Reducing synthetic colorants release from alginate-based liquid-core beads with a zein shell

Authors: LIU, HONGXIANG - Jiangnan University; Chiou, Bor-Sen; MA, YUN - Jiangnan University; CORKE, HAROLD - Israel Institute Of Technology; LIU, FEI - Jiangnan University

Submitted to: Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/14/2022
Publication Date: 2/17/2022
Citation: Liu, H., Chiou, B., Ma, Y., Corke, H., Liu, F. 2022. Reducing synthetic colorants release from alginate-based liquid-core beads with a zein shell. Food Chemistry. 384. Article 132493. https://doi.org/10.1016/j.foodchem.2022.132493.
DOI: https://doi.org/10.1016/j.foodchem.2022.132493

Interpretive Summary: Alginate beads have been used for controlled-release applications, but they have some limitations. In this study, we examined the effects of coating the alginate beads with zein on release profiles of different colorants. We used anti-solvent precipitation of zein from an ethanol/water solution to coat the alginate beads. Precipitation occurred when the local concentration of ethanol around the beads decreased in value due to osmotic pressure migration of water from the beads, leading to deposition of zein on the bead surface. We found the colorants that hydrogen bonded or electrostatically interacted with zein showed much slower release profiles. These results indicated that the alginate beads coated with zein can be be used to improve the controlled-release profiles of different colorants.

Technical Abstract: An innovative method to reduce hydrophilic synthetic colorant release at interface was presented in this work, based on the anti-solvent effect at the membrane outside surface of liquid-core beads manufactured by reverse spherification between alginate and calcium ion. Zein, a hydrophobic protein which formed precipitation shell ensured the stability of colorant. Acidification of solvent made zein particles more kinetically stable, allowed zein stretching and collated more orderly secondary structures even in high polarity solvents. Colorants that hydrogen bonded or electrostatically interacted with zein could have optimized release properties. The zein/erythrosine samples had the most orderly secondary structure from circular dichroism and had the highest stability among all zein/colorant systems. The release rate of erythrosine was only 2.76% after 48 h storage after soaking in zein shell solution. This study demonstrated a promising clean and scalable strategy to encapsulate hydrophilic compounds in zein-based shells of liquid-core beads for food, supplement and pharmaceutical applications.