Pickering emulsions stabilized by essential oil-tannin-chitosan particles: Microstructure, stability, antibacterial activity, and antioxidant activity

Abstract

In this study, four different types of essential oil monomer and tannic acid were used to prepare different kinds of essential oil-tannin particles. As well as encapsulating the chemically labile essential oils, these particles could also be used as Pickering emulsifiers to prepare oil-in-water emulsions. These emulsions were co-stabilized using the essential oil-tannin particles in combination with chitosan. The resulting Pickering emulsions were shown to have good storage stability, viscoelastic properties, antioxidant activity, and antibacterial activity. The emulsions co-stabilized by cinnamaldehyde-tannin and chitosan had the smallest particle size and largest shear viscosity, shear modulus, and physical stability. An in vitro digestion study showed that the cinnamaldehyde encapsulated within these emulsions also had a relatively high bioaccessibility. Considerable differences were observed in the stabilities of emulsions prepared with different oil phase volume fractions. The more concentrated emulsions did not exhibit phase separation after 30 days storage, which was attributed to the fact that the close packing of the oil droplets prevented their movement. This study shows that essential oil-polyphenol particles can be used as multifunctional ingredients, such as antioxidants, antimicrobial agents, and emulsifiers.