Study of Genipin Behavior in Neutral and Acidic Aqueous Solutions at Elevated Temperatures

Abstract

Genipin is known to polymerize under basic conditions, and the obtained genipin oligomers might have an impact on the chemical and physical properties of the crosslinked materials. In this study, we intend to mimic the experimental condition in which genipin is used as a chemical crosslinker. We focus on the degradation of genipin at neutral and slightly acidic conditions using NMR. We report genipin polymerization at neutral and acidic conditions. Unlike dialdehyde crosslinkers, genipin requires heating to promote its crosslinking activity. We found that elevated temperatures enhance the degradation of genipin and promote its polymerization.

Enhancing the Thermal Stability of Zein Particle-Stabilized Aeratable Emulsions Through Genipin-Protein Cross-Linking and Its Possible Mechanism of Action

“…27 Under neutral and acidic pH conditions, heating enhances intermolecular polymerization of GP. 17 When raw particles are suspended in a dilute solution environment, each individual particle can come into full contact with the GP present in the solution, allowing for intraparticle cross-linking reactions to occur. On the other hand, interparticle cross-linking reactions only take place during collisions in Brownian motion.…”

“…Dimerized GP is known to link peptide chains with distances up to 1.6–2.5 nm, and it readily forms intramolecular or short-range intermolecular cross-links within a protein molecule or between two adjacent protein molecules . Under neutral and acidic pH conditions, heating enhances intermolecular polymerization of GP . When raw particles are suspended in a dilute solution environment, each individual particle can come into full contact with the GP present in the solution, allowing for intraparticle cross-linking reactions to occur.…”

“…Upon heating of the particles, the DXL of the H-P x samples increased significantly to approximately 27–70% ( P < 0.05). This suggests that the presence of cross-linking involving primary amino groups in proteins triggered by non-GP factors (e.g., Schiff base in H-P 0 ) as well as thermally induced GP-protein cross-linking in the samples after the heating treatment. , However, particles recovered from heated emulsions (H-IP x ) may be more reflective of the effects of the heating in the emulsion environment. Although the DXL of H-IP x was all significantly higher than that of corresponding unheated raw particles (P x ) ( P < 0.05) and also showed a positive correlation with the amount of GP added.…”

“…Intramolecular or intermolecular cross-linking of proteins is produced by short chain copolymer of GP, or by the nucleophilic attack of a second amine group on the carbonyl group of the methyl ester to give an amide linkage. 16,17 Currently, GP has been employed for cross-linking hydrophilic protein particles such as hempseeds protein, β-lactoglobulin, ginkgo seed protein or their complex particles, and improving the thermal stability or functionality of related protein emulsions. 14,18,19 In addition, within the emulsion family, some emulsion systems with inflatable air have a variety of applications in food, personal care, and home care.…”

“…A heterocyclic compound of GP linked to the residues containing primary amine groups in protein via the primary amine group is thereby formed. Intramolecular or intermolecular cross-linking of proteins is produced by short chain copolymer of GP, or by the nucleophilic attack of a second amine group on the carbonyl group of the methyl ester to give an amide linkage. , Currently, GP has been employed for cross-linking hydrophilic protein particles such as hempseeds protein, β-lactoglobulin, ginkgo seed protein or their complex particles, and improving the thermal stability or functionality of related protein emulsions. ,, In addition, within the emulsion family, some emulsion systems with inflatable air have a variety of applications in food, personal care, and home care . However, it is unknown about the cross-linking properties of GP with zein (as a typical hydrophobic protein) or its particles, as well as the effect of cross-linking products on the thermal stability of aeratable O/W emulsions.…”