SUMMARYBy definition, "cured meat products" contain curing salts, usually salt (sodium chloride) and either nitrites or nitrates. The use of nitrites as a curing agent provides the cured meat colour, the cured meat flavour, and, in combination with other factors, slows or prevents growth of bacterial pathogens.Nitrites exert a concentration-dependent antimicrobial effect in cured meat products, including inhibition of the outgrowth of spores of putrefactive and pathogenic bacteria such as Clostridium botulinum. Their antimicrobial effects are pH-dependent, increasing ten-fold for each unit fall in pH. In most cured meat products, the addition of nitrites (or nitrates) is necessary to prevent the growth and toxin production by C. botulinum.The extent of protection provided to cured meats against microbial growth has been attributed by different researchers to many factors including the input concentration of nitrite, the residual nitrite concentration, the salt concentration of the product, the addition of sodium ascorbate (or isoascorbate / erythorbate), the heat treatment applied, the storage temperature, the initial pH of the meat, and the spore load initially present. The extent of protection is due to a combination of factors rather than any single factor.The antimicrobial effect of nitrite is also markedly influenced by the presence of iron. The availability of iron forms capable of binding and inactivating nitrite varies with the type of animal tissue processed (e.g. it is high in liver and blood sausage, lower in beef, while pork and chicken have the lowest iron content). The absence of a protective effect of nitrite in liver sausages has been ascribed to the presence of high natural quantities of iron in the product.
of 31laboratory investigations is the number of spores of C. botulinum present initially. In the inoculum of experimental studies the number of spores present is several orders of magnitude greater than their relatively rare occurrence in commercial products. This is important because in laboratory experiments there is consistently less growth and less toxin production with a low inoculum than with a high inoculum.There is no direct relationship between the input nitrite and the residual nitrite, especially if sodium ascorbate (or sodium isoascorbate / sodium erythorbate) is present in the formulation to prevent oxidation and to fix the colour.The Panel is of the opinion that the ingoing amount of nitrite, rather than the residual amount, contributes to the inhibitory activity against C. botulinum. Therefore, control of nitrite in cured meat products should be via the input levels rather than the residual amounts.The amount of nitrite necessary to inhibit C. botulinum differs from product to product. With good hygiene, HACCP and realistically short storage times under good temperature control, some meat products can be produced without using nitrites, although these are not strictly "cured meat products". The practices mentioned above are essential whenever levels of nitrites are reduced.In...