Pasteurization Efficiency of a HTST System for Human Milk

An economical, small scale heat processing device was studied for rapid and efficient pasteurization of human milk while preserving immunoglobulins A,G and M. Using a continuous flow HTST milk pasteurizer, human milk inoculated with E. coli (10⁶ CFU/mL) or S. aureus (10⁷ CFU/mL) was heated at 71°C at flow rates of 5.9, 12.3 and 18.9 mL/ min. All conditions completely inactivated both microorganisms and resulted in negative alkaline phosphatase activity indicating complete pasteurization. Heat processing of bovine milk at 71°C, at 5.9 mL/min resulted in retention of 30% of the γ-glutamyl transpeptidase (GGTP) activity. Lower residual activity could therefore indicate overpasteurization. Pasteurization at 71°C for 9.0 sec (12.3 mL/min) resulted in retention of 74% of IgA, 75% IgG, and 68% IgM.