Contribution of non-Saccharomyces yeasts to aroma-active compound production, phenolic composition and sensory profile in Chinese Vidal icewine

Revealing differences in flavor compounds during plum wine fermentation using single and mixed yeast strains through metabolomic analysis

Mixed fermentation can enhance the flavor and aroma of fruit wine, but the mechanisms driving this enhancement remain unclear. This study used non-targeted metabolomics to analyze the effects of mixed versus single fermentation on plum wine flavor. The results showed that compared with single fermentation, mixed fermentation reduced ethanol content and the ability to consume reducing sugars. In single fermentation, volatile compounds increased over time, while in mixed fermentation, they first increased and then declined. Mixed fermentation notably increased esters and reduced higher alcohols, with key differentiators including phenethyl acetate, hexyl acetate, isoamyl acetate, ethyl acetate, isoamyl alcohol, phenethyl alcohol, ethyl caproate, and isobutanol. Furthermore, 40 differential non-volatile flavor compounds were identified, with amino acids emerging as the predominant differentiators. The annotation analysis of these compounds revealed 11 important metabolic pathways for proline, aspartate, glutamate, and β-alanine metabolism. These findings provide insight about producing plum wines with distinct flavor profiles.

Evaluating of effects for the sequence fermentation with M. pulcherrima and I. terricola on mulberry wine fermentation: Physicochemical, flavonoids, and volatiles profiles

This study investigates the variation of physicochemical, flavonoids, and volatiles during sequential fermentation which Metschnikowia pulcherrima and Issatchenkia terricola as sequential co-fermenters and a single fermentation by Saccharomyces cerevisiae in mulberry wine. Sequential fermentation shown that β-glucosidase activity greater and fermentation time declined to 144 h. In addition, 11 flavonoids (apigenin-5-O-glucoside, aromadendrin-7-O-glucoside, kaempferol-3,7-O-diglucoside, and so on) were significantly increased. Significant differences were found between types of metabolic products enriched in flavone and flavonol biosynthesis and anthocyanins biosynthesis, with an enrichment ratio of 46.15 % and 23.08 %, respectively. 16 apple-scented compounds (2-Buten-1-one, (E)-1-(2,6,6-trimethyl-1,3-cyclohexadien-1-yl)-, Butanoic acid, (Z)-3-hexenyl ester, 3-methyl-1-methylethyl-Butanoic acid ester, and so on), 5 rose-scented (e.g. benzyl alcohol, ethyl geranate, hydrocinnamic acid), and 4 balsamic-scented compounds ((-)-myrtenol, benzoic acid 1-methylethyl ester, benzyl alcohol, p-cymen-7-ol) were distinctively present. Interestingly, tryptophan metabolism and indole alkaloid biosynthesis are only enriched in sequential fermentation.

Fermentation Performances and Aroma Contributions of Selected Non-Saccharomyces Yeasts for Cherry Wine Production

This study evaluates the fermentation performances of non-Saccharomyces strains in fermenting cherry must from Italian cherries unsuitable for selling and not intended to be consumed fresh, and their effects on the chemical composition of the resulting wine. Fermentation trials in 100 and 500 mL of must were carried out to select 21 strains belonging to 11 non-Saccharomyces species. Cherry wines obtained by six select strains were chemically analyzed for fixed and volatile compounds. Quantitative data were statistically analyzed by agglomerative hierarchical clustering, partial least squared discriminant analysis, and principal component analysis. Wines revealed significant differences in their composition. Lactic acid and phenylethyl acetate levels were very high in wines produced by Lachancea and Hanseniaspora, respectively. Compared to S. cerevisiae wine, non-Saccharomyces wines had a lower content of fatty acid ethyl esters 4-vinyl guaiacol and 4-vinyl phenol. The multivariate analysis discriminated between wines, demonstrating the different contributions of each strain to aroma components. Specifically, all wines from non-Saccharomyces strains were kept strictly separate from the control wine. This study provided comprehensive characterization traits for non-conventional strains that enhance the aroma complexity of cherry-based wine. The use of these yeasts in cherry wine production appears promising. Further investigation is required to ascertain their suitability for larger-scale fermentation.

Evaluation of Indigenous Yeasts Screened from Chinese Vineyards as Potential Starters for Improving Wine Aroma

Exploitation of the biodiversity of native wine yeast is a means of modifying the sensory characteristics of wine. Samples from different regions in China were analysed to screen native isolates as potential starter cultures. Through morphological and molecular biological analyses, we found six species, belonging to four genera (Hanseniaspora, Saccharomyces, Rhodotorula and Metschnikowia). These species were subjected to stress tolerance assays (ethanol, glucose, SO2 and pH), enzymatic activity tests (sulphite reductase activity, β-glucosidase activity and protease activity) and fermentation tests. Saccharomyces cerevisiae showed a high tolerance to ethanol and completed fermentation independently. Hanseniaspora demonstrated good enzymatic activity and completed sequential fermentation. The fermentation experiment showed that the PCT4 strain had the best aroma complexity. This study provides a reference for selecting new starters from the perspective of flavour enzymes and tolerance and diversifying the sensory quality of wines from the region.

Volatile Profiles and Sensory Characteristics of Cabernet Sauvignon Dry Red Wines in the Sub-Regions of the Eastern Foothills of Ningxia Helan Mountain in China

To elucidate the effects of the different terroir on wine aroma in six sub-regions of Eastern Foothills of Helan Mountain in Ningxia, a premium wine-producing region in China, 71 Cabernet Sauvignon wines were investigated by gas chromatography-mass spectrometry (GC-MS), check-all-that-apply (CATA), and quantitative descriptive analysis (QDA). The bidirectional orthogonal partial least squares-discriminant analysis (O2PLS-DA) results showed that the Cabernet Sauvignon dry red wines from Xixia (XX) and Yongning (YN) had similar volatile profiles due to their geographical proximity and were characterized by higher concentrations of esters, higher alcohols, and volatile phenols because the similar aromatic profiles were detected in their dry red wines. Shizuishan (SZS) and Hongsipu (HSP) wines showed clear differences compared to the wines of the other four sub-regions, being mainly characterized by relatively higher phenolic aldehydes and volatile phenols. The concentrations of methoxypyrazines and norisoprenoids varied mainly depending on the climate diversity of the sub-regions. The highest 3-isobutyl-2-methoxypyrazine (IBMP) concentration was presented in the Helan (HL) wines. The Qingtongxia (QTX) wines have the highest β-damascenone, which might be influenced by the fact that QTX has the lowest effective accumulated temperature and the highest sunshine duration among the five sub-regions. Esters including ethyl octanoate, ethyl decanoate, ethyl butanoate, ethyl hexanoate, and isoamyl acetate were the highest in HL. Additionally, the herbaceous, black berry, and red berry notes in HL and QTX were the most outstanding.

Assessment of traditional clarifiers on the adsorption of ochratoxin A in Cabernet Sauvignon red wine and their kinetics

The effect of clarification on the elimination of Ochratoxin A (OTA) in wine was studied and the adsorption behavior of different clarifiers was evaluated. The results showed that OTA in wine can be effectively eliminated by gelatin with an adsorption rate of 28.59%, followed by chitosan (24.7%), bentonite (22.5%) and polyvinylpyrrolidone (PVPP) (7.6%). The clarification process was significantly affected by the clarifiers and OTA concentration. In addition, the experimental kinetic data for OTA removal were also evaluated by different equations. It displayed that the adsorption of gelatin and PVPP can be simulated by Pseudo-first order equation and Elovich equation, while that of chitosan and bentonite followed Pseudo-second order equation. The adsorption behavior of gelatin, chitosan and bentonite can fit Freundlich equation, Temkin equation and Dubinin-Radushkevich, and that of PVPP can only fitted by Langmuir equation. The thermodynamic parameters further revealed that the adsorption of OTA in wine was non-spontaneous.