Transparent biodegradable films were successfully prepared from fish water soluble proteins (FWSP) in our laboratory, but FWSP films generally have the inferior mechanical and water vapor barrier properties. The objective of this study was to improve physical properties of FWSP using treatments with dialdehyde starch (DAS) and/or sodium dodecyl sulfate (SDS). Film forming solution containing 3% FWSP from blue marlin (Makaira mazara) flesh was mixed with DAS (2.5, 5, 7.5 and 10% of FWSP) or SDS (10, 20, 30 and 40% of FWSP) or the combination of DAS with SDS (2.5/40, 5/40, 7. 5/ 40 and 10/40% of FWSP) prior to pH adjustment to 10.5. Glycerol at a level of 50% of FWSP was used as a plasticizer. Film forming solution was cast and dried at 25 C, 50% relative humidity for 24 h. Increasing DAS concentration enhanced tensile strength (TS) of FWSP films, while increasing SDS concentration improved elongation at break (EAB). Optimum ratios of DAS/SDS were 5/40 or 7.5/40%, which increased EAB by 82 or 56 % with d e creasing water vapor permeability (WVP) by 41 or 26% , respectively. Thus, biodegradable FWSP films with various strength and flexibility were successfully prepared by combining DAS with SDS.

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