Research On Flavor Fingerprints Spectrum Of Characteristic Fermented Dairy Products

In recent years,dairy products,especially in fermented dairy products,has attracted more and more attention.For practitioners,in addition to more attention to nutrition and health functions brought by dairy products,it's more intensive on study of sensory flavor.Therefore,it is essential to establish and improve a fingerprints system of the flavor of fermented dairy products.In this paper some yeast add into traditional fermented dairy products researched formerly to form characteristic ferme nted milk with a unique flavor.Explored its flavor comprehensive by texture analyzer,electronic nose and gas chromatography-mass spectrometry techniques,researched on some of its physical and chemical characteristics simply and established the fingerprints of the flavor in this characteristic fermented milk.Made a comparison with the flavor characteristics of the traditional yogurt and provide theoretical support for further research on traceability and metabolic mechanisms of dairy flavor substances in future.The Conclusions were as follows:1.the physicochemical properties and texture characteristics of the two fermented milk samples were significantly different.This difference is not significant in the early stages of fermentation,but with the extension of the fermentation time,it's obviously that the yeast has promoted the lactic acid bacteria from producing acid.But it will be on the contrary while the yeast is surplus to delay the curd time and increase the holding capacity of the fermented milk with yeast later than the one of the normal yoghurt's.The differences of the two samples is significant at the period of 4h of fermentation and 24h,36h,48h as well asl 4d of ripening and the hardness,consistency,cohesiveness and viscosity index of the fermented milk with yeast are all lower than these of yoghurt in the ripening process.2.Distinguish the differences of the fermented milks' flavor at different fermentation time visually from the PCA and LDA map with the application of an electronic nose system comes with PCA and LDA analysis software to analyze.Analyze the flavor characteristics of fermented milk comprehensive with PCA biplot and establish fingerprint template of the fermented milk flavor which corresponds to the change of fermentation time.It will be used to detect the storage time of an unknown sample.3.Detect volatile flavor of the yoghurt and the characteristic fermented milk with yeast with the use of HS-SPME-GC-MS and as a result,many kinds of flavor substances were detected.This article just analyzed some more abundant and representative substances,containing acids,esters alcohols,carbonyl,aromatic and heterocyclic compounds,a total of 28 substances in 7 kinds.Distinct metabolic differences between the two fermented milk were found after a comparative analysis and establish the flavor fingerprints of yoghurt and the characteristic fermented milk with yeast.