| Wine is generally fermented by Saccharomyces cerevisiae.After fermentation,the content of malic acid in wine is often too high,which leads to sour and dissonant taste.Therefore,malic-lactic acid fermentation(MLF)is generally used to degrade malic acid after wine fermentation.However,MLF has a long period and many unstable factors.Schizosaccharces pombe is a non-Saccharomyces,which has good fermentation performance,can reduce acid,enhance color,improve taste,and has the potential to replace or supplement Saccharomyces cerevisiae to become the main strain for wine fermentation.In the past few years,many researchers have been tried to use different Schizosaccharces pombe yeast strains to ferment wine,in order to find the right Schizosaccharces pombe yeast strain.However,using Schizosaccharces pombe alone to ferment wine has the problem of excess acetic acid and acetic acid metabolites,resulting in a decline in wine quality and flavors.Fifteen Schizosaccharces pombe yeast strains that have been screened out in the past by our research group according to their fermentation kinetics.Our research group also has screened out a Saccharomyces uvarum strain called WY-1 which has better fermentation effect of Muscat wine.This strain is suitable to be mixed fermentation with other non-Saccharomyces yeasts for wine making.The aim of this study was to develop a mixed fermentation method which was suitable for the fermentation of Muscat wine with Schizosaccharces pombe as the main strain.This study involves the following aspects of research:1.15 strains of Schizosaccharomyces pombe were individually innoculated to 15 Muscat wines for fermentaion(15 Schizosaccharces pombe yeast strains that have been screened out in the past by our research group according to their fermentation kinetics).The strain Sp-410wass selected for all the index of the wine are within the national standard range,and the degradation rate of malic acid(97.98%)is the strongest,the chromaticity value(1.26)is the highest,the content of acetic acid(0.18g/L)and acetaldehyde(48.46mg/L)L)was the lowest,and the content of ethyl acetate(5.67 mg/L)and glycerol(4.93 g/L)were at higher levels in the 15 strains of Schizosaccharomyces pombe.2.The fermentation test was carried out by comparing three fermentation temperatures and the three inoculation amounts.The optimum fermentation temperature for Muscat wine innoculated by Schizosaccharomyces pombe Sp-410 was 25℃,and the optimum inoculation amount was 5×10~6 CFU.Under these two conditions,the degradation ability of malic acid(96.81%)was the strongest,and the content of main esters and alcohols in wine were within the standard range.3.Eight different inoculation ratios of Schizosaccharomyces pombe Sp-410 and WY-1 were tried individually for Muscat wines fermentation.It was found that the optimal mixed fermentation ratio of Sp-410 and WY-1 was 500:1,which had the strongest malic acid degradation(96.70%),the content of higher alcohol(218.69mg/L)is the lowest within the standard range,the content of acetic acid,acetic acid metabolites and the chromaticity value of the wines are at the best level.Seven different intervals between Schizosaccharomyces pombe Sp-410 and WY-1 were tried.It was found that the optimal interval betweeen Sp-410and WY-1 is 60 h,which had an effective ability to degrade malic acid,the content of higher alcohol was the lowest in the standard range(149.44 mg/L),and the content of acetic acid and acetic acid metabolites And the color of the wine is at a high level.4.The mix fermentation method of Sp-410 and WY-1 for Muscat wine resulted in a weak overall aroma of the wine.Therefore,other functional non-Saccharomyces were considered to be mixed with Sp-410 for fermentation to make up for this problem.Four kinds of non-Saccharomyces were considered for they have better performance in the wine fermentation process.Torulaspora delbrueckii(TD)was selected finally,for the reasons that the malic acid degradation ability of the wine was the strongest(92.37%),the metabolite of acetic acid was the lowest,and the content of higher alcohol(214.32 mg/L)was the highest.5.For(1)TD,Sp-410 and WY-1 were simultaneously fermented at a ratio of 500:1,(2)TD and Sp-410 were innoculated to the grape juice,WY-1 was sequential innoculated to the grape juice after a 60h-interval.The result showed that there was no significant difference bewtween these two fermentation treatments for the aroma components of the Muscat wine.There were slight effects for the fermentation rate,glycerol content and chroma value,but the effects were not significant.In this paper,the fermentation of Muscat grape was carried out by using Schizosaccharomyces pombe as the main strain mixed with other functional non-Saccharomyces yeasts.By comparing the effects of different strains,fermentation conditions and mixed fermentation methods on wine aroma,Schizosaccharomyces pombe SP-410 was selected.The optimum fermentation conditions for Muscat wine was selected(temperature was 25℃,inoculation amount was 5×10~6CFU/m L).Finally,the optimal mixed fermentation ratio was screened out(SP-410:WY-1=500:1).The optimal sequential fermentation interval was 60h,and the best non-Saccharomyces yeast that could complement SP-410 for Muscat wine fermentation was Torulaspora delbrueckii.The result of this study played the role of Schizosaccharomyces pombe for its degradation ability of malic acid during fermentation.The mixed fermentation method also reduced the risk to produce excess acetic acid and acetic acid metabolites during fermentation which has adverse impact to the wine.Moreover,the addition of the functional non-Saccharomyces yeasts mixed with Schizosaccharomyces pombe has increased the content of aroma compounds.In this study,a mixed fermentation method was provided for the fermentation of Muscat wine by using Schizosaccharomyces pombe as the main strain,which was beneficial to the development of making high quality wine. |
PDF Full Text Request