Drying kinetics of fresh and osmotically pre-treated papaya (Carica papaya L.)

The aim of this work was to study and to model the drying kinetics of fresh and osmotically pre-treated papaya cubes (Carica papaya L.) using the diffusional model (Fick's second law) adapted to a cubic geometry, and an empirical two parameters model. The osmotic pre-treatment was carried out in an incubator at constant temperature and agitation. The drying process was carried out in a fixed bed dryer at two different temperatures and air velocities. At the beginning of the drying process of fresh papaya, drying rate was influenced by both air velocity and air temperature. But lose to the equilibrium condition, the drying rate was affected only by the air temperature. The physico-chemical changes in the papaya cubes during osmotic pre-treatment caused differences in the drying rate in the subsequent air drying process when compared to fresh papaya cubes. The effective diffusivities of water, calculated by diffusional model, were of the order of 10(-9) m(2)/S. (C) 2003 Elsevier Science Ltd. All rights reserved.591859

Influence of the osmotic agent on the osmotic dehydration of papaya (Carica papaya L.)

The objective of the present work was to Study the influence of two different osmotic agents (Sucrose and corn syrup) on the osmotic dehydration of papaya slices (Carica papaya L.). The study was carried out using two factorial experimental designs, with three independent variables whose levels varied from 44% to 56% w/w for concentration, from 34 to 46 degrees C for temperature and from 120 to 210 min for immersion time. The responses of the experimental designs were the weight reduction (WR), water loss (WL), solids gain (SG) and water activity (a(w)). The results showed that, considering the same osmotic pressure for both osmotic agents, the values obtained for WR, WL and SG for dehydration in sucrose solutions were higher than those obtained in corn syrup solutions, due to their high viscosity and polysaccharide content. The opposite behavior was observed for a(w). The models obtained for the response variables followed a linear behavior except for SG. (c) 2005 Elsevier Ltd. All rights reserved.75226727

Effect of osmotic dehydration on the drying kinetics and quality of cashew apple

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)The effect of different osmotic pretreatments on cashew apple drying kinetics and product quality were investigated. The osmotic pretreatment was carried out in an incubator at constant temperature and agitation. The drying process was conducted in a fixed bed dryer at different temperatures and constant air velocity. Experimental data were fitted successfully using the Page and the two-term exponential models for dried fresh and pretreated fruit, respectively. It was found that drying rates of osmosed fruits decreased owing to the presence of infused solutes. Evaluation of the final product was performed by means of ascorbic acid content, water activity and sensorial test. The osmotic pretreated samples showed the highest vitamin C losses and the lowest water activity. The samples pretreated in sucrose solution had the highest acceptance.445980986Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP