Studies On The Formation And Control Of Volatile N-Nitrosamines In Dry-Cured Meat

Volatile N-nitrosamines are potential carcinogenic compounds.Extensive experimental and some epidemiological data suggest that human are susceptible to carcinogenesis by N-nitrosamines and that the presence of these compounds in some foods may be regarded as an aetiological risk factor for certain human cancers including cancers of the oesophagus, stomach and nasopharynx. Therefore, great efforts have been made to investigate these compounds on formation and control in food. Especially, more efforts have been made to investigate meat product for N-nitrosamines because meat product is one of most important component in human food. Bacon and sausage are always used to be as materials to investigate volatile N-nitrosamines. However, there is little knowledge available in literature about formation and control of volatile N-nitrosamines in Chinese traditional dry-cured meat. Therefore, the present studies focused on the formation and control of volatile N-nitrosamines which could provide theoretical support for the modern technological reconstruction of dry-cured meat and enhance the food safety quality.The research comprises four parts:Firstly, study of the method for determination of volatile N-nitrosamines in dry-cured meat and investigation on styles and contents of volatile N-nitrosamines in dry-cured meat; Secondly, the changes of volatile N-nitrosamines and main physico-chemical indexes in dry-cured meat during processing; Thirdly, effects of antiscorbic acid, Vitamin E and tea polyphenols on the formation of volatile N-nitrosamines in dry-cured meat during processing and optimization of the three additives.1. Method for determination of volatile N-nitrosamines in dry-cured meat and investigation on the style and content of volatile N-nitrosaminesVolatile N-nitrosamines in dry-cured meat which was purchased from market were measured by gas chromatogram after pre-trement. The results showed that two kinds of volatile N-nitrosamines were found, which were volatile N-dimethylnitrosamine (NDMA) and volatile N-nitrosopyrrolidine (NPYR), respectively. The average content and detection rate of NDMA were 0.16μg/kg and 84% which the content and detection rate of NDMA were 0.0013μg/kg and 17%. No other volatile N-nitrosamines like NDEA, NPIP, NDBA and NDHA were found.2 Changes of volatile N-nitrosamines and main physico-chemical indexes in dry-cured meat during processingThe content of volatile N-nitrosamines during the processing of pre-treatment, second pickling,7 days after second pickling,15 days after second pickling and after pickling were measured. Moreover, the residual volumes of nitrite, pH, biogenic amines and oxidation condition were also studied. The result indicated that NDMA and NPYR were found and the content of NDMA was high than NPYR during processing. In the pickling protophase, two kinds of nitrosamine increased while 7 days after second pickling, NDMA decreased and NPYR still kept increasing. However,15 days after second pickling, both NDMA and NPYR decreased to the minimum. After pickling, there was a small increase in the content of NDMA and NPYR. The residual volumes of nitrite decreased during processing while the value of pH increased at beginning, and then decreased 15 day after pickling. Since then, there was a decrease in pH.3 Effects of antiscorbic acid, Vitamin E and tea polyphenols on the formation of volatile N-nitrosamines in dry-cured meat during processing and optimization of the three additivesThere were five stages in the processing of traditional dry-cured meat:selecting, sorting, first pickling, second pickling and finishing in turns. It would last 25 day from first picking to maturation of the meat. In the experiment, three additives antiscorbic acid, Vitamin E and tea polyphenols were mixed with salt, and then added to the surface and inner of meat in second pickling. Volatile N-nitrosamines in dry-cured meat which were in the same stage were measured by the methods established. The results indicated that the three additives inhibited the formation of volatile N-nitrosamines, but the inhibition effect had chronergy. Lastly, Optimization of utilization of the three additives was studied by response surface methodology.