Antioxidant capacity of fresh and stored breast milk: is −80°C optimal temperature for freeze storage?

Abstract

Freeze storage of breast milk at -80°C for two months seems not to be the optimal condition to preserve the antioxidant capacity of breast milk.

Stability of Antioxidant Capacity of Human Milk after Freezing and Pasteurization

“…Meantime, different studies have divergent results for freezing, and the differences are not yet clear. This can be observed in studies such as Sari et al [4], in which the freezing of HM at -80°C reduced by 56.25% the antioxidant capacity of mature HM stored at -80°C for two months by the ABTS free radical scavenging method. On the other hand, Akdag et al [5] found no significant difference in the total antioxidant capacity of HM from mothers of preterm infants stored at -80°C for 3 months, also evaluated by the ABTS free radical scavenging method.…”

“…According to Akdag et al [5], the total antioxidant capacity of preterm HM was preserved at -80 °C for 3 months. However, according to Sari et al [4], the freezing samples of colostrum, transition and mature milk at -80 °C for two months did not preserve the antioxidant capacity. According to Hanna et al [6], the antioxidant capacity of HM also decreased with the storage time and refrigeration was better than freezing to preserve it, because the freezing for 48 hours caused greater losses than the refrigeration for seven days.…”

“…They also verified that these losses may be to a lesser or greater extent, depending on the type of process adopted. Regarding storage, the studies to date are still not conclusive [4,5,6]. According to Akdag et al [5], the total antioxidant capacity of preterm HM was preserved at -80 °C for 3 months.…”

“…Among them, stand out the enzymes catalase, superoxide dismutase and glutathione peroxidase, vitamins E and C, retinol and β-carotene [2,3]. Compounds with antioxidant capacity present in HM are relevant for newborns due to situations of high oxidative stress, for example, at the moment of delivery, when there is the transition from a medium with low oxygen concentrations to a medium with concentrations considered normal [4]. These advantages are even more important in preterm newborns, because they have an immature antioxidant defense system, since it develops during the course of gestation [5].…”

“…Given the known importance of bioactive compounds and antioxidant capacity for the development and health of children [3,4,5,6] and the limited literature that evaluate the real conditions of the processing stages of HM by the Network of Human Milk Banks in Brazil, it is important to conduct studies to evaluate the stability of the antioxidant capacity of HM after the procedures adopted. Therefore, this study evaluated the interference of the freezing time and the pasteurization of HM on the content of total phenolic compounds and antioxidant capacity in vitro.…”