Abstract: This study aimed to investigate the effect of different mixed culture fermentation strategies with Rhodotorula mucilaginosa and Saccharomyces cerevisiae on the aroma profile, polyphenols and color of dry red wine produced in the monsoonal region of China, and to optimize wine aroma enhancement. Merlot grapes produced in Heyang country, Shaanxi province were used to make dry red wines by simultaneous or sequential inoculation of the two strains. After completion of fermentation, the aroma attributes of wines were determined by solid-phase microextraction coupled to gas chromatography-mass spectrometry (SPME-GC-MS) and a well-trained panel. A total of 13 color parameters and polyphenols were quantitatively determined by spectroscopy. Results showed that simultaneous inoculation with higher proportion of R. mucilaginosa significantly increased the concentration of the varietal aroma compounds, especially C6 compounds and thiol, whereas sequential inoculation of R. mucilaginosa and S. cerevisiae (1:1) was more conducive to the release of terpenols and β-damascenone. In the case of simultaneous inoculation, the contents of higher alcohols, C6–C12 fatty acids and their ethyl esters elevated with increasing proportion of R. mucilaginosa, while sequential inoculation was markedly advantageous in increasing the contents of acetates, other esters and phenyl ethyls. Both simultaneous inoculation with R. mucilaginosa/S. cerevisiae ratio = 4:1 and sequential inoculation remarkably increased the contents of total anthocyanins, flavonols, and tartaric esters, as well as the proportion of co-pigmented anthocyanins. Sensory analysis revealed that simultaneous inoculation with higher proportion of R. mucilaginosa remarkably improved the intensities of fruity and floral aroma as well as green taste and animal-like flavor. Sequential inoculation moderately enhanced the floral and fruity aroma while reducing off-odor intensity. In summary, significant variations in color and flavor characteristics existed among wines produced using the two inoculation strategies. Sequential inoculation moderately increased wine aroma without producing off-odor, and also improved color quality.

Key words: Rhodotorula mucilaginosa; mixed culture fermentation; red wine; aroma quality; polyphenols