Effects of microwave pasteurization on the thermal resistance of Zygosaccharomyces rouxii and on the physicochemical properties of organic intermediate moisture raisin

摘要

In this study, organic intermediate moisture raisin was pasteurized with microwaveand conventional pasteurization methods. The thermal resistance (D and z values) ofthe target yeast, Zygosaccharomyces rouxii, was determined for both methods at differenttemperatures 60°C, 70°C, and 80°C and at different time intervals. The effect ofpasteurization methods on the quality properties of raisin samples was investigated.The D values of Z. rouxii were found as 6.50 ± 0.49, 2.96 ± 0.02, 1.91 ± 0.01 minfor conventional treatment and 3.46 ± 0.31, 2.02 ± 0.14 and 1 ± 0.01 min for microwavetreatment at 60°C, 70°C, and 80°C, respectively. F_(85)~(37) values for 5-logreduction and come-uptime significantly decreased after microwave pasteurization.Brix, acidity, and color values were preserved better by microwave treatment.Hydroxymethylfurfural content of the microwave pasteurized samples was found42% less than the samples pasteurized conventionally. Microwave pasteurization canbe alternatively used for the conventional method for raisin improving quality withless heating time.