Abstract
Native microorganisms present on grapes can influence final wine quality. Chambourcin is the most abundant hybrid grape grown in Pennsylvania and is more resistant to cold temperatures and fungal diseases compared to Vitis vinifera. Here, non-Saccharomyces yeasts were isolated from spontaneously fermenting Chambourcin must from three regional vineyards. Using cultured-based methods and ITS sequencing, Hanseniaspora and Pichia spp. were the most dominant genus out of 29 fungal species identified. Five strains of Hanseniaspora uvarum, H. opuntiae, Pichia kluyveri, P. kudriavzevii, and Aureobasidium pullulans were characterized for the ability to tolerate sulfite and ethanol. Hanseniaspora opuntiae PSWCC64 and P. kudriavzevii PSWCC102 can tolerate 8–10% ethanol and were able to utilize 60–80% sugars during fermentation. Laboratory scale fermentations of candidate strain into sterile Chambourcin juice allowed for analyzing compounds associated with wine flavor. Nine nonvolatile compounds were conserved in inoculated fermentations. In contrast, Hanseniaspora strains PSWCC64 and PSWCC70 were positively correlated with 2-heptanol and ionone associated to fruity and floral odor and P. kudriazevii PSWCC102 was positively correlated with a group of esters and acetals associated to fruity and herbaceous aroma. Microbial and chemical characterization of non-Saccharomyces yeasts presents an exciting approach to enhance flavor complexity and regionality of hybrid wines.
Highlights
Received: 19 December 2020Saccharomyces cerevisiae has been widely applied to many fermentation processes including baking, winemaking, and brewing for thousands of years [1]
These results suggest that H. opuntiae PSWCC64 and P. kudriavzevii PSWCC102 could adapt to Fermentation 2021, 7, x FOR PEER REVIEW
Our investigations on candidate strains isolated from local PA vineyards suggest the potential of non-Saccharomyces yeasts in winemaking based on the unique fermentation characteristics
Summary
Received: 19 December 2020Saccharomyces cerevisiae has been widely applied to many fermentation processes including baking, winemaking, and brewing for thousands of years [1]. S. cerevisiae are selected for their efficient and reliable fermentation capabilities especially important in producing final wines that are consistent in taste and aroma. Commercial S. cerevisiae yeasts are common in winemaking, there is increasing interest in using non-Saccharomyces yeasts ( known as native ‘wild’ yeasts) during early stages of wine fermentation. Previous studies demonstrate that unique physiological properties of certain non-Saccharomyces yeast strains can influence resulting wine such as alcohol levels and volatile metabolite profile [3,4,5,6,7]. Coinoculation of nonSaccharomyces yeasts such as Hanseniaspora uvarum and Starmerella bacillaris were able to enhance aromatic profile by producing higher alcohols that correspond to floral odor (i.e., βphenylethyl alcohol) [10,11,12]. Coinoculation of nonSaccharomyces yeasts such as Hanseniaspora uvarum and Starmerella bacillaris were able to enhance aromatic profile by producing higher alcohols that correspond to floral odor (i.e., βphenylethyl alcohol) [10,11,12]. β-phenylethyl alcohol is an important phenolic higher alcohol in wine and consumers have responded favorably to richer, fruitier, and more complex
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