Effect of electromagnetic waves (cold pasteurization) on Yolk liquid stored at different time on the logarithmic count of mesophilic aerobic bacteria

摘要

Among the different methods for pasteurization of foodstuff, non thermal methods include electromagneticmethod has received more attention, Because of significant reducing in total count of Bacteria, preventing fromspoilage and increasing shelf life of foodstuffs. In this study yolk liquid was pasteurized by usingelectromagnetic method in 3 different frequencies (2950-3950-4500 MHz) for constant time of 12 sec (6 sec ofsecond pulse) and then results were compared with samples which were pasteurized at 65 C for 120 sec andcontrol samples, after different times of storage(1,3,5,8,10 and 15 days). Results showed that usedelectromagnetic waves had significant effect on reduction of logarithmic count of aerobic mesophilic bacteria.According to results, however thermal pasteurization had a greater bactericide effect at zero time than coldpasteurization, but, a great increase was occurred in the number of aerobic mesophilic bacteria after passingtime, in comparison with non thermal pasteurized product. According to Iranian National Standard, inelectromagnetic method liquid yolk shelf life has been defined 14 days which it is very ideal in comparisonwith thermal pasteurization (7d max) and control sample (2d max).