CHARACTERIZING NAD-DEPENDENT AND NADP-DEPENDENT ALCOHOL-DEHYDROGENASEENZYMES OF STRAWBERRIES

The NAD-dependent and NADP-dependent alcohol dehydrogenase activities of strawberries (Fragaria xananassa Duch.) were found to have broad su bstrate specificities including those alcohols and aldehydes responsib le for strawberry aroma and flavor either directly or through their es ter products. NAD-dependent activities were greatest against short-cha ined alcohols, whereas the NADP-dependent activities were most active against aromatic and terpene alcohols. Differences were seen in substr ate specificity between receptacle and achene alcohol dehydrogenase ac tivities. Alcohol dehydrogenase activities were found to be developmen tally regulated in receptacle tissue and increased during the period o f fruit maturation and ripening. Isoelectric focusing of NAD-dependent ADH activities showed that several isozymes of this enzyme exist, tha t they differ between receptacle and achene tissues, and that they var y among specific genotypes. Our results suggest that NAD- and NADP-dep endent ADH activities are integral components of flavor and fragrance volatile production in ripening strawberries.