Effects Of Different Fermentation Agents And Heat Treatment On NOCs In Pork

Fermented meat products, which fermented by microorganism, has a special flavor, color, texture, and has a longer shelf life. Its unique flavor, and nutritional characteristics are accepted by the most consumers. This thesis focuses on the basic process of fermentation pork; solid phase extraction and determination for nine kinds of N-nitroso compound by HPLC method.Different fermentation starter, and different ways in the heating effects nitroso compound concentrtion were studied,also. The main results are as follows:1. The basic process of fermented pork:the fermentation temperature was 15℃, the amount of salt added was 2.8%, and the added amount of liquor was 3%. Produced by this process conditions dried pork,after fermentation content of TVBN 36.21mg/100g, the end of fermentation required 437 h.2.A solid-phase extraction (SPE)-high performance liquid chromatography (HPLC) method has been developed for simultaneous determination of 9 N-nitroso compounds(NOCs) in meat products. The analytes were extracted with methanol(60℃)with the aid of ultrasonic technique,and purified by CNWBOND HC-C18 SPE column, and analyzed by HPLC-PAD on a Phenomenex AQ-C18 column (250mm X 4.6mm,5μ m),employing Methanol and ultrapure water as the mobile phase in a gradient elution mode. The 9 N-nitroso compounds were qualitatively determined by retention time, and confirmed by the ultraviolet spectrum. The results indicated that the target analytes were in the range with the correlation coefficients(r) greater than 0.99, and the method limits of quantification (MLOQ) of target analytes were ranged 0.047μg/g-0.097μg/g (S/N= 10). The recoveries were in the range between 72.6% and 97.6%,nd the precision (relative standard deviation, RSD) ranged from 3.1% to 7.9%(n= 6).3.Effects of different fermentation starter on the content of NOCs in meat products were studied. At the same time, the changes of main physical and chemical indexes in the process of fermentation were analyzed, also. Finally, the effects of the fermentation starter on NOCs in pork were discussed, from three aspects:the physiological characteristics of the strain, the inhibitory effect on the intestinal bacteria and the activity of diamine oxidase.All results showed that N-nitrosodiethylamine (NDEA), N-nitrosopyrrolidine (NPYR), N-nitroso dimethylamine (NDMA) and N-nitroso dibutylamine (NDBA) were detected in meat. And the content in fermentation meat of Pediococcus pentosaceus, Staphylococcus xylosus and mixed fermentation products was 50%、61% and 58%,compared with that in natural fermentation,90%、56% and 62% of NPYR,74%、80% and 70% of NDEA, and 67%、 61% and 56% of NDBA. Staphylococcus xylosus and Pediococcus pentosaceus do not have protease activity and amino acid decarboxylase activity, with little lipase activity and diamine oxidase activity, but have significantly inhabition on intestinal bacteria.4.Four kinds of heat treatment methods on the results of fermented pork NOCs showed: frying loss rate of the largest, cooking with minimal weight loss; protein and fat content increased in all treatment groups; microwave can reduce the amount of four NOCs in fermented pork, the frying process after the amount of NDMA and NDEA decreased after fried, four kinds of NOCs content after treatment were higher than the raw materia in cooking group, since a long time and minimal weight loss.