Milk pasteurization under laboratory conditions : Thermal damage prediction

A procedure was developed for the evaluation of heat exchangers for pasteurization treatments using a model solution (10% sucrose; pH = 1.15). This procedure allows the indirect prediction of the thermal damage that will undergo (expressed as the degree of denaturation of single soluble whey proteins or as the percentage of soluble whey proteins with respect to total proteins - SWP% when treated in a continuous flow heat exchanger, whose time-temperature and flow velocity profiles are unknown, but whose holding temperature is known. Heat treatments were performed on an indirect heat exchanger at the laboratory level. A relationship (r(2) > 0.998) between the Co values For sucrose hydrolysis and the Co of each whey protein denaturation and two relationships (for temperatures between 80 and 90 degrees C and for temperature of 75 degrees C) between SWP% and residual sucrose (r(2)=0.853 and r(2)=0.889) were found. These equations allow, after treating the model solution in a heat exchanger, to predict, from residual sucrose, the thermal damage of milk treated in the same operative conditions. Graphs are presented that. allow the degree of whey protein denaturation to be determined from the percentage of hydrolysis of the sucrose solution.