Changes in microRNAs during storage and processing of breast milk of Korean mothers

Human breast milk (HBM) is the ideal source of nutrients for infants and is rich in microRNA (miRNA). In recent years, expressed breast milk feeding rather than direct breastfeeding is becoming increasingly prevalent for various reasons. HBM requires storage and processing, which can cause various changes in the ingredients. We investigated how the miRNAs in HBM change due to processes often used in real life. HBM samples collected from 10 participants were each divided into 7 groups according to the storage temperature, thawing method, and storage period. And we analyzed the miRNA changes in each group. Significant changes in expression of several miRNAs were confirmed when HBM were heated by microwave immediately after collection, stored at room temperature for 1 week, or frozen for 1 week. Changes in expression were also dependent on the frozen period or thawing method. However, there was no change in the miRNA expression in all samples refrigerated for 1 week. The expression of miRNA can change depending on the diverse processing, storage, and thawing methods of breast milk, and refrigerated storage may be an ideal method to maintain a state of miRNA. Overall design: HBM samples collected from 10 participants were each divided into 7 groups according to the storage temperature, thawing method, and storage period.