for moisture for absolute moisture even values and accurate give usually methods direct that It known is Handbook of Processed Meats and Poultry Analysis Poultry and Meats ofProcessed Handbook Ⅲ ed into two categories, namely direct and indirect methods. In addition, Tables addition, In methods. 3.4 3.5 and indirect and direct namely categories, into two ed Source: Park, Y.W. in 7 6 5 4 3 2 1 Factors Affecting SamplePreparation forMoisture Determination Table 3.2 Dekker, New York, 2002,55–82. 59–92; Park, Y.W. andL.N.BellinHandbookofFood Analysis, Marcel erefore, the accuracy of indirect methods is dependent on the analytical values c theory shown in Table 3.3 [6]. In direct methods, moisture analysis analysis Table in shown moisture c theory methods, 3.3 [6]. direct In Time tobeanalyzed Storage temperature Storage period Sample storage Equilibriummoisturecontent Desorption Adsorption Stateofhysteresis Environmentalrelative humidity Decomposition Oxidation Aging ofsample Atmospheric(moisture,dust) Microbial(yeast, molds,bacteria) Chemical Sample contamination Quartering Stratified randomsampling Random sampling Representative sampling Homogenization, blending,mixing,grating,milling,sieve size, Sample preparation Particle size andshapeofsample Type ofwater interactionswithinfood Homogeneous versus heterogeneous Solid versus liquid Characteristics offood sample heat frommechanicalsamplingdevice Handbook ofFood Analysis, MarcelDekker, New York, 1996, is indicates that indirect methods must indirect is indicates that be calibrated er the possibility of automation for continuous possibility er the cations. ed 9/8/2008 2:46:05 PM Downloaded By: 10.3.98.104 At: 22:17 27 Sep 2021; For: 9781420045338, chapter3, 10.1201/9781420045338.ch3 CRC_45318_Ch003.indd 45 © 2009byTaylor & FrancisGroup,LLC infrared (IR) heaters and can be equipped with built-in balances for routine and fast analysis, analysis, fast for routine and built-in equippedwith be balances can and heaters (IR) infrared or by electricity heated ovens [18]. convection oven usually than ovens are drying Modern within the oven [1]. Forced-draft ovens off be thermally regulated to ± ovens [1]. ovens or forced-draft either convection-type using Th accomplished world the [1,7]. around be laboratories in can determination for moisture routine Drying ods Air-oven drying is very convenient, and is one of the most widely and commonly used meth- 3.7.1.1 Air-Oven Drying 3.7.1 Direct Methods Source: Park, Y.W. in methods Cryoscopic Conductivity Dielectriccapacitance Microwave absorption Electrical Neutronscattering Refractometry NMR GC NIRreflectance IRabsorption Physical methods Generationofacetylene KarlFischer titration Chemical methods Reflux distillation Directdistillation Distillation methods Thermogravimetricanalysis Chemicaldesiccation Freeze (lyophilization) drying Vacuum drying Oven drying methods Drying Major Principles Classifi bycation Four Classification of Analytical MethodsforMoisture Determination Table 3.3 New York, 2002,55–82. 59–92; Park, Y.W. andL.N.BellinHandbookofFood Analysis, MarcelDekker, Handbook ofFood Analysis, MarcelDekker, New York, 1996, 0.5°C and have minimal temperature variations (less than than (less variations temperature 0.5°C haveminimal and er a more consistent temperature throughout the the throughout er amore temperature consistent Moisture and Water Activity Water Activity and Moisture Thermogravimetricanalysis Cryoscopic methods Cryoscopic Refractometry Neutronscattering Dielectriccapacitance Conductivity Microwave absorption Electricalmethods Massspectrometry NMR NIRrefl IRabsorption Spectroscopicmethods Indirect methods GC Extractionmethod KarlFischer Chemicaltitrationmethod Refl Directdistillation Distillationmethods Chemicaldesiccation Vacuum oven Airoven Oven drying Gravimetricmethods Direct methods Freeze drying Sonic andultrasonic Classifi bycation Direct/ methods ux distillation Indirect ProceduresIndirect ectance eovens should ± Ⅲ 3°C) 45 9/8/2008 2:46:05 PM Downloaded By: 10.3.98.104 At: 22:17 27 Sep 2021; For: 9781420045338, chapter3, 10.1201/9781420045338.ch3 CRC_45318_Ch003.indd 46 © 2009byTaylor & FrancisGroup,LLC Karl Fischer Distillation reedyn Excellent for sensitive, high-value Freeze-drying Vacuum-oven vndyn tnadcnetoa ehdVariations oftemperaturedueto Standardconventional method Oven drying Method Advantages andDisadvantages ofDirect MethodsforMoisture Determination Table 3.4 46 method methods drying

Handbook of Processed Meats and Poultry Analysis Poultry and Meats ofProcessed Handbook Ⅲ The accuracy and precisionare The accuracy A standardmethodfor moisture Suitable for samplescontaining Not affectedbyenvironmental Water dropletsmayadhereto Prevents oxidation ofsample Takes relatively time(30min short paau ssml ohnl Organicsolvents suchastoluene maybegreaterthan Accuracy Apparatus issimpletohandle No case-hardening time Long drying No foaming texturePreserves andappearance Determines water directly rather No bacterialchanges during No oxidation Uniform heating andconstant Lower numberofsamplesthan Prevents sampledecomposition Lower heatingtemperatures Attain thedesiredtemperature ovnetDifficult toremove allwater Loss ofvolatile substancesduring Accommodates large numberof Relative speedandprecision Convenient higher thanwithothermethods analysis volatile substances humidity to 1h)determine oven-drying method oven-drying than weight loss drying liquid foods evaporation possible more rapidly samples Advantages Titration endpointmaybediffi Chemicals ofthehighestpurity Emulsions mayform Can have higherresultsdueto Organic solvents maybetoxic Sample mustbeinitially frozen Low precision ofmeasuringdevice Most applicabletohighmoisture Expensive Drying effiDrying reducedfor ciency high- Possible volatile loss Decomposition ofsample(i.e., to determinevisually reagent must beusedfor preparingthe causing erroneous results oftheapparatus, internal surface alcohol) components (e.g.,glycerol and distillation ofwater-soluble pose afi foods moisture foods drying oven drying sugar) drying position intheoven, etc. size, sampleweight,particle re hazard Disadvantages cult 9/8/2008 2:46:05 PM Downloaded By: 10.3.98.104 At: 22:17 27 Sep 2021; For: 9781420045338, chapter3, 10.1201/9781420045338.ch3 CRC_45318_Ch003.indd 47 © 2009byTaylor & FrancisGroup,LLC Source: Park, Y.W. in GC Thermogravimetric Chemical Method (Continued) Table 3.4 2. Analytical balance with 0.1 with sensitivity. mg balance Analytical 2. steel, 1. should dishes orWeighing aluminum, Metal not porcelain. stainless dishes—nickel, 3.7.1.1.1 Required Apparatus [2,11]. references similar other as [30] well as follows. Th Th reweighing. and cooling, drying, ing, weigh- preparation, sample steps: involve following the generally balance analytical oven and ing compounds [6]. signifi should not and contain stable thermally tobe needs sample the on loss, weight based is principle the of [6]. oven stable is drying food Because the assuming analysis desiccation Operational procedures for the conventional method of moisture determination using adry- using determination of moisture method conventional for the procedures Operational be used when the sample may be corrosive. be may sample when the used be Y.W. andL.N.BellinHandbookofFood Analysis, MarcelDekker, New York, 2002,55–82. ese procedures have been basically adopted from offi Handbook ofFood Analysis, MarcelDekker, New York, 1996,59–92;Park, Results similartoconventional Analysis israpid(takes 5–10min Sample size issmall Weighing error isminimalbecause More automatedmethodthan Moistureequilibrium dependson Good for measuring moisturein Can bedoneatroomtemperature Can serve asareferenceCan serve standard Ascorbicacidandothercarbonyls Automated equipmentavailable Once theapparatusissetup, Useful for determiningwater in methods per sample) sample isnotremoved fromoven standard oven drying compounds substances containingvolatile for othermethods minutes determination takes afew oxidation fats andoilsbypreventing Advantages e general principles of the procedures are described as as described are principles procedures of the egeneral Moisture and Water Activity Water Activity and Moisture Requires expensive equipment Sample extraction required Unit costpersamplemaybehigher Sample maydecomposeoroxidize Small samplemaynotbe Excellent for research,butnot Requires alongtimetoachieve Titration apparatusmustbe The reagent isunstableandneeds than drying oven than drying representative practical strength ofdesiccant constant dry weight constant dry content over-estimation ofthemoisture can reactwithreagents, causing of reagent tomoisture moisture duetoextreme sensitivity protected fromatmospheric standardization before use cially accepted cially AOAC procedures Disadvantages cant amount of volatile volatile of amount cant Ⅲ 47 9/8/2008 2:46:05 PM Downloaded By: 10.3.98.104 At: 22:17 27 Sep 2021; For: 9781420045338, chapter3, 10.1201/9781420045338.ch3 CRC_45318_Ch003.indd 48 © 2009byTaylor & FrancisGroup,LLC odciiyMaueeti ntnaeu Measuresonlyfreewater Measurementisinstantaneous Conductivity RAsrto Canperformmulticomponent IR Absorption Method Advantages andDisadvantages ofIndirect MethodsforMoisture Determination Table 3.5 48 NIR refl Determinationtakes only 5–10 Refractometry Dielectric Microwave spectroscopy Capacitance absorption

Handbook of Processed Meats and Poultry Analysis Poultry and Meats ofProcessed Handbook Ⅲ ectance Nondestructive Simple method System canbemodified tohave Precise Rapid Dependentonhomogenization Temperature-dependent Nondestructive analysis Most versatile andselective Excellent methodfor high-sugar Reasonable accuracy Does notrequirecomplex or Convenient toindustrial Has highsensitivityduetolarge Equipmentisexpensive Nondestructive Minimum samplepreparation No extraction required Nondestructive More accuratethanlow- No extraction required universal applicability analysis products expensive instrumentation measurement system operations withthecontinuous dielectric constantofwater min (rapid) capacitance meters resistanceor frequency Advantages Conversion areneeded to charts Difficult tomeasureboundwater at dependsoncalibration Accuracy Solid samples(e.g.,meat)require Requires uniformity offl Potential calibrationdiffi Affected bytexture ofsample,packing, Interference between chemicalgroups Refl Absorption bandofwater isnot Temperature sensitive Results affectedbyfactors suchas Depends onthefluctuation ofthe Possible leakage ofmicrowave energy dependsoncalibrationof Accuracy Temperature-dependent Has relatively lowsensitivityand obtain totalmoisturevalues high frequencies pH 2.7–6.7 density, andhomogeneity size, shape,packing sample particle effi ofsample ciency against reference standard solvent homogenization inananhydrous moisture distribution temperature,and electrolytes, standard samples (e.g., hydroxyl andamine) specifi of sample contents, polarization,andfrequency size, temperature,solublesalt particle measured material densityinthevolume determinations limited range for moisture during measurement ectance dataareaffectedby c Disadvantages uid samples culty beyond 9/8/2008 2:46:05 PM Downloaded By: 10.3.98.104 At: 22:17 27 Sep 2021; For: 9781420045338, chapter3, 10.1201/9781420045338.ch3 CRC_45318_Ch003.indd 49 © 2009byTaylor & FrancisGroup,LLC Source: Park, Y.W. in Very rapidanalysis NMR Spectroscopy Cananalyze simultaneously a Mass spectroscopy Sonic andultrasonic Neutron scattering Method (Continued) Table 3.5 10. Th products. dairy as such samples high-moisture 9. for predrying used is bath—it Steam 8. Crucible spoon. or plastic 7.Spatula tongs. for low-moisture samples. mill and Grinder 6. samples. for or high-moisture equivalent Waring, Blender—Oster, 5. 4. Atmospheric effi an 3. Desiccator—containing oven. absorption method sulfate, or calcium chloride. or calcium sulfate, ermometer ermometer (0–130°C). Y.W. andL.N.BellinHandbookofFood Analysis, MarcelDekker, New York, 2002,55–82. Handbook ofFood Analysis, MarcelDekker, New York, 1996,59–92; Park, Suitable for soil moistureassay Accurate Nondestructive Bound water canbedetermined The absoluteerror isclaimedto Density andmoisturemeasured Nondestructive No electricalleakage problem Precise Particle size andpackingof Can differentiatebetween free Applicable tomany typesof electrolytes andnonelectrolytes electrolytes in aqueoussolutionof be lessthan±0.5% simultaneously to thebeamtube due tolowpotentialsapplied from acomplex matrix large number of components effect onsignalabsorption granular sampleshave no and boundwater foods Advantages cient desiccant such as phosphorus pentoxide, calcium calcium pentoxide, phosphorus as such desiccant cient Moisture and Water Activity Water Activity and Moisture Dependent onthetypeofmediumfor Expensive Applicable only tosubstancesthatare are Separate calibrationcurves Major instrumentalproblemis High variationbetween theoretical Appropriate standardsrequiredtoget Not applicablefor foods having Constant andcorrect sampleweight Difficult tomaintaincalibrationofthe andprecisionareaffectedby Accuracy Cost ofequipmentishigh sound passes relatively proton-free required for different substances sample effectfromthe preceding memory substances moisture valuesandhydrated total moisturecontent equipment variable lipidcontents required contact between electrodeandsamples content,and temperature, electrolyte Disadvantages Ⅲ 49 9/8/2008 2:46:06 PM Downloaded By: 10.3.98.104 At: 22:17 27 Sep 2021; For: 9781420045338, chapter3, 10.1201/9781420045338.ch3 CRC_45318_Ch003.indd 50 © 2009byTaylor & FrancisGroup,LLC 50 Calculations of Moisture Content 3.7.1.1.3 loss. moisture calculate and balance analytical onWeigh the dish the 5. aspecifi 4.After atmospheric oven, the contact in avoiding shelf without cover its metal on the dish the Place 3. into apreweighed sample a2–5-g weigh quickly thoroughly, sample and prepared the Mix 2. at100°C. hours oven for an several in dry and 1. thoroughly, rinse, Wash dishes empty the Procedure for Drying Oven 3.7.1.1.2

Handbook of Processed Meats and Poultry Analysis Poultry and Meats ofProcessed Handbook Ⅲ Cream (liquidandfrozen) Nuts (almonds,peanuts,walnuts, etc.) Evaporated milk Ice creamandfrozen desserts Egg albumin(dried) Egg albumin(liquid) Cottage cheese Product of MilkandOtherFoods Atmospheric-Oven Temperatures and Time SettingsforOven Drying Table 3.6 Condensed skim Milk (whole,lowfat,andskim) Chocolate andcocoa Cheese (natural-typeonly) Buttermilk (liquid) Source: AOAC,Offi driedonsteambathbefore placingin Xindicatesthatsamplesmustbepartially Note: temperature. toroom tocool min 30 for atleast it desiccator into oven, the place the from and dish products. food for selected times drying and peratures, toTable oven Refer tem- requirements, 3.6 walls. for steam-bath the and dish the between bottom dish. of the the across evenly 0.1 spread should be sample the nearest mg; tothe balance analytical an using dish use. before atroom temperature desiccator Store aclean in oven. tional, Arlington, VA, 1995. ed time in the oven, use tongs to place the cover onto the dish, remove cover onto the dish, the the toplace oven, tongs the use in time ed cial MethodsofAnalysis ofAOAC International,AOAC Interna- Moisture (%) Moisture ois()10moisture (%) 100 Solids (%) ϭ ϭ ls fwih 100) (loss ofweight Steam Bath Ϫ (sample weight) (sample Dry on Dry X X X X X X ϫ Oven Temperature

(°C ±2)

130 100 100 100 130 130 100 0 16–18 100 105 100 100 100 Oven (h) Time in 3 3 3 3 0.75 0.75 3 3 3 3 3.5 9/8/2008 2:46:06 PM Downloaded By: 10.3.98.104 At: 22:17 27 Sep 2021; For: 9781420045338, chapter3, 10.1201/9781420045338.ch3 CRC_45318_Ch003.indd 51 © 2009byTaylor & FrancisGroup,LLC method is used for moisture determination. Diff determination. moisture for used is method It is important to carefully consider the length of time required in the oven when the drying close and reproducible estimate of the true moisture content moisture of[1]. afood true of the reproducible and close estimate a yield can drying but vacuum methods, content absolutean moisture by sample of drying the [1]. reduced dramatically It toobtain be impossible be may can times drying and pressure, reduced toprevent decompositionproducts [1,7,14,18]. atthe more quickly evaporated be can Moisture pressure of 25–100 low with up to98–102°C, foods mm heat can Hg usually Vacuum [1,14]. foods. drying in analysis for moisture Lower temperatures method drying accurate most and standard the as considered generally [6,7], is ing method this (60–70°C) are used for overcome be dry- by vacuum-oven can air-oven drying high-sugar with associated drawbacks many Since food 3.7.1.2 Vacuum-Oven Drying decomposition [14,18]. toprevent kept should below be 70°C sample bath steam of the temperatures predrying the sugar, [1]. 2mg/5 gsample than fl of less of these many Because change should show amass hour apart an Typically, weighings negligible. is successive mass two offi of AOAC International many food products have been determined be found and can in the tages of the vacuum drying method are also described in Table in described also 3.4. are method drying vacuum of the tages by AOAC. recommended as Th of foods determination for moisture methods direct oven other by and vacuum products food for conditions selected some drying lists of 25–100 Hg[30]; hatapressure mm Table oven for 2–6 at100°C avacuum in 3.7by heating [1,18]. foods ture determined usually AOAC contents are tothe moisture According procedures, for high-mois- oven, vacuum especially of the usefulness oven the the reduce would inside water of oven, into vapor the pressure the air dry without purging drying; oven during vacuum into the [1]. of rate drying introduced is the air increase Dry will pressure reduced the because Hg, 50 mm below pressures tohave [7], desirable chamber sample the it inside usually is maintained be Hg can mm of 100–600 avacuum Although gasket. on arubber grease vacuum front using doors airtight Th heated. electrically and line toavacuum nected Table in listed are 3.4. methods, of direct other those as well as methods, of drying air-oven eff buoyancy balance and location and type container, fi as such sample factors Postdrying the of shape and size are decomposition. and compounds, of loss volatile scorching, time, element, drying heating of the conditions drying the with associated humidity. Factors relative velocity, and air pressure, includetemperature, determination moisture infl that conditions Oven accuracy. balance and spillage, time, weighing treatments.drying Sample weighing is infl may result frominfl variations in sample weighings, oven conditions, drying conditions, and post- follows [2,11]:follows cial method, samples are periodically weighed during the drying process until the change in in change the until process drying the during weighed periodically are samples method, cial uenced by a number of factors. Erroneous results in moisture determination by oven drying Th Th Th ere are several types of vacuum ovens available. Laboratory type vacuum ovens can be con- be ovens can vacuum type Laboratory ovens available. of vacuum types several ere are be can of moisture determination for the procedure drying particular of any eaccuracy e required apparatus and general procedure for vacuum-drying method are delineated as as delineated are method for vacuum-drying procedure general and apparatus erequired [30]; some of these are summarized in Table in For [30]; 3.6. without an products summarized are some of these ect may also contribute to erroneous data. Advantages and disadvantages disadvantages and Advantages contribute data. toerroneous also may ect nal temperature at weighing, desiccator effi desiccator atweighing, temperature nal uenced by adsorption of atmospheric vapor, length of of length vapor, atmospheric of adsorption by uenced erent oven temperatures and drying times for times drying and erent oven temperatures ese vacuum ovens are typically equipped with with equipped typically ovens are vacuum ese Moisture and Water Activity Water Activity and Moisture uid products contain large amounts of amounts large contain products uid e advantages and disadvan- and eadvantages ciency, sample, of loss dried Offi ofAnalysis Methods cial uence the accuracy of accuracy the uence Ⅲ 51 9/8/2008 2:46:06 PM Downloaded By: 10.3.98.104 At: 22:17 27 Sep 2021; For: 9781420045338, chapter3, 10.1201/9781420045338.ch3 CRC_45318_Ch003.indd 52 © 2009byTaylor & FrancisGroup,LLC 52 4. Turn off oven, the evacuate dish, uncover the oven, vacuum partially the in dishes sample Put the 3. 2. Weigh the a in cooling oven. After alaboratory in dried and washed be must 1. dishes sample Metal sample Procedure for Vacuum (3.0–5.0 Drying 3.7.1.2.2 g) for air-oven drying. those into as equipment same and the are apparatus Other 3. the preweighed close-fi with dishes Dishes—metal 2. dish using of pump capable avacuum with connected and controlled Vacuum 1. oven—thermostatically an analytical 3.7.1.2.1 Required balance.Apparatus 5. Dry for another hour to ensure that constant weight has been achieved. been has weight constant that hour toensure for another Dry 5.

Handbook of Processed Meats and Poultry Analysis Poultry and Meats ofProcessed Handbook Ⅲ oven. into the desiccant indicating the through by passage dried of aslow air current admit drying, During pressure. vacuum and appropriate atan temperature sample the dry and toprevent splattering. decomposition and for drying air-oven described as predrying require Some samples dish. overof bottom the the evenly sample the Distribute to0.1 dish the mg. desiccator, weigh plate. heating the with contact vacuum. the for releasing atrap and desiccant indicating an through passes that oven the below 25 in Hg.Th mm pressure the maintaining reweigh. and tocool, toadesiccator dish the transfer tongs, using onto dish the cover lightly the the vacuum pump after 5 h and slowly readmit dry air into the oven. into the Press air dry slowly readmit 5hand pump after vacuum the Reineccius,G.A.andP.B. Addis, J. Food Sci., Source: d c b Turkey Cheek meat Bull meat Cow meat Emulsion, frankfurter Salami Navels Pork trim Pork jowl Samples by Conventional andGCMethods Moisture ContentofMeatSamplesObtained Table 3.7 a Fat Oven drying at105°CforOven 24h. drying Emulsion obtainedimmediately before extrusion. Toluene distillation. Mean offi ve determinations. c tting lids and fl and lids tting 75.9 71.4 69.4 55.4 40.5 38.2 36.6 27.2 51.1 GC 6.9 at bottoms to provide maximum area of area toprovide maximum at bottoms Moisture (%) e oven should have a dry air inlet inlet air e oven should have adry Conventional

38, 355,1973. 76.3 69.9 70.6 54.9 39.3 38.0 37.2 27.1 51.0 a 6.6 d d d d b b b b b b 9/8/2008 2:46:06 PM Downloaded By: 10.3.98.104 At: 22:17 27 Sep 2021; For: 9781420045338, chapter3, 10.1201/9781420045338.ch3 CRC_45318_Ch003.indd 53 © 2009byTaylor & FrancisGroup,LLC 3.7.1.2.3 Calculations of Moisture of Calculations 3.7.1.2.3 measured. volume removed the water then of is the tube; agraduated in collected is and condenses, liquid, point [1,14,18]. boiling ahigh has and water with Th immiscible is oil), (e.g., aliquid which in heated is mineral afood method, distillation direct the refl and distillation determination—direct for moisture methods distilled with an immiscible liquid at a constant ratio. Th Th 3.7.1.4 Distillation Methods Table in listed some are of which 3.4. advantages, many has [25]. costs equipment However, and tolower drying freeze-drying process lyophilization the both [25]. on optimizing focused Much development of the has work, therefore, tofi two be may cost its Th technique. drying advanced evolvedinto ahighly has process chops [25]. lyophilization and the years, recent In steaks even and mushrooms, sliced as coff foods. Freeze-drying or lyophilization is especially suited for dryinghigh-value liquid foods such Th 3.7.1.3 Freeze-Drying this freeze-dry method for ordinary moisture analysis of food samples. However, this lyophilization lyophilization this However, samples. food of analysis moisture [1]. determination for moisture method reference acomponent as of astandard desirable is method ordinary for method freeze-dry this 8h or be may longer. Th freeze-drying fi the until food frozen center of the the toward torecede continues and surface removed the from initially is moisture progresses, [25]. ice the of short just melting added freeze-drying is heat As dryer. Th of the chamber vacuum the within rate sublimation the toenhance food frozen applied tothe [25]. sample content frozen of moisture the the frequently in is Heat anetreduction causes which onto food, atmosphere reentering the surrounding the in water than faster food the vapor leaves Hg[31]. water below 4.6mm and sures frozen remains food the in water conditions, Under these pres- and below 0°C attemperatures Water (sublimation) food. ice of from the occurs evaporation structure physical the preserves lyophilization thus, into water; liquid vapor withoutwater melting conversion to of ice direct the is Sublimation conditions. temperature and pressure reduced under nal ice sublimes, leaving a moisture content of less than 5% for [25]. content times than amoisture of less leaving Completion of drying sublimes, ice nal e property of “azeotropy” in water is utilized for this method, where water is simultaneously simultaneously is where water method, for this utilized is water in of “azeotropy” eproperty of dried quality textural and freshness for preserving freeze-drying than method no better ereis Th e main principle of lyophilization is facilitating the sublimation of water from the sample sample of the from water sublimation the facilitating is principle of lyophilization emain ee and juices, as well as high-value solid foods such as strawberries, shrimp, diced chicken, chicken, diced shrimp, strawberries, as such solid foods high-value as well as juices, and ee e maximum drying rate occurs when the vacuum is maintained at 0.1–2 mm Hg and ve times greater per weight of water removed than other drying methods methods drying other of removed water weight per than greater ve times osue() ( Moisture ois()10moisture (%) 100 Solids (%) e high cost of the equipment may limit the availability of % ϭ ϭ () ae volume water () apeweight sample Ϫ e water in the food distills directly from this this from directly distills food the in ewater is method drying has the limitation that Moisture and Water Activity Water Activity and Moisture ere are two main types of distillation of distillation types main two ereare ϫ 100 ux distillation [1,14,18]. First, for for [1,14,18]. First, distillation ux Ⅲ 53 9/8/2008 2:46:06 PM Downloaded By: 10.3.98.104 At: 22:17 27 Sep 2021; For: 9781420045338, chapter3, 10.1201/9781420045338.ch3 CRC_45318_Ch003.indd 54 © 2009byTaylor & FrancisGroup,LLC 4. Run cold water through the condenser and gradually heat the fl the heat gradually and condenser the through cold water Run 4. refl the Assemble 3. solvent mL. suitable enough 60–100 (e.g.,Add toluene) usually 2. food, tocover the 54 1. Weigh a food sample containing 2–5 g water and place the sample in an appropriately sized appropriately sized an in sample the place and gwater 2–5 Weigh containing sample a food 1. Procedure3.7.1.4.3 Xylene or 1. toluene 3.7.1.4.2 Reagents 2. Heating 1. mantle Refl 3.7.1.4.1 Apparatus procedures. distillation the with [18].lems associated disadvantages and Table advantages the 3.4 delineates prob- two these help water with volume the of collected reading before tocool apparatus the allowing and glassware clean Using droplets. water suspended and formation emulsion as such [31]. of products for avariety levels Th comparison between refl have shown consistently the theoretical moisture content to Th within 0.1% compounds. volatile of [6].concentration A moisture value [6–7,31].reactions Th [1,18]. heating during decomposition food of the less Th eff heat volume water measured. the is then and separated is water where the apparatus, measuring asuitable in collected toluene, again is water the with case the in as toluene 80% [31]. and water 20% mately co-distillate, its than denser is water If approxi- is mixture of the ratio 85°C; is distillation the mixture point binary of the boiling the toluene 100 110.6°C, of and points water and are [31]. boiling but respective the example, an As point of eithercomponent boiling the lower than atatemperature frequently and ratio a constant off toluene solvent, distill as Water or such immiscible xylene, an and [1,6–7,14,18].method Th heating source under a round-bottom boiling fl around-bottom boiling under source heating distillation are outlined as follows [2,11]. follows as outlined are distillation solvent (e.g., toluene). Th the side arm of the Bidwell–Sterling receiver. Th Bidwell–Sterling of the side arm the above positioned directly is Acondenser aside arm. in water distilled the measure and collect will

Second, the refl the Second, An apparatus of the refl of the apparatus An transfers which liquid, aboiling with by distillation achieved be can A rapid distillation Handbook of Processed Meats and Poultry Analysis Poultry and Meats ofProcessed Handbook Ⅲ round-bottom fl round-bottom ectively to the sample [1]. Th ux distillation apparatus (see Figure 3.5) (see Figure apparatus distillation ux ux distillation procedure is more commonly used than the direct distillation ask. Th is distillation method is especially suitable method is especially is distillation for samples a having high ux apparatus as shown in Figure 3.5. Figure shown in as apparatus ux e round-bottom fl is procedure makes use of the azeotropic properties of solvent mixtures. of solvent properties mixtures. azeotropic of the use makes procedure is ux distillation using toluene and oven-drying methods showed similar showed similar methods toluene oven-drying using and distillation ux ux distillation system is shown in Figure 3.5. Figure in shown Th is system distillation ux is could be 10–15 be could is orgspice. 40 gcheese e lowered boiling point of the distillation mixture causes causes mixture point distillation of the elowered boiling ere are some potential diffi some potential ereare e research data collected from azeotropic distillation distillation azeotropic from collected data eresearch ask is connected to a Bidwell–Sterling receiver, which receiver, which toaBidwell–Sterling connected is ask ask, and the fl the and ask, e apparatus, reagents, and procedure of the refl of the procedure and reagents, eapparatus, is procedure also minimizes oxidative ask contains the food sample and the the and sample food the contains ask culties for the refl forthe culties ask until refl until ask together during heating at heating during together is system consists of a uxing starts. uxing uxmethod, ux 9/8/2008 2:46:06 PM Downloaded By: 10.3.98.104 At: 22:17 27 Sep 2021; For: 9781420045338, chapter3, 10.1201/9781420045338.ch3 CRC_45318_Ch003.indd 55 © 2009byTaylor & FrancisGroup,LLC Calculations 3.7.1.4.4 side volume arm. the the of in water Record 8. 7. Turn the with condenser the rinse side arm, the in collected is moisture 6. no additional When off of rate water the When second. per of condensate drops two toproduce heating the Adjust 5. Y.W.(Park, Bell, L.N. and Bidwell-Sterling receiver. with method distillation forazeotropic Apparatus 3.5 Figure 1–1.5 more Total a few minutes. typically solvent is h. continue time heating heat and second. per drops four toyield heat increase decreases, accumulation the heat and allow the apparatus to cool, especially the side arm. the to cool,especially apparatus the allow and heat the Bidwell−Sterling Receiver Handbook of Food Analysis ofFood Handbook Moisture (%) Moisture 10 ml ϭ Condenser ls fwih 100) (loss ofweight (sample weight) (sample , Marcel Dekker,, Marcel NewYork, 2002.) Moisture and Water Activity Water Activity and Moisture ϫ

Boiling flask Heate r Ⅲ 55 9/8/2008 2:46:06 PM Downloaded By: 10.3.98.104 At: 22:17 27 Sep 2021; For: 9781420045338, chapter3, 10.1201/9781420045338.ch3 CRC_45318_Ch003.indd 56 © 2009byTaylor & FrancisGroup,LLC method is found in Table found in is method 3.4. Fischer Karl of the disadvantages and advantages of the listing [6]. Amore methods other detailed of those than higher found to be have been Fischer method precision Karl of and the accuracy [6–7,18]. million per parts of toafew water amount the Th able toquantify being methods, [1,30]. foods sugar-rich and molasses, Th liquid products, cacao fats, and oils approved vegetables, been for dried has technique chemical [1,18]. results erratic give methods this heating for using which foods assay in Moisture moisture [9]. precision, speed applicable and for due high measuring solids selectivity, toits It especially is and of liquids determination for moisture method astandard become has Fischer method Karl 2H of the method is 1853. in proposed by of Bunsen water, presence was the ide in which Th Th Fischer Karl Titration Method 3.7.1.5 [2,11]. sources other as [30] ofAOACwell as Analysis International protocols for specifi experimental Detailed 56 Fischer modifi shown as follows [1,18,33]. follows shown as Th methanol. and dioxide, sulfur Fischer apparatus are shown by Pande are [7].Fischer apparatus Karl of the representations by apotentiometer [18].endpoint determined is diagrammatic Several where the or by titration, photometric or determination), by coulometric (detected eithervisually iodine of brown color free from appearance by the endpoint where indicated the is titration, ric Th 1mol methanol. and 3mol pyridine, dioxide, sulfur method for specifi for method moisture content is calculated from the amount of titrant consumed, which is often expressed in in expressed often is which consumed, of titrant amount the from content calculated moisture is Th endpoint reached. the is until Fischer instruments Karl by these performed automatically e Karl Fischer method for moisture analysis is based on the reduction of iodine by sulfur diox- on by reduction of sulfur the iodine based is analysis for Fischer moisture method eKarl

Th Th Th e titration reagent for the Karl Fischer method consists of a mixture of iodine, pyridine, pyridine, of iodine, of amixture consists Fischer method Karl for the reagent etitration e preceding reactions illustrate that titration of 1 mol water requires 1 mol iodine, 1mol 1mol iodine, of 1mol requires water titration that illustrate reactions epreceding e Handbook of Processed Meats and Poultry Analysis Poultry and Meats ofProcessed Handbook Ⅲ Offi cial Methods of Analysis of AOAC International quantifi enabling reaction, of the conditions the ed I 2 + SO c food products O N 2 SO + H 2 2 O +3 + e titration of water with this reagent follows the two-step reaction reaction two-step the follows reagent this of with water etitration 2 CH O +SO

3 and typical use of automated equipment. use Th typical and OH N issuperior method has sensitivity compared to other c be foodfound products the in can 2 +I 2 →H e titration is performed either by volumet- performed is etitration 2 SO 4 O 2HI +2HI [30] offi shows the N H SO N 2 cation of moisture [32]. Th SO 2 + e chemical main principle 4 CH 3 I N Offi cial Karl Fischer Karl cial H cial Methods cial of Methods e titration is is e titration e e e 9/8/2008 2:46:07 PM Downloaded By: 10.3.98.104 At: 22:17 27 Sep 2021; For: 9781420045338, chapter3, 10.1201/9781420045338.ch3 CRC_45318_Ch003.indd 57 © 2009byTaylor & FrancisGroup,LLC 7. Run a blank fl ablank 7.Run Fischer Karl the with titrate vessel, titration into the extract of a10-mL aliquot the Pipette 6. fl stopperRemove the and 5. for 15 letit drain and min. attached, condenser the with Stop heating 4. then injected into the reaction vessel. A methanol blank should also be prepared in a similar man- similar a in prepared be also should ner. Th blank methanol A vessel. reaction the into injected then solution is methanol/water of amount the Aknown not is water accessible. where the solid foods is easily accessible water the if vessel reaction into the to introduced directly be may or samples Liquid the solid food mass. reagent. Th sample initial the using intomoisture percent converted be of can water Milligrams milligrams. methanol, the dilution factor (i.e., factor dilution equation. removed be the 4)may the from methanol, with extracting than rather vessel titration into the directly introduced was mass sample known content. a If moisture tocalculate used is equation following the procedure, preceding the Using 3.7.1.5.4 Calculation Add 40 mL methanol 2. into the fl 50-mL 100 into apredried water approximately mg containing ofWeigh sample amount an 1. Procedure 3.7.1.5.3 2.Karl Fischer reagent—to minimize loss of active reagent from side reactions, many labora- 1. Methanol (anhydrous). 3.7.1.5.2 Reagents pressurized slightly stirrer magnetic as such device agitation an 2. vessel—having Titration ingress moisture against protected fully fi glass, all Burette–automatic 1. type, lling 3.7.1.5.1 Apparatus following. the in described are water inaccessible for asolid Fischer containing method Karl ual Th food. of the value man- moisture of the and from procedure subtracted reagents, be e apparatus, atmosphere was introduced during sample preparation. Th 3. Boil the contents fl the of the Boil 3. 3. Electrometric apparatus and galvanometer—suitable for “dead stop” endpoint for “dead technique galvanometer—suitable and apparatus Electrometric 3. osue() ( Moisture e amount of water in this methanol blank would indicate whether any moisture from the the from moisture any whether indicate would blank methanol this of in water eamount reagent to the “dead stop” endpoint, and record the volume of titrant used. volume stop” the of record endpoint,titrant and “dead tothe reagent round-bottom fl round-bottom Th pyridine. in dioxide sulfur and methanol solutions: in iodine two as Fischer reagent suppliers provide Karl the tory (N gas inert dry with refl ux condenser % ϭ [.] . ([ ask without a sample following the same procedures described earlier. described procedures same the following without asample ask 401 ask. ϫϫϫ 2 or CO or ask gently under refl under gently ask F ask. e solutions are mixed shortly beforeuse. shortly esolutions mixed are 2 e water is frequently extracted into anhydrous methanol in in methanol into anhydrous extracted frequently is ewater ) to exclude air ) toexclude egn sdfrsml m]raetu reagent sample [mL] for used reagent ask, quickly place it on the heating range, and connect the the connect and range, it heating on place the quickly ask, apeweight sample ux for 15ux min. Moisture and Water Activity Water Activity and Moisture e moisture in the blank sample should should sample blank the in moisture e Ϫ e o blank[mL] for ssed Ⅲ ) 57 9/8/2008 2:46:07 PM Downloaded By: 10.3.98.104 At: 22:17 27 Sep 2021; For: 9781420045338, chapter3, 10.1201/9781420045338.ch3 CRC_45318_Ch003.indd 58 © 2009byTaylor & FrancisGroup,LLC mended, especially when Karl Fischer analyses are to be performed on aroutine basis. performed tobe are Fischer analyses when Karl mended, especially equipment, but semiautomated completely automated equipment recom- or using is manually improve and precision its [1]. performed be can analysis up titration the the earlier, described As not compromise the moisture determination. Th [18]. of reagent ofmilliliters per water milligrams in of water. amounts It measured is known Th 58 can be applied to moisture assay of foods [1,6]. of foods assay applied tomoisture be Th can Th 3.7.1.8 Gas Chromatography determination. for moisture heat using methods other in as toavoid sample decomposition results, of erroneous the thermal toprevent taken be However, must care processes. analytical for the not required are transfers multiple sample because TGA, in minimized are weighing sample with associated Errors weight. aconstant reached has sample the until recorded is loss weight the and sample the from rated evapo- continuously is Moisture of temperature. afunction as plot mass sample which the curves, of form thermogravimetric the in recorded are data Analytical program. temperature a controlled under heats then which balance, into the loaded ofis sample amount asmall of TGA, procedure [36]. heated For being is sample the the while temperature and of time afunction as sample food of a loss weight the records and measures automatically which athermobalance, with equipped Th method. oven-drying automated version standard of the an bles Th 3.7.1.7 Thermogravimetric Method contents [30]. of more moisture rapid procedures brating limitations, results obtained using chemical desiccation serve can as reference standards for cali- with the desiccants to enhance moisture removal from the conjunction in food. used be may heating Slight Although desiccant. tothe relative this sample the in water methodholding has some [1,6,20]. weight constant Th toachieve sample for months the even and weeks requiring frequently procedures, lengthy are techniques iccation (Drierite [20]. sulfate Calcium [30].chlorate However, phosphorous it explosive if much pentoxideabsorbs too moisture becomes eff most Table in shown as 3.6 [31,34,35]. studies, several in werecompared agents Th desiccating various from the food depends on the strength of the desiccant Th employed foods. for dried usually absorbsmoisture, strongly that [30].a substance Relative effi Th 3.7.1.6 Chemical Desiccation as well as to analyze total moisture content. moisture total toanalyze as well as bonded chemically water to be it used method of that in quantify is advantageous can hydration, e chemical desiccation method is carried out by desiccation in an evacuated desiccator containing containing desiccator evacuated an in out by desiccation carried is method desiccation echemical e standardization factor of the reagent, F reagent, of the factor estandardization e moisture of a food is removed by heating in thermogravimetric analysis (TGA), which resem- which (TGA), analysis thermogravimetric in removed is by of heating afood emoisture e gas chromatography (GC) method has versatile capability in analytical chemistry, which

Pyridine-free Karl Fischer reagents are available due to health concerns, and these reagents do reagents these and concerns, due tohealth available are Fischer reagents Karl Pyridine-free Moisture assay using TGA has been shown to give results similar to other methods. Th methods. toother similar results togive shown been has TGA using assay Moisture des- exceptions, few With achieved. is sample of the desiccation atroom temperature, Usually Handbook of Processed Meats and Poultry Analysis Poultry and Meats ofProcessed Handbook Ⅲ ective desiccating agents are phosphorus pentoxide, barium oxide, and magnesium per- magnesium and oxide, phosphorus pentoxide, barium are agents desiccating ective ™ ) is a commonly used desiccant despite not being as eff despite as not being desiccant used acommonly ) is , can be determined from titrating samples containing containing samples titrating from determined be , can e equilibrium time depends strongly on the forces forces on the strongly depends time eequilibrium e replacement solvent systems actually can speed speed can actually ereplacement solvent systems e principle of the GC method for moisture for eprinciple moisture method GC of the e amount of removed water eamount e TGA instrumentation is is instrumentation eTGA ciencies of ciencies ective. e TGA e 9/8/2008 2:46:07 PM Downloaded By: 10.3.98.104 At: 22:17 27 Sep 2021; For: 9781420045338, chapter3, 10.1201/9781420045338.ch3 CRC_45318_Ch003.indd 59 © 2009byTaylor & FrancisGroup,LLC previously for moisture analysis of meat products [37]. Th [37]. products meat of analysis moisture for previously used havebeen detector conductivity athermal and APoropak Qcolumn occur. can mixture Th or isopropanol. ethanol, methanol, solvent as such anhydrous into an extracted is water and homogenized, initially is sample food of the amount Aknown follows. as is determination ing, of light as it passes through two diff two through it passes as of light ing, or bend- refraction, content. of presentation the Aschematic moisture its for determining used be of asolution, index can which refractive the measuring method optical an is Refractometry Refractometry 3.7.2.1 curves. appropriate calibration using calculated be dependent is on content. its of that water Th aproperty measure methods Th exist. also determination for moisture methods of indirect mentioned avariety earlier, As 3.7.2 Indirect Methods Table 3.8 [30]. of Offi Association by the recognized [30]. Th analyzed of foods types samples, offi an of diff For analysis investment. the capital initial alarge requires methods, to other comparable ablerapid togive results although control. GC, for quality product amethod as considered tobe much too time requires Vacuum desiccation analyst. performing for the skill Th technique. alaboratory primarily remains time than the oven-drying methods. Th ashorter completed in often and out atatmospheric pressure, carried are methods Distillation methods. oven the from those to values moisture comparable give methods Distillation sition. decompo- product preventing point of while water boiling the atmosphere toreduce of the that lower than pressures uses method vacuum-oven the removed more atlower rapidly pressures, be products). can todecomposition moisture (e.g., Since susceptible foods sugar-containing for useful especially is and removal up moisture speeds Vacuum-ovencombination. drying time/temperature appropriate some at assumed is removal moisture complete A foods. sensitive least for conducted the usually is which temperature- drying, air-oven is method used widely Th analysis. for moisture discussed havebeen methods direct mentioned various earlier, As Application Methodsin Moisture of Direct Determination 3.7.1.9 sive equipment. Th methods. GC and conventional by [33]. methods conventional obtained contents of samples meat Table moisture the 3.7 illustrates methods have shown oven-drying or that the GC values distillation by were determined not values diff with compared GC by determined values ture curve). Th of (i.e., water amounts astandard known of solutions containing areas to the compared then are areas solvent; of and water these areas peak the out by determining carried e extract is then analyzed using GC such that quantitative separation of the water–solvent on the depending selected, be can determination for moisture method cial e offi cial methods for moisture determination of various foods foods of various determination for moisture methods cial e GC analysis is rapid, but requires specialized and expen- and specialized rapid, but is requires analysis eGC cial Analytical Chemists International are described in erent sucrose solutions is shown in Figure 3.6. Th 3.6. erent solutions sucrose Figure shown in is e Karl Fischer titration method is rapid, although it rapid, although is method Fischer titration eKarl is method also requires a considerable degree of degree aconsiderable requires also method is erent from those obtained by the more by the obtained erent those from Moisture and Water Activity Water Activity and Moisture e quantifi cation of moisture content is is content moisture of cation us, moisture contents can erent food e mois- e more e most Ⅲ ese 59 9/8/2008 2:46:07 PM Downloaded By: 10.3.98.104 At: 22:17 27 Sep 2021; For: 9781420045338, chapter3, 10.1201/9781420045338.ch3 CRC_45318_Ch003.indd 60 © 2009byTaylor & FrancisGroup,LLC Source: AOAC, Karl Fischer Distillation i-vndyn 0–0 6 6–8Meatproducts 16 –18 2 760 100–102 Air-oven drying Vacuum-oven Method Moisture-Assaying Recommended by AOAC International ComparisonofDirect MethodsforMoisture DeterminationofFoods as Table 3.8 60 Handbook of Food Analysis by Y.W. (Park, refractometry. determination moisture Schematic Bell, L.N. and 3.6 Figure method drying

Handbook of Processed Meats and Poultry Analysis Poultry and Meats ofProcessed Handbook Ⅲ VA, 1995. Offi cialMethods of Analysis of AOAC International,AOAC International, 10% sugar 90% water Temperature 2–3 6 01 – Cheese(amyl 1–2 10–15 760 129–134 8102 2–5 25 98–100 07 0102526Driedfruits,honey, 2–6 2–5 50–100 60–70 (°C) 0 6 Untilconstant 2 2 5 760 760 760 100 130 100 0 0 – 5Driedmilk,cheese, 4 –5 2–3 100 100 — 57040 760 85 5105 100 75 , Marcel Dekker,, Marcel NewYork, 2002.) R I=1.348 (mm Hg) Pressure –5Afew 5–15 — Light source Weight (g) Sample 0.5–1 5–25 2–3 set up) apparatus is minutes (if weight eurd()Food Products Required (h) Time R I=1.420 – Spices(toluene) 1–2 – Flour 1–2 Caneandbeetsugar 3 Fats andoils 5 Pasta products, 5 50% sugar 50% water Molasses Fats andoils Dried vegetables Cacao products Cacao products alcohol andxylene) nuts, tea syrup coffee, wheatfl Arlington, our 9/8/2008 2:46:07 PM Downloaded By: 10.3.98.104 At: 22:17 27 Sep 2021; For: 9781420045338, chapter3, 10.1201/9781420045338.ch3 CRC_45318_Ch003.indd 61 © 2009byTaylor & FrancisGroup,LLC the NIR–refl the by and method oven-drying by the determined beef of pork and raw values moisture the between coeffi (correlation curves calibration Linear error-prone. be will analysis the then samples, unknown of the range represent the not adequately does set sample calibration the If samples. standard of the analysis chemical wet from derived curve, calibration ated in single- or double-beam mode, which then can be downloaded into acomputer [41,42]. downloaded be can then which mode, or double-beam single- in ated Th of analysis. speed the is method the [41]. foods other as well as seeds oil Th and protein) oil, and of grains ture, Th of products. range for awide method multicomponent arapid, integrated testing as economic importance immense nation. An appropriate calibration technique [18,30] is required for each chemical compound. [18,30] technique appropriate chemical for calibration each An nation. required is determi- for moisture standards of the those with compared be can sample of the values absorption Th measured. compound for absorption being the [39].detector of maximum that is used Ideally, wavelength the ataspecifi energy transmits consequently which [1,6,18,38].curve of asolution appropriate index an calibration or slurry, using refractive the by measuring mined solution. the in Th concentration the higher the refraction, tion of the refl oftion the eff radiation absorb IR can and absorption spectrum Th tool for components analysis. power of refl resolving high Near infrared (NIR)–refl Near3.7.2.3 Infrared–Refl of water. frequently concentrations for standard band same of are the that with intensity nm band the ing 1940 and 1450 at occurring bands [1,6–7,18].used absorption by compar- performed be content nm; moisture ofcan of asample the Determination 700–2400 is interest of region specifi by employing substances of or solid, liquid, gas content variety moisture of the alarge measuring for methods it one is versatile most of the properties, [7]. these properties has physical IR Since Th [1,6–7,18]. determination for moisture used be can spectroscopy IR that haveshown reports Many Spectroscopy Infrared Absorption 3.7.2.2 temperature control is necessary. control is temperature strict and required, is sample auniform temperature-sensitive, is measurement index refractive the solvent. the in Because homogenized ofis food mass the and curve, calibration the using solvent with known amounts of added water. of added Th amounts solvent known with same the of solutions index containing refractive the by produced measuring is curve A calibration arefractometer. using solution of the index measured is refractive the then and foods, semisolid e IR spectrum of a chemical compound has been described as one of its most characteristic one of as characteristic most its described been compound has of achemical spectrum eIR Th Since this methodology developed in early 1970s, early in NIR–refl developed methodology this Since Th Th e basic concept of this methodology is that an IR beam passes through an optical fi optical an through passes beam IR an that is methodology concept of this ebasic e NIR spectrophotometer can generate the refl the generate can spectrophotometer eNIR e sample can be homogenized with an anhydrous solvent (e.g., anhydrous an isopropanol) for with solid or homogenized be can esample c wavelengths at which maximum absorption is expected to occur. For water, the spectral For tooccur. water, spectral the expected is absorption maximum atwhich c wavelengths e IR technique must be calibrated using standards of known concentration. Th concentration. of known standards using calibrated be must technique eIR ectance spectroscopic method [41]. method spectroscopic ectance ectance spectrum is poor [40]. poor is spectrum ectance e NIR technique has been widely used to predict the composition the (i.e., topredict mois- used widely been has technique eNIR ectance spectroscopy technology has been developed recently to use its its touse recently developed been has technology spectroscopy ectance ectance spectra in the NIR range (800–2500 nm) as an analytical analytical an nm) as (800–2500 range NIR the in spectra ectance e mid-IR range (2,500–24,000 nm) has high resolution in the resolution the in high nm) has (2,500–24,000 range emid-IR ectance ectance Spectroscopy e accuracy of the NIR refl NIR of the e accuracy c wavelength through the sample cell and then toa then and cell sample the through c wavelength e moisture content of the sample is calculated content calculated is sample of emoisture the ectance spectra with amonochromator oper- with spectra ectance ectively from many compounds, but resolu- but compounds, many from ectively e moisture content can be rapidly deter- rapidly be content can emoisture Moisture and Water Activity Water Activity and Moisture cients ectance spectroscopy ectance assumed has ectance method depends on the on the depends method ectance > 0.98) have been established 0.98) established havebeen e primary advantage of advantage eprimary en the Ⅲ lter, lter, 61 9/8/2008 2:46:07 PM Downloaded By: 10.3.98.104 At: 22:17 27 Sep 2021; For: 9781420045338, chapter3, 10.1201/9781420045338.ch3 CRC_45318_Ch003.indd 62 © 2009byTaylor & FrancisGroup,LLC 62 transmitting quartz window. Th quartz transmitting IR- aconcentric with contact direct holder into asample maintaining packed are Ground samples Lancaster, PA, Technomic 1998.) Publishing, Approach, Magnetic Nuclear Dekker,Marcel P.L. NewYork, and 1996; Chen, R.R. Ruan, Y.W., (Park, ofNRIequipment. detector solid Large, 3.7 Figure 2 nm (or2 nm refl of 0.5 the width the nm) along into acomputer.fed Th Th refl being radiation NIR 3.7 the depicts Figure sulfi lead four with collected are window incident the beam. around spaced equally de detectors as mentioned earlier [41]. mentioned earlier as Norris [41]. Th by discussed as disadvantages, and advantages has types of these detector. Each tor, small and to the method of collecting the refl [41],lengths analysis. of the complexity the showing diff log(1/R) of attwo the derivative second of data the ratio the of taking consisted [41,42]. data data chemical spectral raw-meatthis of the samples, against For assay moisture data linear-regression method to develop prediction equations by a regression analysis of NIR spectral multiple astepwise with them analyzes which data, NIR the computer with the in along inputted data cannot be used directly for quantitative analysis. Moisture contents of standard samples are [41,42]. overlapping bands absorption evaluate tohelp curves original of the derivative second the as recorded be can log(1/R) the and curve curve e signals from the detectors are amplifi are detectors the from esignals

NIR instruments are commercially manufactured on the basis of three geometries according according geometries of three basis on the manufactured commercially are instruments NIR refl the determination, for moisture method not is adirect method NIR the Since Handbook of Processed Meats and Poultry Analysis Poultry and Meats ofProcessed Handbook Ⅲ Sample e large solid-angle detector was used to collect the moisture data on pork and beef, on pork and data moisture the tocollect used was detector solid-angle elarge Photo cell e wavelength range from approximately 1100 to 2500 nm is scanned every 1100 approximately from every range scanned is to2500 nm e wavelength e refl ectance. Th ectance. ected radiation signals of the diff of the signals radiation ected ed with a logarithmic-response amplifi Monochromatic ectance curve [41,42]. curve refl IR the ectance Both ected from a food sample to surrounding detectors. detectors. tosurrounding sample afood from ected ese are integrating sphere, large solid-angle detec- solid-angle sphere, large integrating are ese radiation Sam p le holder Foods and Biological Materials: and A Foods Handbook of Food Analysis, Analysis, ofFood Handbook used spectra from the glass glass the from spectra used Window Photo cell er, digitized, and and er, digitized, ectance (R) (R) ectance erent wave- erent ectance ectance 9/8/2008 2:46:07 PM Downloaded By: 10.3.98.104 At: 22:17 27 Sep 2021; For: 9781420045338, chapter3, 10.1201/9781420045338.ch3 CRC_45318_Ch003.indd 63 © 2009byTaylor & FrancisGroup,LLC 0.05 diff [30]. of these Because 0.001– is tangent loss the 0.15–1.2, of is water materials tangent loss the for dry GHz, 30 whereas 1and [6].between atfrequencies For substance example, of adry amount asimilar than energy more microwave times thousand it several absorbs that of is water properties One distinct of the Microwave Method Absorption 3.7.2.4 ture content of materials and their electrical properties [6,32]. content properties moisture of afood the As electrical their and contentture of materials circuit a food containing sampleelectrical [1]. relationship the mois- between A distinct exists Th Conductivity 3.7.2.6 Method Th plates. of the capacitance the change and polarized become will plates two the between placed Asample follows. as is instrument tric [1]. current alternating an toyield frequencies Th [1]. but opposite equal charges with apart, Th spaced plates metal two [1]. tocereals principle applied commonly most and on this based weredeveloped determination for moisture measurements dielectric ments utilizing content moisture [6,19,30]. 30% up toapproximately linearly almost increases Instru- substances 0.8[6]. of by DC water-containing DC approximately its addition, the In increase theoretically will content whereby a1% content moisture of in DC, asubstance moisture and increase between about 3[31]. both are sucrose and acids of fatty those whereas Th about 80, is (DC). at20°C Its DC constant dielectric its of is water property distinct Another Dielectric 3.7.2.5 Capacitance ago. years 40 almost meter moisture wave content [30]. moisture increasing Th with linearly increases the development tomicro- is theled of Th products. of food content water the of avariety rect methods. rect [6,18]. indi- other and method DC of the disadvantages Table and 3.5 advantages the describes are infl meter acapacitance using results Analytical determined. be can contents samples of food ture mois- content, moisture known of standards with calibration On instrument. the by measured obtained. havebeen results positive the if even determination, for moisture technique analytical used not into evolved acommonly has oven [43]. adrying Th from tothat similar results togive found Th diff of polarization size, particle temperature, aff [30]. curve can Various factors acalibration toconstruct used content therefore is on and moisture diff the receiver. Th and amicrowave transmitter between placed is sample amplifi adetector, and attenuator amicrowave waveguide, e principle of the conductivity method is that conductivity and resistance are measured in an an in measured are resistance and conductivity that is method eprinciple conductivity of the e microwave absorption device was used to determine the moisture content of cakes, and was was and content moisture of cakes, the todetermine used was device emicrowave absorption ect the accuracy of the microwave measurement, including leakage of microwave energy, sample leakage including microwave measurement, of the accuracy the ect Th Th e microwave absorption method consists of a constant source of microwave radiation, a of microwave radiation, source of aconstant consists method emicrowave absorption e major component of the dielectric instrument is a capacitance cell, which consists of consists which cell, acapacitance is emajor instrument component dielectric of the uenced by moisture distribution, presence of electrolytes, temperature, and sample density density sample and temperature, electrolytes, of presence distribution, moisture by uenced erence in attenuation readings between the transmitter and the receiver, which is dependent is receiver, the which and transmitter the between readings attenuation in erence erences, the absorption of microwaves can be used to determine is capacitance change, aff erent material, and the presence of soluble[30]. presence the and salts erent material, eprinciple by dielec- measurement of moisture e absorption of microwave energy at2450 of eabsorption microwave energy MHz Moisture and Water Activity Water Activity and Moisture er, and an indicating meter [30]. meter Th indicating er, an and e microwave absorption method e attenuation of the sample is is sample of the eattenuation ected by moisture content, is is content, moisture by ected ere is a positive correlation correlation apositive ereis ese charges reverse atfi reverse charges ese xed Ⅲ 63 e 9/8/2008 2:46:08 PM Downloaded By: 10.3.98.104 At: 22:17 27 Sep 2021; For: 9781420045338, chapter3, 10.1201/9781420045338.ch3 CRC_45318_Ch003.indd 64 © 2009byTaylor & FrancisGroup,LLC other standard methods [44]. methods standard other to weresimilar results analytical the and nondestructive, rapid tobe shown and was sonic method [45]. fermented sausages Th dry [44] content, and of moisture chicken position, including Ultrasonic methods curve. havestandard been in laboratory used to determine settings the com- appropriate an contents using into moisture converted are Voltmetervoltmeter reading. readings Th [6]. analysis for microphone and erator method being less than ± method being less than determinations by measuring either resistance content of moisture [30]. afunction as or curvature showing of humidity, although afunction conductanceas of foods [1]. content of either moisture or humidity. Th afunction as Th [18]. plotted is useful most tobe appears of resistance Frequently, resistance logarithm the Measuring sample increases, electrical resistance of the sample decreases, and its conductivity increases [6,18]. 64 foods, but require substantial instrumentation. Th instrumentation. substantial but require foods, Th Methods Instrumental Indirect Other 3.7.2.9 appliedbe tootherfoods. tofl added water tomeasure is method of this use common most of solute [18]. type aconstant of containing present amount water for the liquids Th with related Th solutes of increases. concentration dissolved the as [1,18]. depression freezing-point as known property Th ligative Th Cryoscopic3.7.2.8 Methods refl their enables also waves of ultrasonic frequency energy, high the content of moisture [30]. determination for the developed ofbeen toabsorption sound addition In sonic and ultrasonic absorption [30]. Th transmitted is [6]. Using this principle,Th ultrasonic Sonic Absorption Ultrasonic and velocity measurements 3.7.2.7 have as in the conditions of the dielectric capacitance method [6,30]. method capacitance conditions dielectric of the the in as samples, and electrodes the between of contact quality the as content well as electrolyte and ture, accuracy and precision of the conductivity method are aff are method precision conductivity of the and accuracy Th samples. among of water bound variation due tothe required be may [6]. Conversion charts content moisture total the tomore approximate added closely tobe needs of water bound amount the sample; the in water free the only [32]. measure for temperature sample methods Conductivity corrects that atable contents using into moisture converted are [30]. readings tance Conductance fl current the and trodes elec- [32]. two prunes between meter, placed is food To the by aconductivity moisture determine and of raisins conductivity the tomeasure used circuit electric of the aschematic describes method ere are several other indirect methods that can be applied for determination of moisture in in of moisture applied for be determination can that methods indirect other several ereare col- the utilizes which moisture, for analyzing method indirect another is method ecryoscopic it which through medium of type the on depend would energy sound of absorption of degree e

In this ultrasonic absorption method, the food sample is positioned between an energy gen- Several conductivity instruments are widely used by the industry for rapid routine moisture for rapid moisture routine industry by the used widely are instruments conductivity Several Handbook of Processed Meats and Poultry Analysis Poultry and Meats ofProcessed Handbook Ⅲ us, as moisture content of the medium changes, so too does the amount of amount the does sotoo content changes, moisture medium of the as us, owing through the sample is measured by the change of electrical resis- 0.5% will depend on the proper calibration [30]. An offi e energy output of the sample is amplifi ese methods include nuclear magnetic resonance resonance magnetic include nuclear methods ese erefore, the freezing point is inversely cor- pointinversely is freezing the erefore, e logarithm of resistance is basically linear linear basically is of resistance elogarithm ected by moisture distribution, tempera- distribution, moisture by ected e freezing point of water decreases point of decreases water e freezing uid milk [1,18], milk uid it could although ection and refraction [6]. e accuracy of this of this eaccuracy ed, yielding a cial AOAC cial is ultra- e e 9/8/2008 2:46:08 PM Downloaded By: 10.3.98.104 At: 22:17 27 Sep 2021; For: 9781420045338, chapter3, 10.1201/9781420045338.ch3 CRC_45318_Ch003.indd 65 © 2009byTaylor & FrancisGroup,LLC 3. Makower, B. 1950. Determination of water in some dehydrated foods. In In foods. somedehydrated in of water 1950. B. Makower, Determination 3. (ed.), 2. M.L.N. Y.W. Leo, In Park, of contents foods. ash and of moisture 1996. Determination [30]. sources other found in be can details less frequently employed methods; therefore, they are briefl [30], [30]. [1,6,30,46], neutron scattering and spectrometry Th (NMR) mass 1. Pomeranz, Y. and C.E. Meloan. 1994. Determination of moisture. In In of moisture. 1994. Determination Meloan. 1. Y. C.E. and Pomeranz, References dicted values. pre- precise and accurate achieve can that of instrumentation method indirect areliable establish verifi be must curves calibration accurate and standards of the preparation Nevertheless, worthwhile. investment the make control might rapid on-line quality for application equipment, potential in investment the capital alarge require methods indirect most Although curves. calibration reliable toestablish standards of known analysis and ration prepa- depend on careful methods indirect precision of the and However, accuracy methods. the more the standard as precise and accurate as be can done methods properly,When indirect the Th of Methods Indirect Summary 3.7.2.10 material. organic nonexistent, composed food is primarily because ofmination is virtually proton-rich foods in [9,30]. substances inorganic Th appropriate most low nonaqueous protons, for are in as samples such methods tron-scattering neutrons scatter from any will hydrogen nucleus, not just those with associated water. Th earlier, [9,30]. discussed method methods NMR the with neutron-scattering As using moisture eff most the are atoms uncertainty. due toits determination for moisture method uncommon an remains spectrometry ever, mass quantifi then is which acetylene, toyield carbide calcium with moisture concentrated cryogenically by reacting [9,30]. sample obtained next of been the has results the Some success “memory the eff in [1],samples quantifi the for identifi utilized widely been has spectrometry mass methods. of NMR disadvantages Table and advantages 3.5 the lists contents [47]. of moisture for determination described havebeen techniques [6]. NMR Modern gen-containing substances in the food. Th [6,30,46]. Th [6,30,46]. of water properties of utilizing of protons, its instead properties nuclear the utilizes technique e indirect methods are generally faster than the direct methods for moisture determination. determination. for moisture methods direct the than faster generally are methods eindirect NMR is a fast and nondestructive method of moisture determination [1,6,30,46]. determination Th of moisture method nondestructive and afast is NMR Neutron and γ Neutron and [30]. determination for Although moisture method indirect another is spectrometry Mass Food Industry Marcel Dekker, New York. New pp. Dekker, 59–92. Marcel Analysis. ofFood Handbook Practice e challenge is todiff is echallenge . 3rd ed., Chapman and Hall, New York, New pp. 575–600. Hall, and Chapman . 3rded., . Advances in Chemistry Series 3. American Chemical Society, Washington. Society, Chemical 3.American Series Chemistry in . Advances -ray scattering occur when energized neutrons interact with nuclei. Hydrogen with neutrons interact when energized occur -ray scattering ect” or carry-over eff ective at scattering neutrons; this forms the basis of a determination of of adetermination basis the forms neutrons; this atscattering ective cation of water is more problematic [18,33]. Th e application of the neutron-scattering method to moisture deter- tomoisture method neutron-scattering of the eapplication erentiate the proton NMR signal of water from the other hydro- other the of from water proton signal the erentiate NMR ect from the already analyzed sample, which infl which sample, analyzed already the from ect e accuracy of NMR techniques is approximately 0.2% approximately is techniques of NMR eaccuracy cation of unknown substances in food Moisture and Water Activity Water Activity and Moisture y introduced in this section, and the the and section, this in y introduced ed by a specifi a by ed e greatest problem lies egreatest Food Analysis: Th Analysis: Food Analytical Methods in the c direct method to method c direct ese techniques are ed [9]. 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