Impact of pre-treatments assisted controlled germination and infrared drying on the functional, bioactive components and antinutritional properties of Moringa oleifera seeds

Abstract

Controlled germination is an effective strategy to enhance the quality profile of Moringa oleifera (MO) seeds. This study investigated the influence of dual-frequency ultrasound and microwave-assisted controlled germination (Biochemical Incubator, 25 °C, 15 days), followed by infrared vacuum drying at 70, 60, and 50 °C on MO seeds quality. Functional, mineral, phenolic, flavonoid, and structural properties were comprehensively evaluated. Ultrasonication significantly improved gel formation, water absorption capacity, oil absorption capacity, and other functional properties (P ≤ 0.05). In term of minerals compositions, US10 & 20 samples dried at 50 & 60 °C increased Mg by 16.07 % and Ca by 21.67 %, while K and Na remained stable. In contrast, drying at 70 °C decreased the content of Ca, Fe and Mg by 58.11 %, 2.35 % and 12.17 %, respectively. Mineral composition in US samples was significantly higher than MW, and both were significantly higher when compared with control samples. Regarding the phenolic acid profile, US10 at 60 °C yielded the highest hydroxycinnamic acids and flavonoids, while US20 at 50 °C yielded the hydroxybenzoic content, overall exhibited 1.78–2.41-fold increase in phenolic acids profile of MO seeds. Antinutritional factors decreased significantly, with phytic acid reduced by 42.12–77.64 % and tannins by 46.20–74.51 %. Overall, samples dried at 70 °C demonstrated poor quality attributes. Structural analyses (XRD, FTIR) revealed molecular modifications, with the relative crystallinity of US20 slightly increased from 16.62 % to 36.27 % as compared to control. In contrast, the crystallinity of OGS, US10, MW30, and MW60 samples decreased, ranging from 7.68 % to 19.05 %, indicating structural changes. These alterations suggest enhanced signal transmission in the pre-treated samples compared to the control. SEM analysis confirmed aggregation of germinated MO seeds across drying conditions, showing a film-like structure where starch aggregates coupled with lipids embedded within a protein matrix.