Effects of surfactant type and preparation pH on the droplets and emulsion forms of fish oil-loaded gelatin/surfactant-stabilized emulsions

Abstract

The simultaneous application of proteins and surfactants is a research hotspot in the field of food emulsions. Herein, we explored the effects of surfactant type and preparation pH on the fish oil-loaded gelatin/surfactant-stabilized emulsions. The results demonstrated gelatin/Span 80-stabilized, gelatin/soybean lecithin (SL)-stabilized, and gelatin/Tween 80-stabilized emulsions consisted of three types of droplets with different sizes, whereas gelatin/sodium dodecyl sulfate (SDS)-stabilized emulsions consisted of one. The relative droplet sizes were: gelatin/Span 80-stabilized emulsions > gelatin/SL-stabilized emulsions > gelatin/Tween 80-stabilized emulsions > gelatin/SDS-stabilized emulsions. The smallest droplet size showed no significant differences in all emulsions. Preparation pH significantly decreased the other two droplet sizes of gelatin/Span 80-stabilized and the largest droplet size of gelatin/SL-stabilized emulsions, whereas had no obvious effect on the droplet sizes of the other two emulsions. The gelatin/Span 80-stabilized, gelatin/SL-stabilized, and gelatin/SDS-stabilized emulsions could be changed into emulsion gels. The gelatin/Tween 80 emulsions could be rehomoginized into liquid emulsions. These differences on the droplets and emulsion forms might be resulted from the electric and steric properties of surfactants on the water/oil interfaces at different pH. This work provides useful information for basic understanding of gelatin/surfactant-stabilized emulsions and suggests gelatin/surfactant-stabilized emulsions can be potentially applied in many types of foods.