| Dry-cured duck is a kind of Chinese traditional fermented meat product that is favored by consumer.There are such questions to be improved as outdated processing, long processing time, the instability in quality, singleness of product variety, and the control of quality, etc. According to this research, effects of Lactobacillus sake, Staphylococcus xylosus and Dabaryomyces hansenii on biochemistry quality of dry-salted duck were studied.Analysis of protein content changes of a single strain fermented dry-cured duck, results showed that three strains had the capacity of proteolysis, and S. xylosus> L. sake >D.hansenii. Contents of total nitrogen (TN) were not significant different, but non-protein nitrogen (NPN) and total free amino acids (FAA) were both increased, which sample by S. xylosus the highest level and 1.9 and 1.73 times as CK respectively. Contents of essential amino acid and FAA with sweet were the highest level in sample by D.hansenii and were 1.1 times as CK respectively; contents of FAA with relish in sample by L. sake was the highest level and was 1.4 times as CK and effectively improve the composition of amino acids.Analysis of effects of single strain fermentation on dry-cured duck, results showed that contents of phospholopid decreased significantly, which sample by D.hansenii the lowest level and 0.87 as CK. Substantial increased in free fatty acids, of which samples by L. sake and D.hansenii the increased more for the 1.6 times as CK. The types of FFA were all changing. Contents of saturated fatty acid(SFA) was decreased than that in unfermentation, slightly higher than CK; contents of unsaturated fatty acid(USFA) were higher than CK, which contents of single-unsaturated fatty acids (SUFA) the sample by D.hansenii the highest, 16.7 times as CK and contents of Poly-unsaturated fatty acids(PUFA) the sample by L. sake the highest, 1.6 times as CK. After production, the main types of FFA were palmitic acid, oleic acid and linoleic acid.In conclusion, L. sake and D.hansenii had a stronger ability to decomposite lipid to generate FFA, and S. xylosus had a stronger ability to decomposite FFA. The effects of the microorganism starter culture on liqid of dry-cured duck were significant.Headspace solid phase microextraction combined with gas chromatography-mass spectrometry (HS-SPME/ GC-MS) were used to identify the kinds and amount of volatile flavor compounds of dry-cured ducks. One hundred and seventeen flavor compounds were identified which include ten kind of acids, twenty kinds of aldehydes, seventeen kinds of alcohols, fourteen kinds of ketones, twenty-seven kinds of esters, twenty kinds of hydrocarbons, two kinds of phenols and seven kinds of heterocyclic. There were sixty-nine kinds of compounds in sample by L.sake, sixty-nine kinds of compounds in sample by S.xylosus, seventy-three kinds of compounds by sample D.hansenii and sixty-four kinds of compounds in CK. More acids compounds in sample by L.sake, more aldehydes compounds in sample by S.xylosus , more alcohols and esters compounds in sample by D.hansenii and more hydrocarbons compounds were in CK. It can be said that effects of microorganism on kinds and contents of flavor compounds of dry-cured duck were significant.Study on fermentation of the three joint, the results showed that it had lower contents of FAA than that in sample by S.xylosus, higher than that in sample by L.sake and D.hansenii, proportion of contents of FFA among three strains was reverse to that of FAA. The use of mixed starter culture made volatile flavor compounds of dry-cured ducks increased and flavor good. |
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