Effects of biochar addition on the formation of aromas in fruit wine fermented by Zygosaccharomyces mellis LGL-1

To diversify the aromas and enhance the quality of fruit wines, Zygosaccharomyces mellis LGL-1 (LGL-1), as a non-conventional yeast, was applied for fruit winemaking along with biochar facilitating the fermentation. Results demonstrated that LGL-1 exhibited higher synthesis of ethanol and esters compared to the commercial winemaking yeast CV171 during wampee/grape/litchi winemaking. Intriguingly, the main esters produced by LGL-1 were quite different from those of CV171, resulting in diverse flavors. Four kinds of food-grade biochar were applied to facilitate the fermentation of LGL-1 under the mimic solution of fruit juice (MSM medium) respectively, and results showed that the coconut shell granule biochar (G2) was the best choice with both substrate consumption and product formation improved significantly, especially with esters enhanced by 357.87%, owing to the reduced oxidation-reduction potential, improved intracellular ratio of NADH/NAD + and enhanced activities of esterase. When applied for wampee/grape/litchi winemaking, G2 could also facilitate the fermentation of LGL-1 with total content of esters in each wine improved by 173.7%, 71.8% and 44%. The total concentration of higher alcohols in wampee/grape wine was enhanced by 35.6% and 21.1%, but unchanged significantly in litchi wine. The content of total organic acids in grape wine and litchi wine was changed insignificantly but decreased by 16.7% in wampee wine, which might not affect the flavor based on the taste threshold of organic acids. Data above indicated that LGL-1 is a potential candidate for fruit winemaking, and the fermentation fortified by G2 is a promising method for improved aromas of fruit wine.