Water Adsorption of Peanut Kernels in a Closed System with Respect to Moisture Transfer

Adsorption isotherms of peanut kernels, Tainan # 9 and #11, were determined at 30°C and used as reference to determine the a w at equilibrium. The changes of the apparent a w and moisture of three weighed dried kernels in closed systems stored with distilled water were determined in an electric hygrometer and a series of vessels at 30°C. A nonequilibrium state of moisture and apparent a w gradients of the kernels was observed in the early stages of 144 hr storage. In a 90 min experiment with the hygrometer at 30°C, the vapor adsorption rate and final apparent a w decreased in order with the increase of the number of kernels, from 1 to 7, stored with saturated K 2 Cr 2 O 7 salt (a w = 0.98 at 30°C). Vapor adsorption rate and final apparent a w of Tainan # 9 were slightly higher than those of # 11.