Flavor characteristics and metabolomics of sweet rice wine fermented with different non-Saccharomyces yeasts

Non- Saccharomyces yeasts ( Clavispora lusitaniae , Hanseniaspora uvarum , Kodamaea ohmeri , Meyerozyma caribbica, and Rhodotorula mucilaginosa ) showed potential use in taste and flavor enhancement of fermented products, including sweet rice wine. Herein, various parameters, including physicochemical indices, antioxidant activities, amino acids, volatile organic compounds (VOCs), and metabolites, were examined to investigate the effects of five non- Saccharomyces yeasts on the organoleptic and nutritional properties for sweet rice wine. The results indicated that inoculating non- Saccharomyces yeasts exerted substantial effects on the physicochemical indices and antioxidant activities of sweet rice wine. H. uvarum might provide the most favorable in terms of pleasant VOCs leading to a higher sensory acceptance, compared to other non- Saccharomyces yeasts. Additionally, H. uvarum also exhibited the strongest antioxidant capacities, with significant superiority to C. lusitaniae , M. caribbica, and R. mucilaginosa. The content of bitterness and astringency amino acids, including leucine, valine, phenylalanine, and tyrosine, in sweet rice wine decreased, which might be related to their transformation in tricarboxylic acid (TCA) cycle. Twelve significant contributors to the flavor of sweet rice wine inoculated with non- Saccharomyces yeasts and 11 pivotal metabolic pathways were identified via VOCs and metabolomics analyses, respectively. Of these, ethyl decanoate was the key compound contributing most to the unique flavor, and TCA cycle and pyruvate were the critical metabolic pathways involved in the flavor development of sweet rice wine. These findings offer suitable strategies and ideas for diversifying the sweet rice wine industry.