Salt plays a significant role in directly influencing the flavour, ripening and appearance of cheese. Many points can be written and discussed on salting and cheese, here are just a few points.
Salt has two other important effects, which more precisely determine the amount to be used. These are the extraction of moisture from the curd and the retarding of starter development and bacterial processes associated with cheese ripening. The application of salt to the curd causes more moisture to be expelled, both through an osmotic effect and a salting-out effect on the protein. The osmotic effect may be likened to the creation of suction at the surface of the curd causing moisture to be drawn out. The salting out effect is the natural tendency of the protein to precipitate from a solution in the presence of salt.
Salt is incorporated into cheese by one of the following methods:
- mixing dry crystals with milled or broken curd (Cheddar)
- rubbing dry salt or salt slurry on the cheese surface (washed rind style, lactic, Comte)
- immersing cheese in a brine solution (Edam, Grana and hard Eye Cheese)
- adding salt to the curds and whey (some blue vein and Havarti); and
- using a combination of these methods
The quantity of salt used depends on the variety of cheese for example soft lactic cheese will have less than 1%, a brine salted feta at 4.5%, Cheddar less than 2%, Camembert and Gouda will have slightly more than 2%, an Emmenthal less than 1%, blue vein salting can vary greatly and can be greater than 3%. Cheese with propionic acid bacteria added will have propionic inhibited at salt levels over 2%. In blue mould cheese, the blue spores are germinated at levels of 1% salt. Is white mould cheese, the white mould is mostly unaffected by salt, but the Geotrichum Candidum is heavily affected by salt. Salt can be used to control the final acidity of, e.g. if salting is delayed then acid development may continue to excessive levels, if salting is carried out too early it can slow the development of lactic acid production. Too much salt will leave a definite salty flavour in the cheese and can affect textures, making the cheese dry and crumbly.
However, the effect of salt on the bacterial, both starter cultures and spoilage bacteria depends on the strength of the brine formed by the solution of the salt in the moisture of the curd. Brine strength is expressed as the percentage of salt in the moisture (SM) of the curd or cheese, for example, Cheddar cheese containing 1.7% salt and 36.0% moisture would have salt in the moisture concentration of:
It should be noted that in low concentrations (less than about 2% SM), salt acts as a microbial stimulant but at higher concentrations has a definite inhibitory effect. Starter bacteria are progressively inhibited as the brine strength increases and total inhibition occurs at about 6% SM. However, salt tolerance of bacteria varies and unfortunately some which may cause cheese defects, for example, coliforms, can withstand quite high concentrations of salt. Mucor or black moulds like to grow at low levels of salt in moisture.
When dry salt is applied to milled curd, some of the salt dissolves in the moisture on the curd particles and diffuses into the curd. This causes whey to flow out of the curd and the outer curd layer to shrink. The free whey dissolves some of the remaining salt crystals and these either diffuse into the curd or is lost in the whey. This salty whey is high in fat content. This is thought to occur through the abrasive action of the salt and through curd contraction.
If salting, mellowing (time between salting and pressing) and pressing are properly controlled, the cheese should have a uniform salt content 3-4 days after pressing.
Allowances need to be made when dry salting cheese, for a percentage of salt to be lost in the ‘salty whey’ that comes out of the cheese when salt is added.