Purification of glucomannan from salep: Part 2. Structural characterization.

The aim of this study was to investigate the effects of different extraction temperatures (25, 55 and 85°C) on the structural characteristics of glucomannan (GM) purified from salep. All extraction conditions reduced protein content and molecular weight of salep. The effectiveness of removing the impurities and the highest purity of GM25 were observed with size exclusion profile. FTIR experiments demonstrated the presence of acetyl group, reduction of protein content and increment of polymer interaction of GM25. XRD patterns of GM25 with narrower and higher intensity than GM55, GM85 and native salep indicated strengthened interaction of GM25. Higher particle size was determined for GM25. The degradation peak observed with DSC increased from 293 to 314°C and GM25 had the higher thermal stability which was also supported with TGA results. These results could provide widening the applications in food industry and other fields and also progressing development of salep with a better structural characteristic.