436 - The Effects of Refrigerated Storage on Nutrients in Donor Human Milk with Limited Bacterial Presence after Holder Pasteurization

Poster Number: 436
Publication Number: 436.302

Sydney McCune, University of North Carolina at Greensboro, Greensboro, NC, United States; Maryanne Perrin, University of North Carolina Greensboro, Greensboro, NC, United States

Background: The Human Milk Banking Association of North America (HMBANA) sets the purity and quality standards for donor human milk (DHM) in the United States. These standards include zero bacterial presence after Holder pasteurization. If any bacteria remains in the milk, it is discarded, despite no evidence that bacterial presence is related to infection risk in infants. This stringent standard results in up to 11% of DHM being discarded.

Objective: This study aimed to determine if nutrient and bacterial composition of DHM with limited bacterial presence after pasteurization change over 4 days of 4oC storage.

Design/Methods: Twenty-five unique samples of DHM that had been rejected due to post-pasteurization bacterial growth were collected from 2 HMBANA milk banks. Gerber Good Start GentlePro Powder Infant Formula, Stage 1 was used as a control. The formula was prepared according to package directions when the DHM was fully defrosted, representing time 0. A portion of milk was removed at 24-hour intervals beginning at hour 0 and ending at hour 96. The process for removing milk mimicked home-use (washed hands; no gloves or personal protective equipment; performed on cleaned countertop). Aerobic bacteria colony forming units (CFUs) were measured using 3M™ Petrifilm™ Aerobic Count Plates. Total protein was measured using a bicinchoninic acid kit. Lactose was measured using Megazyme Enzymatic Assay. Longitudinal changes in the composition of bacteria, protein, and lactose in each sample over storage duration were analyzed using repeated measures analysis of variance test. P< 0.05 was deemed significant.

Results: Linear changes in content of lactose, protein, and bacteria are shown in Figure 1. There were no significant differences in lactose, protein, or bacteria content over storage duration (P=0.649, P=0.690, and P=0.385, respectively). Total aerobic bacteria were less than 102 CFUs in 81% of the timepoints tested for DHM samples. Total aerobic bacteria were too many to count ( > 300 CFUs) in the control sample at all time points.Conclusion(s): There were no significant changes in the content of bacteria, protein, or lactose over 4 days of 4oC storage in DHM that had been rejected post-pasteurization. The majority of DHM samples contained less than 102 CFUs of aerobic bacteria, while the powdered formula control contained too many to count at all time points. In periods of high demand for DHM, DHM with low bacteria growth post-pasteurization may be an option as a supplemental food for the growing number of healthy infants who receive DHM.
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