Thermal Properties of Hydrated Soybean Hulls

Abstract

To successfully incorporate soybean [Glycine max (L.) Merr.] hulls (seed coats) into human foodstuff, thermal characterization of the hulls is needed. Our objective was to determine the density, heat capacity, thermal conductivity, and thermal diffusivity of finely (0.84 mm) and coarsely (2.36 mm) ground unprocessed and processed (lignin‐reduced) soybean hulls. The density of the soybean hulls ranged from 1.02 to 1.05 g cm‐3. Heat capacity values ranged from 4725 to 5247 J kg‐1 K‐1. The heat capacity values of the fine of processed soybean hulls were significantly (P < 0.05) greater than the values of the unprocessed ones. The coarsely ground, processed soybean hulls exhibited a 35% greater thermal conductivity value than with other treatments. Thermal diffusivity values ranged from 1.24 to 1.71 ✕ 10‐7 m2 s‐1. Although food scientists and engineers can use these data to help creat efficient food processes and equipment, awareness by crop scientists of these parameters may assist in the future genetic development of desired soybean hull characteristics.