Modelling of millet kernel water absorption and dimensions during hydration at different temperatures using a non-destructive image analysis technique
Thota Niranjan, Kadavakollu Subrahmanyam, Rama Chandra Pradhan, Brijesh K. Tiwari, Madhuresh Dwivedi
Abstract
In the present study, image analysis was introduced to study the water absorbing expansion and water absorption kinetics of two minor millets (Barnyard and Foxtail millet) at temperatures of 30-75°C. The water absorption and water absorbing expansion kinetics of millets during hydration were studied using six and four model equations respectively. The findings proved in the water absorption behavior of millet kernels when the hydration temperature increased from 30 to 75°C and the hydration time decreased with an increase in hydration temperature. It was evaluated that the six model equations can accurately describe the changes in water absorption behaviour in Barnyard and Foxtail millet after hydrating at 30, 45,60, and 75°C (R2 > 0.98). The Page and two-term model provided the best fit and served as an effective tool for determining the water absorption characteristics of millets. Furthermore, we found an increase in the dimensional characteristics of millet kernels, when the hydration temperature increased from 30 to 60°C and but beyond 60°C the dimensional characteristics of millet kernels decreased. The four models used namely Peleg, Fick's, Weibull, and Kaptso models could adequately describe the dimensional changes of hydrated millet kernels at different hydrating temperatures and times. It was noted that the Weibull and Peleg model was best fit model for foxtail and barnyard millet respectively. To anticipate the water absorption expansion of barnyard and foxtail millet, the changes in model coefficients were presented in the well-suitable linear and polynomial equations.