Effect Of Mixed Fermentation Of Rhodotorula And Saccharomyces Cerevisiae On Flavor Substances Of Kiwifruit Wine

In the preliminary study of this laboratory,a strain of suspected red yeast was screened from the kiwi foot of the kiwi wine.However,no relevant research on red yeast in kiwi wine has been reported.The effect of red yeast on the quality of kiwi wine is completely unknown.In order to discuss these contents,this paper firstly carried out molecular biological identification and basic characteristics research on red yeast,and then inoculated it with Saccharomyces cerevisiae in different inoculation methods to study the interaction between the two yeasts and the effect on the quality of kiwi wine.The main findings are as follows:(1)Rhodotorula was identified by morphology and molecular biology.It was confirmed that the strain belongs to Rhodotorula mucilaginosa.Then the tolerance temperature,p H value,SO₂concentration and alcohol concentration of Rhodotorula in YPD medium and kiwi juice were studied respectively.Under the conditions of experimental temperature and p H range,Rhodotorula in YPD medium and kiwi juice The growth situation is basically the same,and it can grow well at 15?30?and p H value of 5?6;it can tolerate 300 mg/LSO₂concentration and 14%alcohol concentration in YPD medium,and can be in kiwi juice tolerates 150 mg/LSO₂concentration and 12%alcohol concentration;in YPD medium and kiwi juice,the carotenoid content of Rhodotorula at 24?,p H value is 6,100 mg/L SO₂concentration and 8%alcohol the highest concentration.(2)In order to study the interaction between Rhodotorula and Saccharomyces cerevisiae,the two yeasts were mixed and fermented according to different inoculation methods,and the growth rules of Rhodotorula and Saccharomyces cerevisiae during the fermentation process were analyzed,and the results showed that Saccharomyces cerevisiae could obviously Inhibit the growth of Rhodotorula.In addition,when Rhodotorula and Saccharomyces cerevisiae are mixed and fermented according to the two inoculation methods of simultaneous inoculation and sequential inoculation,the later the inoculation time of Saccharomyces cerevisiae in sequential inoculation,the greater the growth of Rhodotorula and the longer the survival time.(3)Rhodotorula and Saccharomyces cerevisiae are mixed and fermented kiwi fruit in various ways such as simultaneous inoculation(1:1,1:4,1:8,4:1 and 8:1)and sequential inoculation(S24,S48 and S96)Wine,and using headspace solid-phase microextraction(HS-SPME)and gas chromatography-mass spectrometry(GC-MC)to determine the volatile aroma components in kiwi wine,the results showed that:a total of 32,68 and 64 volatile aroma compounds were detected in kiwifruit like wine by single strain fermentation of Saccharomyces cerevisiae,simultaneous inoculation of Rhodotorula and Saccharomyces cerevisiae and sequential inoculation respectively.The aroma types mainly include esters,terpenes,aromatic compounds and acids,phenols and ketones.Among them,when Rhodotorula and Saccharomyces cerevisiae are inoculated and sequentially inoculated,the content of ester compounds and terpene compounds in the kiwi wine obtained by sequential inoculation fermentation is always higher than that of simultaneous inoculation.It can increase the types of volatile flavor substances and also increase their content.The most obvious changes are mainly compounds such as esters and terpenes.The comprehensive sensory evaluation shows that the inoculated S48 has the highest score,and its fermented kiwi wine has its application some color and taste.