Effect of processing on some antinutritional factors of lentils

Changes in the trypsin inhibitor activity and in the phytic acid, tannin, and catechin content of lentils (Lens culinaris var. Vulgaris) were investigated after soaking in distilled water, citric acid, and sodium bicarbonate solutions. The effect of cooking, after the seeds were presoaked in the above-mentioned solutions and both the soaking and cooking solutions were discarded, was also studied. Finally, two varieties of lentils (L. culinaris var. Vulgaris and Variabilis) were germinated for 6 days, and the effect on the trypsin inhibitor activity and the phytic acid, tannin, and catechin contents was also measured. Soaking did not modify the trypsin inhibitor activity, decreased the physic acid content, and increased the tannin and catechin contents. Cooking the presoaked seed brought about the total removal of trypsin inhibitor activity, a reduction of the physic acid level, and an increase of the content of tannins and catechins. The trypsin inhibitor activity and the physic acid content showed a large decrease after 6 days of germination, while amounts of tannins and catechins in the two lentil varieties studied increased. Cooking and germination seem to be good procedures to improve the quality of lentil flour from the nutritional point of view, despite the fact that a large variation on the effects of processing, related to the different legume varieties, has been observed.