Study On The Dynamic Change And Control Of N-nitrosamine In Dry-cured Duck During Processing

Dry-cured duck is one of the traditional cured meat products of China, in order toproduce a favourite color and inhibit the growth of microorganism, nitrite is an essentialadditives during processing. Yet reaserch showed that in some cases, nitrite can react withsecondary amine which is degradated from protein, finally generat the strong carcinogenicnitrosamines. Thus, it is significant for food safety to study and find out formation andchanges of nitrosamines in the dry-cured duck processing. In this paper, the dynamic changeof N-diethylnitrosamine(NDEA) and peoteolysis was studied, and the correlation betweenthem was slao analyzed. At last, the influence of salt on the content of NDEA was studied,which was expected to give a guide to ensure of the dry-cured duck processing. The contentsand results are as follows:Firstly, the dynamic changes of the nitrosamine and nitrite in dry-cured duck whichadded different concentration sodium nitrite (NaNO2) is studied during processing, and thecorrelation between them was also analyzed. The results showed that: Diethylnitrosamine(NEDA) was not been dectected in the raw duck, and quantities of NDEA generated in thecuring stage. The content of NDEA and residual nitrite reached the maximum in the wholeprocessing after the curing stage, then wth the time passing by, the content of both radiate andNEDA was decrease. The content of NDEA in the dry cured duck were1.39μg/kg,0.78μg/kg and0.33μg/kg according to the addtion of NaNO2from high to low. Correlationanalysis showed that the correlation coefficient of the NaNO2and NDEA is high (about0.9),which explained that nitrite played an important rolw on the content of NDEA.Secondly, the peoteolysis in dry-cured duck during processing was studied. The resultshowed that, protein degradation indexfinal(P.I.) of dry-cured duck was5.61which was notvery high. The content of total nitrogen (TN), non-protein nitrogen (NPN) decreasedsignificantly(p<0.05)after the curing stage, while the content of volatile basic nitrogen(TVB-N), ammonia nitrogen (AN) and free amino acids (FAA) also fell, but the decrease wasnot significant (p>0.05). After that, with the time passing by, the content of NPN firstlyincreased and then decreased, while TVB-N, AN and FAA increased continuously. Althoughincreased during processing, and the final AN/NPN was38.46%. Glu, Arg, Ala, Leu and Valwere much more than other FAA in the dry-cured duck, and part of the FAA increased by2-3times than the raw materials.Correlation analysis showed that the correlation coefficient of the protein index andNDEA is high, excepting the correlation coefficient of the PI and NDEA was0.630, the othercorrelation coefficient was biger than0.84. The correlation coefficient of TVB-N, NPN andFAA was-0.983,-0.960and-0.957respectly, which explain that they were the key factors tothe NDEAand the deep peoteolysis had close relations with the content of NDEA.Finally, the effect of salt content on the formation of nitrosamine in dry-cured duck. Theresult showed that, with the increase of salt content, the content of the NDEA, NaNO2,TVBN,NPN and FAA decreased at the same point during processing. The decrease of FAA was notsignificant(p>0.05), while others were significant(p<0.05). The formation of N-nitrosamine and peoteolysis were effectly inhibited by more salt added. Correlation analysis showed that,the effect of peoteolysis on the formation of NDEA is higher than the low salt content, highsalt decrease the formation of N-nitrosamine through suppress peoteolysis, and at lastdecrease the content of N-nitrosamine.