A method to analyse bound aroma compounds in non-aromatic red grape juices

a method to study the glycosidically bound fractions in red grape juice was developed. bound fractions were fractionated by solid-liquid chromatography on lichroprep rp-18. the release of free aglycones was achieved by acid hydrolysis. in a preliminary approach the acid hydrolysis was performed at ph 1.0 and ph 3.0 levels. the ph 3.0 was selected in this study mainly due to its similarity with the ph levels that occur naturally in juices and grapes. nine extractions of the same juice sample were carried out to study the repeatability of the method at ph 3.0. all the extracts were analysed by gc-ms and gc-fid. the repeatability found in the various quantified components in all extracts of the bound fraction of juice is expressed by their coefficient of variation, which varied in the range between 11.5% and 24.7%. four aglycones, trans-furan linalool oxide, cis-furan linalool oxide, vitispirane, and ？-damascenone were quantified after ph 3.0 hydrolysis.