Improving the stability of EGCG in the emulsified oil droplets by regulating the rheological properties of O/W emulsion

Abstract

In this study, we encapsulated epigallocatechin gallate (EGCG) in emulsified oil droplets of protein-stabilized emulsions for the first time, with the participation of peppermint essential oil (PEO). Gum arabic (GA) and sodium caseinate (SC) were sufficiently crosslinked to construct the oil-water interface of the emulsion, improving the stability of EGCG in the emulsified oil droplets. When SC and 4 g/kg GA were mixed for 12 h before emulsification, the protein adsorption at the oil-water interface was significantly enhanced. Compared with the SC-stabilized emulsion, the retention of EGCG in the emulsion stabilized by mixing SC and 4 g/kg GA for 12 h increased about 2 and 33 times, respectively, after thermal treatment (30 min at 90 °C) and storage 10 weeks at 4 °C. Moreover, the emulsion stabilized by SC and 4 g/kg GA was resistant to the ionic strength of 0–0.6 mol/L and had predominantly elastic characteristics in the rheological properties. This indicates that the stability of active ingredients in emulsified oil droplets can be improved by regulating the rheological properties of the oil-in-water emulsion. The study is of great value for the efficient encapsulation and stability improvement of hydrophilic active ingredients in emulsified oil droplets based on emulsion systems.