Study On Breeding Of Superior Yeast And Which Applies In Pineapple Vineger Fermentation

This paper designed to improve the flavor of pineapple vinerger, whole reseach developsaround improving the qulity of pineapple wine which is intermediate product during the pineapplevinerger fermentation.A yeast named H10select from the skin of different grade maturitypineapple. A goog mutant was screened out through H10protoplast mutagenesis by ultravioletirridiation.The mutant had a good fermentation capability to pineapple juice, and could producehigh alcohol production and typical fruit aroma.Meanwhile, this paper explores how to producehigh qulity dry active of pinapple wine yeast, and optimizes the process of pineapple winefermentation by using the dry active yeast, next to study the condition of pineapple wineacetificaton.Finally the fermtation pineapple vinegar has tipiccality pineapple aroma. The mainresults in this paper showed:1、A good yeast for production of pineapple fruit wine was screened from the pineapplewaste with different grade maturity after three round screening. The strain had a goodfermentation capability to pineapple juice, and could produce high alcohol production and typicalfruit aroma. The tolerance factors including the temperature, pH, the original glucose content,SO2and alcohol were investigated. The results show that temperature over35℃，whichnegatively effect the alcohol production of yeast, suitable temperature is30℃；the optimum pH ispH5.0, The fermentation capability of yeast is inhibited when original glucose content growsover25oBx; SO2treatment concentration at60mg/L is good for fermentation, which continueincreasing will reduce the alcohol capacity of yeast; the limitation of alcohol resistance is11%.2、The optimal protoplast formation condition of yeast H10was:cell culture12h,enzymictemperature34℃，enzymic pH6.2, enzymic time90min,the protoplast formation rate was91.34%and regeneration rate was16.81%.H10protopalst exposure to the power20w ultraviolet lamp150s, which produce34mutants.After selected by two grades, getting a super yeast mutants named H10-15that suitablepineapple juice fermentation. H10-15can tolerate15-30°Brix glucose content, has the normalfermatation capability at peak of35℃and pH2.0, the SO2tolerance is140mg/L.3、To improve the trehalose concentration by optimizing the culture condition,the optimalcultrure condition of high trehalose concentration was determined: Original glucose is14°Brix,culture temperature is34.5℃, culture medium is100mL (250mL flask),the NaCl additiveamount is1.3%.The trehalose concentration is14.08%; the mathematical model of trehaloseconcentration was acquired.Four cytoprotectors selecting among fifteen cytoprotectors. Trehalose, maltose, glycerol,and Sorbitol shows better protective effect.Optimizing the additive amount was determined: trehalose is7.5%, maltose is10%, glycerol is4%, and sorbitol is4.5%. The dry active yeast wasobtained reaches the standard GB/T20886-2007.4、The dry active yeast apply in the pineapple wine fermentation.Obtaining optimum dryactive yeast rehydration condition:6%glucose,36℃rehydration150min.Using Quadratic regression orthogonal rotating design optimizing the pineapple winefermentation condition by dry active yeast. The best condition was obtained:temperature is33.5℃，pH5.6，initial glucose is20.5%，inoculumconcentration is5.5%. Mathematical model oftrehalose concentration was acquired.The pineapple wine has tipically pineapple aroma.According to the analysis of aromacomponets in the pineapple wine by the gas chromatography-mass spectrometry. the identifiedconstituents represented97.441%of total peak area. The main components were43.027%esters，18.691%ketone，11.132%alcohol,9.634%aldehydes,6.139%%phenols,5.271%saturated hydrocarbon.5、The optimal condition of pineapple wine acetification was obtained: original alcoholcontent is7%, inoculum size of aceticbacteria is10%, fermentation temperature is36℃，fermentation time is96h.Finally getting the pineapple vinergar with perfect quality.