Processing Human Milk to Increase Nutrient Density for Preterm Infants

Abstract

Breast milk is the optimal food for infants. It is tailor‐made for each species and each birth. Preterm birth can cause problems with initiation of lactation especially if it is the first pregnancy of the mother, and infants may have inadequate suckling reflexes. In this situation direct intragastric feeding can use donor breast milk from a milk bank, infant formula, or a combination. Concerns regarding the choice of feed are catch‐up growth and health effects. Formula might cause necrotizing enterocolitis and negative long term health effects but has faster catch‐up growth. Preterm infants have better tolerance for human milk, but lower caloric density of term mothers' milk or donor milk might not meet preterm infant growth needs. Preterm infants have higher needs for calories and protein and have a very limited stomach capacity.Aims of this study were to concentrate donor breast milk to have a higher caloric density and protein, but at the same time avoiding side effects of higher lactose concentration and hyperosmolarity by precipitating lactose at low temperature.Donor breast milk was obtained from WakeMed Mothers' Milk Bank. For preliminary results 10 human milk samples of 50 mL were concentrated by evaporation (Rotavap Buchi R‐300) to different concentration levels, held at 0°C overnight, followed by refrigerated centrifugation for lactose removal. Measurement of lactose was performed with enzymatic analysis via Roche Lactose/D‐Galactose kit on skim milk supernate and remixed skim milk.Preliminary data found that low temperature removal of lactose from unprocessed human milk was minimal. Therefore milk was concentrated to varying extents prior to freezing. Volume reductions were 63%, 48%, 40%, 30% and 28%. Macronutrients were concentrated in the milks during the evaporation procedure in proportion to the amount of water removed, so caloric density was higher. Volume reduction (%) vs. Lactose concentration (g/L) yielded a linear relationship (Lactose =1.25 * volume‐reduction +3.50, r2=.77, p<0.05). Lactose was not consistently precipitated at the lower levels of volume reduction.Water can be effectively removed from human milk by low pressure evaporation at temperatures that are unlikely to denature bioactive substances. Regression analysis found that every percent of concentration increased 1.2 g/L of lactose in milk, but the effectiveness of low temperature lactose precipitation was not statistically significant. Similar concentration should be true for protein and other bioactive factors. Additional research is needed to devise techniques to further reduce the osmotic activity in the donor milk concentrate generated by the increased lactose concentration.Support or Funding InformationUSDA HatchProject NC02435; Fulbright Foundation Scholarship to HZU.