Potential of Fish Skin Gelatin for Dough Rheology and Quality Optimization of Extruded Gluten-Free Noodles

• Fish gelatin and pregelatinized flour were key factors shaping dough properties. • Optimal GF noodle formula: 24.5% pregelatinized flour, 4.7% gelatin, 0.5% TGase. • Optimized noodles showed improved nutrients, bioactivity, and microstructure. • Fish gelatin significantly enhanced antioxidant activity and color scores. • Fish gelatin boosted physicochemical quality and consumer acceptance of GF noodles The objective of this study was to examine the effects of fish gelatin (1-5%), in combination with pregelatinized flour (10-30%), and transglutaminase (TGase) (0.1-1.0%) on the rheological properties of dough, on the physicochemical and antioxidant properties, as well as consumer acceptance of rice-based gluten-free (GF) noodles. Using response surface methodology (RSM) with a Box-Behnken design, the quadratic models effectively (high R² values) explained the effects and interactions of these three independent factors on the dependent variable. Fish skin gelatin and pregelatinized flour were the main factors influencing dough rheological properties. All three factors significantly influenced the physical properties of GF noodles. Antioxidant activities and color acceptability score by fish gelatin, while springiness acceptability score was affected by the combined addition of fish gelatin and pregelatinized flour. Multi-optimization showed the optimal levels of the three factors, as 4.7% fish gelatin (code value +0.85), 24.5% pregelatinized flour (code value +0.47), and 0.5% TGase (code value -0.17). These optimized noodles showed 15% cooking loss, 222% cooking weight, and 122% water absorption, and improved nutritional values, including higher total amino acid content and increased levels of several essential and non-essential amino acids. The IC 50 values for DPPH, ABTS radical scavenging activities, and FRAP were 0.83 g/mL, 1.05 g/mL, and 0.006 mmol FeSO₄/g, respectively. Consumer acceptability score ranged from slightly to moderately acceptable. The microstructural morphology, analyzed by CLSM, SEM, TEM, and FTIR, revealed enhanced interactions between proteins and starch in the optimized noodles. Overall, fish gelatin seems promising for future application in GF noodles.