Evidence suggests that nutrients in donor human milk (DHM) are profoundly variable, yet there has been little exploration into how processes within milk banking affect nutrient variability. We hypothesized that processing methods for thawing, decanting, pooling, and mixing during bottling contribute to nutrient retention and distribution in DHM. Our investigation—based on observations from an environmental scan of 9 milk banks in the Human Milk Banking Association of North America (HMBANA) network—was divided into three specific aims. Aim 1: Two pooling attributes—number of donors per pool and if macronutrient analysis was used to select donors for a pool (“target pooling”; yes/no)—were assessed for fat and protein variability using samples of raw, pooled DHM from 20 milk banks (n = 300). Target pooled samples had less fat variability (p = 0.04). In samples not target pooled, more donors per pool reduced fat and protein variability (p < 0.05). Aim 2: Two thaw stages (ice/liquid) and the use of bag manipulation during decanting (yes/no) were assessed for fat retention and bacteria colony forming units. Fresh milk samples (n = 40) were divided into storage bags and frozen at −20 ⁰C for 2 months. Decanting with bag manipulation retained more fat than decanting without bag manipulation, but only when milk was thawed to a liquid state (p = 0.005), not an ice state (p = 0.47). Bag manipulation did not increase bacteria (p = 0.49). Aim 3: Six mixing during bottling treatments were tested using pools of raw DHM—pooling container material (plastic/glass), duration of pre-bottling refrigerated storage (1-hour/24-hours), mixing during bottling method (manual/mechanical; one no-mixing group). Pooled DHM was mixed using the assigned treatment, bottled, then measured for fat, protein, IgA, and lysozyme (n = 6 pools and 114 samples). Holding a pool in the refrigerator 24-hours before bottling created greater fat variability compared to 1-hour (p < 0.01). No differences in nutrient variability were observed between glass/plastic containers or manual/mechanical mixing methods (p > 0.05). In conclusion, fat content was affected by several steps in DHM processing, but the impact may be mitigated under certain conditions: When processing milk frozen in a plastic storage bag, fat retention may be improved by using bag manipulation during decanting when thawing to a liquid state. When milk is pooled on one day and bottled on a subsequent day, more mixing is needed to reduce fat variability. Additionally, for milk banks that do not target pool, using a greater number of donors per pool may reduce both fat and protein variability.
|Commitee:||Morrison, Ron, Armah, Seth, Erikson, Keith|
|School:||The University of North Carolina at Greensboro|
|Department:||School of Health and Human Sciences: Nutrition|
|School Location:||United States -- North Carolina|
|Source:||DAI-B 82/1(E), Dissertation Abstracts International|
|Keywords:||Breast milk, Donor milk, Human milk, Milk bank, Milk processing, Preterm|
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