Complex coacervation of whey proteins to design biocarriers for bioactives
Résumé
Control of molecular assemblies provides possibility of constructing functional materials in a non-covalent bottom-up manner. Adequate mixing of oppositely charged proteins leads to liquid-liquid phase separation with the formation of reversible heteroprotein complex coacervates having great potential for application as functional biomaterials. For instance, the use of complex coacervates as carrier for nutraceuticals and bioactive components is a blooming research field. Here, we investigated the ability of complex coacervates formed between two whey proteins, Beta-lactoglobulin (BLG) and Lactoferrin (LF), to encapsulate an essential vitamin, the vitamin B9.
Across a range of B9:Protein ratios, complex coacervation conditions were determined using turbidity and phase contrast microscopy. Biocarrier efficiency of protein coacervates for B9 was quantified. Stability of B9-Proteins coacervates was monitored after storage at 4°C and 20 °C, and freeze drying. Increasing volumes of B9-Proteins coacervates solutions were tested to evaluate the impact of process conditions on the coacervation yield.
By plotting screening maps of B9:Protein ratios and B9 carrying efficiencies (Fig. 1A), we found an optimal biocarrier efficiency of ≈ 10 mg B9/g Proteins. This efficiency found for protein coacervates (Fig. 1B) is similar to that reported for other encapsulation technology like spray-drying [1]. B9-Proteins coacervates after centrifugation (Fig. 1C) were stable over a month storage at 4°C and 20°C, and after freeze drying, without any detectable degradation of B9. Working volumes showed an important impact of the homogenization and centrifugation conditions on the recovered coacervated phase.
These heteroprotein systems display useful potentialities as carrying biomaterial [2]. Their formation requires minimal energy input and involves co-products of the dairy industry. Few mg of coacervates can cover the recommended daily intake of bioactives and enhance protein intake. They constitute new potential structured biopolymer-based delivery system. They use directly components of the food product as carrying biomaterial, thus limiting the addition of extraneous components to develop natural functional foods or ingredients.