JIA-2018-09

2134 WANG Ying et al. Journal of Integrative Agriculture 2018, 17(9): 2126–2136 In the present study, S . cerevisiae FM-S-115 showed strong adaptability and resistance to SO 2 compared to the spoilage yeast P . membranifaciens Hmp-1. The result was further confirmed that S . cerevisiae had strong competitive position compared to other microorganisms during spontaneous fermentation of wine (Maro et al . 2007; Wang and Liu 2013). Ethanol, a main product of wine fermentation, is well known as a kind of growth inhibitor of microorganisms. It had been reported that ethanol could damage mitochondrial DNA of yeast cells and lead to inactivation of some enzymes, such as hexokinase and dehydrogenase (Ibeas and Jimenez 1997). A previous study found that P . membranifaciens could not grow at a concentration of 6% (v/v) ethanol (Miguel et al . 2013). In this study, P . membranifaciens strain Hmp-1 could still grow and form pellicle in the blackberry wine containing 8.05% (v/v) ethanol. However, its growth could be completely inhibited when the concentration of ethanol was 10% (v/v) or more. Compared to Hmp-1, S . cerevisiae FM-S-115 showed stronger resistance to ethanol, and could still grow at a concentration of 14% (v/v) ethanol. This result was in agreement with previous reports (Fugelsang and Edwards 2007; Miguel et al . 2013; Contreras et al . 2014). Flavor is one of the major factors which determine the nature and quality of wine (Selli et al . 2004). Some of volatile compounds come directly from fruits, others are produced by yeasts as a result of their metabolism during wine fermentation and aging (Fleet 2003). In this study, since the management practices and fermentation conditions were the same for all treatments, the difference of volatile compounds should be ascribed to the spoilage yeast Hmp-1. Some volatile compounds were only found in the blackberry wine fermented by both Hmp-1 and FM-S-115 (Table 5), some of which might be harmful for consumers, such as benzothiazole. Benzothiazole and benthiazole derivatives were a group of xenobiotic heterocyclic chemicals, which had potential toxicity and mutagenic effects toward microorganisms and humans (Janna et al . 2011; Asimakopoulos et al . 2013; Pal et al . 2014). Aldehydes and esters are important flavor compounds, and their formation depends more on the yeast selected as starter rather than the raw materials used in fermentation (Álvarez-Pérez et al . 2012; Cordente et al . 2012). In this study, 18 kinds of aldehydes and esters were detected in the blackberry wine fermented by alone FM-S-115, and their proportion was 53.35% in the total volatile compounds (Table 5). However, in the blackberry wine fermented by FM-S-115 with the spoilage yeast Hmp-1, only 9 kinds of aldehydes and esters were detected, and their proportion decreased to 34.06% (Table 5). 5. Conclusion The present study demonstrated that P . membranifaciens strain Hmp-1 could form pellicle on the surface of blackberry wine, and lead to quality deterioration of blackberry wine. Its growth could effectively be controlled by increasing the concentrations of ethanol or SO 2 during blackberry wine fermentation and storage. Acknowledgements This work was supported by the Natural Science Foundation of Jiangsu Province, China (BK20170603). References Van der Aa Kühle A, Jespersen L. 2003. The taxonomic position of Saccharomyces boulardii as evaluated by sequence analysis of the D1/D2 domain of 26S rDNA, the ITS1- 5.8SrDNA-ITS2 region and the mitochondrial cytochrome- c oxidase II gene. Systematic and Applied Microbiology , 26 , 564–571. 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