Hot air drying of yacon (Smallanthus sonchifolius) and its effect on sugar concentrations

P>This work aimed to experimentally study the drying behaviour of yacon tubers with and without steam blanching. Drying was carried out for 5 h and 30 min in a forced air dryer at 50 degrees C, 60 degrees C and 70 degrees C. The results indicated that the shortest drying time was obtained at 70 degrees C for blanched samples, and that the equilibrium water activity values were significantly lower for the blanched samples at all temperatures. The yacon dried without prior blanching showed lowest concentrations of reducing sugars when dried at 70 degrees C, significantly lower than those dried at 50 degrees C and 60 degrees C. This indicates hydrolysis of the fructo-oligosaccharides at 70 degrees C, a fact verified by the significant increase in reducing sugars content from 36.65 +/- 0.54-44.10 +/- 0.96% and reduction in the non-reducing sugars from 31.62 +/- 0.55-26.18 +/- 0.29%.