Effect of duration of cooking on the levels of some antinutritional factors of nine varieties of Lablab purpureus beans

Abstract

The objective of this study was to determine the effect of duration of cooking of various varieties of Lablab purpureus beans at 1000 on their antinutritional factor compositions. Nine different varieties of Lablab purpureus beans were subjected to cooking for 0.0, 10.0, 200, 30.0), 40.0,50.0 and 60.0 minutes respectively at 100°C. For each batch of cooking, 4 litres of water was first brought to boiling in a 10 litre aluminium cooking pot and about 50g of the seed was poured into the boiling water, covered and allowed to cook for each specified time period. The seeds were sun dried for 3 days before milling. A representative sample for each cooking time and for each variety was taken to the laboratory for the determination of antinutritional factors to include trypsin inhibitors, phyric acid, tannin and hydrocyaric acid. Results obtained indicate that duration of cooking had a significant (P<0.05) effect on the antinutritional composition of the various varieties of lablab beans. The levels of antinutritional factors in the beans were found to decrease significantly (P<0.05) as the duration of cooking increased across the various varieties. However percent destructions of trypsin inhibitor activity, phytic acid and hydrocyanic acid were very rapid at about 30 minutes of cooking.