Examination of Drying Behavior of Mung Bean in Laboratory and the Establishment of the Corresponding Rea Model

Abstract

Drying is an essential preservation technique for agricultural products. It also provides longer shelf life and light-weight for cost-effective transportation. The ability to describe drying of the agricultural products accurately is known to be important. Designing and optimization of drying operations ideally needs a simple, accurate yet mechanically meaningful model. Most published studies have employed diffusion-based models to describe drying kinetics which requires solution of partial differential equation and substantial amount of work to determine diffusivity function. Reaction Engineering Approach (REA) is a simple alternative to the more complex approaches. It can take a lumped form which can be implemented in computational fluid dynamics (CFD) for coupling of objects being dried and surrounding flow field. In this study, moist mung bean was dried in a range of pre-set constant drying conditions and the appropriate REA parameters were obtained. The changes of temperature and moisture content of mung bean samples during drying were measured experimentally and the results were compared with the REA model calculations. The model predictions were in very good agreement with the experimental data under all the conditions tested. The agreement of moisture content was revealed by R2 higher than 0.991 and RMSE lower than 0.003. The agreement of particle temperature was also revealed by R2 higher than 0.932 and RMSE lower than 0.08. Based on the experimental data, REA model was established for the necessary parameters. The REA model has been shown to represent the experimental drying data very well. Practical Applications Mung bean is an important legume of Asian origin, now widely cultivated throughout Asia, Australia, New Zealand and Africa. It contains a number of essential fatty acids, antioxidants minerals and proteins that are known to reduce the risk of coronary heart disease, diabetes and obesity, and can considerably lower blood cholesterol. Most of mung beans are dried and only small amounts are consumed fresh. With the fast, effective and economical technique to reduce the moisture content of materials, for better storage and transportation, mung bean are dried usually using appropriate machinery (such as fluid bed dryer). The ability to describe drying of these products quantitatively for better designs of the drying facilities urges the necessity of developing an appropriate drying model for dehydrating of mung beans. The basic aim of this article was to present a new mathematical model to describe drying kinetics of mung bean and establish the corresponding REA model. The established model parameters would be applied in fluid bed drying modeling.