Influence of nitrogen status on fermentation performances of non-Saccharomyces yeasts:a review

Nitrogen,one of the most crucial nutrients present in grapes and musts,plays a key role in yeast activities during alcoholic fermentation.Such influences are imposed on yeast growth and fermentation performances including the formation of secondary metabolites.Saccharomyces cerevisiae,the main yeast responsible for fermentation,has been studied extensively regarding nitrogen impacts.On the other hand,a similar study for non-Saccharomyces yeasts,whose contributions to winemaking have gradually been acknowledged,remains to be fully explored,with a few studies being reported.This review starts by discussing nitrogen impacts on non-Saccharomyces yeast growth and fermentation kinetics in different case scenarios,then proceeds to summarize the nitrogen preferences of individual yeast strains with regulation mechanisms elucidated by recent studies.Detailed discussions on the influences on the production of volatile compounds and proposed pathways therein are made,followed by future work suggested as the final section.In summarizing the nitrogen impacts on non-Saccharomyces yeasts throughout alcoholic fermentation,this review will be helpful in obtaining a more comprehensive view on these non-conventional wine yeasts in terms of nutrient requirements and corresponding volatile production.Research gaps will therefore be elucidated for future research.

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

To acquire candidate non-Saccharomyces strains for preparation of high-quality Vidal icewine,11 representative indigenous non-Saccharomyces strains were selected for analyzing their production of organic acids,phenolic compounds,aroma-active compounds and evaluating their sensory profile in Vidal juice.The results showed that the contents of organic acids in the wines were controlled and balanced well by the non-Saccharomyces strains as well as polyphenol concentrations were well improved during the fermentation.The strains differed from each other in their ability to produce aroma compounds,causing diversity and complexity of aroma characteristics in wine.Fermentation by Saccharomycopsis crataegensis YC30(Sc)and Hanseniaspora uvarum QTX22(Hu)could enhance the sweet and floral notes in Vidal icewine,especially Sc,which has never been reported before.It can not only enrich the aroma categories,but also increase the content ofδ-decalactone,γ-decalactone,ethyl isobutyrate,ethyl butyrate,phenethyl acetic acid,etc.The evaluation and optimization of non-Saccharomyces yeast strains could provide theoretical basis for the improvement of ice wine quality,and supply new ideas and strategies for the brewing of ice wine.

Microbiota for production of wine with enhanced functional components

Microbial communities during winemaking are diverse and change throughout the fermentation process. Microorganisms not only drive alcohol fermentation, flavor and aroma, but also enhance wine functional components such as extraction of polyphenols from the berries, production of γ-aminobutyric acid, hydroxytyrosol and melatonin. Polyphenols such as resveratrol, catechin and quercetin determine the functional quality of the wine. Moderate wine consumption, particularly red wine has been associated with functional benefits to human health, which includes anti-inflammation, promoting healthy aging, prevention of cardiovascular diseases, cancers, type 2 diabetes and metabolic syndrome. Indeed, the management of microbiota allows the production of wine with distinct features and functional components that benefits human health. This review scrutinizes the possible contributions of wine microbiota to the production of wine with enhanced functional components and highlights the contributions of Saccharomyces and non-Saccharomyces yeasts and bacteria to enhance wine functional components during winemaking. Thus, contributing to the dissemination of the benefits of light to moderate wine intake to human health.

Impact of a Non-<i>Saccharomyces</i>Yeast Isolated in the Equatorial Region in the Acceptance of Wine Aroma

The aim of this work was to isolate and identify the yeasts prevalent in fresh grapes cultivated in the “S&atilde;o Francisco Valley” region (Brazil), as well as evaluating the cell growth of these indigenous yeasts during the fermentation of grape musts and their contribution to the improvement of wine aroma. The Chenin Blanc grape must fermented by H. opuntiae presented higher acceptance means at the three points analyzed (6.74, 6.78 and 7.30) and in the fermentation carried out by the yeasts H. opuntiae and S. cerevisiae, the highest mean acceptance (7.22) was observed after 120 hours, with no statistical difference from the sample fermented by H. opuntiae alone. Since these samples that showed higher acceptance means also receiving higher scores for purchasing intention, corresponding to the concepts of “definitely would buy” and “probably would buy”. The present study suggests that the fermentations of grape musts carried out by the yeast H. opuntiae and mixed cultures of H. opuntiae and Saccharomyces cerevisiae, positively influenced the sensory qualities of the wines and showed greater potential to increase the aroma of the musts and to develop specific wine styles.