Study on the impact of temperature, salts, sugars and pH on dilute solution properties of Lepidium perfoliatum seed gum.

The functional properties of food gums are remarkably affected by the quality of solvent/cosolutes and temperature in a food system. In this work, for the first time, the chemical characterizations and dilute solution properties of Lepidium perfoliatum seed gum (LPSG), as an emerging carbohydrate polymer, were investigated. It was found that xylose (14.27%), galacturonic acid (10.70%), arabinose (9.07%) and galactose (8.80%) were the main monosaccharaide components in the LPSG samples. The uronic acid content of LPSG samples was obtained to be 14.83%. The average molecular weight and polydispersity index of LPSG were to be 2.34 × 10 5  g/mol and 3.3, respectively. As the temperature was increased and the pH was decreased and the concentration of cosolutes (Na + , Ca 2+ , sucrose and lactose) presented in the LPSG solutions was enhanced, the intrinsic viscosity [ η ] and coil dimension ( R coil , V coil , υ s ) of LPSG molecular chains decreased. Activation energy and chain flexibility of LPSG were estimated to be 0.46 × 10 7  J/kg.mol and 553.08 K, respectively. The relative stiffness parameter ( B ) of LPSG in the presence of Ca 2+ (0.079) was more than that of Na + (0.032). Incorporation of LPSG into deionized water (0.2%, w/v) diminished the surface activity from 76.75 mN/m to 75.70 mN/m. Zeta potential ( ζ ) values (-46.85 mV--19.63 mV) demonstrated that dilute solutions of LPSG had strong anionic nature in the pH range of 3-11. The molecular conformation of LPSG was random coil in all the selected solution conditions. It can be concluded that temperature and presence of cosolutes can significantly influence on the LPSG properties in the dilute systems.