Quality Enhancement of Riesling Wine Through Co-Fermentation of Non-Saccharomyces Yeasts with β-Glucosidase Activity and Saccharomyces cerevisiae.

Co-fermentation with Saccharomyces cerevisiae (SC) and non-Saccharomyces (NS) yeasts is currently one of the most used strategies for improving wine quality. To investigate the effects of simultaneous and sequential co-fermentations with SC and NS yeast, Pichia kudriavzevii F2-24, Metschnikowia pulcherrima HX-13, and Issatchenkia terricola SLY-4 on flavor and quality of Riesling wine, the oenological characteristics and aroma indexes of different wine samples were evaluated. The results indicated a reduced alcohol content in all co-fermented wines (12.39%, v/v-12.55%, v/v), except for simultaneous co-fermentation using P. kudriavzevii F2-24/SC (12.83%, v/v), compared to the SC fermentation (12.82%, v/v); and a lower volatile acidity in all co-fermented wines (0.19 g/L-0.35 g/L), compared to SC fermentation (0.40 g/L), which positively impacted the wine quality. All co-fermented wines exhibited higher content of esters (406.29 mg/L-649.62 mg/L), compared to SC fermentation (313.71 mg/L), with distinct flavor compound profiles. Sequential co-fermentations with F2-24/SC and SLY-4/SC had the highest content of C13-norisoprenoids and esters, recognized as essential flavor contributors. Simultaneous co-fermentation using M. pulcherrima HX-13/SC (406.29 mg/L) exhibited a lower content of total esters compared to other co-fermentations. The sensory attributes of Riesling wine were improved in all co-fermentations, except for simultaneous co-fermentation using M. pulcherrima HX-13/SC. Furthermore, sequential co-fermentation with P. kudriavzevii F2-24/SC and I. terricola SLY-4/SC proved to be the most suitable in improving Riesling wine quality. This study provides a valuable reference for improving the flavor and quality of Riesling wine through co-fermentation of NS yeasts and SC.