Control nitrite/nitrate addition

Besides the estimation of the animal species and the control of additives, the analysis of processed meats is associated with verifying composition. Here the emphasis is on the content of extraneous added water, carbohydrate-containing thickeners and binders, nonmeat protein additives and fat. In addition, the determination of nitrites, nitrates, nitrosamines and, for enhancing the... 

In order to define the conditions of the growing cultures, buffered medium (VL) inoculated with E, coli ATCC 11775 and supplemented with nitrate, glucose and DMA was incubated at 37 C, and pH, nitrite concentration, nitrate concentration, cell growth and nitrosamine formation were followed (Fig. 1). Within 2 hrs, >90% of the nitrate is converted to nitrite (some of the nitrite is further reduced) and over 8 hrs the pH drops from 7.3 to 6.0. This would indicate that in experiments carried out for 20 hrs or more the control medium should be adjusted to pH 6.0 to 6.5 and nitrite should be added rather than nitrate. Such a control medium (VL) was supplemented with nitrite and DMA and NDMA formation was followed (Fig. 2). It can be seen that even without the addition of cells the rate of nitrosation is 4 fold greater than... 

This technique has been established for many years particularly for water, soil and feeding-stuff analysis, where a large number of analyses are required for quality control or monitoring purposes. A number of applications have been published for food additives including aspartame (Fatibello et al., 1999), citric acid (Prodromidis et al., 1997), chloride, nitrite and nitrate (Ferreira et al., 1996), cyclamates (Cabero et al., 1999), sulphites (Huang et al., 1999 AOAC Int, 2000), and carbonate, sulphite and acetate (Shi et al., 1996). Yebra-Biumm (2000) reviewed the determination of artificial sweeteners (saccharin, aspartame and cyclamate) by flow injection. 

Nitrates are found in fairly high concentrations in beets, spinach, kale, col lards, eggplant, celery, and leltuce. Additionally, nitrates and nitrites are commonly used in the curing solutions of bacon, ham. and other cured meats. In cured meats, nitrates and nitriles control the growth of microorganisms, particularly Clostridium bonilinum, and also serve as color preservatives. 

Statutory legislation to control the levels of such substances in food has been introduced in the UK and elsewhere. In more recent years, other potentially toxic elements have come into focus. Lead, cadmium and mercury have been the subject of much monitoring of the food chain and other metals, in particular aluminium, are continuing to attract attention. Nitrate and nitrite in food from food additive use is regulated across the European Union, but its presence in food crops has raised concerns. 

At room temperature, Htde reaction occurs between carbon dioxide and sodium, but burning sodium reacts vigorously. Under controlled conditions, sodium formate or oxalate may be obtained (8,16). On impact, sodium is reported to react explosively with soHd carbon dioxide. In addition to the carbide-forming reaction, carbon monoxide reacts with sodium at 250—340°C to yield sodium carbonyl, (NaCO) (39,40). Above 1100°C, the temperature of the DeviUe process, carbon monoxide and sodium do not react. Sodium reacts with nitrous oxide to form sodium oxide and bums in nitric oxide to form a mixture of nitrite and hyponitrite. At low temperature, Hquid nitrogen pentoxide reacts with sodium to produce nitrogen dioxide and sodium nitrate. 

Production of dried sliced pork and control of various parameters utilized in production were described by Kuo and Ockerman (1985). They considered the effects of nitrate, packaging methods, and storage time on residual nitrite, TEA values, and sensory properties. Residual nitrite decreased with increasing storage times at 1°C. The addition of nitrate plus vacuum... 

Hentschel et al. [139] measured heat production and nitrate respiration rates simultaneously in the gill tissue of L aequizonata to answer the above questions. After an aerobic trace had been established, perfusion conditions were switched to anoxia. Upon the addition of nitrate to the anoxic perfusion medium of the open-flow calorimeter, an immediate increase in heat dissipation was seen (Figure 11). A second point to be observed from Figure 11 was that the nitrate-stimulated heat production was proportional to the concentration of nitrate added (30 mol 1 to 1 mmol 1 ). Nitrite appearance in the effluent seawater followed the same pattern as the heat dissipation (data not shown). Half-maximal stimulation of heat production by nitrate was achieved at 0.81 mmol 1 nitrate. The mean experimental ratio of heat produced per mole nitrite was -130+22.6 kJ mol nitrite (N = 13, +SEM). Gill tissue from Mytilus edulis, which does not contain symbionts, was used as a negative control. A change in heat flux was not observed upon exposure to 1 mmol 1 nitrate. Similarly, a calorimetrie run without gill tissue showed that nitrate or nitrite had no effect on the baseline. 

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