Application of γ-cyclodextrin-lysozyme as host materials for encapsulation of curcumin: characterization, stability, and controlled release properties.

BACKGROUND: In this study, a safe and relatively stable γ-cyclodextrin-lysozyme (γ-CD-Lys) was synthesized using epichlorohydrin as the cross-linking agent, and curcumin was successfully encapsulated in γ-CD-Lys. RESULTS: The successful Lys grafting onto γ-CD can be demonstrated by a high grafting ratio (79.02%) and was further confirmed by Fourier transform infrared (FTIR) band shifts and the new signal obtained at δ 2.75 in proton nuclear magnetic resonance. The encapsulation efficiency value of γ-CD-Lys was 76.74%, and the successful encapsulation of curcumin into γ-CD-Lys was confirmed by crystal structure change, increased melting point, and FTIR band shifts. The intermolecular bonds results suggested that associative forces between curcumin and γ-CD-Lys were electrostatic interaction, hydrogen bonds interaction, and hydrophobic interaction. The designed nanoparticles had excellent stability at low pH and low salt concentration. The release rate of these nanoparticles was inhibited in simulated gastric conditions, whereas it increased significantly in intestinal media. Simulated gastrointestinal digestion experiments further confirmed that nanoparticles showed higher bioaccessibility (86.05%) compared with curcumin (58.82%). CONCLUSION: Overall, our study showed that the nanoparticles were highly promising for delivering curcumin because of their enhanced functional attributes and stabilization in acid or low salt environments. Also, it was an excellent wall material for targeting hydrophobic bioactive compounds in the intestinal tract via oral administration. © 2022 Society of Chemical Industry.

Aggregation of egg white peptides (EWP) induced by proanthocyanidins: A promising fabrication strategy for EWP emulsion.

Egg-white peptides (EWP, <1 kDa) have been shown to possess various bioactive properties. However, poor emulsification of EWP limits its application in functional foods. In this study, EWP aggregation induced by proanthocyanidins (PC) contributed to the improvement of emulsion properties. The two-step binding process of PC-EWP-EWP was confirmed by isothermal titration calorimetry, fluorescence spectroscopy, surface hydrophobicity, and Fourier transform infrared spectroscopy. We found that first EWP combines with PC via hydrogen bonding and hydrophobic interactions. Next, more EWPs bind to the EWP in PC-EWP via hydrogen bonding, thereby forming PC-EWP-EWP aggregates. The aggregates (PC to EWP ratio of 1:4) reduced the surface tension (6 %) and improved the contact angle (53 %). The co-adsorption of EWP and aggregates at the O/W interface improved the contact angle, protein adsorption rate, and emulsion stability. This study establishes EWP aggregates induced by PC as an effective emulsifier, thereby expanding the application fields of EWP.

Stability of oil-in-water emulsions improved by ovalbumin-procyanidins mixture: A promising substrate with emulsifying and antioxidant activity.

The aim of this study is to develop a dual-functional ingredient with antioxidant activity and emulsification. The emulsion stability of ovalbumin (OVA) was improved by procyanidins (PC). The interactions between OVA and PC were investigated using multi-spectroscopy and molecular docking. Furthermore, the effect of the addition of the OVA-PC mixture on emulsion stability was evaluated as well. The fluorescence results showed that the quenching mechanism of PC to OVA's endogenous fluorescence was static quenching, and the binding ratio of OVA and PC was 1:1. Circular dichroism (CD) and Fourier Transform Infrared Spectrometer (FT-IR) showed that the addition of PC promoted the unfolding of OVA, and transformed the secondary structure of OVA from α-helix to ß-sheet. The main driving force of OVA and PC was hydrogen bonding, according to molecular docking analysis. Among all the samples, the stability of the emulsion of OVA-PC at a ratio of 1:30 exhibited extremely high stability and the smallest particle size. In comparison with individual OVA emulsions, the OVA-PC emulsions had excellent physical stabilities. Meanwhile, the oxidation degree of protein and oil for the OVA-PC emulsions was lower than that of the native OVA emulsion after 8-day storage. Our work provides important insights for understanding the interaction between OVA and expanding the application of OVA-PC.