Effect of freezing and radiofrequency pretreatments on quality and kinetics of convective air‐drying of potatoes

Abstract

The effects of freezing and radiofrequency (RF) pretreatments on drying kinetics and qualitative properties of hot air-dried potatoes were evaluated. Results showed that the use of an RF pretreatment before potatoes drying reduced the color changes, firmness, and increased shrinkage, rehydration ratio, and the effective diffusion coefficient. Whereas, the amount of activation energy was reduced by applying freezing and RF pretreatments. So that the amount of activation energy from 28.82 ± 0.4 kJ/mol (control sample) to 22.84 ± 0.1 kJ/mol (sample treated with CF), and 19.93 ± 0.2 kJ/mol (sample treated with CF and RF) decreased. The Henderson-Pubis model with the highest R2 and the lowest RMSE and χ2 was selected as the best model. Freezing pretreatment has weakened the tissue and created cell holes in the samples. When using RF, the amount of damage to the cell wall is greater, which makes the samples have a more porous structure using scanning electron microscopy. Practical applications Potatoes are one of the four main foods of the people of the world. Most of the potatoes produced are stored for use in the food industry. Due to the problems of storage, transportation, and seasonality of potato production, drying can be used as a suitable method to reduce potato waste. The most common method of drying is the use of hot air drying, which involves the simultaneous transfer of mass and heat. Since hot air drying uses high temperatures or long time, which in addition to high energy consumption and time-consuming process, causes some undesirable physical and chemical changes such as changes in color, flavor, and reduction of nutrients and shrinkage in the product. Therefore, using other drying methods or using pretreatment, the quality of the dried product can be maintained in a desirable. So far no research has been done on the use of CF and RF as a pretreatment in the potato drying. Therefore, the aim of this study was to investigate the effect of freezing pretreatments on drying kinetics and quality characteristics of hot air-dried potatoes.