Assessment of the contributions of Saccharomyces cerevisiae, Hansenula sp. and Pichia kudriavzevii to volatile organic compounds and sensory characteristics of waxy rice wine

The production of waxy rice wine (WRW) usually requires multiple strains for fermentation. However, information about the contributions of individual strains to the quality of WRW remains limited. In this study, WRWs were produced through fermentation with three strains (Saccharomyces cerevisiae H1 [Sc], Hansenula sp. H3 [Hs] and Pichia kudriavzevii H6 [Pk]), and the quality of the WRWs was evaluated. The results indicated that Sc wine produced high levels of phenylethyl alcohol and 3-methyl-1-butyl acetate, reaching 31,622.78 mu g/L and 351.67 mu g/L, respectively; Hs wine produced the highest contents of ethyl acetate and lactic acid, reaching 69,535.58 mu g/L and 17.46 g/L, respectively, and had the highest score for "acidic "; Pk wine produced high contents of 2-methyl-1-propanol, 3-methyl-1-butanol and 2-methyl-1-butanol, reaching 46,951.56 mu g/L, 163,674.83 mu g/L and 52,238.51 mu g/L, respectively. The average concentrations of ethyl acetate, 2-methyl-1-propanol, and 3-methyl-1-butanol in mixed fermentation products increased by 126.80%, 25.82% and 17.02% compared to Sc wine, respectively, thus increasing the sensory scores for "malty " and "acidic ". In addition, high ethanol content resulted in higher scores for "winey " in WRWs. These results reveal the potential of S. cerevisiae H1 to produce ethanol, Hansenula sp. H3 to produce esters and P. kudriavzevii H6 to produce alcohols in WRW. Simultaneously, advantages of mixed fermentation for integrating the characteristics of various pure cultures were observed, namely increasing the number of volatile organic compounds (VOCs) and appropriately extending the fermentation time. The application of mixed fermentation has the potential to enrich the flavour and improve the quality of WRWs.