Kinetics of osmotic dehydration and air-drying of pumpkins ( Cucurbita moschata)

• Published in: Journal of food engineering 2007-10, Vol.82 (3), p.284-291
• Main Authors: Garcia, Carolina Castilho, Mauro, Maria Aparecida, Kimura, Mieko
• Format: Article
• Language: English
• Subjects: air drying; aqueous solutions; Biological and medical sciences; Convective drying; Cucurbita moschata; Dehydration; Deviation; Diffusion coefficient; Diffusion coefficients; Diffusivity; drying; Food engineering; Food industries; food processing; food quality; Fruit and vegetable industries; Fundamental and applied biological sciences. Psychology; General aspects; heat treatment; mass transfer; Mathematical models; osmosis; Osmotic dehydration; osmotic treatment; pretreatment; process control; Pumpkin; Pumpkins; raw foods; reaction kinetics; Shrinkage; Sucrose; sugars; Variable thickness; water
• ISSN: 0260-8774; 1873-5770
• DOI: 10.1016/j.jfoodeng.2007.02.004

Kinetics of osmotic dehydration (OD) and effects of sucrose impregnation on thermal air-drying of pumpkin slices were investigated. A simplified model based on the solution of Fick’s Law was used to estimate effective diffusion coefficients during OD and air-drying. In order to take into account shrinkage, average and variable thicknesses were considered. Pumpkin slices were dehydrated in sucrose solutions (40%, 50% and 60%, w/w, 27 °C). The effective water diffusion coefficients were higher than the sucrose, and low diffusivity dependence with solution concentration was observed. Samples non-treated and pre-treated in 60% osmotic solutions during one hour were dried in a hot-air-dryer at 50 and 70 °C (2 m/s) until equilibrium was achieved. Pre-treatment enhanced mass transfer during air-drying. Great volume reduction was observed in pre and non-treated dried samples. Using variable thickness in the model diminished the relative deviations between predicted and experimental OD and drying data.