Effects of microwave heating on textural properties of morama (Tylosema esculentum) beans

Abstract

Morama beans were heated for 60, 90, and 120 s at 200, 600, and 1000 W using a domestic microwave oven to assess their potential as a pre-decortication treatment and to evaluate the effects on peak force, work, and modulus of deformability, which are key textural properties determined by compression using a texture analyzer. One sample was left unheated as a control for comparison. Bean temperatures after microwave heating ranged from 33 to 86°C, with rates of temperature increase of 0.09, 0.32, and 0.61°C/s at 200, 600, and 1000 W, respectively. Peak force significantly decreased (p<0.05) from 579.3 N in the control sample to 437.2 N in the sample heated for 60 s at 600 W, while the work done during compression did not differ significantly with microwave heating (p>0.05) and ranged from 469.9 to 313.7 Nmm. Similarly, the modulus of deformability did not change significantly (p>0.05) with microwave heating and ranged from 34.3 to 24.2 MPa. It can be concluded, therefore, that microwave heating of morama beans can affect their textural properties in a way that facilitates cracking during decortication, and there is potential for further optimization of the process.