Evaluation of freezing, ultra-cold freezing, and freeze-drying on the main components of human breast milk

Breastfeeding is the ideal food during the first two years, but only 31 % of children under six months of age receive exclusive breastfeeding, below the global recommendation. Alternative methods to direct breastfeeding have been used, including the creation of personal milk banks and the practice of deferred breastfeeding. This research aimed to evaluate the changes in human breast milk composition under freezing, ultra-cold freezing, and freeze-drying conditions in terms of: 1) carbohydrate profile as lactose and Human Milk Oligosaccharides; 2) protein quantity and characteristics (total crude protein, free amino nitrogen, in vitro digestibility, electrophoretic profile and secondary structure), and 3) functional and physicochemical components/ characteristics as pH, density and moisture, as well as pro- and anti-inflammatory cytokines and levels of secretory immunoglobulin A. With different preservation methods, no differences were detected in pH, density, moisture, total crude proteins, cytokines, four Oligosaccharides (3’-Sialyllactose, 6’-Sialyllactose, Lacto-N-Tetraose, and Lacto-N-neoTetraose), and secretory immunoglobulin A. The immunological components remain stable when frozen at –20 and −80°C and during freeze-drying, allowing women to prolong breastfeeding without changing the carbohydrate, protein, and functional or physicochemical main profile. Our results improve the understanding of human breast milk quality when alternative preservation methods are required beyond direct breastfeeding, aiming to extend the duration and rates of breastfeeding.