Research On Isolation And Screening Of High Quality Yeast Strain For Orange Wine And Its Fermentation Characteristics

Yeast strains applied to orange wine were isolated from ripen orange skins and soil icollected in orange orchard and screened by indexes as gas potential, fermenting capacity, tolerance to alcohol and SO2as well as other factors such as color, flavor and taste. The screened yeasts were identified by method of26S rDNADl/D2and their growth and fermentation characteristics were researched either. Then, taking active dry yeast as control, aroma components, physical and chemical indexes, sensory quality of orange wine fermented by yeast F076and S017were compared. The main results were as follows:1. A total of138yeast strains had been isolated from ripen orange skins and soil icollected in orange orchard. Yeasts F076and S017with high fermentation character-istics had been selected from four level screening. Both of them has capacity of yielding gas in first24hour of fermentation and the fermentation tub could reach full in48hour. Their alcoholic strength were6.8%VoL and7.0%VoL. Ethanol tolerance of yeast F076and S017were up to15%volume fraction, and SO2resistance were150mg/L、175mg/L. With single budding, yeasts’cells were oval in shape. And colony diameters were1.7±0.32mm,1.2±0.47mm, with characteristic of saccharomycetes.The identified result of screened yeasts was Hanseniaspora uvarum.2. The results of growth and fermentation characteristics of yeast F076are as follows: optimum growth temperature was34℃, optimum growth pH was5.5, bens value was1.7±0.16(strong flocculation), optimum fermentation temperature was30℃, optimum fermentation pH was5.5, the dynamic equation of alcoholic fermentation at optimum fermentation temperature was y=11.43/[1+e0.11(x-25.09)].The results of growth and fermentation characteristics of yeast S017are as follows:optimum growth tempera-ture was24℃, optimum growth pH was5, bens value was3.5±0.47(strong flocculation), optimum fermentation temperature was24℃, optimum fermentation pH was5, the dynamic equation of alcoholic fermentation at optimum fermentation temperature was y=10.44/[1+e0.10(x-25.68)].The total sugar consuming tendency of yeast F076was close to S017, while its alcohol fermentation activity was less intensive. The total acid change tendency had raised at the beginning then dropped down. The two screened yeast strains has close ex-tent of the decreased. In initial stage of fermentation, the result S017had stronger acid-producing proved that its fermentation capacity was stronger than yeast F076.3. Aaroma components of orange wine fermented by yeast F076, S017and active dry yeast were researched, results are as follows:73aroma compounds were identified, common compounds are ethyl hexanoate, ethyl caprylate, ethyl caprate, ethyl laurate, ethyl palmitate, phenylethyl alcohol, alpha terpineol, and BHT. Relative amount of Ester contents were86.69%、86.75%.With such a high scale, F076and S017has excellent characteristics in producing ester contents, and F076has the capacity in keeping characteristic aroma components in orange.Results of colour paramaters and transmittance are as follows:yellow value S017>F076>CK, transmittanceS017> F076>CK. Orange wine fermented by screened yeasts had better transmittance, taste, smell and characteristics. Above all, with excellent transmittance and inviting aromas of ripe orange, the golden yellow wine sample S017has high sense quality. Yeast S017has great developmental potential in brewing industrial.