EFFECTS OF POLYPHENOL CONTENT AND POLYPHE NOLOXIDASE ACTIVITY ON BROWNING REACTION OF APPLE FRUITS

The effects of hydroponic culture (water culture) and Ca-solution spra y to tree of conventional soil culture on enzymatic browning of the ap ple fruits were examined in comparison with the conventional soil cult ure (soil cultured fruit : SCF). The cultivars of apple were Fuji and Jonagold of water cultured fruit (WCF), and Starking of Ca-solution sp rayed fruit (CaF). We investigated the relationship among the enzymati c browning, polyphenol (PP) content and polyphenoloxidase (PPO) activi ty by using the apple fruits harvested at Morioka in 1992-1994. The re sults were as follows. (1) Total PP (TPP) contents in WCF and CaF with low browning degree were higher than that in SCF with high browning d egree. It seemed that TPP content didn't relate to the browning direct ly. (2) Chlorogenic acid content was found to be higher in WCF than in SCF, however the relationship between culture condition and epicatech in content of same samples was not clear. (3) The contents of chloroge nic acid and epicatechin in Starking were not affected by spraying of Ca-solution. (4) The PPO activity in WCF was weaker than that in SCF s ignificantly. These results indicated that the browning reaction of WC F was influenced by the PPO activity. (5) The PPO patterns by Native P AGE differed between the apple cultivars but had no difference among t he culture conditions. It is evident that the low browning degree of W CF depended on only quantity of PPO, not on quality.