Casein micelle as a natural nano-capsular vehicle for nutraceuticals

Casein micelles (CM) are in effect nano-capsules created by nature to deliver nutrients, such as calcium, phosphate and protein, to the neonate. A novel approach is herein presented, to harness CM, for nano-encapsulation and stabilization of hydrophobic nutraceutical substances for enrichment of non-fat or low-fat food products. Such nano-capsules may be incorporated in dairy products without modifying their sensory properties. This study introduces new possibilities for encapsulation and delivery of sensitive health-promoting substances using natural GRAS (generally regarded as safe) ingredients. As a model hydrophobic nutraceutical compound we studied the fat-soluble vitamin D2, which is essential for calcium metabolism. A protocol for incorporation of vitamin D2 into CM was established. The encapsulation process was evaluated, and so was the protective effect of the micelles against photochemical degradation of the vitamin. We have demonstrated, for the first time, the possibility to load a nutraceutical compound into CM, utilizing the natural self-assembly tendency of bovine caseins. The vitamin was about 5.5 times more concentrated within the micelles than in the serum where it was only present bound to residual soluble caseins. Moreover, the morphology and average diameter of the re-assembled micelles were similar to those of naturally occurring CM. We have also demonstrated that the re-assembled CM can provide partial protection against UV-light-induced degradation to vitamin D2 contained in them. This study suggests that CM may be useful as nano-vehicles for entrapment, protection and delivery of sensitive hydrophobic nutraceuticals within food products. (c) 2006 Elsevier Ltd. All rights reserved.