Effects of the Ratio of Alaskan Pollock Surimi to Wheat Flour on the Quality Characteristics and Protein Interactions of Innovative Extruded Surimi–Flour Blends

Snack foods (e.g., extruded flour-based products) are widely favored by consumers because of their convenience, affordability, and time-saving attributes. However, with the growing demand for high-quality snacks, several challenges have emerged that hinder industry development, such as relatively underdeveloped industrial standards, limited raw material diversity (primarily starch and soy protein), and, consequently, insufficient nutritional value. In this study, a novel type of puffed snack was developed using Alaskan pollock surimi and wheat flour using extrusion puffing technology. The effects of varying ratios of surimi to wheat flour (0:10, 1:9, 2:8, 3:7, and 4:6, which served as SFBC, SFB1, SFB2, SFB3, and SFB4, respectively), on the physicochemical properties, apparent morphology, microstructure, thermal stability, and protein structure of spicy strips were systematically investigated, and the interaction between extruded protein and flour mixtures was analyzed. The results indicated that increasing the proportion of surimi led to decreases in hardness, elasticity, and chewiness, whereas the moisture content and water solubility index increased. The maximum expansion rate (202.2%) was observed in the SFB1 sample. Morphological and microstructural observations further revealed that a higher surimi content resulted in a denser internal structure and a reduced degree of puffing. The protein distribution was relatively uniform, with large pores. Moreover, increased surimi content increased the proportion of immobilized water and improved the thermal stability. These findings provide valuable insights into starch-protein-complex-based extrusion puffing technologies and contribute to the development of innovative surimi-based puffed food products.