Optimisation of microwave-rotary drying process and quality parameters of terebinth

Abstract

Different aspects of terebinth drying in a microwave-rotary dryer were investigated including energy and exergy analysis, quality, and bioactive compounds. Experiments were performed using different parameters of microwave power (270, 450, and 630 W) and chamber rotation speed (5, 10, and 15 rpm). Drying time and effective moisture diffusivity were ranging from 43 to 137 min and 6.25 × 10 −9 to 9.28 × 10 −8 m 2 s −1 , respectively. Energy and energy efficiency increase with increasing microwave power and rotation speed. Exergy loss and improvement potential decreased with increasing microwave power and rotation speed. The physical parameters (shrinkage and total colour difference) increased with increasing microwave and rotation speed, while for the rehydration rate, an inverse relationship was observed. Also for bioactive compounds like total phenolics, total flavonoid content, and antiradical activity, a higher reduction was noticed with used higher microwave power and with higher rotation speed. Thus, the best parameters to obtain the highest content of bioactive compounds were microwave power of 270 W and rotation speed of 5 rpm. Comparison of different algorithms revealed that the grey wolf optimisation (GWO) algorithm had greater accuracy than the whale (WO) optimisation algorithm to predict all parameters of dried terebinth. • Efficiency of the drying process was calculated. • Shrinkage and colour change increased with increasing microwave & rotational speed. • Rehydration rate decreased with increasing microwave and rotational speed. • Bioactive compounds increased with lower microwave power and rotational speed.