The Kinetic Changes Of Fatty Acid Frofile Of Goat Milk During Fermentation And The Biotechnology In Improving The Gaoty Flavor

The goat milk has rich nutrition, characteristic flavor, certain proportion of protain andfat, and characteristic fatty acid profile, differ from milk. A large number of studies hasproved that the goaty flavor comes from the high level of short chain of fatty acid (SCFA)with branched-chain or not; and the fermentation process can promote the metabolism oflactose, protein and fat of goat milk in different pathways during fermentation; thedegradation of milk fat is very important for improving the nutritional value and especiallythe goaty flavor. In order to investigate the mechanism of the improvement of the goaty flavorby fermentation, as well as to determine the technical parameters under which the fermentedgoat milk has a pleasant flavor, the paper firstly determined the varieties of fatty acids causinggoaty flavor based on the differs of fatty acid profile of ovin and bovin milk and sensoryevaluation, with the special of SaNeng goat milk from ShanXi and gas chromatographymethod; and then, the variation of fermented goat milk incubated by different lactobacillusand the effect of the fermentation codition, such as proportion of lactobacillus, ratio of startercultures, fermentation temperature and time, amount of sugar addition and the storage timefor ripening et al, for the kinetic changes of fatty acid profile of goat milk during fermentationwas studied. The mainly obtained results were listed as the following.(1) The mechanism of L. diacetylactis fermentation for alleviating the goaty flavor hasbeen explained. L. diacetylactis can better facilitate the degradation of milk fatty acidcoordinate with S. thermophilus and L. bulgaricus, and then translate SCFA generated by thedegradation of media and long chain fatty acid (MCFA, LCFA) into some flavor substance,such as aldehydes and butanedione etal. As a whole, goat milk fermented by L. diacetylactis,S. thermophilus and L. bulgaricus mixed cultures has smaller proportion of goaty flavorsubstance (mainly SCFA), a better distribution of fatty acids for pleasure flavor and moreflavor substance which can conceal the goaty flavor.(2) The optimum of fermented goat milk with abantant carbonyls substance wasdetermined. The detail parameters: the proportion of S. thermophilus and L. bulgaricus, L.diacetylactis was1:1:0.5; the ratio of starter cultures was3%; fermentation temperature andtime was36℃,3hours; the amount of suger addition was5%; the storage time for ripening was18hours; fermented goat milk under this condition has10.05%of SCFA,15.93%ofMCFA and72.95%of LCFA, as well as a proper concentrantion of butanedione (2.44mg/L)and acetaldehyde (11.8%), with a better flavor, less sugar, higher level of nutrition, cateringthe need of the modern food with “low-energy, low-fat, high-protein”.