Inactivation of Staphylococcus aureus and native microflora in human milk by high pressure processing

The storage of unpreserved food, including breast milk, is associated with the growth of microorganisms, including pathogenic bacteria. It is therefore necessary to use suitable processes to eliminate pathogenic microorganisms and reduce the total microbial count in order to ensure product safety for consumers. In the present study, samples of milk obtained from volunteers donating to the human milk bank were artificially contaminated with Staphylococcus aureus ATCC 6538. This bacteria was the model microorganism of choice, being relatively resistant to high pressure as well as posing the most serious risk to infant health. The results obtained show that high pressure processing can reduce the count of S. aureus by about 5 log units at 4 degrees C and about 8 log units at 50 degrees C, and totally eliminate Enterobacteriaceae after 5 min of treatment, and result in a total microbial count reduction after 10 min treatment at 500 MPa at 20 degrees C and 50 degrees C. This suggests the possibility of this technology being applied to ensure the adequate safety and quality of human breast milk in human milk banks.