Effect of ozone application on product quality of apple juice

In this study, raw apple juice samples were pasteurized (92 °C, 30 s) and treated with ozone for varying times (15-90 min). The effects of these treatments on microorganisms (E. coli, coliform, total aerobic mesophilic bacteria [TAMB] and yeast-mold) were investigated. Different levels of microbial inactivation were achieved by pasteurization and ozone treatments. It was observed that the counts of coliform bacteria decreased below detectable limit after the ozone treatment for 15 min. It was determined that TAMB and yeast-mold were more resistant to ozone compared to coliforms and that the counts of all microorganisms tested decreased below detectable limit after the ozone treatment for 90 min. The effect of ozone treatment on the pesticides (Acetamiprid, Difenoconazole, Dimethoate, Fluopyram, Imidacloprid, Methoxyfenozide, Pyrimethanil, Thiachloprid, Trifloxystrobin) in apple juice was also investigated. It was observed that degradation of pesticides generally increased by increasing ozone treatment time. After treating with ozone for 90 min, limited (7.1-23.7%) degradations were recorded for some pesticides while some others were highly (74.9-100%) degraded. Pasteurization caused 20% decrease in total phenolic content of apple juice while decreases of 31 and 55.4% were recorded after ozone treatments for 15 and 90 min, respectively. Antioxidant activity of apple juice increased by 16% after pasteurization, however decreased by 31.3-48.7% and 92% after short time (15-30 min) and 90 min ozone treatments, respectively. Ozonation process is a promising alternative to pasteurization for removing microorganisms and pesticide residues from fruit juice, in the condition of preventing losses in nutritional value caused by long treatment.