13 research outputs found
Glycosidase activities in sound and rotten grapes in relation to hydrolysis of grape monoterpenyl glycosides
ÎČ-D-glucopyranosidase, α-L-arabinofuranosidase and α-L-rhamnopyranosidase activities were studied in grapes, both during maturation and in sound and rotten mature fruits. Enzymic activities increased during maturation. At maturity, in sound grapes, ÎČ-D-glucopyranosidase and α-L-arabinofuranosidase activities were the highest ones. Berry infection by fungi results in a decrease in ÎČ-glucosidase activity, while the others increase. The effect of an enzymic extract from a culture of Botrytis cinerea towards synthetic terpenyl glycosides showed that hydrolysis was strong for ÎČ-terpenyl rutinosides and weak for ÎČ-terpenyl 6-0-α-L-arabinofuranosyl-ÎČ-D-glucopyranosides
Etude du brunissement des vins blancs
On admet depuis longtemps que les composĂ©s phĂ©noliques jouent un rĂŽle important dans la coloration des vins blancs et sur leur Ă©volution au cours du brunissement. Cependant, de nombreux problĂšmes thĂ©oriques restent Ă rĂ©soudre dans ce domaine de l'Ćnologie pour avoir une interprĂ©tation correcte de la nature chimique de la couleur des vins blancs.
Dans une publication précédente nous avons montré l'existence de variations de la teneur en composés phénoliques au cours du brunissement. Cependant, l'étude d'un grand nombre d'échantillons ne permet pas de mettre en évidence des relations directes entre les teneurs en composés phénoliques ou leurs variations, d'une part, et l'intensité du brunissement d'autre part
The browning capacity of grapes. 1. Changes in polyphenol oxidase activities during development and maturation of the fruit
An Endoglycosidase from Grape Berry Skin of Cv. M. Alexandria Hydrolyzing Potentially Aromatic Disaccharide Glycosides
HPLC study of the efficiency of extraction of phenolic compounds
The rate of extraction of phenolic compounds in two different solvents has been studied by liquid chromatography (HPLC) under reverse phase, gradient elution conditions. The solvents were diethyl ether and ethyl acetate. The method has been applied to two natural samples, a white wine and apple pulp.The authors acknowledge the financial support of the Comision Interministerial de Ciencia y Tecnologia (C.I.C.Y.T.).Peer reviewe