MICROWAVE PASTEURIZATION OF MILK IN A CONTINUOUS-FLOW UNIT - EFFECTS ON THE CHEESE-MAKING PROPERTIES OF GOATS MILK

Goat's milk was pasteurized in a continuous microwave heating system a t 72.5 and 80.1 degrees C for 15 s. The extent of the heat treatment w as estimated by determinations of undenaturated beta-lactoglobulin and lactoperoxidase activity. The total bacterial counts, proteolytic act ivity and renneting properties of the heated milk were also evaluated. Results were compared with those obtained in the case of milk heated in a plate heat exchanger under the same conditions. beta-lactoglobuli n denaturation and lactoperoxidase inactivation caused by the plate he at exchanger were considerably higher than those brought about by the microwave pasteurization system, although the degree of microbial dest ruction was similar in both systems. In addition, the enhanced surviva l of plasmin activity, important for cheese ripening, together with si milar renneting properties as compared with milk heated in the plate h eat exchanger, indicate that continuous microwave treatments could be useful for pasteurizing goat's milk intended for cheese making.