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This work focused on studying the drying kinetics of sesame coat at different microwave drying levels (100, 180, 450, 700, and 850 W) and investigating its effect on physico‐chemical and functional properties. Results showed that the drying time was significantly affected by microwave power level. In fact, it decreased from 14 min at 100 W to 2 min at 850 W. Raw sesame coat, as an industrial by‐product, is characterized by a high water activity value (0.98) and fiber content (47.91 ± 3.60 g/100 g dry basis). The microwave drying had reduced significantly (p < .05) water activity to about 0.5. ANOVA test indicated that increasing microwave power level had no significant (p > .05) effect on both total phenol content and browning index. However, it had improved the functional properties (water and oil holding capacities). Practical application The by‐products of sesame seed (Sesamum indicum L.) processing industries are considered as an excellent source of dietary fiber and may be used as a functional ingredient in food industry. This work evaluated the impact of microwave drying, as a new trend, on sesame coats’ quality. Experimental results showed that microwave application had a shorter processing time and it enhanced the quality of final products.

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The present study aims to find the best drying method to minimize the duration of the operation while respecting the nutritional value of the product. Experiments of convective drying and microwave radiation were respectively carried out with a convective dryer (heat temperature: 65 °C and air velocity: 1.3 m/s) and a microwave oven (power level: 100 W and frequency: 2450 MHz). Six coupling tests between the convective drying and microwave radiation were conducted. The only variable condition is the time output of tomatoes from the convective dryer or the microwave oven corresponding to an intermediate mass ratio (IMR) 0.5, 0.4 and 0.3. The microwave drying removes the bound water faster than convective drying. This explains the observed time savings due to convection-microwave and microwave-convection combined drying. The combination of convection drying and microwave drying to an IMR 0.5 preserved better the red color and the antioxidants of the tomato. Thus, the convection–microwave combined drying (IMR 0.5) proved most suitable for preserving the quality of tomatoes. Keywords: convective drying; microwave; coupled drying; color.