Characteristics of film based on protein isolate from red tilapia muscle with negligible yellow discoloration.

The properties of film from fish protein isolate (FPI) prepared by prior washing followed by alkaline solubilization process (ASP) from red tilapia muscle were monitored during the storage of 20 days at 50% RH and 25°C, in comparison with those of films from washed mince. Lipid, heme iron and non-heme iron contents in FPI were decreased by 98.8, 36.8 and 91.9%, respectively in comparison with those of washed mince (p<0.05). Films from FPI had higher tensile strength (TS) and elongation at break (EAB) than those from washed mince for both pH (3 and 11) used for film preparation (p<0.05). Film from FPI at pH 3 showed the highest TS, while that from washed mince at pH 11 had the lowest TS (p<0.05). Nevertheless, films from FPI had higher WVP than those from washed mince for both pH used (p<0.05). At the same pH used for film preparation (3 or 11), films from FPI showed the lower TBARS values than those from washed mince (p<0.05). Nevertheless, films from both FPI and washed mince had the higher TBARS values when pH 3 was used for film preparation, compared with pH 11 (p<0.05). Among all films, those from FPI prepared at pH 3 had the highest transparency and no yellow discoloration was observed during the storage of 20 days, in comparison with other films (p<0.05). Conversely, film from washed mince prepared at pH 3 had the higher increase in b*-value and ΔE*-value than other films. Therefore, FPI could serve as a potential material for film preparation with lower contents of lipid and prooxidants, thereby preventing the yellow discoloration of the fish myofibrillar protein-based film during extended storage.