ENZYMATIC BROWNING IN APRICOTS (PRUNUS-ARMENIACA)

Enzymic browning in apricots (Prunus armeniaca L) was found to be catalysed by a catechol oxidase (o-diphenol oxidase) and a laccase (p-diphenol oxidase), both acting on catechin and chlorogenic acid as the natural substrates. The laccase was identified as such by substrate specificity tests and the effects of selective inhibitors. The enzymes were tightly bound to the fruit tissue and were inactivated by holding at 80-degrees-C for 10 min. The levels of phenolic compounds in healthy and rotted apricot tissue were compared by paper chromatography; the levels of catechin and chlorogenic acid were reduced in the rotted tissue.