| The wine-related lactic acid bacteria play an important role to wine quality byundertaking Malolactic Fermentation (MLF), especially Oenococcus oeni, thus to select O.oeni which can adapt to the indigenous wine environment and with excellent properties wasone of the important method for improving wine quality. Most of the aroma component ingrape juice existed was in form of non-volatile glycoside, which cannot contribute to winearoma. Some O. oeni strains could produce glycosidase enzymes, releasing volatile aromaticcompounds through hydrolysis of grape-derived aroma precursors during MLF, thus improvethe aroma complexity of the wine.O. oeni strains were isolated from Inner Mongolia wine region in this study firstly, theenological characteristics and identification of strains were studied, and seven strains withgood enological characteristics were obtained. Then to investigate the five kinds ofglycosidase activities,27strains of O. oeni from six different wine regions of China wereselected as materials. According to the result, six strains with high glycosidase activities wereused to study the glycosidase enzyme properties in wine environment. Finally, two strainswere chose to study the influence of MLF on wine aroma through GC-MS analysis. Theconclusions were as follows:1. The enological characteristics of the30strains isolated from Inner Mongolia werestudied and7strains which showed high resistance to single factor were conductedthree-factor combination selection,3strains standout from them, that were NM-1e，NM-2aand NM-2g. Through morphological identification, we considered these strains were O. oeni.To confirm this result, the species-specific PCR identification result showed a unique clearband of1025bp length, and16S rRNA gene gave a705bp length specific band, thensequencing displayed that the16S rRNA gene sequence of the strains have a homology morethan99%with the O. oeni in the Genbank database, which demonstrated that the7strainsisolated were O. oeni.2. The results of glycosidase activities of O. oeni from6different wine regions were asfollows:27strains of selected O. oeni produced detectable glycosidase activities on the corresponding substrates. Significant differences were concluded between differentglycosidase of strains, while not between different wine regions. The overall trends of strainglycosidase activities were α-D-glycosidase>β-D-glycosidase>β-D-xylosidase>α-L-arabinosidase≥α-L-rhamnosidase. The result of potential inhibition parameters onglycosidase activities were between slight promotion and strong inhibition. Five kinds ofglycosidase have a peak at pH4.0, and only lower activity displayed at pH value of wine. Theoptimum temperature was45℃. Ethanol, glucose and fructose could stimulate theglycosidase activities at low concentration, nevertheless, at high concentration significantinhibition were viewed, but the response of enzyme activities were strain-dependant. Underthe model wine environment, only9.805～32.331%of the glycosidase activities were keptcompared with the strain glycosidase activities. In conclusion, SD-1f displayed the highestglycosidase activities in wine environment of all the selected strains.3. Comparing the basic physical index and GC-MS analysis result, we could draw aconclusion that inoculation fermentation can improve the rate of fermentation, MLF couldreduce the total acid, and the reduction range24.177～28.811%, and a corresponding rise0.2of pH value and the volatile acid content increased. The GC-MS analysis showed that MLFcould increase the volatile aroma content, and the total content were strain SD-1f MLF> strain31DH MLF>spontaneous MLF>not implemted MLF, but there were no significantdifference among different simple wines. |
PDF Full Text Request