Properties of a protein-based film from round scad (Decapterus maruadsi) as affected by muscle types and washing

The effects of muscle types and washing on the properties of a protein-based film from round scad (Decapterus maruadsi) mince were investigated. Washing resulted in an increase in the protein content with a coincidental decrease in the fat content of mince, especially from whole muscle and dark muscle. Among all types of muscle (ordinary, dark and whole muscle), the ordinary muscle rendered the film with the highest tensile strength (TS) (p < 0.05). TS of films from washed mince was greater than that of films prepared from unwashed mince for the same type of muscle used (p < 0.05). Nevertheless, the water vapour permeability (WVP) of films from unwashed mince was higher than that of films prepared from washed mince (p < 0.05). Films from washed mince had higher solubility but lower protein solubility than those from unwashed mince (p < 0.05). Regardless of washing, films from ordinary muscle showed the highest L∗-value (p < 0.05). However, films prepared from dark muscle were more yellowish than those prepared from other muscles, as evidenced by the greater b∗-value. Films from round scad mince and washed mince had excellent barrier properties to UV light at the wavelength of 200–280 nm. Generally, films from round scad mince had a lower preventive effect on visible light transmission than had those from unwashed mince. Among films from all muscles, those prepared from dark muscle exhibited the highest barrier to visible light transmission (p < 0.05). Therefore, the properties of films from round scad meat were governed by muscle type as well as by washing.