Optimizing Microwave Drying of Black Carrot Pretreated with Osmotic Dehydration: Taguchi Based Desirability Function Approach

This study aimed to optimize the microwave drying process of black carrot pretreated with ultrasound-assisted osmotic dehydration (UAOD). The effect of salt concentration (2-10%), sonication time (5-15 min), and microwave power (300-600 W) on total phenolic matter (TFM) and drying time was monitored. Single response optimization was performed using the Taguchi method (TM), while the desirability function approach (DFA) was used to optimize multiple responses. The analyses were conducted using Taguchi L9 orthogonal design. Single response optimization results showed that TFM content was changed between 11.59 and 18.57 mg GAE/g sample dry matter, while the drying time ranged from 8 to 20 min. In multiple response optimization, the DFA with a composite desirability (CD) value of 0.973 demonstrated that the optimal conditions for both maximizing TPC and minimizing drying time were obtained with 10% salt concentration, 15 min sonication, and 600 W microwave power. ANOVA results revealed that microwave power contributed the highest to both responses, followed by salt concentration and sonication time, respectively. However, microwave power and salt concentration had a substantial impact on the CD. Overall results showed that the Taguchi-based DFA was successfully applied to optimize the microwave drying process of black carrots pretreated with UAOD, maximizing the phenolic compound content and minimizing the drying time.