Effect of the mixtures of squid ink tyrosinase and tannic acid on properties of sardine surimi gel

Effect of the mixture of squid ink tyrosinase (SIT) at 300 and 500 U/g protein and tannic acid (TA) at 0.5 and 1 % (based on protein) with different reaction times (90 and 180 min) on gel properties of sardine surimi was investigated. Surimi gel incorporated with mixture of SIT (500 U/g protein) and 1 % TA with a reaction time of 90 min had the highest breaking force and deformation (p < 0.05), in which the increases by 29.3 % and 11.9 % were observed, in comparison with the control. However, gels added with SIT/TA mixture had the lower whiteness, compared to the control (p < 0.05). Gel added with SIT/TA mixture showed more compact and finer network with higher connectivity of strands, compared to the control. This was coincidental with decreased expressible moisture content. Based on sensory evaluation, the highest overall likeness score was found in gel added with the mixture of SIT (500 U/g protein) and 1 % TA (p < 0.05). Therefore the mixture of tyrosinase from squid ink and tannic acid could be used as additives to improve the properties of surimi gel.