Mechanical Properties of Cowpea Beans at Different Moisture Contents

Abstract

Cowpea production has gained considerable ground in Brazil. Cowpea grain undergo different types of pressure and may crack and break during processing and storage, thus, there is a need to classify the mechanical properties of the beans. Therefore, this study aimed to evaluate the influence of the moisture content of cowpea beans on the maximum compressive force for fixed deformation and determine the proportional modulus of deformity under compression. The cowpea cultivars Novaera and Tumucumaque were evaluated at different moisture contents (0.12; 0.15; 0.18; 0.20; and 0.23 decimal d.b.). The experiment was arranged in completely randomized design for each moisture content and 10 deformation rates were applied (0.02; 0.04; 0.06; 0.08; 0.10; 0.12; 0.14; 0.16; 0.18; and 0.20 mm). The compression force was assessed using a universal testing machine and the proportional deformation modulus was determined. Following, hardness and elasticity of cowpea beans ??as a function of the moisture content were established. The compressive force required to deform cowpea beans decreases with increasing moisture content: between 2 and 105 N (Tumucumaque) and between 2 to 97 N (Novaera). The proportional deformation modulus of cowpea increased as the moisture content and deformation reduced, ranging from 4.9 x 107 to 31.9 x 107 Pa (Tumucumaque) and from 5.9 x 107 to 42 x 107 Pa (Novaera).