Tannin content of pulses: Varietal differences and effects of germination and cooking

Abstract

The tannin content of different varieties of pigeonpea, chickpea, blackgram and greengram were estimated. Significant varietal differences were observed in the tannin content of the four pulses. Decortication of the pulse resulted in 83–97% loss of tannin. As a result of overnight soaking in water, 50% of tannin was lost in pigeonpea and chickpea while in blackgram and greengram the loss was 25%. When germination was continued for 48 h, a further 10% loss of tannin was observed in pigeonpea and chickpea varieties and 25% loss in blackgram and greengram varieties. Cooking of raw pulse brought about a 70% decrease in their tannin content. Loss of tannin during germination may be due to enzymatic degradation. Thus traditional methods employed for pulse processing are able to remove a major part of the tannin present in the pulse.