Optimization of extrusion parameters for germinated Tubtim Chum Phae rice flour-based extruded snack fortified with silkworm pupae using response surface methodology

• Developed a healthy extruded snack using germinated Tubtim Chum Phae rice flour and silkworm pupae powder. • The fortified snack is rich in protein, GABA, phenolic compounds, and antioxidants. • Fortifying extruded snacks with silkworm pupae powder significantly improved the amino acid profile, particularly methionine, valine, and lysine. • This innovation addresses nutritional deficiencies while contributing to environmental sustainability. This study optimized the extrusion parameters using a co-rotating twin-screw extruder for developing a fortified nutritional snack by incorporating silkworm pupae powder (SWP) into germinated Tubtim Chum Phae rice flour (GRF). Response surface methodology (RSM) with a central composite design (CCD) was employed to evaluate the effects of SWP content (10–30%), screw speed (SC; 350–420 rpm), and feed moisture (FM; 18–24%) on the quality attributes of the snack. The responses analyzed included expansion ratio (ER), hardness, protein content, γ-aminobutyric acid (GABA), total phenolic content (TPC), total flavonoid content (TFC), antioxidant activity (AOA), and overall liking (OL). The results showed that increasing SWP decreased ER and OL but significantly increased hardness, protein, TPC, TFC, and AOA. Higher SC reduced protein, GABA, TPC, and AOA, whereas higher FM negatively impacted hardness, protein, GABA, and OL. The optimized conditions of 24% SWP, 397 rpm SC, and 18% FM, the ER, hardness, and protein content of the extrudates were 1.97%, 5.22 kg, and 21.55%, respectively. The corresponding GABA, TPC, TFC, and AOA values were 19.27 mg/100 g, 3,294 mg GAE/100 g, 331.50 mg QE/100 g, and 211.14 mg TE/100 g, respectively, with an OL score of 6.9. The prototype snack had response values close to the predicted values and had higher protein content, TPC, TFC, AOA, and total essential amino acids compared to GRF. These findings indicate that incorporating SWP into GRF improves the nutritional quality of extruded snacks, supporting their potential as functional foods with health benefits.