Properties and microstructure of protein-based film from round scad (Decapterus maruadsi) muscle as affected by palm oil and chitosan incorporation

The properties of protein-based film prepared from round scad (Decapterus maruadsi) muscle in the absence and the presence of palm oil and/or chitosan were investigated. Films added with 25% palm oil (as glycerol substitiution) had the slight decrease in water vapor permeability (WVP) and elongation at break (EAB) (p < 0.05). WVP and tensile strength (TS) of films increased but EAB decreased when 10-40% chitosan (as protein substitution) was incorporated (p < 0.05). Hydrophobic interactions and hydrogen bonds, together with disulfide and non-disulfide covalent bonds, played an important role in stabilizing the film matrix. The a* and b*-values increased with increasing chitosan levels (p < 0.05). Films added with chitosan were less transparent and had the lowered transmission in the visible range. The incorporation of 25% palm oil and 40% chitosan yielded the films with the improved TS but decreased water vapor barrier property. Apart from film strengthening effect, chitosan inconjunction with Tween-20 most likely functioned as the emulsifier/stabilizer in film forming solution containing palm oil.