Preparation, characterization and stability of water-in-oil Pickering emulsions stabilized by acylated EGCG derivatives

Abstract

Excessive intake of trans and saturated fatty acids from solid fats contributes to the development of chronic diseases. Food-grade water-in-oil (W/O) emulsions for the replacement of trans and saturated fat products, delivery of active compounds and microreactors remain to be further explored. Camellia oil-based W/O Pickering emulsions were prepared using acylated EGCG derivatives with various carbon chain lengths, including EGCG myristate (MYR-E), EGCG palmitate (PAL-E), and EGCG stearate (STEA-E). The acylated EGCG derivatives exhibited a contact angle of 90–100° with water droplets and could theoretically be used as Pickering emulsion stabilizers. The acylated EGCG derivatives were dissolved in the oil phase as needle-like crystals, which stabilized the emulsion against aggregation by adsorption at the oil-water interface. Pickering emulsions developed with STEA-E (PE-STEA) maintained higher stability after three freeze-thaw cycles, with a creaming index (CI) of 0% at oil-water volume ratios greater than 4:6. PE-STEA with varying oil-water volume ratios were stable at room temperature and 4 °C after long-time storage, with a maximum CI of only 1.39%. This study could provide new perspectives on the application of acylated EGCG derivatives and broaden the application of surfactant-free W/O Pickering emulsions in the food industry.