关键词: 葡萄牙棒孢酵母, 发酵特性, 红谷提取物, 耐受性, 代谢产物

Abstract: The growth characteristics, tolerance, and fermentation metabolite profiles of the non-Saccharomyces yeast Clavispora lusitaniae J5 in red rice extract medium were studied, comparing it with the traditional brewer's yeast Saccharomyces cerevisiae J2. Morphology was observed using optical microscopy, Subsequently, its growth curve was determined. The tolerance of J5 to ethanol concentration, sugar concentration, pH, and temperature was then investigated. Finally, its fermentation products were analyzed, and the volatile metabolites were compared with those of Saccharomyces cerevisiae (strain J2). Results showed that J5 exhibited typical yeast morphology, entering the stationary phase after 20 h of cultivation at 30℃. J5 demonstrated relatively weak ethanol tolerance but was able to grow at sugar concentrations below 15%, pH 3.5–6.0, and temperatures ranging from 25 to 40°C. After 72 h of fermentation at 30°C in the red rice extract matrix, J5 produced 5.34 ± 0.15 g/L ethanol, with citric acid, succinic acid, and acetic acid accumulating during fermentation. Compared to the J2 fermentation broth, J5broth contained significantly higher levels of alcohols, aldehydes & ketones, pyrazines, phenols, hydrocarbons, and sulfur-containing compounds. Additionally, J5 broth contained a greater number of aldehydes & ketones, nitrogen-containing compounds, and hydrocarbons. Principal Component Analysis (PCA) revealed that J5 and J2 fermentation broths could be distinguished based on common volatile metabolites. Nonadecane, ethyl acetate, 2-octanol, nerolidol, dodecanoic acid ethyl ester, and octanoic acid 3-methylbutyl ester contributed most to this differentiation. The unique volatile metabolites in J5 broth were primarily aldehydes and ketones, with 1-octen-3-one exhibiting the highest Odor Activity Value (OAV) (5990), contributing herbal notes to the broth. Clavispora lusitaniae J5 is capable of growing under rice wine brewing conditions, and its distinct metabolite profile, differing from S. cerevisiae, can contribute to the flavor complexity of red rice wine products.

Key words: Clavispora lusitaniae, fermentation characteristics, red rice extract medium, tolerance, metabolites