Effects of traditional cooking methods on some antinutrients and in vitro protein digestibility of dry bean varieties (Phaseolus vulgaris L.) grown in Turkey

The phytic acid, tannin and total phenol content of different varieties of dry beans were investigated. The trypsin inhibitor activity and protein digestibility were also determined in raw and cooked dry bean. The effects of different cooking methods, which are commonly used domestically and in commercial restaurants were investigated. The results obtained showed that dry beans had 1.51% phytic acid, 0.56% total phenols, 0.06% tannin, 3374.74 TUI g(-1) (trypsin unit inhibitor per gram) trypsin inhibitor activity and 70.74%in vitro protein digestibility as average. Among the cultivars, Cali had higher contents of phytic acid, total phenols, tannins and trypsin inhibitor activity than the others, while Dermason variety had the highest value in protein digestibility (72.24%). Important reductions were observed in phytic acid, total phenol, tannin contents and trypsin inhibitor activity in soaked-cooked beans and pressure-cooked beans. The soaked-cooking method caused a higher reduction in antinutrients in all the dry bean varieties. Significant improvement in the digestibility of protein also occurred after two different cooking methods.