Inactivation of Zygosaccharomyces rouxii in organic intermediate moisture apricot and fig by microwave pasteurization

Abstract Zygosaccharomyces rouxii is an osmotolerant yeast that is responsible for the spoilage of high sugar content foods. Microwave heating technology is used as an alternative to conventional pasteurization. Main purpose of this research was to determine the thermal resistance of Z. rouxii in organic intermediate moisture content (IMC) fruits (apricot and fig) during the microwave pasteurization process and comparing the D, z and F values with the conventional method. F85 values were calculated both theoretically and experimentally. Additionally, the effects of the pasteurization methods on the quality properties (total soluble solid, pH, acidity, water activity, moisture content, rehydration capacity, weight loss, hydroxymethylfurfural (HMF) and color) of the samples were investigated. The results show that come up time (CUT) and D values were significantly reduced by microwave treatment. The yeast reached a five log10 reduction by the microwave heating method with the F8533.8 value of 3.6 min for apricot and F8532.15 value of 3.35 min for fig. Total soluble solids, weight loss, and color values were preserved better in microwave pasteurization than the conventional method in both samples. Hydroxymethylfurfural content of the microwave pasteurized samples was 23.5% and 32% less than the samples pasteurized conventionally for apricot and fig samples, respectively.