Properties of composite film based on bigeye snapper surimi protein and lipids

Lipids were incorporated into bigeye snapper surimi protein films through emulsification using Tween-20 as a surfactant to form protein/lipid composite films. The effects of lipid types (palm oil, butter or shortening) and concentrations (0-100% glycerol substitution) on film properties were investigated. Additionof lipids up to 75% glycerol substitution resulted in the improved water vapor barrier, lowered tensile strength (TS) and increased elongation at break (EAB) of the composite film (P<0.05). However, an increase in TS was observed with increasing lipid concentration, plausibly caused by increasing protein aggregation in film matrix. Transparency of films was decreased with increasing lipid concentrations used (P<0.05), especially for those added with solid lipids. Generally, the mechanical properties and water resistance of surimi protein films incorporated with palm oil were superior to those modified with butter or shortening. An increase in Tween-20, nonionic surfactant, might be associated with the decrease in non-disulfide covalent cross-links in the film. Scanning electron microscopic study revealed that dispersion of palm oil in the film was more uniform than that of butter and shortening. This might contribute to the varying properties of resulting films.