Nitrite Mode of Action: Inhibition of Yeast Pyruvate Decarboxylase (E.C. 4.1.1.1) and Clostridial Pyruvate:Ferredoxin Oxidoreductase (E.C. 1.2.7.1) by Nitric Oxide

Thermoplastic starch blown films functionalized by plasticized nitrite blended with PBAT for superior oxygen barrier and active biodegradable meat packaging

Functional bioplastic packaging was produced from thermoplastic starch (TPS) with nitrite (1-5%) and polybutylene adipate terephthalate (PBAT) (PBAT/TPS at 30/70 and 40/60) via blown-film extrusion. TPS-nitrite interaction increased thermal destabilization and decreased α-relaxation temperature of TPS phase, indicating improved plasticization and disruption of starch granules. Nitrite modified C=O bonding of PBAT and improved compatibility with TPS networks, resulting in compact microstructures that reduced oxygen and water vapor permeability. Films containing nitrite showed up to 39.7% decrease (p≤0.05) in mechanical properties while effectively improving and stabilizing redness of vacuum-packaged pork during storage for 12 days. Nitrite release led to up to 0.66 ppm residual nitrite, which corresponded to formation of nitrosyl myoglobin (3.4-9.6 ppm), and effectively reduced total viable count, lactic acid bacteria and yeast and molds (p≤0.05). Stabilized lipid components also increased with increasing nitrite. Novel nitrite-containing biodegradable film enhanced functional properties and retained quality of packaged meat.

Quality attributes and consumer acceptance of new ready-to-eat frozen restructured chicken

The aim of the present study was to develop a new restructured product, cooked and frozen ready-to-eat product that was prepared with boneless chicken meat (breast and drumstick) and mechanically separated chicken meat (MSCM). Non-meat ingredients, such as transglutaminase (TG) and egg albumin powder, were tested to obtain a better strength of adhesion between the meat particles. Five formulations for restructured chicken were developed as follows: T1 (1 % transglutaminase), T2 (1 % transglutaminase and 15 % MSCM), T3 (1 % egg albumin powder), T4 (1 % egg albumin powder and 15 % MSCM) and T5 (1 % transglutaminase, 1 % egg albumin powder and 15 % MSCM). The results of the experiment showed a greater luminosity (L*) in the treatments with TG (T1) and albumin (T3). The treatments without MSCM (T1 and T3) presented significantly lower mean values for redness (a*) when compared to treatments with MSCM (T2, T4 and T5) (p ≤ 0.05). No significant differences were noted between the treatments (p ≥ 0.05) when analyzing the percentage of total saturated fatty acids (SFA), polyunsaturated fatty acids (PUFA) and cholesterol content. Consumer testing showed a high acceptance of the restructured products in all evaluated attributes. Similarly, with regard to the purchase intention, consumers mostly expressed that they would probably or certainly buy the products, for treatments T1, T2, T3 and T5. Moreover, the meat cuts with no commercial value, can transform into new ready-to-eat products that have a high probability of success in the market.

Nitrite and nitrosyl compounds in food preservation

Nitrite is consumed in the diet, through vegetables and drinking water. It is also added to meat products as a preservative. The potential risks of this practice are balanced against the unique protective effect against toxin-forming bacteria such as Clostridium botulinum. The chemistry of nitrite, and compounds derived from it, in food systems and bacterial cells are complex. It is known that the bactericidal species is not nitrite itself, but a compound or compounds derived from it during food preparation. Of a range of nitrosyl compounds tested, the anion of Roussin's black salt [Fe4S3(NO)7]- was the most inhibitory to C. sporogenes. This compound is active against both anaerobic and aerobic food-spoilage bacteria, while some other compounds are selective, indicating multiple sites of action. There are numerous possible targets for inhibition in the bacterial cells, including respiratory chains, iron-sulfur proteins and other metalloproteins, membranes and the genetic apparatus.