Abstract: In this study, the effects of cyclodextrin (CD) structure, the amount of CD added, oil phase type and oil-to-aqueous phase ratio on the formation of oil-in-water (O/W) Pickering emulsions were investigated. The microstructures, microrheological properties and stabilities of medium-chain triglyceride (MCT)-based Pickering emulsions stabilized by α-, β- and γ-CD were systemically compared. In order to clarify the difference among CDs in emulsifying capacity, we simulated the formation of CD/MCT inclusion complexes using molecular docking. We found that both α- and β-CD exhibited good emulsion stability, which could be further enhanced with increasing the oil-to-water ratio and the amount of CD added and could also be obviously affected by oil phase type. Both α- and β-CD could reduce the O/W interfacial tension with similar effects. Thanks to its stronger interaction with MCT, α-CD could more easily form an amphiphilic supramolecule with MCT, thereby exhibiting higher emulsion stability than β-CD at a low addition amount (5 mg/mL). Although β-CD had slightly lower adsorption capacity at the O/W interface than α-CD, it could not only act as an emulsifier at the interface but also prevent the collision and coalescence of oil droplets through its participation in aggregation in the aqueous phase, which contributed to its stronger performance at high addition amounts (15 and 25 mg/mL). The obtained results are of reference significance to develop new food-grade Pickering emulsions and promote the application of CDs in foods.

Key words: cyclodextrins; Pickering emulsions; emulsifying properties; microrheology; molecular docking