The Effect Of Wickerhamomyces Anomalus And Saccharmyces Cerevisiae Fermentation On The Quality Of Mulberry Wine

Mulberry is a berry with high nutritional and functional properties.As raw materials,mulberry fermented into wine is cherished by most wine patrons and consumers.To enhance the aroma components of mulberry wine and improve its quality,a non-Saccharomyces yeasts with rich ester production and high tolerance was screened out from the spontaneous fermentation of berries juice.The screened abnormal Wickerhamomyces anomalous was applied in a single and mixed culture ferment with Saccharomyce cerevisiae to ferment mulberry juice into wine using different inoculation methods.The physicochemical properties,aroma active substances,bioactive components and antioxidant capacity of the produced wine were then compared to select the optimal yeast inoculation method.The main research contents and results were as follows:（1）A non-Saccharomyces yeasts（No.D1-4）with strong aroma-producing ability was obtained through the three-level screening of sniffing,fermentation efficiency and total fruity esters production.Its mulberry juice fermentation broth has a strong floral and fruity aroma.According to the morphological and microscopic observation,the colony of D1-4 yeast on the YPD medium was milky white with tidied edges.They also appeared oval,opaque and viscous.Colonies on WL medium are white round with serrated edges and wrinkled surface.After 18S r DNA molecular biology sequencing and comparison of the phylogenetic tree,it was confirmed that D1-4 yeast was abnormal W.anomalus.The results of the strain tolerance test also showed that the optimal growth temperature of D1-4 yeast was 28℃,p H was 5.5,and sucrose concentration was 100 g/L.Furthermore,the maximum ethanol,SO₂ and tartaric acid tolerance were at 10%,250 mg/L and 30 g/L,respectively.（2）Using W.anomalus and Saccharomyces cerevisiae for pure culture and a mixed culture,as well as simultaneous and sequential inoculation for fermentation,seven different samples of mulberry wine were obtained.Subsequently,the aromatic compounds of the different samples were analyzed and compared.Using the electronic nose to detect the aroma components of mulberry wine,principal component analysis,the linear discriminant analysis combined with sensor discrimination analysis found significant differences in aromatic compounds among the seven groups of mulberry wine,mainly reflected in alcohols and terpenes.The aroma of mulberry wine was significantly improved by mixed fermentation,and the sequential inoculation of S.cerevisiae（ONS）,which was inoculated with D1-4 at an interval of 24 h,had the most aromatic substances and was the optimal inoculation method.A total of 36 main aroma compounds were detected in the seven mulberry wine samples by gas chromatography-mass spectrometry（GC-MS）.Among the detected volatile compounds,ethyl caprate,ethyl caprylate,ethyl laurate and ethyl palmitate were detected in high concentration in both N and OSN.The sensory evaluation also indicated a rich,fruity and balanced wine aroma for OSN,suggesting a better sensory quality.In conclusion,mixed culture fermentation is desirable for the fermentation of high-quality mulberry wine with a rich aroma and mellow taste.（3）To uniquely characterized each sample,the physicochemical properties,colorimetric indices,bioactive components and in-vitro antioxidant capacity of the mulberry wines produced from the seven different fermentation methods were evaluated and compared.The results showed that the mixed culture fermentation was superior in maintaining high alcohol content than the S group.It also showed a high p H value reduction ability to stabilize anthocyanin and other phytochemicals.The chromaticity of the mixed fermentation OSN group was significantly higher than that of the S group.The mulberry wine obtained was the best.Except for flavonoids,where there was no significant difference between the groups,the OSN group had the highest anthocyanin（467.40±1.06 mg/L）and A group had the highest total polyphenol content（82.17±0.63）.This observation indicates that mixed culture fermentation had a significant effect on improving the bioactive components of mulberry wine（P<0.05）.Correspondingly,the DPPH·radical scavenging ability（antioxidant activity）of OSN and ONS groups was significantly higher than that of other groups.