Abstract
The aim of this study was to evaluate the parameters of mass transfer in the dehydration of yacon slices with different polyols as osmotic agents. The samples were immersed on hypertonic solutions (40 °Brix) of xylitol, maltitol, erythritol, isomalt and sorbitol at 25 °C. The kinetics of solid gain (SG), water loss (WL) and water activity (aw) of the yacon slices were evaluated over 120 minutes of osmotic dehydration. The effective diffusion coefficients of water and solids were calculated by the diffusive model of Fick. The results showed that the SG was greater in samples treated with solutions of erythritol and lower in isomalt and maltitol solutions. Samples immersed in solutions of sorbitol and xylitol showed intermediate SG. The samples treated in solutions of sorbitol, xylitol and erythritol presented higher water diffusion coefficients and were more effective at reducing parameters of WL and aw than the other polyols. The model of Fick represented well the differences between the kinetics of WL and SG for the tested polyols.
Highlights
Yacon is an eatable root originally from the Andean region of South America
Due to its prebiotic properties, high content of fructooligosaccharides and low glycemic index, this tubercle has been studied for controlling diseases as obesity and diabetes (Pereira et al, 2013)
The development of processing techniques to increase the shelf life of yacon and improve its selling is important because it could allow the availability of the tubercle all-over the year and by pass its perishability
Summary
Due to its prebiotic properties, high content of fructooligosaccharides and low glycemic index, this tubercle has been studied for controlling diseases as obesity and diabetes (Pereira et al, 2013). The development of processing techniques to increase the shelf life of yacon and improve its selling is important because it could allow the availability of the tubercle all-over the year and by pass its perishability. On one hand, drying is a common method for food conservation. The exposure to high temperatures for long periods in drying process decrease the prebiotics, nutritional and sensory content of yacon (Lenart and Dabrowska, 1999). The osmotic dehydration (OD) is a pretreatment to drying that could aid to preserve the physical, chemical and nutritional characteristics of the dehydrated product with respect to the fresh one (Mujumdar and Law, 2010; Ferrari et al, 2011; Vieira et al, 2014)
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