Comparison of direct and indirect methods of measuring the precursors of β-methyl-γ-octalactone and their application to the analysis of Sessile oak wood [Quercus petraea (Matt.) Liebl.]

A new indirect method for measuring the level of beta -methyl-gamma -octalactone precursors in oak wood by GC-MS is described. This level is calculated from the difference between the amount of free beta -methyl-gamma -octalactone and the amount formed after hydrolysis and lactonization. It is compared to the level of a precursor of cis-beta -methyl-gamma -octalactone, a 6'-O-gallate derivative of (3S,4S)-4-beta -D-glucopyranosyloxy-3-methyloctanoic acid, determined directly by HPLC. These two methods are applied to 12 powdered samples of Sessile oak wood and the results show that the 6'-O-gallate derivative of (3S,4S)-4-beta -D-glucopyranosyloxy-3-methyloctanoic acid is by far the most abundant precursor of beta -methyl-gamma -octalactone in this wood. (C) 2001 Elsevier Science B.V. All rights reserved.