Coenzyme A-dependent Esterification of Alcohols and Acids in Separated Cells of Banana Pulp and its Homogenatet

Abstract

his study was conducted to ascertain whether the formation of volatile esters in banana fruit would be a reverse reaction of esterase or a coenzyme dependent reaction. Esterase activity during ripening of banana fruit became higher with the increase of esterification of added alcohol and acid to banana slices. Esterase activity was, however, observed in green banana pulp, and vascular tissues from banana pulp had fairly high capacity of esterification of added alcohol and acid, whereas esterase activity in the tissue was very low. Furthermore p-nitrophenyl phenyl-phosphonothionate(EPN), inhibitor of esterase, almost completely inhibited esterase activity from vascular tissue of banana pulp with low concentration, but the esterification in the tissue was not inhibited in the same concentrations.
Acetyl CoA and butyl alcohol changed to butyl acetate with very high extent in homogenate of pulp at over ripe stage. Acetyl CoA also made acetate ester in homogenate of mesocarp cells and in that of vascular tissue more distinctly. Homogenates and mesocarp cells could only produce acetate esters in the presence of acetyl CoA instead of acetic acid. Experiment with inhibitors also emphasized that acyl CoA is the real intermediate of esters of banana aroma.