1* 2 Department of Food Science and Technology, Botswana University of Agriculture and Natural Resources, Lot1, A1 Road, Content Farm, Sebele, Private Bag 0027, Gaborone, Botswana Morama beans were heated for 60, 90 and 120 s at 200, 600 and 1000 W using a domestic microwave oven to examine its potential as a pre-decortication treatment and effects on peak force, work and modulus of deformability as textural properties were determined by compression using a texture analyser. One sample was unheated as a control for comparative purposes. Bean temperatures after microwave heating ranged from 33 to 86°C and rates of temperature increase were 0.09, 0.32 and 0.61 °C/s at 200, 600 and 1000 W, respectively. Peak force significantly reduced (p<0.05) from 579.3 N in the control sample to 437.2 N in the sample heated for 60s at 600W, while work done during compression did not differ significantly upon microwave heating (p>0.05) and ranged from 469.9 to 313.7 Nmm. Similarly, modulus of deformability did not change significantly (p>0.05) with microwave heating and ranged from 34.3 to 24.2 MPa. It may be concluded, therefore, that microwave heating of morama beans can influence their textural properties to facilitate cracking during decortication, and potential exists for further optimization of the process.

Keywords: Microwave heating, morama beans, textural properties, pre-decortication treatment