Effects of chemical treatments, pelleting or extrusion on the elimination of antinutritional factors in Phaseolus vulgaris beans

Phaseolus vulgaris can be used as a model for legume seeds. It combines the presence of antinutritional factors (ANFs) such as trypsin inhibitors and lectins with a storage protein with low digestibility in the natural state. Process treatment of P. vulgaris beans have to eliminate the antinutrition al factors and to improve the digestibility of the storage protein simultan eously. To identify, or exclude, options to meet these requirements, the ef fect of chemical treatment on the storage protein, and of pelleting and dou ble screw extrusion on ANFs were investigated. The results indicate that chemical treatment of ground P. vulgaris beans wi th buffer solutions of propionic acid, cysteine, sodium sulphite and acetyl -cysteine, hardly effect the peak temperature and enthalpy (Delta H) of pro tein denaturation in Differential Scanning Calorimetry (DSC) studies. Steam pelleting at temperatures of 65 and 80 degrees C of beans, or feed mixture s containing 25 % beans did not reduce the lectin or trypsin inhibitor acti vity (TIA) (N.S.). Double screw extrusion at 110, 130 and 148 degrees C, an d moisture content of 20 and 28 % using two screw speeds eliminated lectins , regardless of treatment conditions and reduced TIA depending on the proce ss conditions.