Optimization of Drying Parameters of <i>Moringa</i> Seeds in a Tray Dryer Using Box-Behnken Technique of RSM

Abstract

Moringa oleifera seeds, being good sources of valuable nutrients, contain appreciable amounts of crude fat, crude fibre, carbohydrate, crude protein, moisture and ash. The seeds contribute significantly to the nutrient requirements and health management of man and should be recommended in diets. So, efforts need to be made to make the seeds be well preserved while still retaining the nutrients contained in them. In an attempt to contribute to that, this research work has been carried out to obtain the optimum values of the parameters required to appropriately make the seeds be dried without much loss in the nutrients. The optimization of the drying parameters has been carried out, in this work, using Box–Behnken design technique of response surface methodology. The technique was used to design a set of 13 experiments that were carried out. The input factors considered were contact time, temperature and fan speed while the response (output) chosen was the residual moisture content of the seeds. A model of the system was formulated and optimized. The results obtained revealed that temperature, contact time and fan speed were affecting the drying of the seeds. Also, a very good agreement given by the comparison of the experimental and the simulated residual moisture content of the seeds showed that the developed model could represent the system very well. Furthermore, the results of the optimization revealed that moringa seeds having a residual moisture content of a value as low as approximately 9.28% could be obtained using the optimum values of drying temperature, contact time and fan speed that were estimated, through the use of a statistical program known as Design Expert, to be 49.40 °C, 90.45 min and 2.5 m/sec, respectively.