Fermented insoluble fiber enhances the emulsifying property and bioaccessibility of essential oil emulsion with its whey protein isolate conjugates and chitosan.

BACKGROUND

Using polysaccharide-protein conjugates to deliver essential oil has garnered widespread attention in the food industry. In this study, conjugates between insoluble dietary fibers (IDF) from Chenpi pomace and whey protein isolate (WPI) were first improved by fermentation, and then dual-layer Pickering emulsions were prepared by the conjugates and chitosan (CS) using layer-by-layer self-assembly technology and used for Chenpi essential oil (CEO) delivery.

RESULTS

Fermentation was found to enhance the Maillard reaction between IDF and WPI, and the emulsion controlled the release of CEO. Fermented IDF (FIDF) bound more WPI and the grafting degree increased by 54.1%, compared to the original IDF, due to the augmentation of FIDF specific surface area and the exposure of glucose, mannose, and galacturonic acid terminals. Furthermore, FIDF-WPI conjugates exhibited high thermal stability, hydrophobicity, and emulsifying properties, and the CEO-loaded dual-layer emulsions demonstrated uniform droplet size, strong storage stability, and excellent antioxidant activity. This effectively controlled the release of CEO and protected eight CEO components in gastrointestinal digestion, resulting in an increase of 167% in the bioaccessibility of CEO. These results can be attributed to the formation of a compact interfacial film composed of dense hydrophobic FIDF-WPI conjugates around the CEO droplets, the isolating effect of the improved three-dimensional structure formed by the FIDF-WPI-CS complexes, and the electrostatic repulsion between the emulsion droplets.

CONCLUSION

Fermentation can enhance the delivery of CEO in emulsions prepared with IDF-WPI conjugates and CS, and these findings contribute to the development of related functional foods. © 2025 Society of Chemical Industry.