Optimization of ultrasound-assisted hydration of oat seeds: Effects of amplitude and exposure time on water absorption, germination, and antioxidant capacity

Abstract

Ultrasound (US) technology is a nonthermal technique for enhancing grain hydration properties. In this study, oat seeds were treated with US at different amplitudes (20, 30, and 40%) and exposure times (20, 30, and 40 min). The effects of germination time (30, 36, 42, and 48 h) were evaluated in both US-treated and untreated oat seeds by measuring the water absorption kinetics, germination rate, root length, imbibition weight, total phenolic content (TPC), antioxidant activity, and beta-glucan content. The Weibull model best described the soaking kinetics of oat seeds across the investigated amplitudes and ultrasonic durations owing to the highest R² (0.98–0.99) and the lowest standard errors (0.013–0.028). The results demonstrated that US treatment enhanced both hydration and bioactive component levels. Compared to the control, the optimized oats germinated through US treatment had approximately 220% and 64% increase in TPC and DPPH scavenging activity, respectively. Germination times of 42–48 h favor germination rate and antioxidant properties. The recommended conditions for producing germinated oats with optimal properties and high TPC, DPPH, and β-glucan are 30% US amplitude, 40 min of sonication, and 42 h of germination. This technique enhanced the nutritional and functional properties of seeds germinated through US, supporting their potential use in functional foods, nutraceuticals, and fortified grain products.