Microstructure, rheology and freeze-thaw behavior of double (W1/O/W2) emulsions prepared with palm oil: Effect of Tween 80/sodium caseinate ratio

Abstract

The objective was to study the effect of the variation of Tween 80/sodium caseinate ratio on the microstructure, rheology and freeze-thaw behavior of double (W1/O/W2) emulsions prepared with palm oil. Particularly, the impact of the composition of the outer interfacial film on partial coalescence and retention of inner water droplets was investigated. Partial coalescence was restrained in the emulsion prepared with sodium caseinate only, because aggregation of oil globules was prevented due to electrostatic and steric repulsions and a resistant interfacial film. The inclusion of Tween 80 produced competitive adsorption of emulsifiers, promoting partial coalescence and increasing the elastic and viscous modules of the system. A higher Tween 80 proportion led to lower retention of inner water droplets after cold storage, attributed to the formation of smaller oil globules and a thinner interfacial film. A cooling-heating-cooling cycle was applied by differential scanning calorimetry, showing that a higher oil globule aggregation degree led to higher retention of inner water droplets during freezing and higher release of inner water droplets during thawing. The findings expand the knowledge regarding the influence of the composition of the outer interfacial film on both partial coalescence and retention of inner water droplets in W1/O/W2 emulsions.