Screening,Identification And Application Of Yeast Strain FJZ Producing Fragrant Flavor

In this paper,the yeast strain FJZ was separated and screened from fermented grains of a certain clear flavor liquor by using the flavor guidance technology.and the main flavor components in the fermentation process were determined by GC-MS technology.The strain was identified by morphological,physiological and biochemical tests and phylogenetic analysis of 26 S r DNA sequence;and the growth,enzyme production capacity and tolerance of the strain were studied.The single factor experiment and response surface method were used to establish the fermentation conditions of high-yield esters,which were applied to the fermentation of liquor and vinegar.The test results are as follows:(1)GC-MS technology was used to determine the strong ester aroma substances produced by the strain in the fermentation process,in which the relative content of ethyl acetate accounted for 20.67% of the ester substances.Through morphological observation,physiological and biochemical tests and sequencing and comparison of 26 S r DNA region sequence,the strain FJZ was identified as Pichia kudriavzevii and named as FJZ.Through the study on the biological characteristics of the strain,it is found that the strain has strong osmotic pressure resistance,acid resistance and alcohol resistance,the optimum growth sugar is 20%,alcohol is 12%,and p H2.5;the strain FJZ has a competitive relationship with Saccharomyces cerevisiae,and the competitiveness is stronger than that of Saccharomyces cerevisiae;the strain has a certain alcohol production capacity.(2)Through single factor and response surface experiments,the optimal fermentation parameters of Pichia Kuder FJZ were determined as follows: 5% inoculum amount,36 h inoculum age,32 ℃fermentation temperature and 7d fermentation time.Under this condition,the total ester content of fermentation was(6.14 ± 0.02)g/L,which was 57% higher than that of raw materials.(3)Applying Pichia kudriavzevii FJZ to the fermentation process of liquor,it was concluded that: the total ester content of the finished liquor obtained by intensive fermentation of liquor was(2.41 ± 0.15)g/L,and the alcohol content was(66.7 ± 0.11)%,GC-MS measurement results showed that the ethyl acetate concentration was(2.00± 0.01)g/L;the total ester content of the best fermentation group of the second-fermented liquor(4.95 ± 0.01)g/L,the alcohol content is(68.9 ± 1.13)%;quantitative analysis by GC-MS shows that the concentration of the main ethyl acetate aroma component in the liquor sample increases,reaching(4.80 ± 0.20)g/L compared with the Daqu control group.6.6 times,giving the wine a light fruity aroma.(4)It was found that the content of total acid and total ester in vinegar increased significantly(P <0.05).Compared with the normal fermentation,the content of total acid and total ester increased by22.05% and 30.67%,respectively.