Compositional changes in lower molecular weight flavans during grape maturation

Grapes of the Gamay Beaujolais and Siebel varieties have been sampled during the period from just before the onset of colouration to harvest. Extraction has yielded data on the composition and quantities of lower molecular weight and polymeric flavanoids present. The structure of the major flavans of these grapes has been established and the variation in their relative amounts monitored during the growth season. The basic structural unit of the grape proanthocyanidin polymer is a monomer with (?)-epicatechin stereochemistry.