Physicochemical characterization of Saccharides powder obtained from yacon roots (Smallanthus sonchifolius) by membrane technology

Abstract

Fructooligosaccharides (FOS) are food ingredients applied due to combination of prebiotic benefits and interesting technological properties, being used as a sugar substitute. The knowledge of their physicochemical characteristics is important for predicting the stability of the food products where they are added. For this reason, a saccharides powder extracted from yacon (Smallanthus sonchifolius) roots by membrane technology and freeze-dried was investigated. Color, water activity (aw), microstructure by Scanning Electron Microscopy coupled to Energydispersive X-ray Spectroscopy (SEM-EDS) and crystallinity by X-ray diffraction were evaluated. The obtained product, containing 19.75% FOS, 36.66% glucose and 43.59% fructose (w/w) was a whitish granulated powder, with aw of 0.284 and CIELAB color coordinates L*, a* and b* of 76.25±1.19, -1.03±0.09 and 1.02±0.03, respectively. It was highly hygroscopic and with agglomeration tendency, confirmed by the formation of bridges between particles on the SEM images. No peaks were identified at X-ray diffractograms, indicating its amorphous characteristics, but sample high hygrospicity and formation of a rigid mass might have hampered a trustable X-ray analysis.