Physicochemical properties of peanut oil-based diacylglycerol and their derived oil-in-water emulsions stabilized by sodium caseinate

Abstract

High purity peanut oil-based diacylglycerol (PO-DAG) (94.95 wt%) was prepared via enzymatic glycerolysis from peanut oil (PO). The resulting dominance of DAGs was proven to greatly influence the properties of corresponding fresh or frozen-thawed emulsions. Stable fresh oil-in-water emulsions were produced using either PO-DAG or PO, with stability enhanced by increased concentrations of Na-CN. The lower equilibrium interfacial tension along with greater negative ζ-potential of PO revealed that Na-CN was preferentially adsorbed to the PO interface. Adding 0.05 mol/L NaCl to the PO emulsions minimized depletion flocculation caused by the unadsorbed Na-CN, but further NaCl addition increased oil droplet size and concomitant coalescence. For the PO-DAG emulsions, adding 0.2 mol/L NaCl did not significantly (p>0.05) affect their ζ-potential but adding 0.05 or 0.1 mol/L NaCl lowered ζ-potential, although NaCl at these concentrations increased oil droplet size and coalescence. Freezing-thawing process considerably weakened the stability of PO-DAG emulsions.

Keywords: Emulsion stability; Interfacial characteristics; Oil-in-water emulsion; Peanut oil-based diacylglycerol; Sodium caseinate concentration; Sodium chloride addition.