Blanching pretreatment enhances puffing quality of rainbow trout (Oncorhynchus mykiss) skin by modifying protein structure and water distribution.

The high production of farmed rainbow trout (Oncorhynchus mykiss) generates large amounts of underutilized by-products, particularly skin. Its dense structure restricts water mobility, resulting in a hard texture and poor crispness in puffed products. To address this issue, blanching was employed as an efficient and economical pretreatment to modify protein structure and regulate water distribution. By combining pre-drying with puffing, intact puffed fish skin was obtained. Blanching at 60 °C yielded the highest expansion ratio (202.56 ± 3.51%) and optimal crispness (0.26 ± 0.01 mm). Critically, by correlating blanching-induced protein structural changes, water redistribution, and key quality attributes (expansion ratio, texture, and pore architecture), this work revealed the protein-water regulation mechanism responsible for the enhanced puffing performance. These findings offer theoretical and technical guidance for directly converting intact aquatic by-products into high-quality, protein-rich puffed foods.