INHIBITION OF POLYPHENOL OXIDASE ACTIVITY AND BROWNING BY HONEY

The inhibitory effect of honey on polyphenol oxidase (PPO) and on browning reactions was studied in apple slices, grape juice, and model systems. Browning was prevented by immersing apple slices in a honey solution. Grape juice preparations with added honey exhibited less browning and retained a higher concentration of polyphenols than juices made with no added honey. In model solutions of caffeoyl tartrate and epicatechin, the browning rate was inversely proportional to the added honey concentration. A kinetic study showed that honey is noncompetitive with epicatechin. Preincubation of PPO with honey progressively decreased the PPO activity with time. The compound responsible for this inhibitory effect of honey appeared to be a small peptide with an approximate molecular weight of 600. © 1990, American Chemical Society. All rights reserved.