USE OF A MODEL SOLUTION FOR THE EVALUATION OF HEAT DAMAGE IN MILK TREATED IN AN ULTRAHIGH-TEMPERATURE HEAT-EXCHANGER

Heat damage in milk can be determined by measuring either reaction pro ducts, whose formation is time-temperature dependent, or the loss of t hermolabile constituents contained in raw milk. The purpose of this st udy was to find a relationship between heat damage in milk and the per formances of a 10% sucrose solution at pH 3 used as a model solution. Heat treatments were performed on a laboratory indirect heat exchanger especially assembled. The investigation was based on the experimental determination of the time-temperature profiles in the plant, the kine tics of sucrose inversion in the model solution, and the reaction kine tics of some indices of heat damage in milk, such as the formation of lactulose and the loss of alpha-lactalbumin. On the basis of the perce ntage of noninverted sucrose remaining in the model solution, a calcul ation procedure is proposed for checking the performance of an ultrahi gh-temperature plant with reference to heat damage and the bacteriolog ical reduction.