Study On Isolation And Optimization Of Incubation Condition Of Osmophilic Yeast In Apple Juice Concentrate

Osmphilic yeast grows fast and causes apple juice concentrate spoilage, produces gas at the same time, damages the package, make bigger ecomonical loss, when apple juice concentrate is stored and shipped at normal temperature, so it is very important to control the osmophilic yeast in the apple juice concentrate. This article researched the isolation method of osmophilic yeast and identificated it, Methods orthogonal test was applied to study and optimized the incubation condition of the medium for detecting osmophilic yeast in apple juice concentrate, the four factors in incubation condition included the content of sugar, pH value, dilution degree of apple juice concentrate and incubation temperature, the comprehensive evaluation was based on the growth of bacteria colony. The results of test indicated that the isolated bacteria were polymorphous, high concentration of suger inhibited the growth of osmophilic yeast evidently; the optimizing combination condition of isolation of osmophilic yeast is A₁B₄C₃D₃。That is the pH value was 3.6, the dilution degree was 1:40, the concentration of suger in medium was 60%, the incubation temperature was 30℃. the results of research are as following in detail:(1)The osmophilic yeast mainly comes from air and soil and apple juice concentrate, then comes from leaf of apple tree, there was no osmophilic yeast in water used in production line .(2)The effect of sugar for the growth of osmophilic yeast was different at different concentration of sugar, the number of colonies decreased when the concentration of sugar increased.The number of colonies of osmophilic yeast had a trend of increasing when the incubation time increased at different concentration of sugar.(3)The osmophilic yeast can not grow whent the incutation time is from 24h to 120h at low temperature 10℃and high temperature more than 50℃. It growed at incubation time is from 24h to 120h,the incubation temperature is 20～40℃, it growed well at 30℃.(4)The osmophilic yeast growed well when the incubation time was from 48h to 120h at different pH value, the number of the colonies was nearly the same ,the optimal incubation time was 48h, pH value was 5.4.(5)Osmophilic yeast can not grow at different dilution during incubation 24h,it can grow well when the incutation time is from 48h～120h at different dilution degree,and the number of the colonies was nearly same, the optimal incubation time was 48h, dilution ratio was 1:20.(6)The optimum condition of isolation and incutation of osmophilic yeast was combination A₁B₄C₃D₃。That is pH value was 3.6,dilution degree was 1:40,concentration of sugar was 60%,incubation temperature was 30℃。...