Enhancement of Gel Properties of Sardine Surimi using Squid Ink Tyrosinase in Combination with Coconut Husk Extract

Squid ink tyrosinase (SIT) at levels of 300 and 500 KU kg(-1) protein in combination with ethanolic extract of coconut husk (EEC) at concentrations of 1 and 1.25 g kg(-1) protein was added into sardine surimi and the resulting gels were examined. The use of SIT (500 KU kg(-1) protein) and EEC (1.25 g kg(-1) protein) yielded the gel with the highest breaking force and deformation (p < 0.05). Nevertheless, the expressible moisture content and whiteness scores were markedly decreased. Protein cross-linking of surimi gels increased as evidenced by the decreased band intensity of myosin heavy chain (MHC). This coincided with the increased storage modulus (G'). Based on microstructure study, finer and more compact structure of surimi gels added with both SIT and EEC were obtained, compared to the control. Thus, SIT in conjunction with EEC could be used as the novel surimi gel strengthener.