CHEMICAL AND FUNCTIONAL-CHANGES IN MILK CAUSED BY HEATING IN A WATERBATH OR MICROWAVE-OVEN

Raw milk was heated in a waterbath (71.1 degrees C for 15 sec) or a mi crowave oven (71 degrees C or 76.7 degrees C for 15 sec) and analyzed using Fast Protein Liquid Chromatography to determine the extent of wh ey protein denaturation. Coagulation properties of the treated milks w ere determined using the Formagraph. Denaturation patterns of alpha-la ctalbumin and beta-lactoglobulin were similar regardless of the heat t reatment given to the milk. However, denaturation of beta-lactoglobuli n-B was greatest in milk heated in the microwave oven at 76.7 degrees C for 15 sec. Longest coagulation time (R) and slowest curd firming ra te (K-20) were associated with milk heated in the waterbath. Curd firm ness of heated milks was similar, but the firmest curd developed in un heated raw milk.