SUMMARY: As a means of effective utilization of fish water‐soluble proteins (FWSP), which are mostly discarded into the waste water of seafood processing plants, the development and characterization of edible films from FWSP of blue marlin meat were investigated. The film‐forming solutions were prepared from 3% FWSP solutions at pH 10 with 1.5% glycerol as a plasticizer, followed by heating at 70°C for 15 min. Edible films were successfully prepared by drying the film‐forming solutions at 25°C for 20 h. It was revealed that FWSP had to be denatured somehow to unfold the protein structure, and the interaction of FWSP molecules, particularly through disulfide linkages, was attributed to the formation of films. Transparent edible films thus formed had better flexibility and lower water vapor permeability compared with most of the other protein films.

SUMMARY: The effects of type and concentration of plasticizers on the mechanical properties and water vapor permeability (WVP) of edible films from fish water‐soluble proteins (FWSP) were investigated. Among plasticizers investigated in the present study, glycerol and polyethylene glycol (PEG) gave the films flexible structure. As the concentration of glycerol increased, tensile strength (TS) decreased with concomitant increase of elongation at break (EAB) and WVP. In contrast, PEG showed more marked influence on TS than on EAB. The FWSP films containing a glycerol : PEG ratio of 2 : 1 exhibited the maximum EAB value, while the increased ratio of glycerol to PEG reduced the water vapor barrier properties of FWSP films. It was revealed that the mechanical properties as well as WVP of edible films prepared from FWSP can be modified by the combination of glycerol and PEG.