title: A novel extracellular glycosidase activity from Rhodotorula mucilaginosa: its application potential in wine aroma enhancement.
abstract: The aim of the work was to evaluate the application potential of a glycosidase extract of one indigenous non-Saccharomyces strain in wine aroma enhancement. The isolate was selected from a local winemaking region in China for its high β-glucosidase level and was identified as Rhodotorula mucilaginosa. The tolerance of the glycosidase extract to the typical winemaking conditions was assessed using the activity of its β-glucosidase. After that, the hydrolysis capacity of R. mucilaginosa glycosidase for liberation of grape aroma glycosides was characterized in comparison to commercial enzyme preparations. Results of this work revealed that glycosidase extract from R. mucilaginosa proved to be active in the presence of 0-20% (w/v) glucose, 0-20% (v/v) ethanol and at pH 3·0-5·0. In the hydrolysis of aroma precursors, enzymes obtained from different origins possessed various levels of specificity and activity, showing high origin dependence (α = 0·05). Compared to commercial enzymes, the indigenous R. mucilaginosa glycosidase extract presented better catalytic preference for the 'fruity and floral' glycosides of benzenic compounds and C13 -norisoprenoids, but less sensitivity to the glycosides of C6 compounds and volatile phenols.
  
  
  CONCLUSIONS
  This work presents a novel extracellular glycosidase preparation from an indigenous Rhodotorula mucilaginosa strain selected from a local winemaking region in China. This enzyme extract exhibits strong tolerance towards winemaking conditions. It shows hydrolysis specificity for glycosides of benzenic compounds and C13 -norisoprenoids, proving a potential candidate for improving floral and fruity aroma characteristics of wine.
authors.affiliation: College of Enology, Northwest A&F University, Yangling, Shaanxi, China.
authors.forename: K
authors.initials: K
authors.lastname: Hu
authors.affiliation: College of Enology, Northwest A&F University, Yangling, Shaanxi, China.
authors.forename: X L
authors.initials: XL
authors.lastname: Zhu
authors.affiliation: College of Enology, Northwest A&F University, Yangling, Shaanxi, China.
authors.forename: H
authors.initials: H
authors.lastname: Mu
authors.affiliation: College of Enology, Northwest A&F University, Yangling, Shaanxi, China.
authors.forename: Y
authors.initials: Y
authors.lastname: Ma
authors.affiliation: College of Enology, Northwest A&F University, Yangling, Shaanxi, China.|Department of Human Nutrition, The University of Agriculture, Peshawar, Pakistan.
authors.forename: N
authors.initials: N
authors.lastname: Ullah
authors.affiliation: College of Enology, Northwest A&F University, Yangling, Shaanxi, China.|Shaanxi Engineering Research Center for Viti-Viniculture, Yangling, Shaanxi, China.
authors.forename: Y S
authors.initials: YS
authors.lastname: Tao
mesh_terms: D002681:China; D000431:Ethanol / Q000378:metabolism; D005285:Fermentation; D005638:Fruit / Q000378:metabolism; D005947:Glucose / Q000378:metabolism; D006026:Glycoside Hydrolases / Q000378:metabolism*; D006027:Glycosides / Q000378:metabolism; D006868:Hydrolysis; D045792:Norisoprenoids / Q000378:metabolism*; D009812:Odorants; D012248:Rhodotorula / Q000201:enzymology / Q000378:metabolism*; D027843:Vitis / Q000378:metabolism*; D014920:Wine / Q000032:analysis / Q000382:microbiology*; D001617:beta-Glucosidase / Q000378:metabolism*
chemical_list: D006027:Glycosides; D045792:Norisoprenoids; D000431:Ethanol; D006026:Glycoside Hydrolases; D001617:beta-Glucosidase; D005947:Glucose
keywords: Rhodotorula mucilaginosa; aroma glycosides; catalytic specificity; non-Saccharomyces; β-glucosidase