火龙果果酒酵母的分离鉴定及其混菌发酵工艺优化OA

To address the issue of insufficient flavor complexity in pitaya wine fermented with pure Saccharomyces cerevisiae,non-Saccharomyces were isolated and screened from naturally fermented pitaya wine in this study.Strains characterized by prominent aroma production and weak alcoholic pungency were selected via sensory olfactory evaluation,followed by identification through morphological observation and molecular biological techniques.Their stress tolerance properties were further assessed,and mixed-strain fermentation combining the screened strain with S.cerevisiae SY was performed to brew pitaya wine.The mixed-culture fermentation parameters were optimized using single-factor tests coupled with orthogonal experiments,and volatile flavor compounds in pitaya wines produced by single-strain and mixed-strain fermentation were systematically analyzed.The results revealed that an aroma-enhancing yeast strain,designated DBS-1,was isolated and identified as Pichia manshurica.This strain displayed favorable growth performance under the conditions of pH 3.0,8%ethanol concentration and 18 °Brix initial sugar content.The optimal fermentation conditions for pitaya wine were determined as follows:initial sugar content of 22 °Brix,initial pH of 4.5,inoculum of 4%,and a mixing ratio of SY to DBS-1 of 1:1.Under these optimized conditions,the resulting pitaya wine attained an alcohol content of 8.5%and a high sensory evaluation score of 95.5.A total of 45 volatile flavor compounds were identified in the mixed-fermentation pitaya wine,among which 20 compounds were classified as key volatile components(odor activity value(OAV)≥1).Compared with pure S.cerevisiae fermentation,mixed-strain fermentation increased the total contents of esters,acids and alcohols by 82.4%,47.6%and 37.7%,respectively.Furthermore,it elevated the OAVs of key aroma compounds including ethyl hexanoate,octanoic acid and phenylethanol,thereby effectively improving the overall flavor balance and sensory quality of pitaya wine.