Effect of Process Parameters on Foam Mat Drying Kinetics of Yacon (Smallanthus sonchifolius) and Thin-Layer Drying Modeling of Experimental Data

Because of the health benefits provided by the consumption of yacon and its perishability, the foam mat drying (FMD) was applied in order to increase its shelf life. Yacon juice foams formed by the addition of two different foaming agents (emulsifier and egg albumin) and incorporation of air were subjected to dehydration, with different air temperatures (50, 60 and 70C) and layer thicknesses (0.5, 1.0 and 1.5 cm). The drying rate and effective diffusivity increase with the rise in temperature and the thickness of foam, being higher for the foam formed with egg albumin rather than emulsifier. The experimental data were fitted to several thin-layer models, among which the logarithmic model was the most suitable to represent the process. The effect of temperature, thickness and foaming agent on the drying kinetics has not been studied previously; hence, this research can aid the design of optimized FMD processes. Practical Applications Yacon is a food with great potential for research because of its beneficial properties to human health, especially the prebiotic activity, which is ascribed to the high concentration of inulin and fructooligosaccharides in its composition. However, the high percentage of water renders this tuber extremely perishable, hindering transporting and processing. The foam layer drying reduces drying time and energy demand with respect to other drying techniques and allows the formation of products with excellent physicochemical and sensorial characteristics. The assessment of the process kinetics and application of mathematical models to predict it provides information for the process design, increasing the use of yacon in the agro industry.