Optimization of the germination time of proso and foxtail millets to enhance the bioactive properties, antioxidant activity, and enzymatic power and reduce antinutritional factor

The germination of millets is a traditional yet underutilized method to enhance their nutritional and functional attributes. This study investigates the impact of germination time on the bioactive, enzymatic, and antinutritional properties of proso millet (Chino Dude) and foxtail millet (Kaguno Red and Kaguno White) varieties. Germination was conducted over five days (0–5 days), and changes in total phenolic and flavonoid content, tannin content, antioxidant activity, diastatic power, α-amylase activity, reducing sugars, and trypsin inhibition activity were measured. A two-way ANOVA revealed significant effects (p < 0.05) of varietal differences and germination time on these properties. Total phenolic and flavonoid content and antioxidant activity increased significantly (p < 0.05) unit day 3 of germination after which it decreased until day 5. Tannin content and trypsin inhibitor decreased significantly (p < 0.05) from day 1 to day 5 of germination, whereas diastatic power and α-amylase increased (p < 0.05) with an increase in germination time. The optimal germination time was determined to be 3.46 days using multiple regression models to maximize bioactive compounds and enzymatic activity while minimizing antinutritional factors. Moreover, Kaguno Red exhibited the highest bioactive levels, while Kaguno White had the lowest trypsin inhibition activity, indicating varietal-specific differences in analyzed parameters. This study highlights the potential of tailored germination strategies to enhance the nutritional and functional profiles of millets, providing actionable insights for functional food development in regions reliant on millet as a staple crop.