Valorising Defatted Soy Flour into High-Moisture Textured Vegetable Protein by Single-Screw Cooking Extrusion

Domas Galih Patria (Department of Food Science, College of Agriculture, National Pingtung University of Science and Technology, Pingtung, Taiwan/Department of Agro-Industrial Technology, Faculty of Agro-Industrial and Biosystem Technology, Universitas Brawijaya, Malang,)
Cindytia Selvina Bernas (Department of Food Science, College of Agriculture, National Pingtung University of Science and Technology, Pingtung, Taiwan)
Annur Ahadi Abdillah (Study Program of Fish Processing, Faculty of Fisheries and Marine, Universitas Airlangga, Surabaya, Indonesia/Research Group of Post-harvest, Processing Technology and Bioproducts, Faculty of Fisheries and Marine, Universitas Airlangga, Surabaya, Ind)
Dodyk Pranowo (Department of Agro-Industrial Technology, Faculty of Agro-Industrial and Biosystem Technology, Universitas Brawijaya, Malang, Indonesia)
Jenshinn Lin (Department of Food Science, College of Agriculture, National Pingtung University of Science and Technology, Pingtung, Taiwan)

SRIWIJAYA JOURNAL OF ENVIRONMENT
Vol. 11 No. 1 (2026): Sriwijaya Journal of Environment

Background: Conventional meat production is approaching ecological limits, motivating sustainable, circular-economy protein alternatives. Defatted soy flour (DSF), a low-value co-product of soybean oil extraction, is protein-dense, fibre-rich and abundant in Indonesia, yet its use in high-moisture textured vegetable protein (HM-TVP) is unexplored. Objective: To valorise DSF into HM-TVP by single-screw cooking extrusion and determine how substitution ratio and screw speed govern its functional, proximate, textural, colour, microstructural, isoflavone and sensory quality. Methods: Three DSF:pea-protein-isolate (PPI) ratios (0:70, 15:55, 30:40) and three screw speeds (30, 40, 50 rpm) were examined in a 3×3 factorial design (n=3) at the Food Pilot Plant, National Pingtung University of Science and Technology (NPUST), Pingtung, Taiwan. Water absorption/solubility indices, proximate composition, texture-profile analysis, HunterLab colour, SEM microstructure, RP-C18 HPLC isoflavones and hedonic scores were determined, and data were analysed by two-way ANOVA with Tukey HSD, effect sizes (η²), Pearson correlation and principal component analysis. Results: DSF substitution dominated most responses (partial η²=0.57–0.99, p<0.001). Raising DSF from 0 to 30% increased water absorption index (1.92→3.43 g/g), crude fibre (2.79→6.40%), hardness (25.7→56.9 N) and chewiness, and shifted the isoflavone profile toward higher glycoside (genistin up to 1741 µg/g) and bioavailable aglycone concentrations, while reducing crude protein (77.1→63.3%), crude fat (1.86→0.93%), lightness (L* 78.1→72.4) and springiness. Higher screw speed raised water-soluble index and soluble-fibre release but lowered hardness and browning. Crude protein of all extrudates (63–77%) far exceeded the ≥50% benchmark for texturised soy products, and the 15% DSF blend at 40 rpm (D15S40) achieved the highest overall acceptability (4.10/5). Conclusion: DSF can partially replace pea/soy protein isolates in sustainable, phytonutrient-enriched meat analogues at lower cost.