Characterization of Powdered Yacon (Smallanthus sonchifolius) Juice and Pulp

The present work aimed to study the drying behaviour of a 40ºBrix concentrated yacon juice preparation using native corn starch as the encapsulating agent and also the drying of yacon pulp. The experimental trials were carried out in a forced air dryer at temperatures of 50, 60 and 70°C for 5 h. The values for the equilibrium moisture content were 0.0071, 0.0052 and 0.0050 g/g dry matter (d.m.) for the yacon pulp and 0.0075, 0.0030 and 0.0030 g/g d.m. for the encapsulated juice at 50, 60 and 70°C, respectively, resulting in values for water activity below 0.25. The dehydrated products were ground and then visualized using a scanning electronic microscope. Powdered yacon pulp showed a laminar-type structure, and good encapsulation of the yacon juice by starch was observed in the samples of concentrated juice powder. The glass transition temperatures of the encapsulated concentrated juice powder were 44.74, 45.14 and 49.72°C for water activity values of 0.15, 0.07 and 0.03, respectively, and for the yacon pulp powder, it was 48.78°C at a water activity of 0.13.