Optimal conditions for extracting gelatin and preparing gelatin film from horse mackerel scale, such as extraction temperature and time, as well as the protein concentration of film-forming solutions were investigated. Yields of extracted gelatin at 70 °C, 80 °C, and 90 °C for 15 min to 3 h were 1.08% to 3.45%, depending on the extraction conditions. Among the various extraction times and temperatures, the film from gelatin extracted at 70 °C for 1 h showed the highest tensile strength and elongation at break. Horse mackerel scale gelatin film showed the greatly low water vapor permeability (WVP) compared with mammalian or fish gelatin films, maybe due to its containing a slightly higher level of hydrophobic amino acids (total 653 residues per 1000 residues) than that of mammalian, cold-water fish and warm-water fish gelatins. Gelatin films from different preparation conditions showed excellent UV barrier properties at wavelength of 200 nm, although the films were transparent at visible wavelength. As a consequence, it can be suggested that gelatin film from horse mackerel scale extracted at 70 °C for 1 h can be applied to food packaging material due to its lowest WVP value and excellent UV barrier properties.

Properties of gelatin film derived from horse mackerel scales can be improved by adding of phenolic compounds. Phenolic compounds containing a large number of hydroxyl groups should be selected to enhance physical properties of the gelatin film. A biodegradable film prepared from horse mackerel gelatin incorporated with phenolic compounds, which has good physical properties and antioxidant properties, can solve environmental problems caused by synthetic plastic materials.

The eŠect of NaCl and organic salts (Na-citrate, Na-acetate, Na-benzoate and Na-tartrate) on the properties of surimi-basedˆlms prepared from Alaska pollack frozen surimi was investigated. The solubility of the surimi protein increased upon addition of the salts. Na-citrate and NaCl appeared to have the highest ability to dissolve the protein among the salts. The surimi were dissolved into salt solutions at neutral pH and dried (25±0.5°C and 50±2 RH) to form theˆlm. Physical properties and SDS-PAGE of the resultantˆlms were determined. Thê lms with Na-tartrate and NaCl were crystallized during the drying process. By adding the salts, tensile strength (TS), elongation at break (EAB), and water vapor permeability (WVP) of theˆlm were increased while transparency of theˆlm was decreased (became transparent) compared to those of the control (no salts added). SDS-PAGE indicated that the protein patterns of theˆlm were not signiˆcantly diŠerent among the salt types used as a solubilizer. Na-citrate showed the highest eŠects on increasing TS and decreasing transparency of theˆlm among the salts used in the study.