Food processing nitrite addition

In addition to the use of nitrite and nitrate as additives, a second general mechanism by which foods may become contaminated with NA is through the drying of foods in air which has been directly heated in an open flame. The highest levels of VNA resulting from this common method of food processing have been in the kilning of malted barley. Concentrations of NDMA in the dried malt of over 100 yg/kg have been reported (Hotchkiss et al. 1980 Preussmann et al. 1981). 

The major chemical reactions that take place during food processing, as would be expected, occur between the main food components—the carbohydrates, proteins, fats and vitamins. These components can react with each other and with various food additives such as nitrites, sulphite, aldehydes and alkali to give food products of lower nutritional value to produce desirable and undesirable browning and flavours and very occasionally to produce toxic materials. 

Nitrite A safe food additive that has been used for centuries to preserve meats, fish and poultry. It also contributes to the characteristic flavor, color and texture of processed meats such as hot dogs. 

Some additives clearly serve an important function. Preservatives help to prevent food from spoiling and enable processed food to be stored for much longer. They reduce the likelihood of bacterial contamination in the food we eat. Sodium nitrite is added to cured meat, for example, to prevent the growth of organisms like Clostridium botulinum, which causes severe toxicity, botulism (see pp. 249-51). Preservatives also reduce chemical degradation and so allow food to have a longer shelf life. Other additives may also have a beneficial function, for example artificial sweeteners reduce the sugar intake of people who suffer from diabetes or obesity. 

The antibiotic Nisin is inhibitory against several grampositive Streptococci, Lactobacilli, Clostridia, Staphylococci and Bacilli (61-62). Goel et al. (63) noted that the addition of Nisin increased the shelf life of low fat dairy spread (Table X). In 20 countries outside the United States, Nisin is permitted as a direct food additive (64), and one major application has been to prevent the growth and subsequent gas production by Clostridia in hard cheese and processed cheese products. In France, for example, Nisin-producing Streptococci have been employed in the manufacture of processed cheese. Nisin has also been studied as a possible alternative to nitrite in the preservation of meats (65). 

Nitrosoamines or nitrasamines are derivatives of amines, containing V-nitroso groups ( N—N=0)- Typically, a nitrosamine is formed by the reaction of an amine with a nitrite. These substances are also produced by the action of nitrate-reducing bacteria. Nitrosoamines occur in trace quantities in tobacco smoke, processed food, meat products, and salted fish. Many nitrosoamines are used as gasoline and lubricant additives, antioxidants, stabilizers, and softeners for copolymers. These compounds are noncombustible liquids or solids at ambient temperature. The hazardous properties of nitrosoamines are different from those of their parent aliphatic or aromatic amines. 

The suspicion that the use of nitrite in foods might result in the formation of NA stems from an incident in which animals fed nitrite preserved fish meal developed liver necrosis. The causal agent was determined to be NDMA and it was shown that the compound resulted from the nitrosation of the amines in the fish by nitrous acid formed from nitrite (Ender et al., 1964). Nitrite is an economically and technically important food additive in the curing process in order to fix color, develop flavor and inhibit toxigenesis by Cl. botulinum. 

NOTE WELL Many processed foods contain high levels of sodium due to the addition of salt and other sodium- containing additives among them, sodium alginate, sodium aluminum sulfate, sodium benzoate, sodium citrate, sodium diacetate, sodium erythorbate, sodium nitrate, sodium nitrite, sodium propionate, and sodium sorbate. 

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