Effect of thermal conditions on the concentration of biological active whey protein in cow milk

Abstract Text: Biological active whey protein in cow milk play an important role in the health of human, which is sensitive to thermal conditions during dairy processing. The objective of the present study was to investigate the variation of mainly immune active proteins concentration in cow milk, which was heated by reference commercial pasteurized milk processing technical specification of China dairy industry standards. The contents of the immunoglobulins (IgG、IgM、IgA), lactoferrin (Lf) and bovine serum albumin (BSA) were determined after different thermal processing by Sandwich enzyme-linked immunosorbent assay (ELISA), respectively. The results showed that pre-heat treatment and homogenizing had relatively mild effects on immune active protein concentration. From 75 to 115℃ with holding times for 15s, immune active proteins contents were decreased significantly. The concentration of immune active proteins remained fairly constant and lightly decreased over time when heating temperature maintained at 85℃. Immune active proteins contents were extremely low and the diversity among different treatments was small at heating temperatures ranging from 125 to 145℃ for 4s. When heated at 138℃ for 4s, 6s and 8s, concentrations of immune active proteins had shown no significant difference. When milk heated at UHT and superheated conditions, treatment of raw milk at 140℃ for 4s had a relatively higher content. These finding indicated that the appropriate condition of pasteurization heating at 75℃ for 15s, and treatment at 140℃ for 4s are fit for UHT processing. Moreover, there is no need for superheated which has no benefit for dairy nutritional properties.

Keywords: cow milk, biological active whey protein, heat-stability