Mechanical properties of cowpea beans at different moisture contents

Abstract

The cowpea has taken up a lot of space in Brazil's grain production, thus, the need arises to classify it as to its mechanical properties, because during all the processing and storage of the grain, it can suffer different types of pressure that cause cracks and breaks in the grain, therefore, this study aimed to determine the influence of water content on the values of maximum compression force for fixed deformations and to determine the proportional modulus of grain deformity of cowpea cultivars submitted to compression. Were used grains from two bean cultivars, Novaera and Tumucumaque in the water content of (0.12; 0.15; 0.18; 0.20 and 0.23 decimal b.s.), the work was carried out in a completely randomized design, where for each water content, 10 deformations were applied (0.02; 0.04; 0.06; 0.08; 0.10; 0.12; 0.14; 0.16; 0.18 and 0.20 mm). Soon after the compressive strength was analyzed with the aid of a universal testing machine of model test, then the proportional deformity module was determined, with the deformation values evaluated, the hardness and elasticity values of the cowpea grains were established as a function of the water content. The compression force required to deform the cowpea decreases with increasing water content, between 2 and 105 N for the cultivar Tumucumaque and between 2 and 97 N for the cultivar Novaera. The proportional deformity module increases with the reduction of the water content and the product deformation, obtaining values, for the studied humidity range, between 4.9 x 10⁷ to 31.9 x 10⁷ Pa for the cultivar Tumucumaque and of 5.9 x 10⁷ to 42 x 10⁷ Pa for the Novaera cultivar.