Effect of alkali treatment on the milled grain surface protein and physicochemical properties of two contrasting rice varieties

A systematic study was conducted to explore the effect of grain surface proteins on the physicochemical properties (pasting, retrogradation and textural quality) of rice. Milled rice grains of two selected glutinous (Thadokkham-8 (TDK8)) and non-glutinous (Doongara (DG)) varieties were treated with different concentrations (0%, 0.004%, 0.02%, 0.04%, and 0.2% w/v) of NaOH solution for 1 h. After surface protein removal, the cooked rice grains showed a significant (P 0.05) effect of alkali treatment was observed on the retrogradation thermal temperatures (T, T, and T), but the amount of retrograded starch (as indicated by reduction in ΔH) was decreased significantly (P < 0.05) in both varieties. These findings suggest a good potential of applying alkali pre-treatments in the processing of rice to alter the hardness and stickiness properties of rice