Stability of the Trolox Equivalent Antioxidant Capacity (TEAC) of Human Milk Frozen at –20°C for 6 Months

Abstract

The practice of storing human breast milk (HM) for later use has substantially increased over the last few decades because it allows lactating mothers to continue breastfeeding despite lifestyle changes. Several studies have focused on the safety and nutritional value of milk during the period from the time of storage to that of consumption. To date, few studies have investigated the effect of the storage duration on the antioxidant capacities of stored HM. This study aimed to evaluate the impact of different storage times on the Trolox equivalent antioxidant capacity (TEAC) of frozen HM (−20°C). HM samples from 186 healthy women were collected from women who had term deliveries and a lactating duration between 1 and 24 months. The TEAC values of the frozen HM stored for 1, 2, 4, and 6 months were determined using a working 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) solution. The mean TEAC level of an HM sample, which was frozen and stored at −20 °C for 1 month (1.86 ± 0.82 mM), was compared to those of samples stored for different lengths of time. No significant difference in the mean TEAC values was observed after frozen storage for 2 months (1.88 ± 0.86 mM), 4 months (1.96 ± 0.93 mM), and 6 months (1.91 ± 1.01 mM) (p > 0.05). These results suggest that in cases in which HM needs to be stored for more than 1 month, the storage of frozen HM at −20 °C appears to be the optimal condition for preserving the antioxidant capacity of HM for up to 6 months.