Omar, Y., El-Kady, A., Nagy, K. (2020). Effect of Using Microwave Radiation in Milk Pasteurization. Egyptian Journal of Agricultural Research, 98(1), 95-112. doi: 10.21608/ejar.2020.114370
Younes S. Omar; Amgad A. El-Kady; Khaled Nagy. "Effect of Using Microwave Radiation in Milk Pasteurization". Egyptian Journal of Agricultural Research, 98, 1, 2020, 95-112. doi: 10.21608/ejar.2020.114370
Omar, Y., El-Kady, A., Nagy, K. (2020). 'Effect of Using Microwave Radiation in Milk Pasteurization', Egyptian Journal of Agricultural Research, 98(1), pp. 95-112. doi: 10.21608/ejar.2020.114370
Omar, Y., El-Kady, A., Nagy, K. Effect of Using Microwave Radiation in Milk Pasteurization. Egyptian Journal of Agricultural Research, 2020; 98(1): 95-112. doi: 10.21608/ejar.2020.114370
Effect of Using Microwave Radiation in Milk Pasteurization
Food Engineering and Packaging Department, Food Technology Research Institute, Agricultural Research Center, Giza 12619, Egypt
Abstract
The aim of the present study is to modify a microwave device to be used as a continuous pasteurization device and to study the ability of the device to inhibit microorganisms٫ and to improve the thermo-physical and chemical properties of the pasteurized milk. The buffalo milk was pasteurized by microwave at 72° C for a time ranging between 20 -400 seconds, then a sudden cooling was introduced in the refrigerator at a temperature of 5° C and stored on this degree for a period of 15 days. The microbial and chemical analysis were performed, Each milk sample was divided into four groups: A, B, C and D, where group (A) represents the milk control sample, group (B) represents the milk subjected to radiation intensity of 800W with flow rates of 75, 150 and 225 ml/20 – 40 – 80 seconds respectively, group (C) represents the milk subjected to radiation intensity of 480W with flow rates of 75, 150 and 225 ml/ 40 – 80- 160 seconds respectively and group (D) represents the milk subjected to radiation intensity of 160 W with flow rates of 75, 150 and 225 ml / 100 – 200 – 400 seconds respectively, keeping the coil length of 200 cm constant for all the previous treatments. The device productivity reached 13.5 liters/hour and heating rate was 3.6°C/second. Results showed that chemical properties of milk were as follows: pH, fat, protein, lactose, ash values of group (B) was significantly higher than control sample (P <0.05), followed by group (C) and group (D), while the titratable acidity, moisture values was significantly less than the control sample (P <0.05). Microbiological tests before treatment included the total number of microbes, coliform group. After microwave treatment, the thermo-physical properties of milk included density, thermal conductivity, viscosity, and specific heat at different temperatures were also calculated. The results were: (1031.146 - 1012.792 kg/m3) ،(0.566191 - 0.644071w/m.k)، (0.000858 - 0.0006901 Pa.s)،(3855 - 3939 J/kg.k) respectively. The results were seriously significantly increased by increasing the heating time compared to the control samples (p < 0.05)٫ whereas the viscosity of milk and its intensity were significantly decreased by increasing the heating time in comparison to the control sample (p < 0.05). Results had been improved that after pasteurization where the total number of microbes, chloroform group, tuberculosis, Lysteria microbes and alkaline phosphatase had been eliminated in the pasteurized milk.
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