Process parameter optimization for instant pigeonpea dhal using response surface methodology

Designed experiments were conducted to study the effects of salt solutions and their concentration, soaking time and cooking time on quality of instant pigeonpea dhal and to optimize their levels. Sodium carbonate, sodium bicarbonate and ammonium carbonate were used individually and in combination. The salt concentration varied from 1.93% to 4.73%. The soaking time ranged between 22 and 38 min. Cooking time was in the range 95–146 s. The results of the study showed that instant pigeonpea dhal could be prepared by soaking dhal in salt solution, cooking and drying at 65 °C. The soaking time and cooking time showed significant effect on expansion ratio and rehydration ratio of pigeonpea dhal, while salt concentration had insignificant effect. Ammonium carbonate was most effective in its effect of rendering instantization characteristics to the pigeonpea dhal. In general, the samples with more expansion ratio exhibited higher rehydration ratio. The expansion ratio and rehydration ratio were optimized and common range of parameters was selected by overlapping their contour plots. The optimum conditions were different for different salt solutions.