Kinetics of biodegradable film drying in microwave oven

Drying is one of the conservation methods of food that reduces moisture through the simultaneous transfer of heat and mass. In this study, the drying kinetics of biodegradable film based on Carrageenan and using microwave was investigated as a new, fast and relatively inexpensive method and it was introduced as the most suitable mathematical model for describing drying kinetics. For this purpose, the prepared films were dried using microwave oven at 350, 500, 750 and 900 W. Also, 10 mathematical models were fitted to test data and their fitting quality was analyzed. The fitting quality of the proposed models was evaluated based on the parameters of the coefficient of explanation (R2), square mean square error (RMSE) of the square (χ2). Comparison between different models showed that the Midley model could be the most suitable model for estimating moisture variations and describing the film drying behavior. The highest effective moisture penetration coefficient was also obtained at a power of 900 watts of 41.7 × 10-4 and the lowest effective moisture penetration coefficient at 350 watts was found to be 2.78 -10.5 -5. The results showed that microwave power has an important effect on drying rate and drying time is decreased by increasing the dryer power. The initial drying rate at 900 watts 9.8 g/min and it was 4.3 g/min at 350 watts. The longest drying time was observed at 350 watts which lasted 425 minutes. Also, the drying time of films with this method was significantly reduced by 97% compared to the conventional method (at 25°C warm air).