Properties of Celery Soluble Dietary Fiber and Its Synergistic Effect with TG Enzyme to Improve Gel Properties of Nemipterus virgatus Unrinsed Surimi

Addressing the issue of poor gelation and easy deterioration of unrinsed surimi, the basic properties (average particle size, solubility, water holding capacity, oil holding capacity, swelling capacity), antioxidant properties (DPPH radical scavenging activity, ·OH scavenging activity, reducing power) and structural properties (infrared spectroscopy, microstructure) of celery soluble dietary fibers (SDF), were determined after extraction. The effects of different amounts of SDF (0, 0.1%, 0.3%, 0.5%, 0.7%, 0.9%) and TGase on the gelation properties (water holding capacity, steaming loss, moisture distribution, gel strength, hardness, elasticity, adhesion, chewiness, microstructure) of unrinsed surimi were studied. The results showed that the average particle size of SDF was 11.35 μm, compared with the control group, the solubility, water-holding capacity, oil-holding capacity and swelling capacity of SDF were more improved, and it had a degree of antioxidant capacity, and it was arranged in a large and loose space. With the addition of SDF and TGase, the water holding capacity, gel strength and texture of unrinsed surimi gel showed a trend of increasing and then decreasing, however, the change in steaming loss was first decreased and then increased, all of which reached the maximum or minimum in the TG-UW-0.5%, at this point, the water holding capacity was 78.07%, the steaming loss was 6.65%, the free water content on the surface was 0.95%, and the gel strength was 288.95 g·cm, and the hardness, elasticity, gumminess and chewiness were 3485.87 g, 0.83, 1891.19, and 1565.33 g, respectively. The surface of surimi gel showed uniformity and denseness with good gelation properties. The synergistic effect of SDF and TGase in improving the gel properties of unrinsed surimi provides a theoretical basis for the application of both in unrinsed surimi products and the development of low-fat surimi products.