Maillard-reaction based nano-capsules for protection of water-insoluble nutraceuticals in clear drinks

摘要

One of the most important aims of contemporary food engineering is the enrichment of foods with health enhancing components. There is a growing public awareness for healthy nourishment that should include necessary daily amounts of required micronutrients. Moreover, there is demand for natural ingredients and processes. Integrating a hydrophobic nutraceutical (HN) in aqueous media, particularly clear beverages, is a challenging task. The complications associated with such systems are poor HN solubility and stability, which are usually improved by addition of emulsifiers. One of the emulsifiers traditionally utilized is gum arabic which is a natural protein-polysaccharide conjugate (PPC). Its main disadvantages are its high price and highly variable composition, quality and availability. Therefore, many efforts are aimed at finding good inexpensive substitutes. Producing PPC may be done by enzymatic, chemical or electrosynthesis reactions. A particularly attractive way to form PPC is via Maillard reaction, achieved only by heating, typical of cooking and food processing. We formed casein (CN)-maltodextrin (MD) Maillard reaction conjugates and used them to nanoencapsulate hydrophobic and hydrophilic nutraceuticals. Clear solutions were obtained with nanoencapsulated VD. Particle size of VD loaded PPC nanoparticles was much smaller than that of MD-caseinate mixture with VD; e.g. at 3:1 VD:CN molar ratio, 70% of the mixture-based nanoparticles were >100 nm, while ~100% of the PPC-based nanoparticles at this ratio were <100 nm. Unencapsulated VD at same concentrations was very turbid. Conjugation significantly improved the protection against oxidation and low pH conferred to VD, important for acid drinks, and for survival through gastric digestion. PPC protection conferred to epigallocatechin-3-gallate (EGCG) was also demonstrated. Overall the study showed the very good potential of Maillard conjugates of proteins and oligosaccharides for nanoencapsulation of nutraceuticals for clear drinks application, good solubilization, stabilization and protection conferred to the sensitive bioactive compound against degradation during shelf life, and gastric digestion.