Development of impact acoustic detection and density separations methods for production of high quality processed beans

Abstract

Impact acoustic detection (IAD) and density separation (DS) techniques were used to process and study the acoustic and physical properties of dry beans. The IAD’s data analysis software consisted of real time Fast Fourier Transform (FFT) function and the integral against frequency 0–20 kHz was called signal level (SL). Solutions of calcium nitrate and water were used for DS. Bean with low SL (LSL: SL ⩽ 0.04) had higher percentage of skin damage and vice versa. Beans with high SL (HSL: SL > 0.04) were larger sized than those with LSL. Beans with low density had more skin damage than beans with high density. The quantity of broken dehydrated precooked pinto beans in LSL fraction was four times more than in HSL fraction. The percentages of burst and split beans in LSL fraction were higher than in HSL fraction. Higher solid losses and hydration ratio were associated with low density. Contrary to conventional methods, IAD could separate beans based on skin damage. Both techniques could improve high quality processing of dehydrated precooked beans.