Drying rate and damage to navy beans

Abstract

The effect of drying air temperature and relative humidity on the rate of drying and damage to navy beans was investigated. A thin-layer apparatus was developed to dry beans from an initial moisture content of around 25% to 14% wet basis (w.b.) using temperatures between 328 and 62 degrees C and relative humidities between 7.5% and 45%. The rate of moisture diffusion from the beans was mathematically defined as a function of drying air temperature and bean moisture content. The degree of bean damage was inversely proportional to the relative humidity of drying air when it was below 26%. No damage was observed for relative humidities greater than 26% for the range of temperatures used.