Application of microwave and ohmic heating for pasteurization of cantaloupe juice: microbial inactivation and chemical properties

BACKGROUNDCantaloupe melon (Cucumis melo L.) is one of the most important dessert fruits and is cultivated in many countries of the world. The effects of microwave (400 and 800W for 110s), ohmic (100 and 200V for 110s) and conventional heating (27-75 degrees C for 30min) treatments on inactivation of Escherichia coli, Salmonella Typhimurium, S. Enteritidis and Staphylococcus aureus pathogens; pH and degradation of vitamin C, beta-carotene and phenolic compounds of cantaloupe juice were investigated. RESULTSAs time passed, all of the treatments resulted in significant (P <= 0.05) decreases in the number of pathogens and vitamin C, beta-carotene and phenolic compound content, whereas the pH of samples did not show significant changes. The mentioned parameters were more reduced by increasing the power, voltage and temperature of ohmic, microwave and conventional heating treatments, respectively. Comparison of the results for conventional heating with those of ohmic and microwave heating revealed that the complete inactivation time of pathogens by the two latter treatments was much shorter than that of the former. After 20s, the effect of ohmic heating at 200V on decreasing vitamin C content was significantly (P <= 0.05) higher than that of the other treatments. The amounts of beta-carotene and phenolic compounds showed the most reduction under 800W microwave treatment. CONCLUSIONThe results obtained for conventional, ohmic and microwave heating treatments indicated a higher degradation of beta-carotene and phenolic compounds and a lower loss of vitamin C in the former. (c) 2019 Society of Chemical Industry