PHYSIOLOGY OF COLOR CHANGES OF FRESH-CUT VEGETABLES DURING STORAGE

Abstract

This experiment was carried out in the laboratory of Vegetable Handling Department, Horticultural Research Institute, Agricultural Research Center, Giza. The aim of this study was controlling the PPO activity by using different inhibitors i.e. ascorbic acid, cysteine and citric acid and some other amino acids i.e. glycine, valine, phenyl alanine and methionine.The mechanisms of various PPO inhibitors also studied. This experiment was conducted with and without addition of antibrowning agents against a blank of phosphate buffer. Inhibition kinetics of PPO was performed at the unsaturation level of substrate (catechol) at various final concentrations (0.84 – 7.15mM). Linewaver-Burkcurves were used to calculated Michalies (Km) and inhibition. On the other hand, the effect of temperature on enzymatic browning in vitro been studded, the PPO was extracted from eggplant fruits. PPO enzyme and catechol (1:3 v/v) were mixed and incubated at various temperature (10 – 100°C) up to 13 min. the samples were taken to measure the browning changes (PPO activity).