W-J Song1, H-J Sung, D-H Kang. 1. Department of Food and Animal Biotechnology, Department of Agricultural Biotechnology, Center for Food and Bioconvergence, and Research Institute of Agriculture and Life Sciences, Seoul National University, Seoul, Korea; Institutes of Green Bio Science & Technology, Seoul National University, Pyeongchang-gun, Gangwon-do, Korea.
Abstract
AIMS: This study evaluated the combined effects of ozone and heat treatment to inactivate Escherichia coli O157:H7 and Salmonella Typhimurium in three types of apple juice of different soluble solids content. METHODS AND RESULTS: Three types of apple juice (18, 36, 72 °Brix) inoculated with pathogens were subjected to ozone (3·0 l min(-1) flow rate and 2·0-3·0 g m(-3) concentration) and heat treatment (25, 45, 50 and 55°C) simultaneously for 20, 40 and 60 s. Initial populations of pathogens in inoculated apple juice were approximately 10(5)-10(6) CFU ml(-1). Heat treatment alone (25, 45, 50 and 55°C) for 1 min reduced populations of E. coli O157:H7 by 0 to 4·75 log CFU ml(-1) in three types of apple juice. The combination of ozone and heat treatment for 1 min at 25 and 45°C reduced E. coli O157:H7 by 0·93-3·87 log CFU ml(-1) and below the detection limit (>1 log CFU ml(-1)) at 50 and 55°C. A similar tendency was observed for S. Typhimurium. In several instances, results showed a synergistic effect of ozone and heat treatment. Colour values were not changed during ozone and heat treatment. CONCLUSION: These results show that the combination of ozone and heat treatment can be used as a potential inactivation intervention for E. coli O157:H7 and S. Typhimurium in apple juice. SIGNIFICANCE AND IMPACT OF THE STUDY: The combination of ozone treatment and mild heat can be used as an alternative intervention for pasteurization of varying soluble solids content apple juice in food industries.
AIMS: This study evaluated the combined effects of ozone and heat treatment to inactivate Escherichia coli O157:H7 and Salmonella Typhimurium in three types of apple juice of different soluble solids content. METHODS AND RESULTS: Three types of apple juice (18, 36, 72 °Brix) inoculated with pathogens were subjected to ozone (3·0 l min(-1) flow rate and 2·0-3·0 g m(-3) concentration) and heat treatment (25, 45, 50 and 55°C) simultaneously for 20, 40 and 60 s. Initial populations of pathogens in inoculated apple juice were approximately 10(5)-10(6) CFU ml(-1). Heat treatment alone (25, 45, 50 and 55°C) for 1 min reduced populations of E. coli O157:H7 by 0 to 4·75 log CFU ml(-1) in three types of apple juice. The combination of ozone and heat treatment for 1 min at 25 and 45°C reduced E. coli O157:H7 by 0·93-3·87 log CFU ml(-1) and below the detection limit (>1 log CFU ml(-1)) at 50 and 55°C. A similar tendency was observed for S. Typhimurium. In several instances, results showed a synergistic effect of ozone and heat treatment. Colour values were not changed during ozone and heat treatment. CONCLUSION: These results show that the combination of ozone and heat treatment can be used as a potential inactivation intervention for E. coli O157:H7 and S. Typhimurium in apple juice. SIGNIFICANCE AND IMPACT OF THE STUDY: The combination of ozone treatment and mild heat can be used as an alternative intervention for pasteurization of varying soluble solids content apple juice in food industries.