Effects Of Raw Material Freshness And Fermentation Conditions On Changes Of Nitrite And N-nitrosamines In Fermented Sasuages

Nitrite is an essential food additives in fermented sausages,which can give products afavourite color,inhibit the bacterial, prevent corruption,and antioxidant capacity,et al.Yetresearch showed that nitrite have significant influence on the strong carcinogenN-Nitrosamines.Thus,it has important significance for this food safety issue to study and findout changes of nitrite and N-nitrosamines in fermented sausages.In this research,changes ofnitrite residues and N-diethylnitrosamine(NDEA) formation was studied at the aspect of rawmaterial characteristics and fermentation conditions,which was expected to give a guide tocontrol the harm of nitrite and N-Nitrosamines,and we also explored the formationmechanism of N-Nitrosamines. The contents and results are as follows:A comprehensive physical and chemical changes in different freshness meat wasstudied,and principal component analysis was used to confirm the key indicators thatinfluence meat freshness.Based on this,meat freshness on nitrite residues and NDEAformation was studied,and the correlation between freshness indicators and nitrite residues orNDEA formation was deeply analysised. The results showed that meat freshness have littleeffect on changes of nitrite residues,but extreme positive effect on NDEA formation.Furtheranalysis showed that microorganisms activity and cadaverine content have highly positiveeffect on nitrite residues(p＜0.05),and total volatile basic nitrogen(TVB-N) content wasextreme highly positive correlated with NDEA formation(p＜0.01), which meansmicroorganisms activity and protein degradation has important influence on nitrite residuesand NDEA formation;as for the degradation of lipid and pH values,have a declined effect onthe two observation variables.The effect of secondary sterilization temperature at80℃and121℃on nitrite residuesand NDEA formation in fermented sausages was studied. The results showed that high heattreatment temperature(121℃) can significantly promote the nitrite residues decrease andNDEA formation,which means that heat treatment temperature is an important factor toinfluence these two substances.Through the way of adding neutral protease to meat to promote protein degradation,further study on effect of different protein degradation on nitrite residues and NDEAformation was carried out.It was found that protein degradation have a little effect on changesof nitrite residues,but can significantly promote NDEA formation.The correlation analysisbetween TVB-N content and NDEA formation (p＜0.05) means that deep degradation ofprotein was the key factor to NDEA formation.Exogenous putrescine and cadaverine was added to meat for studying these twobioamines as NDEA precursors and their influence on nitrite residues.The results showed that the correlation between both putrescine or cadaverine content and NDEA formation was notsignificant(p＞0.05),yet the two observed biogenic amines could slightly decrease nitriteresidues,which indicated that bioamines may participated the nitrosation reaction and formedother N-Nitrosamines.The fermentation conditions on nitrite residues and NDEA formation was studied.Andwe concluded that the order of the factors studied on these two observation variables were:fermentation time＞amount of added nitrite＞fermentation temperature＞starter culture(Staphylococcus.xylosus and Staphylococcus.carnosus). Furthermore, fermentation time is animportant factor to these two observation variables; amount of added nitrite can significantlypromote NDEA formation(p＜0.05);fermentation temperature also have a significant impacton NDEA formation(p＜0.05),while have no effect on changes of nitrite residues;as for thetwo starter cultures used in this study,both of which have no effect on changes of nitriteresidues and NDEA formation.