Effects of indigenous yeast NX11424 inoculation on the yeast diversity and aroma compounds during Cabernet Sauvignon wine fermentation

Abstract:

[Background] The indigenous Saccharomyces cerevisiae NX11424 in Ningxia enjoys a reputation in fermentation, as it endows the Cabernet Sauvignon wine with strong fruit aroma. [Objective] To investigate the fruit aroma characteristics of Cabernet Sauvignon wine fermented with NX11424. [Methods] Cabernet Sauvignon was used for wine fermentation. Three fermentation conditions were designed:spontaneous fermentation, inoculation with NX11424 after grape sterilization, direct inoculation with NX11424. 26S rDNA D1/D2 sequencing was used to analyze and identify the yeast species during wine fermentation. The aroma components of Cabernet Sauvignon wine fermented under different conditions were determined by head space-solid phase microextraction (HS-SPME) and gas chromatography-mass spectrometry (GC-MS). [Results] The physicochemical indexes of wine fermented under the three conditions showed no significant difference. The isolated yeasts belong to 3 species in 2 genera:Hanseniaspora uvarum, S. cerevisiae, and S. boulardii. All the 3 species were detected in spontaneous fermentation and only H. uvarum and S. cerevisiae in fermentation with NX11424. A total of 69 kinds of aroma components were identified respectively in the wine fermented under the three conditions:28 esters, 25 alcohols, 5 organic acids, 2 terpenes, and 9 others. There were no significant differences in species of these aroma components among different treatments but significant differences in the content of them. Cluster analysis showed that these 69 kinds of aroma components were clustered into 3 clades. Clade Ⅰ contained 9 components such as citronellol and propanol, among which 7 had high content in the wine fermented by inoculation with NX11424 after grape sterilization. The 31 components in clade Ⅱ such as ethyl hexanoate and ethyl palmitate had high content in the wine fermented by in direct inoculation with NX11424. Clade Ⅲ had 29 components such as ethyl butanoate and ethyl lactate, among which 27 had high content in the wine under spontaneous fermentation. Although the yeast diversity under direct inoculation fermentation was lower than that under spontaneous fermentation, the wine fermented by direct inoculation showed high content of esters and strong fruit aroma. [Conclusion] The interaction between NX11424 and other indigenous yeast during wine fermentation could improve wine quality. This study lays a solid foundation for using S. cerevisiae NX11424 to improve wine quality of Cabernet Sauvignon wine.

Key words:Cabernet Sauvignon;wine;aroma;NX11424;yeasts