Effect Of Indigenous Saccharomyces Cerevisiae Strains On Wine Quality And Strain Selection

Saccharomyces cerevisiae is the principal species for wine making and plays an important role in wine quality. At present, the most popular wine yeasts in wine industry are imported and limited knowledge of indigenous S. cerevisiae for wine-making has been known in China. So far, few Chinese indigenous S. cerevisiae strains were applied to wine industry. In this dissertation, the effect of Chinese indigenous S. cerevisiae strains on the quality of three varieties wines(Merlot, Cabernet Sauvignon and C hardonnay, separately) was studied for selecting the excellent indigenous strains to make good wine. The major results were summarized as follows:1. Flocculation capacity, foaming capacity, killing capacity and H2S-producing capacity of 16 Chinese indigenous S. cerevisiae strains and 7 commercial strains were analyzed and compared. All commercial strains in this study and 11 indigenous strains, including LFE1225, LFN524, LFA711, LFE1809, LFP525, LFP529, NX11424, NX8316, NX12413, NX3315 and NX1134, had the middle/low foam-producing capacity, middle/low H2S-producing capacity and middle/high flocculation capacity. Except of indigenous strains(LFA711, LFE1219, LFE1809, LFN524, LFP525 and LFP529) and commercial strains VL1 and AWRI796, most of strains had no k illing capacity. All indigenous strains studied could complete alcohol fermentation.2. The effect of 8 indigenous S. cerevisiae strains(NX12413, NX3315, NX8316, NX1134, NX349, NX8422, NX9412 and NX11424) on the aroma profile and sensory characters of Chardonnay wines was evaluated. The result indicated the contents of esters, acids, aldehydes and ketones in the wines differed significantly among indigenous strains. The wine produced by NX11424 had the significant higher content of ethanol esters than other strains, and three ethanol esters(ethyl octanoate, ethyl hexanoate and ethyl butanoate) were characterized as the active odorants of this wine. These compounds contributed the pleasant typical flavor of pineapple, violet, banana and strawberry to the wine produced by NX11424. The strain NX9412 was characterized with the lower content of fusel alcohols than other indigenous strains; the strains NX8316 produced significant higher content of 2-phenylethanol and 2-nonanol than other strains, contributing the rose flavor to wine. By sensory evaluation, NX11424, NX8422 and NX9412 produced the wines with plenty of complex fruit, osmanthus and honey aroma.3. The effect of 8 indigenous S. cerevisiae strains on the aroma profile and sensory characters of Merlot wines was evaluated. These strains were isolated from different varieties, including LFA711, LFP522, LFE1225, LFE1504, LFE1809, LFN524, LFP525 and LFP529. The results indicated that the content of esters present significant difference among yeast strains, and the difference on the total content of alcohols was not significant. Indigenous strains LFE1225, LFE1504 and LFN524 produced the wines with significant higher content of esters than that of other strains. The wines fermented with indigenous strains LFE1225 and LFN524 were characterized with higher content of ethyl hexanoate, ethyl octanoate and isoamyl acetate, with rich flower and fruity flavor. The wine fermented with LFE1809 had the highest content of terpenes(197.45 μg/L), with distinct lilac aroma. Electronic nose was also used to evaluate the aroma-producing ability. It was found that two strains LFE1809 and LFN524 were obviously differentiated from other strains. By sensory evaluation, the wines produced by LFE1225 and LFN524 were rated with the higher scores. Therefore, indigenous S. cerevisiae strains LFE1225 and LFN524 had potential to be used in Merlot wine production for more fruit flavor.4. The effect of indigenous S. cerevisiae(NX12413, NX3315, NX8316, NX1134, NX349, NX8422, NX9412 and NX11424) on Cabernet Sauvignon wine quality(aroma volatiles, anthocyanidins, non-anthocyanidins and sensory quality) was investigated. The result indicated these strains could complete wine fermentation. The higher content of esters was found in NX11424 and NX12413, while the least of alcohols present in NX9412 wine. The concentrations of anthocyanins were significantly influenced by yeast strains and the control treatment(commercial yeast F15) showed the highest concentration. Among these pyranoanthocyanins detected, most of them were significantly in?uenced by these yeast strains. The wine fermented with indigenous strain NX11424 had highest pyranoanthocyanins concentration(30.57 mg/L) among strains studied. The effect of strains studied on the non-anthocyanidins phenolic substances was significant. The difference of non-anthocyanidins phenolic compounds among strains was obvious on the composition, especially on the compositon of phenolic acids. After odor activity value(OAV) analysis and sensory analysis, the wines produced by NX11424 and NX9412 with more esters as active odor compounds, were characterized with more floral and fruit aroma descriptors. Therefore, indigenous NX11424 had potential to be used in Cabernet Sauvignon wine production.5. The effect of indigenous S. cerevisiae NX11424 on the aroma profiles of three varieties wines(Merlot, Cabernet Sauvignon and Pinot Noir) was investigated and compared with control strains RC212 and NX8422. The result indicated that the indigenous strains NX11424 and N X8422 had different performance on the aroma profiles of wines produced from different varieties grapes. NX11424 produced the higher content of esters and lower content of fusel alcohols than those of other two strains in Cabernet Sauvignon wine and Merlot wine, separately; however the higher alcohol content in NX11424 treatment was higher than that of the control strain NX8422 in Pinot Noir wine; the Pinot Noir wine produced by N X8422 had lowest content of higher alcohol among these three strains, and had the better aromatic series profiles with intense floral and fruit aroma.