Effect of soaking and cooking on nutritional quality and safety of legumes

Legumes are widely grown and are consumed as a source of plant protein throughout the world. They rank second after cereals with respect to their consumption order. Legumes have anti‐nutritional factors which make their uses limited. This study aims to check the effect of soaking and cooking on the anti‐nutrient contents and nutritional quality of the legumes.

Five legumes (white kidney bean, red kidney bean, lentil, chickpea, and white gram) frequently used by the masses were selected for soaking and cooking trials. Legumes were tested for their weight, volume, density, swelling capacity and water absorption capacity before soaking and cooking. Legumes were soaked in simple water, 2 per cent sodium chloride solution, acetic acid and sodium bicarbonate and cooked in a beaker with 1 : 5 seed water ratio to uniform soft mass. After soaking and cooking, legumes were tested for anti‐nutrients (phytic acid and tannin) and their nutritional quality.

The statistical analysis of the study results revealed that dark colour legume (red kidney bens) has a high level of phytic acid and tannin compared with light colour (white kidney beans and white grams). Soaking and cooking of legumes result in significant reduction in phytic acid and tannin contents. Maximum reduction of phytic acid (78.055) and tannin (65.81 per cent) was found for sodium bicarbonate soaking followed by cooking. These treatments also result in a slight reduction in nutrients such as protein, minerals and total sugars.

Soaking and cooking of legumes reduce their anti‐nutrients; phytic acid and tannin significantly. These treatments may be used domestically as well as commercially to increase the nutrients' availability from legumes to meet the problem of protein and minerals deficiencies.

Along with water different soaking solutions which are easily available in the market were used to test out their effect on the nutritional quality and safety. These may be used by the common people to raise their nutritional status.