Process optimization of intermediate-wave infrared drying: Screening by Plackett–Burman; comparison of Box-Behnken and central composite design and evaluation: A case study

Abstract

Choosing a suitable intermediate-wave infrared drying condition for dried seeds and selecting the appropriate statistical technique for the drying of seeds to improve bioactive components and desired functionality is paramount in the food industry. In this study, process parameters of the intermediate-wave infrared dryer were optimized for dried Ginkgo biloba L. seeds. The screening by Plackett-Burman design (PBD) indicated that drying time, temperature, and the distance between infrared emitter and samples were the significant factors for green-red (a*), yellowness (b*), ascorbic acid (AA), and rehydration capacity (RC) responses. However, none of the factors was significant for the total flavonoid content responses’. Hence, a*, b*, AA, and RC were used for further optimization. Rotatable central composite design (RCCD) and Box-Behnken design (BBD) optimization were performed to get a minimum AA and a* degradation, maximum b*, and RC. Both designs had acceptable models. Although PBD-BBD had a higher coefficient of determination (R2), PBD-RCCD was selected for further experiment due to a higher lack of fit and lower residual standard error. The optimum conditions using RCCD were temperature =74.6 °C, time =173 min and height = 22 cm. Although dried ginkgo seeds had a lower physicochemical assessment, it had higher product quality, bioactives, antioxidants, and lower toxic components than fresh ginkgo seeds. This provides an opportunity to use an intermediate-wave infrared dryer under these optimum conditions in food processing.