Effect of Processing on Anti-nutritional Factors of Red Kidney Bean (Phaseolus vulgaris ) Grains

The effect of different processing methods (soaking in water or solutions of sodium bicarbonate, citric acid, soaking plus cooking, and germination) on anti-nutritional factors (phytic acid, total polyphenols, tannins, and hydrocyanic acid) of red kidney bean was studied. The anti-nutritional factors were reduced significantly ( P < 0.001) with processing techniques. Cyanide contents were most effectively (25%) reduced by cooking after soaking in sodium bicarbonate solution, followed by germination. The most drastic effect was noted on tannin contents. Cooking after soaking in either citric acid or sodium bicarbonate solutions almost eliminated it. However, simple soaking in water did not result in any reduction in tannin contents. Reduction in total polyphenols was 78.7% with cooking after soaking in sodium bicarbonate solution. Phytic acid contents were reduced only with germination treatment (42.6%), while the other treatments did not bring about any large reduction.