As shown inFig. 1, ozone gas was produced by an ozone generator (Ozonetech Co., Ltd, Korea) at generation rates of 2.0–3.0 g/m 3 from ambient air at aflow rate of 3.0 l/min. The concentration of ozone was controlled by an ozone monitor (Okitrotec Co., Japan). Ozone was pumped directly into the juice through a delivery tube and sparged through a perforated tube into a 500 ml bottle. As soon as the preset temperature (25, 45, 50 and 55 °C) was stabilized by using a water
bath, heat treatments were conducted. Juice samples not subjected to ozone treatment, but heat treated, were designated as the heat treatment alone group. Each apple juice sample treated at 25 °C without or