Contribution of Free and Glycosidically Bound Volatile Compounds to the Aroma of Muscadine Grape Juice

Abstract

Free and glycosidically bound volatile compounds were isolated and identified from muscadine grape juice. Most abundant in free and bound form was the m u s c a d i n e c h a r a c t e r -i m p a c t a r o m a c o m p o u n d 2,5-dimethyl-4-hydroxy-3(2H)-furanone (Furaneol). Other aroma compounds, such as o-aminoacetophenone and 2-phenylethanol were found in free and bound forms. A high level of 2-phenylethanol was in the glycoside form and many bound monoterpenes were identified. p-Vinylguaiacol, a potential off-flavor in muscadine juice was found at a low level in bound form. Enzymatic hydrolysis of glycoside precursors could lead to release of volatile compounds with both potentially positive and deleterious effects on the overall aroma.

A UDP-Glucose:Monoterpenol Glucosyltransferase Adds to the Chemical Diversity of the Grapevine Metabolome

“…Enzyme activity studies were performed with UDP-[ 14 C]Glc and various putative substrates (terpenols, flavonoids, and different monoalcohols). The alcohols were selected because they have been identified as aglycones of glycosides in grape (Sefton et al, 1994;Baek and Cadwallader, 1999;Mateo and Jiménez, 2000;Wirth et al, 2001). The VvGT12 proteins exhibited no activity toward any of the substrates and were not further analyzed.…”

Glycosidically Bound Volatile Aroma Compounds in Grapes and Wine: A Review

“…Three fermentation treatments done in duplicate on Muscat blanc were carried out at 18°C with either no skin contact, 15 hr of skin contact, or 23 hr of skin contact. Released compounds were measured following enzymatic hydrolysis with a commercial enzyme preparation, AR2000, which has activity for all reported glycosides (Baek and Cadwallader 1999). Free and released volatiles were measured by GC-MS. A descriptive analysis of the wines was done according to a previous method (Noble et al 1984).…”

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

“…The commercial enzyme preparation AR2000 (DSM, France) contains several glycosidase activities, including β-D-glycosidase, α-L-arabinofuranosidase, α-L-arabinopyranosidase, and α-L-rhamnosidase, all of which can hydrolyze different glycosides to yield free flavour aglycones 2 . The second enzyme, β-D-glycosidase (EC 3.2.1.21, from Aspergillus niger), was purchased from Sigma.…”