Abstract: In order to improve the quality of freshwater fish surimi products, the effect of adding 4% of native cassava starch or modified cassava starch (starch phosphate, hydroxypropyl starch, acetylated distarch phosphate, or a 3:2 (m/m) mixture of acetylated distarch phosphate and hydroxypropyl starch) on improving the quality of surimi gels prepared from frozen tilapia surimi was investigated by measuring texture, rheological properties, water-holding capacity, moisture distribution and microstructure. The results showed that compared with the control group, the whiteness of tilapia surimi gels with native and modified cassava starch significantly decreased (P < 0.05), the gel strength, hardness, chewiness and water-holding capacity significantly increased (P < 0.05), the percentage of cooking loss decreased (P < 0.05), the bound water content increased (P < 0.05), and the microstructure was more uniform and compact. The best gel texture and highest water-holding capacity were achieved with the addition of the modified starch mixture. Low-field magnetic resonance imaging and optical microscopy results showed that both native and modified cassava starch could effectively keep the water in the surimi gel. The native and modified starch could absorb water and expand during the heating process, concentrating and filling the surimi gel network structure, and the surimi gel structure with the modified starch mixture was most compact and uniform. Therefore, addition of acetylated distarch phosphate-hydroxypropyl starch mixture can effectively improve the quality of tilapia surimi products, which will provide theoretical support for the development of freshwater fish surimi products.

Key words: tilapia surimi; starch; texture properties; water-holding capacity; microstructure