Effects of Different β-D-Glycosidases on Bound Aroma Compounds in Muscat Grape Determined by HS-SPME and GC-MS

Wenhuai Kang³, Yan Xu^1,2,3,*, Ling Qin4 and Yuxia Wang³
¹ Jiangnan Univ, State Key Lab Food Sci & Technol, Wuxi 214122, P.R. China.
² Jiangnan Univ, Minist Educ, Key Lab Ind Biotechnol, Wuxi 214122, P.R. China.
³ Jiangnan Univ, Sch Biotechnol, Wuxi 214122, P.R. China.
⁴ Department of Life Science, Hebei Normal University of Science and Technology, 066004 Changli, Hebei, P. R. China.
^* Corresponding author. E-mail: biosean@yahoo.com.cn.

J. Inst. Brew. 116(1), 70–77, 2010 | VIEW ARTICLE

ABSTRACT
Important “floral” aromas naturally occur in grapes predominantly as flavourless glycoconjugate precursors. Since these aroma compounds can be released by hydrolysis, different glycosidase enzymes can potentially contribute different aromas to wines. In this paper, we first established a procedure for profiling the free and bound volatile compounds in grape using GCMS combined with headspace solid-phase microextraction (HSSPME). Comparison of the free and bound aroma compounds revealed that non-volatile glycosides, known as aroma precursors, occur in high concentrations in musts. Among all compounds identified, 11 were fully quantified according to established standard calibration curves, while others were semi-quantified. Using three different glycosidase enzymes, a total of 38 bound volatile compounds were identified in Muscat grape, including terpenes, higher alcohols, C-6 compounds, and phenols, among others. The different enzymes had significant effects on the varietal aroma. Principal component analysis indicated that the characteristic aroma hydrolyzed by the commercial enzyme AR2000 was clearly different from that produced by other enzymes.

Key words:
Bound aroma compound, flavour, GC-MS, β-Dglycosidase, HS-SPME, Muscat grape.