Resumo

MAURY, Eduard et al. Changes in Protein Composition of Mature Breast Milk during Storage by Freezing. Pediatr. (Asunción) [online]. 2010, vol.37, n.3, pp.187-194. ISSN 1683-9803.

Introduction: Breast milk is the ideal food for children from birth to age six months. For various reasons many mothers stop breastfeeding early, for which reason supply of breast milk from milk banks is an alternative that should be evaluated. Objective: To determine variations in protein composition of breast milk during frozen storage. Materials and Methods: We collected 31 samples of mature milk of women between ages 17 and 35. Samples were stored frozen (-20° C) for periods of 15, 30, 60, and 90 days. An aliquot of each sample was analyzed for baseline control. Total protein concentration (g/dl) was determined by Lowry method and protein calories as g/day were calculated based on a consumption of 850 ml of milk. Protein fractions of milk were determined by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). Results: Results showed a protein concentration of 1.58 g/dl at baseline and 1.61 g/dl at 90 days. Comparison found no significant differences in protein content or protein and calorie value of the milk during frozen storage (P>0.05). The electrophoretic profile showed changes only in low molecular weight protein fractions. Conclusions: The stability of the protein components demonstrates safe storage of frozen human milk in milk banks for a period of 3 months.

Palavras-chave : Mature breast milk; protein; freezing; electrophoresis; milk bank.

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