The Effects of Fortification and Refrigerated Storage on Bioactive Proteins in Holder-pasteurized Donor Human Milk

Point-of-care human milk concentration by passive osmosis: comprehensive analysis of fresh human milk samples

OBJECTIVE

Preterm infants need enrichment of human milk (HM) for optimal growth. This study evaluated a novel, point-of-care human milk concentration (HMC) process for water removal from fresh HM samples by passive osmotic concentration.

STUDY DESIGN

Nineteen fresh HM samples were concentrated by incubation with the HMC devices for 3 h at 4 °C. Pre- and post-concentration HM samples were compared by HM properties for: pH, osmolality, macronutrients, enzyme activity, bioactive, and total cell viability.

RESULTS

Passive osmotic concentration reduced HM volume by an average of 16.3% ± 3.8% without a significant effect on pH or cell viability. Ten of the 41 HM components did not differ significantly (p > 0.05) between pre- and post-concentration samples. Twenty-three increased within the expected range by volume reduction. Six increased more than expected, two less than expected, and none decreased significantly.

CONCLUSION

Passive osmotic concentration of fresh HM can concentrate HM components by selective removal of water. HM osmolality and pH remained within neonatal feeding parameters.

The Effects of Refrigerated Storage of Donor Human Milk with Limited Bacterial Presence After Holder Pasteurization on Nutrient Concentration and Bacterial Growth

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, which includes zero bacterial presence after Holder pasteurization. This study aimed to determine if nutrient and bacterial composition of DHM with limited bacterial presence after pasteurization change over 4 days of refrigerated storage. Methods: Twenty-five unique samples of DHM with limited bacterial growth postpasteurization were collected from two HMBANA milk banks. Infant formula was used as a comparison. Samples were stored in the refrigerator and a portion of milk was removed at 24-hour intervals beginning at hour 0 to 96 for analysis. Aerobic bacteria, protein, lactose, and immunoglobulin A (IgA) content were measured. Longitudinal changes between 0 and 96 hours were analyzed using repeated measures analysis of variance and mixed models test. p < 0.05 was deemed significant. Results: There was no significant difference in lactose, protein, bacteria, or IgA content over storage duration (p = 0.649, p = 0.690, and p = 0.385, p = 0.805, respectively). Total aerobic bacteria were less than 10² colony-forming units (CFUs) in 81% of the time points tested for DHM samples. Total aerobic bacteria were too many to count (>300 CFUs) in the infant formula sample at all time points. Conclusion: In periods of high demand for DHM, DHM with low bacteria growth postpasteurization may be an option as a supplemental food for the growing number of healthy infants who receive DHM. Future studies should investigate the bacterial strains in this milk.

Stability of the Antimicrobial Capacity of Human Milk Against Cronobacter Sakazakii During Handling

BACKGROUND

Neonatal infections with Cronobacter sakazakii have recently been associated with the consumption of expressed human milk.

STUDY AIMS

(1) To evaluate whether human milk has antimicrobial capacity against C. sakazakii and (2) to determine the stability of its capacity when it is subjected to various treatments.

METHODS

The antimicrobial capacity of human milk against C. sakazakii was evaluated using an observational, cross-sectional, comparative design. Mature human milk samples (N = 29) were subjected to different treatments. After incubation at 37°C for 72 hr, samples were compared with fresh milk on the stability of their antimicrobial capacity. Two-way analysis of variance (ANOVA) was performed.

RESULTS

In fresh milk, counts of C. sakazakii were reduced by 47.26% (SD = 6.74) compared to controls. In treated milk, reductions were: refrigeration at 4°C for 72 hr (M = 33.84, SD = 13.84), freezing at -20°C for 1, 2, and 3 months (M = 40.31, SD = 9.10; M = 35.96, SD = 9.39; M = 26.20, SD = 13.55, respectively), Holder pasteurization (M = 23.56, SD = 15.61), and human milk bank treatment with (M = 14.37, SD = 18.02) and without bovine fortifier (M = 3.70, SD = 23.83). There were significant differences (p < .05) between fresh and treated milk.

CONCLUSIONS

Human milk has antimicrobial capacity against C. sakazakii. However, its capacity is negatively influenced by common preservation and hygienization methods. Milk should be stored refrigerated for a maximum of 72 hr or frozen for a short period of time.