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 profile of the non-Saccharomyces yeast Clavispora lusitaniae J5 in a red rice extract-fortified medium were studied. Cell morphology was observed using optical microscopy. Subsequently, its growth curve was determined, and its tolerance to ethanol, sugar, pH, and temperature was investigated. Finally, its fermentation products were analyzed, and its volatile metabolites were compared with those of Saccharomyces cerevisiae J2. Results showed that J5 exhibited typical yeast morphology, entering the stationary phase after 20 h of cultivation at 30 ℃. J5 demonstrated low ethanol tolerance, but was able to grow at sugar concentrations below 15 g/100 mL, at pH 3.5–6.0, and at temperatures ranging from 20 to 40 ℃. After 72 h of fermentation at 30 ℃ in the red rice extract-fortified medium, J5 produced (5.34 ± 0.15) g/L of ethanol, accompanied by citric acid, succinic acid, and acetic acid accumulation during fermentation. Compared with the fermentation broth of J2, that of J5 contained significantly higher levels of alcohols, aldehydes and ketones, pyrazines, phenols, hydrocarbons, and sulfur-containing compounds. Additionally, the fermentation broth of J5 contained a greater number of aldehydes and ketones, pyrazines, hydrocarbons and sulfur-containing compounds. Principal component analysis (PCA) revealed that the fermentation broths of J5 and J2 could be distinguished based on their shared volatile metabolites. Nonadecane, ethyl acetate, (R)-(-)-2-octanol, nerolidol, dodecanoic acid ethyl ester, and octanoic acid 3-methylbutyl ester contributed the most to this differentiation. The unique volatile metabolites in the fermentation broth of J5 were primarily aldehydes and ketones, with 1-octen-3-one exhibiting the highest odor activity value, contributing to the herbal aroma of the broth. Therefore, it could be concluded that C. lusitaniae J5 has the potential for application in the brewing of Chinese rice wine.

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