Encapsulation behavior of curcumin in heteroprotein complex coacervates and precipitates fabricated from β-conglycinin and lysozyme

The associative phase separation of oppositely charged biopolymers produces liquid-like coacervates or solid-like precipitates, whereas the effect of the physical state difference on applications is often overlooked. This study investigated the application of complexes coacervates and precipitates fabricated from β-conglycinin (β-CG) and lysozyme (LYS) for the encapsulation of curcumin. The β-CG-LYS complexes encapsulating curcumin at charge stoichiometric ratios appeared as coacervates at pH 6 and precipitates at pH 7 and 8. The curcumin encapsulation efficiency and loading capacity of these complexes reached 95% and 410–486 μg/mg. Coacervates and precipitates both significantly improved the curcumin stability when exposed to light and heat treatment. During storage, the curcumin in coacervates had an extremely long half-life value (t1/2), whereas curcumin in the precipitates had a short t1/2. When the coacervates encapsulating curcumin adhered to the bottom of the cuvette, 35.2% of the curcumin was still retained after rinsing with ethanol 30 times. The β-CG-LYS coacervates were promising carriers to encapsulate functional molecules, which may be used as functional dressings and coatings.