A layer-by-layer protein-polysaccharides emulsion enhances the bioavailability of butyrospermol in camellia oil

Butyrospermol is a critical triterpene alcohol, known for its remarkable anti-inflammatory properties in camellia oil. However, its low bioavailability in camellia oil necessitates the development of an effective delivery system. Gum arabic (GA) and chitosan (CH) were sequentially added to the whey protein isolate (WPI) emulsion to form a layer-by-layer structured emulsion. The droplet size, zeta potential, and storage stability were characterized to optimize the ratios. FTIR and fluorescence labeled confocal laser scanning microscopy were employed to characterize the emulsion structure. Pharmacokinetic experiments and in vitro organ imaging were conducted to evaluate the bioavailability enhancement of emulsions. Results showed that adding 1.6 % GA and 1.7 % CH to the WPI emulsion resulted in a stable WPI-GA-CH emulsion with 0.97 μm mean droplet diameter and 36.27 mV zeta potential. WPI and GA tightly surrounded the oil-water interface, and the droplets were encapsulated within the cavity of CH cluster. Apart from electrostatic interactions, WPI was linked to polysaccharides through hydrogen bond. The prepared WPI-GA-CH emulsion exhibited no stratification after 60 d storage. It enhanced the bioavailability of butyrospermol from 2.48 % to 11.35 %, correspondingly, the in vitro organ imaging showed that the CH in the emulsion slowed the transit of oil through the intestine. This study presents a novel emulsion method for delivering butyrospermol in camellia oil and provides insights into the factors influencing its absorption and elimination.