EFFECTS OF PROCESSING TREATMENTS AND STORAGE CONDITIONS ON THE STABILITY OF FATTY ACIDS AND IL-5 AND IL-6 CYTOKINES IN MATURE HUMAN MILK DURING 180 DAYS OF STORAGE

Abstract

Human milk banks face challenges related to the storage and distribution of human milk. This study evaluated the stability of fatty acids and the interleukins IL-5 and IL-6 using gas chromatography, multiplex assay, and multivariate analysis in samples of raw (RAW), pasteurized (PAST), and freeze-dried (FD) human milk stored for up to 180 days (D). Samples were stored under specifically recommended conditions, with RAW and PAST maintained at −18 °C, while FD samples were stored at room temperature (FD25) or under refrigeration (FD5). The results revealed two distinct groups in fatty acid composition, corresponding to D0–D30 and D60–D180. RAW and PAST exhibited similar profiles during the initial storage periods and greater changes between D60 and D180, likely associated with lipolytic reactions resulting from the higher susceptibility of lipase activity in the frozen liquid state. In contrast, FD samples differed due to their powdered form. FD5 showed superior preservation of polyunsaturated fatty acids (PUFAs) and saturated fatty acids (SFAs), indicating that freeze-drying combined with refrigerated storage minimizes oxidative and hydrolytic reactions. IL-5 and IL-6 were sensitive to the applied treatments, with active expression detected only in RAW samples. Principal component analysis confirmed the transition of bioactive profiles throughout storage, associated with the balance of inflammatory biomarkers. These findings highlight the importance of evaluating human milk quality under real storage conditions to estimate the stability of bioactive compounds and ensure the nutritional and immunological quality of the milk provided, considering neonatal requirements and supporting more appropriate distribution practices.