Preparation of water-in-oil Pickering emulsion stabilized by Camellia oleifera seed cake protein and its application as EGCG delivery system

The use of plant proteins as stabilizers for Pickering emulsions is attracting attention in the food industry. Herein, a protein extract with a high hydrophobic content (extraction ratio up to 21.6%) was obtained from the byproduct generated by the extraction of oil from Camellia oleifera. The effects of different oil-towater ratios and protein concentrations on the stability and rheological properties of the Pickering emulsions were investigated. A stabile emulsion that exhibited gel characteristics was made using an oil:water ratio of 6.5:3.5 and a protein concentration of 3%. The EGCG encapsulation efficiency of the Pickering emulsion was 82.3%. The emulsion remained stable during different environmental pressures (pH, ionic strength, heat, UV) and long-term storage, effectively protecting EGCG from chemical degradation in extreme environments. In vitro digestion results showed that the Pickering emulsion significantly delayed the release of EGCG from 80.52% to 26.81% and that the bioaccessibility of the EGCG was increased by 30.8% in the intestine when incorporated into the Pickering emulsion compared to free EGCG. This research indicates that Camellia oleifera seed cake could be used in plant-based protein emulsions for improved nutrient delivery.