DRYING CHARACTERISTICS OF ONION PROCESSING WASTE

Abstract

Onion processing waste (OPW) was dried in a convective hot-air laboratory scale dryer at 50, 60, 70 and 80ºC. The effect of drying temperature on the drying characteristics and on the total phenolic and total flavonoid content of dried samples was determined. Three mostly used models were applied for fitting the experimental drying curves. The results indicated that the constant rate-drying period was not observed and that the logarithmic model was the most suitable for fitting the experimental drying kinetic data. The drying temperature significantly affected the total phenolic and total flavonoid content of dried OPW. The values of effective diffusivity were calculated and the determined value of activation energy was 28.05 kJ/mol.