Salt and Its Significance in Cheese Making
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ALP forum No 59 | May 2012 SALT AND ITS SIGNIFICANCE IN CHEESE MAKING Discussion groups - applied cheese technology Authors: Daniel Goy. Jean-Pierre Häni, Patricia Piccinali, Karin Wehrmüller, Ernst Jakob, Marie-Therese Fröhlich-Wyder, Revision 2012: Walter Bisig Agroscope Liebefeld-Posieux Research Station ALP, CH-3003 Berne AAlpforum_59_en.inddlpforum_59_en.indd 1 115.05.125.05.12 009:079:07 Impressum Impressum ISSN 1661-0660 / 15.05.2012 Publisher Agroscope Liebefeld-Posieux Research Station ALP Schwarzenburgstrasse 161, CH–3003 Berne Telefon +41 (0)31 323 84 18, Fax +41 (0)31 323 82 27 [email protected], www.agroscope.ch Photos Agroscope Liebefeld-Posieux Research Station ALP Liebefeld-Posieux Layout RMG Design, CH-1700 Fribourg Copyright © 2012 ALP Reproduction is permitted on the condition that the source is cited and a specimen copy is sent to the publisher. Translation and revision of ALP forum no. 59 published in 2008 2 ALP forum No 59 | 2012 AAlpforum_59_en.inddlpforum_59_en.indd 2 115.05.125.05.12 009:079:07 Salt and its signifi cance in cheese making Contents Summary 4 1. Introduction 5 2. Infl uence of salt on the sensory quality of food 5 3. Salt in the human diet 6 3.1 The function of salt (NaCl) 6 3.2 Consumption and recommendations 6 3.3 Diseases associated with high salt consumption 6 4. Possibilities for reducing the sodium content in cheese 7 5. The salting of cheese 8 5.1 Salt absorption in cheese 8 5.2 Salting methods 9 5.3 Salt diffusion 10 5.4 Possibilities for speeding up cheese salting 11 6. Signifi cance of salt in cheese technology 12 6.1 Infl uence on taste and aroma 12 6.2 Infl uence on the surface, rind formation and the smear fl ora 12 6.3 Cheese consistency and structure 12 6.4 Weight loss 12 6.5 Development of microfl ora in curd 12 7. Salt as “inhibitor” for propionic acid bacteria 13 7.1 Inhibition of propionic acid fermentation in Cheddar type cheese using NaCl 13 7.2 Inhibition of propionic acid bacteria using NaCl in a model Gruyère 14 8. Salts and additives currently recommended for cheese dairies 16 9. Use of iodised salt 17 9.1 Declarations regarding the use of salt in Switzerland 17 10. References 18 ALP forum No 59 | 2012 3 AAlpforum_59_en.inddlpforum_59_en.indd 3 115.05.125.05.12 009:079:07 Salt and its signifi cance in cheese making Summary The use of salt is widespread due to its fl avour-enhancing effect. Salt (NaCl) is essential in human nutrition but its consumption needs to be controlled. An insuffi cient or excess amount can have a negative effect on health. For cheese, it is possible to replace a maximum of one third of NaCl (sodium chloride) with KCl (potassium chloride). Larger amounts of KCl produce an unpleasant bitter taste. The necessary labelling of KCl as an additive is a disadvan- tage. Because of the fact that potassium in human nutri- tion may in rare cases have an impact on health, the use of KCl is not actively encouraged by many food authorities. The use of salt is indispensable in cheese production. It is imperative to respect the desired content of the different types of cheese. Salt plays a versatile role. Salt infl uences the following characteristics and processes in cheese: • Ripening • Preserving against pathogenic bacteria and against spoilage bacteria • Development of microfl ora • Stabilising the surface and rind formation • Consistency and structure of the cheese • Taste and aroma The currently used salt contents in cheese, e.g. 13 to 16 g/ kg for Gruyère cheese, have an inhibitory effect on propi- onic acid bacteria (PAB), which are considered to be spoil- age bacteria in many cheese varieties. For brine salted Gru- yère type cheese, a salt content of 3.5% in moisture (≈ 1.2% in cheese) had a reducing effect on PAB, 5% salt in moisture (≈ 1.7% in cheese) completely inhibited growth of PAB. In curd salted cheese, a salt content of 12 g/kg (3% in moisture) was suffi cient already to keep propionic acid below the critical 2 mmol/kg limit in 6 months old cheese. The inhibiting effect of the currently used salt contents on the growth of propionic acid bacteria is too low to com- pletely protect the cheese against unwanted propionic acid fermentation. It is therefore necessary to make sure to keep the contamination of the milk with propionic acid bacteria to a minimum (< 20 cfu/g). The use of cooking salt with added iodine and fl uorine in the production of cheese is no longer recommended due to legal requirements in a number of export countries. 4 ALP forum No 59 | 2012 AAlpforum_59_en.inddlpforum_59_en.indd 4 115.05.125.05.12 009:079:07 Salt and its signifi cance in cheese making 1. Introduction 2. Infl uence of salt on the Salt has been known for its qualities as a seasoning and sensory quality of food preservative in food since early history. It has a fl avour- enhancing effect, which explains its widespread use in Nowadays, salty is considered to be a basic taste in the cooking. Salt is also an indispensible element in the pro- same way as sweet, sour, bitter and umami (sodium gluta- duction of cheese in terms of taste and quality. mate is an example of a carrier of the umami taste). The tastes arising from the dissolving of molecules in saliva are The following article looks at salt from a number of angles identifi ed by human beings via taste buds in the oral cav- and deals with its signifi cance in nutrition and the technol- ity. The mechanisms responsible for recognising tastes ogy of cheese making. have been the subject of scientifi c research for decades. There is relatively good information available on the rec- ognition of sweetness and bitterness, whereas many ques- tions remain unanswered regarding the perception of salinity. The human perception of salt is normally related to the sensory perception of sodium chloride (NaCl). It appears the sodium ions penetrate the sensory cells of the taste buds via ion channels found in the membrane. Exactly how the receptors of the taste cells convert the chemical information of the sodium ion into electrical nerve impulses, is a puzzle that still remains to be solved. Salt, or to be more precise sodium, has two different char- acteristics in terms of taste. The fi rst, and most well- known, is its ability to cause a salty taste. Most adults and children like salty things. This is an innate reaction that probably refl ects the fact that salt is essential to the human diet. And then there is a liking for salty things that human beings primarily develop during their childhood, which leads to a salt intake over and above the required daily amount. The second characteristic of salt is its interaction with the components of fl avours, which we understand as a combi- nation of taste, aroma and the so-called trigeminal per- ceptions (hot, burning, cooling etc.). We use this interac- tion to improve the sensory qualities of food. Salt is a powerful suppressor of numerous bitter substances and in certain food it intensifi es the taste of sugar to a certain extent. Moreover, salt has a fl avour-enhancing effect. For this reason, salt is systematically added to processed food. Current research work is focussed on the characteristics of the ion channels, which probably consist of three to four subunits. The need to solve the puzzle of the perception of salinity has gained considerable signifi cance given the relationship between health problems and excessive salt intake. ALP forum No 59 | 2012 5 AAlpforum_59_en.inddlpforum_59_en.indd 5 115.05.125.05.12 009:079:07 Salt and its signifi cance in cheese making 3. Salt in the human diet 3.1 The function of salt (NaCl) Cooking salt is the chemical combination of the elements However, not everybody reacts in the same way to high or sodium (Na) and chlorine (Cl), which perform important low salt intake. Patients sensitive to salt react to increased functions in the human body. Sodium is responsible for the salt intake with an increase in blood pressure, whereas regulation of the water balance and osmotic pressure in that is not infl uenced in people who are not sensitive to cells and is also involved in the regulation of the acid-base salt. However, there is no general defi nition of what con- balance. Sodium is also important for the stimulation of stitutes sensitivity to salt and the mechanisms involved muscles and nerves. Chlorine also plays a signifi cant role in remain to be explained. It is estimated that around 15% of the acid-base balance. The physiological salt requirement people with normal blood pressure are sensitive to salt in human beings has not been precisely defi ned. The mini- while the proportion with patients suffering with hyper- mum sodium and chlorine requirements in adults are 550 tension is around 50 – 60%. Based on decreasing kidney mg and 830 mg respectively, which is equivalent to 1.4 g of functions, it is highly likely a large part of the elderly pop- cooking salt. ulation (approx. > 65 years) is sensitive to salt. That means “only” patients sensitive to salt will benefi t from a reduc- 3.2 Consumption and recommendations tion in salt in their diets. The contention that a reduction in salt consumption across the population will bring health Salt consumption in Switzerland is between 7 and 13 g per benefi ts is unproved and a matter of debate amongst day per person and according to offi cial recommendations experts.