Impact of an innovative two-step temperature-controlled accelerated germination process on phytochemical enhancement, digestibility, and morphological changes in colored rice.

Traditional accelerated germination methods for rice are often inefficient due to extended processing times. This study developed an innovative two-step temperature-controlled germination process for colored rice varieties, completed within 48 h. Two methods were compared: a two-stage process (W: soaking at 30 °C for 6 h, followed by wet incubation at 30 °C for 18 h and 40 °C for 24 h) and a soaking or single-stage process (S: continuous soaking at 40 °C for 48 h) using Jao Kham Hom Maejo 1A (M1A) and Jao Hom Nin (HN) rice. The W process significantly enhanced bioactive compounds, particularly in M1A rice, increasing GABA (40-fold), polyphenols (45 %), and flavonoids (42 %), which improved antioxidant activity and enzyme inhibition. Despite a slight reduction in grain crystallinity, digestibility and glycemic response were maintained. This innovative M1A-W provides a commercially feasible approach to producing nutrient-enriched functional rice products with enhanced health benefits.