Journal of Dairy Research

Research Article

Simultaneous pasteurization and homogenization of human milk by combining heat and ultrasound: effect on milk quality

Charles Czanka1 c1, Karen Simmera2 and Peter E Hartmanna1

a1 Discipline of Biochemistry and Molecular Biology, School of Biomedical, Biomolecular and Chemical Science, The University of Western Australia, Crawley, Western Australia, 6009

a2 School of Women's and Infants' Health, The University of Western Australia, The University of Western Australia, Crawley, Western Australia, 6009

Abstract

The combination of ultrasound and heat (thermoultrasound) is an emerging food preservation technique that retains higher quantities of bioactive components compared with current thermal pasteurization practice, but has not yet been assessed for pasteurizing human milk. Artificially contaminated human milk samples were treated with ultrasound (20 kHz, 150 watts) with and without heating. The retention of four human milk proteins was quantified by biochemical assay and laser scattering particle sizing was used to determine the extent of homogenization. While ultrasonic treatment was effective at inactivating Escherichia coli (D4 °C=5·94 min), Staphylococcus epidermidis exhibited resistance (D4 °C=16·01 min). Thermoultrasonic treatment was considerably more effective (Esch. coli D45 °C=1·74 min, D50 °C=0·89 min; Staph. epidermidis D45 °C=2·08 min, D50 °C=0·94 minutes) with a predicted retention (2·8 min treatment, 50°C) of secretory IgA lysozyme, lactoferrin and bile salt stimulated lipase of 91, 80, 77, and 45%, respectively. Homogenization of the milk samples occurred after 5 min and 2 min of ultrasonic and thermoultrasonic treatment, respectively. Thermoultrasonic treatment is an effective method for pasteurizing donor human milk and retaining a greater proportion of bioactive components compared with current practices. However, further studies are required to assess the practicality of applying this technique routinely to donor human milk.

(Received June 03 2009)

(Accepted November 24 2009)

(Online publication January 07 2010)

Correspondence:

c1 For correspondence; e-mail: czankc01@student.uwa.edu.au