Research On Screening Yeast Of Processing Characterization With Antibacterial Properties From Natural Fermented Milk

For these days, China dairy in liquid milk market has been rapidly and competitively developed. But for time being, our yeast fermented dairy product is mainly consisted of fermented dairy by lactobacillus, and the kind of the product is fewer. In addition, about 10 to 20% of the loss from the food corruption in the world, which because is preservative of the chemical combination is, more or less, poisonous to the body of human being. On the contrary, natural preservative of antimicrobial nature is capable of being nontoxic and security, which makes an important role all over the world. Natural food preservative in food science is one of the hot pots.Yeast is the main microorganism of fermented dairy product. This article is studied mainly as follows. Screening yeast from natural fermented milk is to study the rearch of physiological property of screening yeast, which turns out to be to collect accumulately the second grade product in the process of yeast fermentation, which is to maximize the dose of fermented liquid for antibacterial property, with condition of the study containing temperature 28℃,44h of fermentation termination.Through determination of the antimicrobial activity of probiotics by oxford plate assay system,the first screening 32 yeast strains and 18 yeast strains in the labortary as detected bacteria, in the meanwhile, E.coil mind and Bacillus subtilis as common food corruption, both of which are used for antibacterial tests. The result of the experiment turns out to be 6 yeast strains have great effect on that of detected bacteria, the effection of antimicrobial activity is 12.2mm,12.3mm,11.1mm,10.1mm,10.2mm,10.7mm, Excluding the acid of antibacterial property, yeast fermented liquid had little effect, which is showed that the antibacterial property of yeast strains is simply consisted of acid.Studied on the previous research of yeast strains processing characteristic, screening 12 yeast strains that contains high quality and advantages, has two fermented ways of fermented dairy product.YF4(acid 90.2°T,pH4.45),YF2(acid 70.9°T,pH4.75),YC2(acid 89.1°T,pH4.76), which is to develop single fermentation with proportion of 1:1. According to lists of sensory evaluation, the yeast strains selected the characteristic of sticky and smoothy, tasty as the further tested strains are the strains of YF4, YF2 and YC2, which is to fermentation experiment respectively. According to the yoghourt index of its stringiness, smoothness, wilting, and surface wetness, which to choose the YF4/ YF2 as a new combined fermented agent for fermenting dairy product.