A novel extracellular β-glucosidase from Trichosporon asahii: yield prediction, evaluation and application for aroma enhancement of Cabernet Sauvignon.
The production and application of novel β-glucosidase from Trichosporon asahii were studied. The β-glucosidase yield was improved by response surface methodology, and the optimal media constituents were determined to be dextrin 4.67% (w/v), yeast extract 2.99% (w/v), MgSO(4) 0.01% (w/v), and K(2) HPO(4) 0.02% (w/v). As a result, β-glucosidase production was enhanced from 123.72 to 215.66 U/L. The effects of different enological factors on the activity of β-glucosidases from T. asahii were investigated in comparison to commercial enzymes. β-Glucosidase from T. asahii was activated in the presence of sugars in the range from 10% to 40% (w/v), with the exception of glucose (slight inhibition), and retained higher relative activities than commercial enzymes under the same conditions. In addition, ethanol, in concentrations between 5% and 20% (v/v), also increased the β-glucosidase activity. Although the β-glucosidase activity decreased with decreasing pH, the residual activity of T. asahii was still above 50% at the average wine pH (pH 3.5). Due to these properties, extracellular β-glucosidase from T. asahii exhibited a better ability than commercial enzymes in hydrolyzing aromatic precursors that remained in young finished wine. The excellent performs of this β-glucosidase in wine aroma enhancement and sensory evaluation indicated that the β-glucosidase has a potential application to individuate suitable preparations that can complement and optimize grape or wine quality during the winemaking process or in the final wine.


CONCLUSIONS
The present study demonstrated the usefulness of response surface methodology based on the central composite design for yield enhancement of β-glucosidase from T. asahii. The investigation of the primary characteristics of the enzyme and its application in young red wine suggested that the β-glucosidase from T. asahii can provide more impetus for aroma improvement in the future.
State Key Laboratory of Food Science and Technology, Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, Jiangsu 214122, China.
Yuxia
Y
Wang
Yan
Y
Xu
Jiming
J
Li
D003470:Culture Media / Q000737:chemistry; D000431:Ethanol / Q000737:chemistry; D005511:Food Handling / Q000379:methods; D005516:Food Microbiology; D005947:Glucose / Q000737:chemistry; D006801:Humans; D006863:Hydrogen-Ion Concentration; D009812:Odorants / Q000032:analysis; D012903:Smell; D014250:Trichosporon / Q000201:enzymology* / Q000254:growth & development; D027843:Vitis / Q000382:microbiology; D055549:Volatile Organic Compounds / Q000737:chemistry; D014920:Wine / Q000032:analysis / Q000382:microbiology*; D001617:beta-Glucosidase / Q000032:analysis / Q000096:biosynthesis*
D003470:Culture Media; D055549:Volatile Organic Compounds; D000431:Ethanol; D001617:beta-Glucosidase; D005947:Glucose