Milk Pasteurization - Evaluation of Thermal-Damage

Thermal damage of raw milk was evaluated during pasteurization treatments performed in a laboratory plant that allowed well defined thermal profiles to be established. The thermal damage of the different treatments, carried out at temperatures between 70 degrees and 90 degrees C and for holding times between 12.2 s and 178.6 s, was expressed as soluble whey proteins, as extent of denaturation of each whey protein and as the ratio between the sum of the peak areas of the most thermal sensitive whey proteins (immunoglobulin 1 and 3 + bovine serum albumin) and the total amount of beta-lactoglobulin A and B. Whey protein denaturation kinetics were evaluated obtaining the following activation energy (Ea) (kJ mol(-1)) and Z (degrees C) values: Ig3 Ea = 351, Z = 6.79; BSA Ea = 193, Z = 12.35; beta-LGB Ea = 286, Z = 8.33; beta-LGA Ea = 224, Z = 10.64; alpha-LA Ea = 132, Z = 18.06. On the basis of Z values, the Co parameter was calculated. This allowed the different heat treatments to be compared in terms of loss of thermolabile constituents.