Nitrite meats cured with

PEGG R B, FISH K M and SHAHIDI F (2000) The replacement of conventional meat curing with nitrite-free curing system, Fleischwirtschaft, 80 (5) 86-9. 

In the last fifteen years there has been considerable interest in the analysis of volatile N-nitrosamines in foods. The primary focus has been on meat cured with nitrite (3 ) although nitrosamines have been shown to occur occasionally in other foods such as fish and cheese (, 3) Recently, attention has been directed to volatile nitrosamines in beer and other alcoholic beverages. The purpose of this paper is to review current information on the presence of nitrosamines in beer, and to discuss work done in our laboratory and elsewhere on the mode of formation of nitrosamines in beer. 

N-Nitrosamines are widely distributed in various human environments. The concern was initially focused on their widespread occurrence in food and consumer products, as beer, meats cured with nitrite, smoked fish, tobacco and tobacco smoke, rubber products including baby bottle nipples and pacifiers, cosmetics, drug formulations, or herbicides formulations. Much data of their occurrence have been obtained by inadequate analytical methods and must await confirmation. Considerable progress has been made in the development of adequate and specific methods for trace analysis of nitrosamines, and reliable information is expected in the near future. 

Sodium nitrite can react with proteins in the stomach or during cooking, especially in high heat (such as frying bacon), to form carcinogenic N-nitrosamines. To prevent this, ascorbic acid or erythor-bic acid is commonly added to cured meats. 

In meat curing, nitrite is traditionally used for developing the pink, heat-stable pigment. Its other important role is the inhibition of the outgrowth of Clostridium botulinum spores in pasteurized products and, in some countries, in several types of smoked fish. Nitrite also serves as an antioxidant and contributes positively to the development of the flavor of cured-meat. The undesirable side-effect, however, is the reaction of nitrite with amino groups of food constituents, leading to the formation of NNCs. 

A U.S. patent was issued in 1917 for the use of nitrite as a replacement for nitrate in curing brines (Doran, 1917, as cited in Binkerd and Kolari, 1975). Kerr et al., (1926) found that hams cured in a brine containing about 2000 ppm sodium nitrite were equivalent in flavor and color to hams cured with nitrate. The maximum nitrite level found in any part of the hams was 200 ppm. Based on these experiments, the U.S. Department of Agriculture (USDA) in 1925 authorized use of sodium or potassium nitrite in curing brines in federally inspected establishments, at 0.25 to 1 ounce per 100 pounds of meat, such that the finished product would contain no more than 200 ppm sodium... 

In canned meats, ascorbate also enhanced NOMb production (Reith and Szakaly, 1967b). Without ascorbate, a Mb nitrite molar ratio of 1 5 was needed for optimum formation of NOMb. With ascorbate, a ratio of 1 Mb 3 nitrite was sufficient for maximum NOMb formation. Sodium erythorbate was equivalent to sodium ascorbate for NOMb formation. Canned meats formulated with potassium nitrate showed no formation of cured meat pigment. 

Thus, antioxidant effects of nitrite in cured meats appear to be due to the formation of NO. Kanner et al. (1991) also demonstrated antioxidant effects of NO in systems where reactive hydroxyl radicals ( OH) are produced by the iron-catalyzed decomposition of hydrogen peroxide (Fenton reaction). Hydroxyl radical formation was measured as the rate of benzoate hydtoxylation to salicylic acid. Benzoate hydtoxylation catalyzed by cysteine-Fe +, ascorbate - EDTA-Fe, or Fe was significantly decreased by flushing of the reaction mixture with NO. They proposed that NO liganded to ferrous complexes reacted with H2O2 to form nitrous acid, hydroxyl ion, and ferric iron complexes, preventing generation of hydroxyl radicals. 

Lee et al. (1978) investigated the possibility that sulfhydryl groups were required in the formation of the clostridial inhibitor in cured meats. Sulfhydryl groups of meat proteins were blocked by treatment with silver lactate, then the samples were cooked with sodium nitrite before inoculation with C. botuli num spores. Botulinal growth as measured by gas and toxin production was similar to controls without silver lactate treatment. They thus concluded that sulfhydryl groups were not required for the antibotulinal effects of nitrite in cured meats. 

In our search for nitrite alternatives, as far as flavor and oxidative stability Is concerned, we examined the effect of commonly used adjuncts In meat curing, as well as a large ntimber of antloxldant/sequesterant systems (40-42). In particular, the effect of sodium ascorbate (SA) and sodium tripolyphosphate (STFF) on the oxidative state of cooked meats was studied. These additives lowered the TEA numbers by a factor of about 2 and 4, respectively (Table IV). When used In combination, a strong synergism was observed. Furthermore, an Increase In the concentration of SA and/or STFF resulted In a decrease In the TEA values as depicted In Figure 6 (43). Addition of 30 ppm of butylated hydroxyanlsole (EHA) or tert-butylhydroqulnone (TEHQ) further reduced the TEA numbers and In fact the latter values were even lower than those obtained for meats treated with sodium nitrite (Table IV) (41). 

How nitrosamines, compounds formed in cured meats preserved with sodium nitrite, are thought to be cancer-causing (Section 7.16)... 

Meat. For preservation purposes, meat has been cured with added salt (NaCl) and nitrates (saltpeter) since ancient times. With the recognition that nitrate was reduced by microbial action, about 60 years ago, added nitrite began to replace nitrate. The typical red color of cured meat results from the reaction of nitric oxide with myoglobin to form nitrogen monoxide myoglobin, more frequently referred to as nitro-somyoglobin, and with heat, nitrosomyochrome. 

The rate of /V-nitrosation increases with the pKa of the amine and depends on the pH — it is highest at a pH range of 2-4. The reaction can be inhibited by compounds capable of binding the nitrosating agents — in meat curing, sodium ascorbate is very effective. Foods low in amines and nitrites generally contain about 1-10 ppb, while cured and heavy smoked meat and fish contain up to several hundred ppb of /V-nitroso compounds. 

For cooked, cured meat products with minimum of 100 ppm sodium nitrite (ingoing). (These guidelines are independent of the addition of organic adds or salts.)... 

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