THE EFFECT OF ELECTRIC FIELD ON THE ACIDS AND ESTERS IN BRANDY AGING

Acetic acid,butyric acid,octoic acid and capric acid which are the main organic acids in brandy accounting for 80% of the total wine acid,can react with alcohols affording esters,such as ethyl acetate,ethyl hexanoate,ethyl lactate,ethyl caprylic acid,capric acid ethyl ester and lauric acid ethyl ester which are the main aroma esters compounds in brandy. The present study was to investigate the effect of applying an electric field treatment on acids and esters of brandy stored in French medium toasting oak barrels. The results showed that the content of esters and acids in both barrels increased gradually with aging time,meanwhile,the EF treatment caused the reduction of acids,but enhanced the increment of esters. The results showed that the concentration of acids in brandy treated by EF was 20.1% lower than those of the control brandy after 12 months of maturation in5 L oak barrels,but esters in brandy treated by EF was 9.4% higher than those of the control brandy in 5 L oak barrels. It was demonstrated that the application of electric field treatment directly on oak barrel could increase the ester contents and decrease the acids excess generation. The mechanism was that,under the effect of electric field,the motion velocity and interaction between molecules were accelerated inducing the increase of the activity and ionization of the molecules. The activation energy required for the chemical reactions were reduced,so as to accelerate the esterification reaction,association reaction and oxidation reduction reaction,etc. And the energy of the electric field could accelerate the Brown thermal motion of the molecules in the wine,thereby promoting the diffusion of volatile matter in the bucket.