Brining, curing, pickling

Field of application

Brining and curing are applied in the production of certain types of cheese, meat, fish and vegetables (e.g. sauerkraut). Salt levels in the product can range from 1 to 5 %. Cucumber, tomatoes and some other garden vegetables may be pickled.

Description of techniques, methods and equipment

In the brining and curing of meat products, the meat is treated with common salt (NaCl) and with one or more of the following curing salts: sodium nitrate (NaNO₃), sodium nitrite (NaNO₂), potassium nitrate (KNO₃) or potassium nitrite (KNO₂). The process is designed to produce an acceptable salt level in the product of about 1-3%, or a level of curing salt sufficient to produce an acceptable cured meat colour (which is produced by reaction of the meat pigment myoglobin with nitrite). Nitrite may be used per se or derived from nitrate, which is converted to nitrite in the curing system. The presence of salt and nitrite in the product inhibit microbial growth and enhance the durability and safety of the product. Thus salt and nitrite are essential to the curing process. Whereas the salt content is determined by consumer acceptability, the curing salt content is constrained by law. At present this is a maximum of 100 mg/kg of nitrite and 250 mg/kg of nitrate, as measured in the finished product. Other ingredients may be added to cured meats for a number of reasons, including taste. These include polyphosphates, sugars, spices, non-meat proteins and starches. Also certain types of cheese are brined for reasons of taste and preservation. Pickling of vegetables can be made by adding organic acids until the pH is below pH 4.3. In the process of making sauerkraut, salt is added (brining) to promote the growth of lactic acid bacteria, again for taste reasons and for conservation.

Methods and equipment

The following methods are applied for brining and curing:

a) Dry-brining/curing

Dry-brining/curing is applied to meat and cheese. In making cured meat products, salt and other curing ingredients are deposited on the surface of the meat and are absorbed by diffusion over a period of days or even weeks. At the same time liquor diffuses out of the meat, equivalent to about 10% of the initial meat weight. In the production of certain types of cheese (e.g. Cheddar) dry salt is added to the curd.

b) Injection-brining/curing

Injection-brining/curing is used in meat processing (e.g.bacon, ham). A prepared solution (i.e.brine) containing the ingredients is injected by needle(s) into the meat, either manually or by machine, to achieve a rapid deposition of curing salts and salt throughout the mass. After injection, the meat may be further processed or sealed in a plastic vacuum bag for a number of days, or immersed in a brine that will be identical or similar in composition to the injected brine.

c) Immersion brining/curing

Immersion brining/curing is applied to cheese, meat and vegetables (e.g.sauerkraut). During immersion, salt gradually penetrates into the product while water containing soluble product components are extracted from the product. The immersion brine may be discarded after each usage or it may be continually re-strengthened and re-used with only a bleed being discharged. Water extraction by brining can range from 5-15 % of the product weight. The salt content of the brine ranges from 5-20 %.

d) Tumble/massage brining/curing

This type of process is especially applied to meat. In this process, the movement of brine into the meat is accelerated by mechanical action. The meat may be injected with the brine before treatment or it can rely on the mechanical action, possibly assisted by vacuum, to accelerate absorption of the brine. This process is normally used when the meat is to be subsequently cooked or canned.