Improvement of Properties of Sardine Myofibrillar Protein Films Using Squid Ink Tyrosinasein Combination with Tannic Acid

The effect of squid ink tyrosinase (SIT) and tannic acid (TA) on the properties of myofibrillar protein films from washed sardine mince was studied. The film made from film forming solution added with SIT (5 k units L-1) and TA (1 g L1) had the highest tensile strength (TS) (9.49 ± 0.11 MPa) but lowest elongation at break (EAB) (25.91 ± 1.81%) (P<0.05). The addition of mixture of SIT and TA reduced the water vapour permeability (WVP) of films (P<0.05).Fourier transform infrared (FTIR)spectra of films containing both SIT and TA showed a shift in the amide-III band to the lower wavenumberof 1230 cm-1. The decrease in myosin heavy chain (MHC) band intensity with the presence of high-molecular-weight aggregates in the film added with the mixture of SIT and TAwas observed, indicating the increased cross-linking. The films added with the mixture of SIT and TA were less transparent, compared to the control film. The microstructure studyrevealedthat the surface of films added with only SIT or the mixture of SIT and TA became slightly rougher. Thus, the use of SIT in conjunction with TA could improve mechanical property and water barrier property of resulting film.