The salt level in cheese varies from about 0.7% (w/w) to about 6% (w/w) and depends on the type of cheese. Salt has three main functions in cheese: acting as a preservative, it directly contributes to flavor, and it is a source of dietary sodium. However, cheese generally makes a relatively small contribution to the sodium supply in the diet, unless large amounts of high-salt cheeses such as feta are consumed.
Salting is an essential step during cheese production. Salt is added to the curd to inhibit the activity of the starter and enhance the flavor of the product. Salt not only adds flavor to the cheese but also helps the curd to dry out and cause it to wrinkle. However, the main reason for salting is to slow or stop the growth of bacteria from converting lactose (milk sugar) into lactic acid. Salt is the main determinant of water activity and therefore controls microbial growth, enzyme activity, biochemical changes during cheese ripening, and the development of desired flavor and aroma.
In general, the effect of salt on cheese includes the following:
- Inactivating or reducing the activity of spoilage bacteria
Salt acts as a preservative and directly affects the taste and quality of the salt. The preservative effect of salt is actually due to its reducing effect on the water activity of cheese. In addition, salt increases the osmotic pressure of the aqueous phase of foods and causes dehydration of bacterial cells, preventing their growth.
- Preventing the activity of the starter and highlighting the taste of the product
The salt directly contributes to the saltiness of the cheese, a flavor that is generally much appreciated. It indirectly contributes to cheese flavor by controlling microbial and enzymatic activities, which in turn affect lactose metabolism, cheese pH, degradation of fats and casein, and formation of flavor compounds such as peptides, free amino acids, etc.
- Creating syneresis in the curd
By removing whey proteins from the curd, salt increases syneresis and reduces the level of moisture. This is especially important in the preparation of aged cheese.
- Texture improvement (soft and creamy texture)
Salt, along with pH and calcium level, has a great effect on the degree of hydration or aggregation of paracasein, which in turn affects the water-binding capacity of the casein matrix, its tendency to synersis, its rheological and textural properties, and its curing properties.
Effects of increasing salt concentration on cheese texture:
- Increasing the firmness of cheese curds
- Increasing the fragility of cheese curds (crushing of cheese)
- Reducing the elasticity and cohesiveness of the cheese
- Increasing syneresis and reducing curd moisture
Salt reduction in cheese, challenges, and solutions
Salt reduction strategies in cheese mainly include reducing sodium chloride (NaCl) and replacing it with potassium chloride (KCl). However, these strategies present many challenges such as adverse effects on the taste, microbiological stability, and functional properties of the final product.
When the salt content of cheese decreases, proteolysis, water activity, acidity, and bitterness increase, while hardness decreases. In addition, irregular fermentations may occur, which may change the desired characteristic flavor of the cheese, causing an unacceptable bitter taste. Additionally, studies have shown that at salt levels below 1.5% compared to higher levels of 1.8 to 3%, increased growth of spoilage bacteria occurs, which in turn causes a bitter taste due to excessive proteolysis.
Replacing salt (sodium chloride) with other salts is considered an alternative method to reduce sodium in cheese. In general, KCl has been recognized as a potential salt to replace NaCl in various foods, mainly due to the similarity between the cations of NaCl and KCl. This approach to reducing sodium is more beneficial from a nutritional perspective. It has been observed that potassium has a significant effect on lowering blood pressure and thus reducing the risk of cardiovascular diseases. Mixtures of sodium chloride and potassium chloride have been successfully used in various kinds of cheese without significantly affecting the properties of the cheese. However, the extent of substitution of NaCl by KCl is limited by the unpleasant bitter taste that may occur due to KCl.
Reference:
Guinee, T.P., 2004. Salting and the role of salt in cheese. International Journal of Dairy Technology, 57(2‐3), pp.99-109. DOI: 1111/j.1471-0307.2004.00145.x
Salt in cheese; DOI: 1533/9781845693534.80
