The Influence of Time and Temperature on Human Milk Storage Antioxidant Properties, Oxidative Stress, and Total Protein

Abstract

Background: Human milk is an essential source of nutrition for an infant’s health. When breastfeeding working mothers or students, for example, are unable to breastfeed, storing their milk is recommended. Therefore, it is crucial to know the storage conditions to ensure their antioxidant capacity and avoid oxidative damage. Research Aim: To evaluate the stability of the antioxidant and pro-oxidant profiles and the amount of total protein in fresh human milk after different storage times (1, 2, 7, 14, and 21 days) and temperatures (4 ºC and -20 ºC). Methods: This was a prospective, longitudinal, and observational study with milk samples grouped according to age for comparisons, which included 20 lactating women. The antioxidant activity was evaluated using the colorimetric methods of free radical scavenging 2,2’-azinobis-3-ethylbenzothiazoline-6-sulfonic acid and the decrease of ferric ion. Oxidative stress was determined by the lipid peroxidation product formation through malondialdehyde concentration, and the total protein content was assessed by the Bradford method. Results: The antioxidant profile of human milk was maintained with minimal losses until the 14th day when stored at 4 ºC and -20 ºC. The evolution of malondialdehyde concentration over storage revealed significant changes only 21 days after human milk storage at 4 ºC. There was no change in the value of total protein content. Conclusions: To sum up, there is no difference in the storage of human milk at a temperature of 4 °C or -20 °C over 14 days. Therefore, the lactating woman may choose the most convenient way of storage.

Influence of Maternal Dietary Pattern on the Pro-Oxidant and Antioxidant Status of Mother’s Own Milk

“…The assessment of total antioxidant activity in human milk enables a comprehensive characterization of its value and offers insights into the oxidative stress experienced by newborns. Oxidative stress is involved in the pathogenesis of numerous neonatal diseases (Castillo-Castañeda et al, 2019; Lawrence, 2022; Ribeiro et al, 2023). Colostrum tends to have a high antioxidant capacity, important in preventing oxidative stress that can result from the newborn’s exposure to an environment four to five times higher in oxygen than the uterine environment.…”

“…The ABTS assay, which quantifies the relative capacity of antioxidants to neutralize ABTS radicals, was employed to assess the antioxidant potency of human milk samples, following previously established protocols (Lorençoni et al, 2021; Ribeiro et al, 2023). Briefly, 30 µl of each sample previously diluted in water (1:5 v/v) was added to 270 µl of ABTS reagent and incubated at 25 °C for 10 min.…”

“…The thiobarbituric acid test (TBA) was used to quantify secondary oxidation products. TBA primarily reacts with malondialdehyde (MDA), a common secondary oxidation product, as well as with other reactive species (TBARS; Lorençoni et al, 2021; Ribeiro et al, 2023). A total of 10 µl of each milk sample was mixed with 45 µl of ultrapure water.…”

“…The analysis of advanced oxidation protein products (AOPP), a significant biomarker for monitoring oxidative stress, was conducted following established protocols (Lorençoni et al, 2021;Ribeiro et al, 2023). Briefly, 0.2 ml of milk was diluted in phosphate-buffered saline solution (PBS) at 1:5 volume/ volume ratio.…”

“…When the infant transitions from an environment with limited oxygen in utero to one where oxygen is much more abundant after birth, the formation of ROS in their body needs to be neutralized. The infant body does this primarily by limiting the nutrients they receive from human milk (Castillo-Castañeda et al, 2019; Ribeiro et al, 2023).…”