Mediation of Peanut Moisture Content and System Optimization for Improved Shelling Performance of Small Peanut Sheller

Highlights A whole-process experiment was done to incorporate both machine and peanut properties. Wetting and drying control for unbalanced moisture contents improved shelling performance. A Box-Behnken design and response surface method were used for system optimization on the small sheller. Unbalanced moisture contents resolved the controversial response between MDR and SE. System optimization quantified the optimum combination of moisture, drying time, and speed. Abstract . Improvement of peanut shelling performance for smallholders is challenging due to the numerous influential factors involved with both machinery and peanut properties. A Box-Behnken design (BBD) and response surface method (RSM) were used to simplify the experimental investigations. Sequential laboratory observations were made on wetting-and-drying pretreatments, single-factor tests, multiple-factor couplings, modeling and significance analysis, response surface analysis, and system optimization. Results showed that wetting-and-drying pretreatment can effectively mediate the physical properties of peanut pods for unbalanced moisture contents between the peanut shell and kernel, contributing to improved mechanical damage rate (MDR) and shelling efficiency (SE). Statistical analysis of MDR and SE models identified the rated effects as: moisture content (MC) > cylinder speed (CS) > drying time (DT) for MDR, and DT > CS > MC for SE. The coupling effects among the variables were: MC × CS > MC × DT > DT × CS for MDR, and DT × CS > MC × DT > MC × CS for SE. System optimization with RSM provided the optimal combination as MC = 11.63%, DT = 26.87 min, and CS = 234.78 rpm. This combination resulted in a minimum MDR of 3.94% and a maximum SE of 97.17%. The optimized results were evaluated in production trials, revealing the mean values of MDR and SE as 4.18% and 93.87%, respectively. It is suggested that a suitable wetting-and-drying pretreatment can be a powerful means to enhance the shelling performance of small shellers. Keywords: Mechanical damage rate, Optimization, Peanut, Response surface method, Shelling efficiency.