| Non-Saccharomyces cerevisiae is present in the vineyard, grape skin and wine environment, soil orchard, fruit skin and the brewing process, the involvement of wine brewing, can produce some metabolic products and improve arom of wine by autolysis yeast involved in complex formation fresh flavor Saccharomyces cerevisiae outside in general. NSC can secrete pectinase, glucosidase, hydrolase, proteolytic enzymes and a variety of extracellular enzymes to produce alcohols, esters, acids, terpenes and other flavor ingredients. In the winemaking process, non-Saccharomyces yeast on grape metabolic intermediate compounds have complex and diverse volatile and non-volatile flavor compounds play a key role, affecting the quality of the different wine-producing areas significantly. In this paper, isolated non-Saccharomyces yeast from different varieties of grapes from the main producing areas in Xinjiang widely cultivated grape, vineyard soils and fermenting mash, isolated and identified on the basis of tradition, through the 26 S r DNA D1 / D2 region of sequence determination methods, analysis of non-Saccharomyces diversity. By GC-MS analysis and comparison of different non-Saccharomyces yeast fermentation aroma composition changes, analyze the main aroma components typical non-Saccharomyces relevance. Reveal yeast development groups, functional groups change and the relevance of quality wine, explore and evaluate the wine production process. The main contents and results are as follows:1. Isolation and identification of non-Saccharomyces yeastAcquisition Shihezi main producing grape wine grape samples, vineyards and fermenting mash soil samples, 54 cases of grape samples, soil samples were 18 cases, 18 cases of fermenting mash, morp Hological and molecular biological classification method combining separation the NSC strains were identified and p Hylogenetic analysis. Isolation and identification of the strain 250, belonging to six genera. Are: Candida, Meyerozyma,Rhodotorula, Hanseniaspora, Geotrichumand Pichia. A total of 10 kinds, including six suspected similar species.2. Research NSC strains enzyme productionBy β-glucosidase, lipase, amylase, protease screening medium, from Candida,Meyerozyma, Rhodotorula, Hanseniaspora, Geotrichum and Pichia, six genera 21 strains screened three strains having β- glucosidase hydrolyzing activity, numbered: Y8, Y9, Y21; 3strains proteolytic activity, numbered: Y2, Y7, Y18; 8 strains produced amylase strains.numbered: Y13, Y2, Y14, Y7, Y18, Y8, Y20, Y15; 9 yeast strains producing lipase.numbered: Y13, Y4, Y21, Y5, Y6, Y19, Y3, Y17, Y2. Enzyme studies show, β- glucosidase activity descending order of the corresponding strains: Y9>Y21>Y8, protease activity corresponding to strain descending order of: Y18>Y2>Y8, amylase activity low corresponds to strains were: Y18>Y14>Y13>Y2>Y20>Y15>Y8>Y7, lipase activity descending order of the corresponding strains: Y17>Y19>Y3>Y6>Y20>Y13>Y4>Y5>Y21.Study on effect of NSC by p H. The results showed that the NSC β- glucosidase, lipase,amylase, protease activity optimum p H 6.0. p H of increase and decrease will affect the activity, to bring it down. Different strains of activity changes with temperature the overall trend is consistent, optimum temperature is about 30-50 ℃, when the temperature is lower than the optimum temperature, with a corresponding decline in the temperature lowering activity, with a temperature higher than 50 ℃ approaching 60 ℃ All activity decreased rapidly. Concentration(1mmol / L) of the metal ion test results show that: Fe2 +, Cu2 + on enzyme activity with different degrees of inhibition, K +, Na + on activity has no significant effect, Ca2 + and Mg2 + relative activity environments are in relatively high level.Study on Effects of alcohol on the activity indicate that ethanol, fructose and glucose on β-glucosidase enzyme, lipase, amylase, protease inhibited, with simulated wine ethanol,fructose, glucose concentration(content increase) activity in opposite directions, falling.3. NSC influence on wine aroma componentsNon-Saccharomyces different due to the different structure of its own enzymes,fermented wine flavor components are also different, with excellent properties of enzyme production strains Y9, Y21, Y8, Y18, Y2, Y7, Y15, Y14, Y17, single strain was inoculated natural fermentation Cabernet Sauvignon, by GC-MS analysis, a total of 107 kinds of aroma components detected substances, esters 39 kinds, 31 kinds of alcohols, ketones 8 kinds, 10 kinds of alkanes, 15 kinds of acids and other aroma 4 kinds.PCA and LDA methods use different fermentation wine flavor compounds were analyzed, the results show that the method can distinguish different strains fermented wine.Different fermentation and wine volatile components PC1 was mainly ethyl acetate was positively related to 3-methyl-1-butanol, hexyl acetate, heptane, ethyl, 1-propanol,2-methyl-1- propanol, 3-methyl-1-butanol, was negatively correlated with the PC1 volatile compounds mainly butyrate, ethyl hexyl acrylate and 2-hexenoic acid.Analysis showed: I-2, I-5 and A1, A3, A5, A6, I-3, I-8 and B1, B2, B3, I-6, I-4A2, I-, 1,I-9 obvious correlation with A4, A7. I.e., non-Saccharomyces Y12, Y7 of3-methyl-1-butanol, hexyl acetate, heptyl acetate and other ingredients are an important contribution to effect, Y8, Y4 of 1-propanol, 2-methyl-propanol, 3-methyl-1-butanol and other ingredients that contribute to the role, Y2, Y18 butyrate contributing role, Y9, Y17 to themselves and 2-ethyl hexyl acrylate acid has an important contribution to the role.4. NSC strains affect winemakingAccording to traditional wine production process for the separation of high-quality screening for enzyme production capacity in Hong non-Saccharomyces Y9, Y21, Y8, Y18,Y2, Y7, Y15, Y14, Y17 to produce ethanol and acetate production as the main indicator by tolerance screening and other biochemical characteristics, industrial control strain, strain through optional continuously mixed fermentation, fermentation process optimization,analysis of the final wine flavor components, evaluation of strain accumulation of wine flavor ingredients. The results show: The study screened out alcohol fermentation ability of the yeast strain Y9, it can withstand 15% alcohol content and 400mg/kg of SO2. Medium screened from the product ester colony morp Hology good and pure flavor rich Y2, glycerin and esters in high yield at 25-30 ℃. The yeast stronger than control strains produce esters capability, total sugar fermentation 203 g / L of grape juice may produce 10.2 percent of alcohol, can withstand 15% alcohol and 425 × 10-6 of SO2. Continuous mixing fermentation initially identified the optimum conditions: pre-add yeast Y2, fermentation temperature is 25 ℃, 54 hours fermentation, yeast is added later Y9, fermentation temperature was 28 ℃, 120-144 hours of fermentation, yeast total dosage 0.06%, the addition ratio of Y2: Y9 = 1: 3.Wine quality analysis showed that Y2 and Y9 joint action, the bitterness of fermented wine eventually esters, ethyl butyrate, ethyl caproate, succinate, diethyl hexyl acetate enrichment evident. |
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