Continuous flow microwave pasteurization of milk. Comparison between microwave and conventional heating
1996
Villamiel, M. | Lopez-Fandino, R. | Corzo, N. | Olano, A. (Instituto de Fermentaciones Industriales C.S.I.C., Madrid (Spain))
Microwave treatment has well-known potential advantages over conventional heating systems. Foods are heated directly and rapidly and there is no contact with hot surfaces. This allows good temperature control and avoids equipment fouling. Moreover, the application of microwave energy in a continuous flow unit provides a good temperature distribution, thereby eliminating "hot and cold spots" which are often observed for milk heated in a batch unit. In the present communication we report the results of a comparative study of the effect of both continuous microwave and conventional heating of milk on enzyme activity (alkaline phosphatase and lactoperoxidase) and whey protein denaturation. The results obtained showed that most of the assayed heat treatments were effective for pasteurization with regard to the loss of activity of alkaline phosphatase. Heat treatments in the conventional system caused a similar degree of whey protein denaturation and lactoperoxidase inactivation to that observed during microwave heating under the same temperature and time conditions. The slight differences observed between the two systems were probably due to milk contact with hot surfaces in the conventional system. These results seem to indicate that cow's milk could be effectively pasteurized in a continuous flow microwave unit with a minimum of deterioration in the milk constituents.
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