Optimization of Soaking Conditions to Enhance Protein and Reduce Phytate Content in Foxtail Millet (Setaria italica)

Aims: The study aimed to evaluate the effect of millet-to-water ratio of soaking and time-temperature combination used for soaking on the protein and phytate content of foxtail millet.

Study Design: This was an experimental, laboratory-based study.

Place and Duration of Study: The study was conducted at the Department of Dairy Microbiology, Dairy Science College, Hebbal, Bengaluru, Karnataka, India, between January 2024 and October 2024.

Methodology: Foxtail millet (Setaria italica) was soaked in potable water at varying millet-to-water ratios (1:1, 1:1.5, 1:2) under ambient conditions (27 ± 1°C) for 6 hours and at different time-temperature combinations (20°C, 25°C, 30°C for 6, 12, 18, and 24 hours). The protein content was determined using the micro-Kjeldahl method, while phytate content was estimated via titration with ferric chloride. Statistical analysis was performed using ANOVA, with a critical difference (CD) at a 5% significance level used to determine significance among treatments.

Results: The 1:2 millet-to-water ratio showed the highest protein content (10.68%) and the lowest phytate content (3.07 mol/kg) after 6 hours of soaking under ambient conditions, with these differences being statistically significant (P =.05). Increasing the soaking temperature and duration further enhanced protein content and reduced phytate levels, with the most pronounced effect observed at 30°C for 24 hours. This condition yielded the highest protein content (10.99%) and the lowest phytate content (1.79 mol/kg), both significantly improved (P =.05) compared to unsoaked millet (10.50% protein, 4.96 mol/kg phytate).

Conclusion: The study concluded that soaking foxtail millet at a 1:2 millet-to-water ratio and at 30°C for 24 hours are effective strategies to enhance its nutritional quality. These findings provide a scientific basis for optimizing soaking conditions to improve the protein content and reduce antinutritional factors in millet.