The Effect of HTST and Holder Pasteurization on Bacterial Agglutination by Breast Milk

Background: Not only do infant formulas lack nutritional components supplied in breast milk, they lack a variety of maternal immune components normally transferred through breast milk, including microbial agglutinins. Bacterial aggregation by these agglutinins potentially reduces the likelihood of infection and is a critical step in the formation of the normal ecosystem of the infant’s gut, which is vital to proper immune system development. Objective: Given the need for better sources of breast milk for children who cannot receive their own mother’s milk, the effect of High Temperature, Short Time (HTST) pasteurization and Holder pasteurization methods on agglutinins in human breast milk was assessed. Methods: For this purpose, a small scale HTST pasteurization apparatus and protocol was created and validated. Bacterial aggregation was assessed indirectly by measuring initial changes in CFUs following post-pasteurization addition of exogenous bacteria, with less increase in CFUs being indicative of aggregation. Results: Raw milk and Holder pasteurized milk resulted in the fewest CFUs, with no difference observed between the two preparations. Interestingly, HTST pasteurized breast milk did not result in fewer CFUs than Holder pasteurized milk (p = 0.03), suggesting that the Holder method of pasteurization is at least as effective as HTST pasteurization at preserving bacterial agglutinins in human breast milk. Conclusion: Although more CFUs were observed in the assay using boiled human breast milk than any other milk preparation, the most CFUs were observed with infant formula, suggesting a propensity for that material to support uncontrolled planktonic bacterial growth.