Does a plant protein substitution strategy endow hybrid plant protein/surimi gels with nutritional quality surpassing pure meat?

Although the inferior protein bioavailability of purely plant-based meat alternatives relative to animal-derived meats is well-established, the digestion and absorption characteristics of hybrid animal-plant protein products formulated through partial substitution remain poorly characterized. To address this, the hybrid surimi/plant protein (HSP) gels crosslinked by transglutaminase (TGase) with uniform gel strength were prepared by modulating TG dosage (wheat: 18 U/100 g surimi; soybean and rice: 9 U/100 g; pea: 6 U/100 g). In vitro gastrointestinal digestion revealed no significant differences (P > 0.05) in protein or dry matter digestibility (61.50%-69.15%) across groups. However, the legume-based composites (soybean and pea) exhibited significantly higher digestion rate constants (k = 0.029 min⁻¹) than cereal-based composites (k = 0.024 min⁻¹), alongside reduced half-digestion times (t_0.5 = 163.3 min vs. 170.9 min), indicating enhanced digestibility. Particle size distribution analysis showed a significant reduction (P < 0.05) in pea protein gel particle size after pepsin digestion, whereas wheat protein gels retained larger residual particles (D₅₀ = 27.48 μm) post-pancreatin digestion, suggesting greater hydrolytic resistance. Electrophoresis confirmed digestion products were predominantly <20 kDa fragments. Notably, pea protein digests exhibited potent antioxidant activity, strongly correlated with six high-abundance antioxidant peptides identified by mass spectrometry: TLEDQLSEIK, VLNAGVIPEGQF, DAGDGVTHNVPVYEG, VGLLHSQNTSL, LASLYPAVVEDTTK, and LLVVPQNF. Collectively, partial plant protein substitution conferred favorable protein digestibility and nutrient acquisition potential to hybrid surimi gels, with pea protein emerging as particularly valuable for enhancing nutritional functionality in meat-reduced formulations.