Enhancing purple rice nutritional profile, γ-amino-butyric acid and bioactive substances by germination time optimization and ultrasonic techniques

Purple rice (Oryza sativa L.), an antioxidant and a functional resource for humans, contains anthocyanins. In this study, germination periods of purple rice (0, 12, 24, 36, and 48 h) were evaluated to assess changes in bioactive compounds, antioxidant activity, and overall quality parameters. Germination was found to significantly enhance both bioactive components and antioxidant properties. At 24 h of germination, the highest levels of total anthocyanins (477.78 mg/kg), DPPH radical scavenging activity (57.1%), and γ-amino-butyric acid (9.64 ± 0.22 mg/100 g) were observed. At 12 h, maximum values were recorded for flavonoid content (6.69 mg QE/g), ABTS•+ activity (76.99%), and FRAP value (43.83 mg TE/g). The highest total phenolic content was detected at 48 h of germination. Furthermore, enzymatic saccharification using α-amylase and α-glucoamylase led to a marked increase in sugar content, including total sugar, reducing sugar, and glucose, in purple rice extract, with the extent of increase dependent on enzyme incubation time. These findings suggest that germinated purple rice holds significant potential for enhancing the nutritional quality of functional food products. © Akadémiai Kiadó Zrt. 2025.