Effects of drying process parameters on the quality attributes of hot air dried okra and its statistical optimization

This study investigated and evaluated the linear or main and interactive effects of drying process conditions on the cabinet hot air drying and quality traits of dried okra slices using the method of response surface (RSM). Rotatable central composite design (RCCD) with four-factors-five-levels of RSM was utilized to evaluate the effect of four process condition, namely air velocity, AV (0.0–2.0 m/s), relative humidity, RH (60–80%), drying temperature, DT (40–80 °C), and drying time, DRT (90–450 min) on dried okra quality traits (product moisture content (PMC), total plate count (TPC), protein content (PTC), and carbohydrate content (CHC)) and to optimize the process conditions to achieve a dried product with minimum PMC, TPC, and maximum PTC and CHC quality attributes as well as to develop statistical regression models for the quality attributes. The results demonstrated that DRT and the DT are the most significant drying conditions that exerted more pronounced linear and interactive effects on the dried okra quality attributes. Second-order quadratic regression models adequately fitted the data to predict the quality attributes. The optimized drying conditions for minimum PMC and minimum TPC as well as maximum PTC and maximum CHC quality attributes were obtained as DT, 55°C; AV, 1.64 m/s: RH, 60% and DRT, 450 min. The drying treatment generally preserved and retained the PTC and CHC of the fresh okra as well as reduced the microbial load to an acceptable limit allowed for consumption.