Preliminary Study On Screening And Application Of Yeast Strain For Fruit And Vegetable

Yeast is a kind of microorganism which is closely related to human life.The vast majority of yeasts are beneficial to humans.The diseases that occur in fresh fruits and vegetables are more than the fungi.Some yeasts can be antagonistic to pathogenic bacteria.Through the long-term study,the antibacterial activity of the plant disease control,food preservation,medical and so on has a broad application prospect.At present,the research on the mechanism of action of yeast is still in the laboratory stage,and yeast as a biological agent directly applied to production has also been reported less.The first using in vitro and in vivo separation method of five kinds of antagonistic yeasts isolated from different samples,the antibacterial efficiency of test yeast and by means of microscopy,the antibacterial mechanism were preliminary inquiry,found that yeast can inhibit the germination of spores of Rhizopus and yeast mixed culture will produce teratogenic effects of Rhizopus wire.Preliminary identification of yeasts from the level of cells and the level of colony.Determine the growth curve.The best strain of antagonistic effect was induced by UV.After the test,the antibacterial and resistance of the modified yeast strains were significantly improved.Optimization of fermentation medium for yeast.Through the orthogonal experimental design,the optimal combination as the fermentation of yeast culture based optimal formula:malt sugar 1.5%?1%lactose,potassium chloride 0.15%,protein peptone 2%,0.5%of yeast extract.On yeast and the optimum growth conditions tested,found in the condition for the pH 6.0,temperature is 30±1 ?,shaker speed is 100r/min,the growth of yeast reached maximum value.By vacuum freeze drying technology in the production of yeast powder,study of glycerol,sucrose,sodium ascorbate,skimmed milk powder,mannitol and soluble starch variety protection agent in the freeze drying process of protective effect of yeast by compounding obtained optimal combination of freeze-drying protective agent:skim milk powder 5%,4%mannitol,sodium ascorbate 3%.On the application of the fungus powder,the yeast dry powder was used to deal with the grape fruit,and the effect of corruption on the fruit of the grape was found.