Haibo Shi,Ruyi Zhang,Jiabao Zheng,Xianqi Yao,Wei Wang,Igor Tomasevic,Weizheng Sun
The effects of NaCl partially substituted by KCl, MgCl 2 , and KCl/MgCl 2 on the gel characteristics, oral mastication, and in vitro gastric digestion of myofibrillar protein (MP) gel were investigated. The results indicated that partial substitution of NaCl by KCl or MgCl 2 did not cause obvious deterioration of gel properties within 30 % substitution levels. MgCl 2 substitution significantly increased the surface hydrophobicity of MP, and formed homogeneous network structure for effective limitation of moisture loss. The MgCl 2 -substituted gel exhibited relatively lower viscosity and hardness for better swallowing. The high pepsin diffusivity in MgCl 2 -substituted gel (59.57 ± 4.28 μm 2 /s, 30 %-Mg group) improved protein hydrolysis, and produced more shorter peptides due to the loose and relatively uniform structure compared to those of the gels only containing NaCl and partial KCl. Therefore, the changes of textural parameters, microstructure, and water mobility in sodium-reduced gel with different substitution levels could influence the subsequent gastric digestion characteristics.
This study investigated the interactions between pepsin (PEP) and the organophosphite antioxidant Irgafos 168 (I 168), its metabolite 2,4-di-tert-butylphenol (24DP), focusing on structural, functional, and antioxidant implications. UV–Vis absorption spectra, fluorescence lifetimes and Stern-Volmer quenching analyses show that I 168/24DP statically bursts PEP with high binding affinity. Thermodynamic parameters, molecular docking analyses and molecular dynamics simulations (e.g. RMSD, Rg) indicate that the spontaneous formation of the stable complexes is mainly driven by van der Waals forces and hydrophobic interactions. I 168 exhibited higher pepsin inhibition (6.97 %–27.51 %) than 24DP (5.04 %–19.29 %), with dose-dependent suppression linked to altered catalytic residue accessibility (e.g., Asp32/Asp215, Tyr75) and disrupted proton transfer efficiency. Structural analyses revealed I 168 increased PEP's flexibility and hydrophobic residue exposure, while 24DP enhanced rigidity and compactness. Antioxidant assays showed 24DP's superior DPPH scavenging capacity (9.45 %–47.35 %) compared to I 168 (2.28 %–8.00 %), though PEP significantly suppressed 24DP's antioxidant efficacy. These findings underscore the necessity of evaluating both parent compounds and metabolites in safety assessments, as metabolic processes retained biological impacts on enzymatic and antioxidant functions. The study provides critical insights into the molecular mechanisms of antioxidant-induced enzyme inhibition and highlights risks to digestive health and food safety.
危险品化学品经营许可证（带存储）