Characterizations and rheological study of the purified polysaccharide extracted from quince seeds

The functional characteristics of hydrocolloids are mainly dependent on their physicochemical properties. Thus, it is essential to characterize the new sources of hydrocolloids. Quince seed gum (QSG) is a high molecular weight polysaccharide (9.61×10⁶ g/mol) composed of 85.04±2.87% carbohydrate (6.39% L-arabinose, 40.43% D-xylose, 5.60% D-galactose, 5.75% D- glucose and 31.11% D-mannose), 13.16±1.73% uronic acid, 5.77±0.83% moisture, 2.78±0.21 % protein, 5.64±0.21% ash, and 0.75±0.09% fat. Our findings indicated that this gum could be introduced as a value-added by-product in the food and pharmaceutical industries. ¹³C NMR and FT-IR suggested a highly substituted xylan structure for QSG. In dilute regime, an increase in the ion concentration was accompanied by a decrease in intrinsic viscosity of QSG. When the salt concentration increased from 0 to 50 mM, the consistency coefficient (as a measure of apparent viscosity) declined. On the other hand, with further increasing of salt concentration, the consistency coefficient (as a measure of apparent viscosity) values increased. Similarly, G' and G" values for 10 and 50 mM CaCl₂ concentrations were less than control samples. The rheological behavior of the QSG studied in this paper can provide insight into its potential application in food and pharmaceutical industries.