An investigation of four commercial galactomannans on their emulsion and rheological properties

Four types of galactomannans, namely fenugreek gum (FG), guar gum (GG), tara gum (TG) and locust bean gum (LBG), were investigated in the present study on their emulsion and rheological properties. The M/G ratios of the four galactomannans were 1.2, 1.7, 3.0 and 3.7, respectively. The results revealed that the M/G ratio, along with molecular weight and intrinsic viscosity, played an essential role on emulsion and rheological properties. Surface activity followed the trend: FG > GG > LBG > TG. Emulsion capacity and stability followed the trend: GG > FG > TG > LBG. Storage modulus (G′) followed the same order as intrinsic viscosity, which was: GG > FG > TG > LBG. By fitting the shear-thinning region of the flow curves into the Power law model, power law index (n) increased with increased concentration. Zero shear viscosity (ηsp)0 was derived by fitting the Newtonian regions of the flow curves into Cross model, and followed the same order with viscosity based molecular weight (Mv), which is: FG > GG > TG > LBG. Exponents of the four gums were generated from Master curves (log (ηsp)0 versus log C), which were 4.57, 3.92, 4.31 and 4.19 for FG, GG, TG and LBG, respectively.