The Effect of Freeze-Drying on the Nutrient, Polyphenol, and Oxidant Levels of Breast Milk.

ABSTRACT

OBJECTIVES: Human milk banks need to extend the suitability of milk for breastfeeding, and for this technological advances are required. Our aim was to establish the capacity of freeze-drying to conserve milk properties without further oxidative deterioration. METHODS: One hundred sixteen healthy women participated from the city of Cordoba (Argentina). Proteins, glucose, triglycerides, polyphenols, and markers (nitrites, superoxide anion, hydroperoxides, lipoperoxides, and γ-glutamyl transpeptidase) were measured in their fresh milk. Samples were then separated for three treatments as follows freezing and conservation for 6 months at -80°C (F positive control); freeze-drying for 24 hours at ≤-70°C and ≤1.33 Pa and conservation for 6 months at 4°C (FD treatment of interest); and freeze-drying for 24 hours at ≤-70°C and ≤1.33 Pa and conservation for 6 months at -80°C (FD+F). Next, analyses were repeated and compared by ANOVA and Tukey tests. RESULTS: Fresh milk showed these values per L as follows proteins 12.62 ± 2.51 g, glucose 4.44 ± 0.25 g, triglycerides 34.26 ± 0.59 g, polyphenols 53.27 ± 8.67 mg, nitrites 62.40 ± 19.09 mg, superoxide 3,721.02 ± 198.80 OD, hydroperoxides 7,343.76 ± 294.53 OD, lipoperoxides 7,349.72 ± 398.72 OD, and γ-glutamyl transpeptidase 4.66 ± 0.55 IU. Glucose was decreased after F treatment (p < 0.05), all variables were conserved by FD and were not improved by the FD + F combination. CONCLUSIONS: Freeze-drying achieved suitable conservation and may improve bank functioning, by protecting nutritional properties, polyphenol-related functionality, and oxidative integrity of human milk through a 1-day treatment with easy maintenance.