Influence of Red Seaweed Polysaccharides on Gel Properties and In Vitro Antioxidants of Surimi Product Fish Balls

The effects of red seaweed polysaccharides, e.g., carrageenan, agar gum, <i>Porphyra haitanensis</i> polysaccharide (PHP), and <i>Bangia fusco-purpurea</i> polysaccharide (BFP), on the physicochemical properties and <i>in vitro</i> antioxidants of silver carp surimi gels were studied. Adding appropriate concentrations of carrageenan and agar gum increased hydrophobic interactions, resulting in a denser and more uniform gel network as observed by SEM, and shortened the relaxation time of the fish balls, thus improving the gel strength and hardness of the products. When adding 0.75% carrageenan and 0.50% agar gum, the gel strength of the fish balls reached its maximum value, increasing by approximately 28.84% and 12.08%, respectively, compared to the control group (<i>p</i> < 0.05). However, with the over-addition of PHP and BFP, the cross-linking of surimi proteins was inhibited, resulting in a decrease in gel strength and hardness. In addition, red seaweed polysaccharide improved the free radical scavenging activity of fish balls, especially fish balls with 0.50% and 1.00% PHP and BFP exhibited better free radical scavenging activity after digestion. These findings offer insights and actionable strategies for enhancing the gel properties and function of surimi products with seaweed polysaccharides.