Preparation and structural characterization of allicin and whey protein isolate conjugates

Studies have shown that the disulfide bond conjugate formed by allicin (TS) and whey protein isolate (WPI) could significantly enhance the stability of TS. Based on this, the reaction conditions of TS and WPI were optimized, and the influence of binding rate on the molecular structure, rheological properties and microstructure of the conjugates was as well examined. The results showed that the optimal conditions for the binding of TS to WPI were: temperature 25 °C, TSmol: sulfhydrylmol = 2, pH 4, and time 30 min. With increased binding rate, surface hydrophobicity of the conjugates increased, whilst fluorescence intensity decreased. TS increased the degree of dispersion of WPI, but decreased the probability of interaction between molecules and the viscosity of the conjugates. After WPI was bound with TS, the macromolecular components decreased and the micromolecular components increased. TS-WPI conjugates were distributed in sheet-like shape, and the spherical structure of the WPI was lost. The diameter of the aggregates for 61% binding rate conjugate (following ultrasound treatment) was smaller and the distribution was more dispersed. In summary, characterization of TS-WPI conjugates could aid it applicability in the food industry, and broaden the application range of TS.