ASSESSMENT OF THE THERMAL-TREATMENT OF MILK DURING CONTINUOUS MICROWAVE AND CONVENTIONAL HEATING

The effect of continuous-flow microwave treatment of milk was estimate d by using indicators of the heat treatment intensity (beta-lactoglobu lin denaturation, inactivation of alkaline phosphatase and lactoperoxi dase). Results were compared with those obtained using a conventional process having the same heating, holding, and cooling phases. Continuo us microwave treatment proved to be an effective system for pasteurizi ng milk, with the inclusion of a holding phase to maintain the time an d temperature conditions required. At high pasteurization temperatures , the extent of thermal denaturation observed with the microwave treat ment was lower than that obtained with the conventional system. This r esult could be attributed to a better heat distribution and the lack o f hot surfaces contacting the milk in the case of the microwave unit.