Soybean protein isolate hydrolysates-liposomes interactions under oxidation: Mechanistic insights into system stability

Soybean protein isolate hydrolysates (SPIHs) prepared through proteolysis by pepsin/trypsin/alcalase and flavourzyme (termed PF, TF and AF) were added to liposomes, and SPIHs-liposomes interactions were investigated using techniques including synchronous fluorescence, circular dichroism and fourier transform infrared spectroscopy. The presence of SPIHs in liposomes was realized via electrostatic force, hydrophobic effect and hydrogen bonding, causing enhanced liposomal rigidity. SPIHs inhibited lipid peroxidation in a dose-dependent manner (best dose: 0.50 mg/mL; best SPIH: AF). The conformational changes of AF responding to lipid oxidation and interaction with liposomes differed slightly from TF and PF. Antioxidative and hydrophobic amino acids (Tyr and Trp) in SPIHs played important roles in stabilizing liposomal systems under oxidation (TF functioned through suppressing the increase of liposomal size). SPIHs-liposomes interactions and lipid peroxidation favored high hydrophobicity, beta-structure (beta-helices, beta-sheet and beta-turn) and disordered structure. This research extends the knowledge for developing liposome-containing food systems with high stability and nutritional value.

Automated summary

The study found that SPIHs can enhance the rigidity of liposomes through electrostatic force, hydrophobic effect, and hydrogen bonding, while inhibiting lipid peroxidation in a dose-dependent manner. Antioxidative and hydrophobic amino acids in SPIHs play important roles in stabilizing liposomal systems.