Effects of flaxseed gum concentrations and pH values on the stability of oil-in-water emulsions

This study investigated the effects of flaxseed gum (FG) concentrations (0.1–0.5%, w/w) and pH values (5.0, 6.0 and 7.0) on the stability of 10% (w/w) liquid lard emulsions. The emulsions were analyzed for particle size, rheological properties, creaming stability, optical microscopy and nuclear magnetic resonance (NMR) measurement. With the increase of FG concentration, there was an improved packing of polysaccharide onto the droplet surface, which caused a significant reduction in particle size, with the smallest oil droplets being formed in 0.5% (w/w) FG emulsions. Rheological and creaming stability measurements showed that FG solutions had thickening and gelling properties. When FG concentration increased to greater than 0.3% (w/w), the samples no longer exhibited creaming behavior, and pH values no longer had significant effect on the emulsion stability. Shorter spin-spin relaxation time (T 2 , by low-field 1 H NMR) were observed for emulsions containing 0.1% (w/w) and 0.2% (w/w) FG, suggesting more restriction of mobility of oil droplets. The increased line-width in high-field 1 H, 13 C NMR spectra with increasing FG concentration indicated an increased interaction between FG and oil molecules. These results showed that FG had the potential to substitute for protein emulsifiers which is sensitive to pH to stabilize the emulsion-type products.