Study On The Diversity Of Fungi In Sweet Liquor And Analysis Of The Nutritional Components

Six different kinds of distillers’ yeast(1#、2#、3#、4#、5#、6#) samples which were collected from six different area of China were choose a s the object of my study. In this research, we mainly analysis the fungi diversity of the distillers’ yeast samples, and study the physicochemical indexes of the sweet ferment rice wine. Among the six kinds of samples, 2# and 4# were selected from the folk, and the others were taken from the supermarket.DGGE were utilized to analysis the fungi diversity. The results showed that the main bacterial community were Saccharomyces cerevisiae 、Saccharomyces fibuligera、Rhizopus oryzae and uncultured fungus. 25 yeast strains and 13 mould strains were totally filtrated from the six kinds of samples by cultured methods. 26 S rDNA sequence was utilized to identify the yeast strains, the results show that they belong to 4 groups: Saccharomyces cerevisiae 、Saccharomyces fibuligera、Issatchenkia orientalis and Pichia kluyveri. The mould strains were identified by the 18 S r DNA and ITS rDNA sequence respectively, results indicated that the 13 mould strains were identificated as Rhizopus oryzae 、 Rhizopus microsporus 、 Rhizopus microsporus var. chinesis、Rhizopus microsporus var. rhizopodiformis、Mucor indicus and Mucor circinelloides.Fermentation broth which were fermented for 36h、48h、60h、72h、84h、96h were collected respectively, and the variation of the total sugar content、total acid content、amino acid nitrogen content and alcoholic strength were studied. The results showed that the total sugar increased first then decreased in content, the other indexes increased gradually and changed to stabilized along with the fermentation process; 2# and 4# express high alcoholic strength and total acid, but low total sugar; 1# and 6# showed high total sugar content and low alcoholic strength; while the microbial species, especially the yeast strains in 3# and 5# were richer that that in 1# and 6# samples, so 3# and 5# showed higher alcoholic strength.In addition, fermentation broth which were fermented for 36h、60h、72h、96h were collected respectively in order to analysis the free amino acid content. It turned out that all the six kinds of sweet ferment rice wine included eighteen kinds of amino acids, which included eight kinds of essential amino acids. When it fermented for 36 h, all the amino acids showed lower content, the content were increased as the extension of the fermentation time, when it fermented time exceed 72 h, the content of the amino acid didn’t change much. But the same kind of amino acid showed difference in the content and the variation trendency of the 6 kinds of samples. Among the 18 kinds of amino acid, Lys、His、Met、Asp、Ser、Cys and Ile were below 4.5mg/100 ml, and the content of His was below 1.2mg/100 ml,it showed the lowest level; Tyr、Phe、Trp、Ala、Val and Leu showed a higher level, and the content of Phe was the higher than the others. Among the eight kinds of essential amino acids, the content of Met、Lys、Leu、and Thr were below other kinds of essential amino acids, while the content of Phe was far above other kinds of essential amino acids in all the samples except 5#. The average content of essential amino acids in 5 # sample showed a low level, all the content were below 3mg/100 ml, among which the Ser and Phe were below other kings of samples obviously.This study analyzed the relationship between the dominant bacterial community of the distiller’s yeast and the quality of the sweet ferment rice wine. The dominant strains were obtained by means of the cultured methods. The aim of the report is to provide experiment basis for the quality improvement and deep processing of the sweet ferment rice wine.