Intrinsic viscosity of cress (Lepidium sativum) seed gum: Effect of salts and sugars

Intrinsic viscosity of the hydrocolloids in different solvent/cosolute systems provides deep insight on the fundamental molecular properties of biopolymers in food systems. In this research, the influence of some salts and sugars were investigated on intrinsic viscosity ([η]) of cress seed gum (CSG) as a new potential source of hydrocolloid. The concentration range of the additives were 0–40% w/w, 0–15% w/w, 0–100 mM and 0–15 mM for sucrose, lactose, NaCl, and CaCl2, respectively. Various models i.e. Huggins, Kraemer, Tanglertpaibul-Rao, and Higiro were used to estimate the intrinsic viscosity. The polyelectrolyte behavior of the CSG is confirmed by the decrease of [η] with addition of salts. The addition of sucrose and lactose was shown to initially decrease the intrinsic viscosity, possibly due to either a reduction in solvent quality or a reduction in polymer/polymer association, followed by an increase in [η] at higher concentrations. Berry number and the slope of master curve demonstrated that CSG samples in all salt and sugar concentrations were in dilute domain without entanglement occurrence. The exponent b (slope of power-law model) also revealed that CGS samples had the conformation between random coil and rigid rod; however selected salts and sugars changed slightly the CSG conformation to random coil.