Effect of Osmotic Dehydration on Air-Drying Characteristics of Chayote

Abstract

In this study the effect of osmotic dehydration (OD) on the air-drying kinetics of chayote (Sechium edule (Jacq.) Swartz) fruits was investigated. Fresh and osmotically dehydrated chayote parallelepipeds (1 Â 1 Â 2 and 4 Â 4 Â 2 cm) were subjected to convective drying at air temperatures of 50 and 60 C, with air velocities of 1.5 and 2.5 m/s. The OD pretreatments were performed in 10 and 25% NaCl solutions (w/w) at 25 C during 3 h using a solution-tofruit mass ratio of 4:1. The use of higher air velocities notably accelerated drying rates as manifested through significantly higher drying rate constants estimated with Page's model, whereas no effect of temperature was observed. A previously reported analytical solution that considers both product shrinkage and variable diffusivity was generalized to describe the drying kinetics of food products with parallelepiped geometry. Selected drying experiments were then fitted to this solution using six different sets of model assumptions. Results indicated that product shrinkage is the main factor to be considered in order to estimate reliable values for diffusion coefficients. The OD pretreatments produced a significant reduction of the initial moisture content of chayote slabs before drying, thus allowing shorter drying time, which may lead to reduced energy consumption.

Influence of Drying Processes and Pretreatments on Nutritional and Bioactive Characteristics of Dried Vegetables: A Review

“…Moreover, since osmotic dehydration can lower the water content of fruits and vegetables up to a 50 %, the energy requirements for subsequent thermal drying can be considerably reduced [79]. However, periods of 1-7 h were required to achieve efficient osmotic dehydration, which are substantially larger operating times when compared with traditional water or steam blanching, that can be performed in a few minutes.…”

Modeling of kinetics, equilibrium and distribution data of osmotically dehydrated carambola (Averrhoa carambola L.) in sugar solutions

“…This operation has gained a broad acceptance in fruits and vegetable processing as it improves quality characteristics such as color, texture and flavor in the final product (Bidaisee and Badrie, 2001;Pereira et al, 2006). Moreover, since OD is able to produce a significant dewatering of foods, energy requirements for a further thermal drying can be considerably reduced (Ruiz-López et al, 2010). A good understanding of mass transfer rates for both solute gain and water loss as well as the final impregnation-dehydration levels of a given product under different OD conditions (such as osmotic agent concentration, process temperature and solute type) is required for an adequate design of this operation (Shi and Le Maguer, 2002).…”

“…A feasible way of increasing shelf life of carambola is through the development of reduced moisture products. However, even though air drying is the most widely used technique for dehydrated fruit and vegetable production, it may be detrimental, affecting both nutritional and sensory quality of heat-sensitive products (Ruiz-López et al, 2010). Moreover, available information on dehydration processes of carambola is limited.…”

Study on Equilibrium Distribution Coefficients during Osmotic Dehydration of White Gourd Slices

“…Moreover, because osmotic dehydration is able to produce a significant dewatering of foods, energy requirements for a further thermal drying can be considerably reduced (Ruiz‐Lopez et al . ).…”

“…Osmotic dehydration has gained a broad acceptance in fruits and vegetable processing as it improves quality characteristics, such as color, texture and flavor, in the final product (Pereira et al 2006). Moreover, because osmotic dehydration is able to produce a significant dewatering of foods, energy requirements for a further thermal drying can be considerably reduced (Ruiz-Lopez et al 2010).…”