| Sichuan Tibetan Plateau is obtained most interesting as the newly found area office grape wine producingin the word, which could be produced according to the international standard.However, until now, the icewine is still produced by the natural fermented technology.Itsinferior positionsare including the low safety, the higher risk, and the difficulty to real the standardized production, which significantly restricted the development of icewine industry.In this investigation, the dominant yeast strains were isolated and identified firstly from Vidal ice grapes in the Sichuan Tibetan Plateau.Then, the microencapsulated yeasts for the fermentation of icewine weredeveloped by using the spray freeze drying technology. Finally, the fermented property and technology were optimum investigated. This investigation is wanted to breakthrough the key point for the standard production of icewine.First, the dominant yeast strains in Vidal ice grapes were isolated and identified. Five strains of yeast was isolated and purified from Vidal ice grape, which were named as JH,JH1,JH2, JH3 and JH4, respectively. Though the observation of WL culture and microscope, and with the analysis of molecular identification and sequence alignment molecular identification and sequence alignment using the 18 s r RNA1/D2, the phylogenetic tree was conducted and five strains were identified, which were Hanseniasporauvarum, Metschnikowia pulcherrima,Saccharomyces cerevisiae,Yarrowia lipolytica and Wickerhamomyces anomalus, respectively.Second, the tolerance and fermentation performance were analyzed and investigated.Results from the analysis of tolerance were showed that, five strains of yeast could five strains of yeast could five strains of yeast grow in low temperature of 8?, glucose concentration of55%, p H value of 1.5, SO2 of 500mg/L and alcohol concentration of 16%. Yeast fermentation was evaluated according to the main index and sensory quality of wines as the reference. The results indicate that the selected three strains were more sui Tab for the brewing of ice wine,which were JH, JH1 and JH2, respectively. Icewine fermented with JH exhibited the full flavor of ester. The total ester content was highest, 134.30mg/m L. Moreover, the sensory quality of icewine fermented with JH1 was the highest, 86.5 scores.Third, fermented microencapsulated agents were developed by using the spray freeze drying technology. By the preliminary study on the technology with the method of spray drying prepared the three yeast agent, protective agent was used with four factors and three levels of orthogonal test. The optimal formula was determined, which was skimmed milk powder 6%, maltodextrin 4%, trehalose 0.6% and yellow gum 0.15%.Finally, the fermented property and brewing technology of icewine agents were optimum investigated. The order of factors to affect the volatile acid level in icewine was confirmed,which was kind of yeast agent firstly, fellow the sugar content in raw material, fermentation temperature and the dosage of yeast agent. The optimized major wine-making technology of icewine were also investigated, which was including the yeast strains agents of Hanseniasporauvarum and Metschnikowia pulcherrima, the yeast agent dosages of 0.2g/L and 0.2g/L,fermentation temperature 10°C-15°C, the sugar content 380g/L, respectively, according to sensory quality and related indexes of icewines. Added inoculants Icewine fermentation time,fermentation temperature, fermentation temperature was better than that of natural fermentation, and the sensory score high, higher alcohols and total ester content was significantly higher than that of the natural fermentation of the wine, volatile acids content lower than international standards, and lower than the natural fermentation. The volatile acids content of the natural fermented wine was 1.23(g/L). |
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