The effects of freezing and thawing on mature breast milk's contains:A systematic review

INTRODUCTION AND AIM: The fact that mother works or the situations where the mother and her baby cannot be together bring forward the issue of storing the breast milk. This study was carried out to examine the effect of freezing and thawing mature breast milk at -18 / -20 ° C at different times on milk content. MATERIAL AND METHOD: The articles published between 01 January and 01 June 2020 were searched for in 11 different databases. Quality assessments for each study were made by two researchers independently and the "Quality Assessment Tool for Quantitative Studies" was used. When the screening results were evaluated, eight studies were included in the study with strong-medium scores. RESULTS: The protein in the milk increased 6% on average when the freezing time was 2 days, yet it significantly decreased when the freezing time exceeded 1 week. Carbohydrate increased 1.1% on average when the freezing time is 2 days, and did not show any significant change when the freezing time exceeded 1 week. However, the energy levels decreased when the milk is frozen for more than 8 weeks. Fat decreased with increased freezing time, and fatty acid concentration increased. Vitamin E in frozen-thawed milk was analyzed, and showed a statistically insignificant decrease. The studies on some of the immunological factorspresented no change in cytokine (interleukin-10) levels, however the same studies showed that antioxi-dant (glutathione peroxidase), antioxidant capacity and infection-protection factor (lactoferrin) levels decreased. CONCLUSIONS: Although there were some changes in the contents of the milk when it is frozen, with an appropriate storage, the milk did not negatively affect the babies. Nevertheless, more studies with high level of evidence thereabout are needed. Key Words: Breast milk, mature breast milk, breast milk content, storage, freezing, thawing