Lepidium perfoliatum seed gum: investigation of monosaccharide composition, antioxidant activity and rheological behavior in presence of salts

Background: In the present study, the effects of NaCl and CaCl2 (0-200 mM) on the rheological properties of Lepidium perfoliatum seed gum (LPSG) as a novel potential source of hydrocolloid were investigated. Sugar composition and FTIR analysis were measured to supply more structural information. Results: The results illustrated that LPSG had small amounts of uronic acids (6.65%) and it is likely an arabinoxylan-type polysaccharide (it has 44.66% and 31.99% xylose and arabinose, respectively). The FTIR spectra also revealed that LPSG behaved like a typical polyelectrolyte due to the presence of carboxyl and hydroxyl groups. It was observed that the gum solutions exhibited viscoelastic properties in the presence of NaCl and CaCl2 salts. The tan delta values for all samples were less than 1 but greater than 0.1, exposing the weak gel-like behavior at different ion types and ionic strengths. With increasing salts concentrations, the limiting values of strain mostly increased due to the interchain interactions (from 1.46 to 4.61 and from 0.99 to 2.13 for NaCl and CaCl2, respectively). Therefore, the addition of salts increased the stiffness of mucilage solutions in the concentrated regime. The results of frequency sweep tests revealed that storage and loss moduli were increased with increasing ion concentration. This effect was more pronounced for LPSG solutions containing Ca2+. Among various models, the model of Higiro1 showed a higher efficiency to evaluate the intrinsic viscosity of LPSG for all co-solutes (R-2 >= 0.98). With increasing the concentration of salts, the intrinsic viscosity of LPSG decreased. Calcium ions had a more diminution effect on intrinsic viscosity than sodium ions. Conclusions: Trying to adjust the salt concentration could modify the rheological properties of food products. Because food contains a variety of additives, further research should look into the rheological properties of LPSG at different pHs, as well as the presence of other salts and sugars often employed in the food industry. LPSG has the potential to be used in biomedical, pharmaceutical, food industries, tissue engineering, and cosmetic applications due to its biocompatibility, rheological properties, and antioxidant activities.