Effects of Span surfactants on the preparation and properties of fish oil-loaded sodium alginate-stabilized emulsions and calcium alginate-stabilized capsules

Encapsulation is an efficient protection method for oil in both liquid (e.g., emulsion) and solid (e.g., capsule) forms. In this work, we mainly explored the effect of different Span surfactants (Span 20, Span 40, Span 60, and Span 80) on the properties of fish oil-loaded sodium alginate/Span-stabilized emulsions and calcium alginate/Span capsules. For emulsions, different Span surfactants induced different initial droplet sizes and emulsion creaming stability. The emulsifying stability of Span surfactants for sodium alginate/Span-stabilized emulsions was: Span 40 < Span 20 < Span 80 < Span 60. For capsules, a Span addition could decrease the water content and change the particle morphologies. Compared with the calcium alginate capsule (12.2 %), the Span 60 addition increased the fish oil loading ratio (20.2 %). Moreover, the addition of Span 20, Span 60, and Span 80 decreased the production of primary lipid hydroperoxides of the capsules. Span surfactants had different effects on the free fatty acid release of calcium alginate capsules in the gastrointestinal digestion process, such that: Span 40 > Span 80 > control > Span 20 > Span 60. This work suggests that Span surfactants are capable of adjusting and optimizing the properties of emulsions and capsules for potential food applications.