Structure-function relationships of industrial-dried soy protein hydrolysate processing: Dual antihypertensive and antidiabetic properties with gastrointestinal-plasma stability

• Neutrase hydrolysis at 4 h biocatalysis yielded peptide <3 kDa. • Spray-drying enhanced random coil structure, improving enzyme accessibility. • Spray-drying optimized peptide structure for enhanced bioactivity and solubility. • Post GI digestion, bioactivity increased with more peptides released <400 Da. • Post plasma digestion, the peptide exhibited dual ACE and DPP-IV inhibition. This first comparative study presents a novel industrial approach for producing dual antihypertensive and antidiabetic bioactive peptides from soy protein through optimized processing technologies. Neutrase-catalyzed hydrolysis was systematically optimized, achieving maximum peptide yield (87.5%) with optimal molecular weight distribution favoring bioactive fragments <400 Da. This study uniquely compares industrial-scale drying methods—spray-drying versus freeze-drying—for their effects on bioactive peptide structure and functionality, addressing a critical knowledge gap in scalable production. Spray-dried soy protein hydrolysates (SD-SPH) demonstrated enhanced physicochemical properties including superior solubility (97.17% vs 87.81%) and improved lightness (L* = 89.37 vs 78.17), critical parameters for food manufacturing applications. Critically, Fourier transform infrared (FTIR) spectroscopy analysis revealed that spray-drying induced favorable structural modifications, increasing random coil content (37.70% vs 23.32%), which enhanced enzyme accessibility and bioactivity retention—a structure-function relationship not previously established for dual-functional peptides. Both formulations exhibited comparable initial dual antihypertensive and antidiabetic activities with ACE inhibition (IC₅₀: 0.51-0.57 mg/mL) and DPP-IV inhibition (IC₅₀: 1.07-1.13 mg/mL). Notably, simulated digestion studies demonstrated enhanced gastrointestinal-plasma stability with increased bioactivities post-digestion, correlating with higher proportions of small bioavailable peptides (70.32% <400 Da)—the first evidence of bioactivity enhancement through digestive processing in spray-dried soy peptides. Principal component analysis confirmed distinct structural clustering between drying methods, establishing clear structure-function relationships. This biocatalytic processing approach provides the first scalable, cost-effective industrial strategy for producing stable, dual-functional ingredients targeting cardiovascular and metabolic health applications simultaneously, addressing industrial demands for value-added protein hydrolysates with enhanced bioactivity and processing characteristics.