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Milk Proteins Hold Promise for Nano Delivery Systems

by siebo last modified November 15, 2006 - 15:00

Nature has endowed a milk protein, casein, with the capability to form nano-sized micelles. That trait is now being actively investigated by researchers from the Israel Institute of Technology in Haifa to see if casein could unlock a huge potential to nano-encapsulate sensitive ingredients.

Milk Proteins Hold Promise for Nano Delivery Systems

The molecular modeled structures of as1-Casein variant B, b-Casein variant

Using fat-soluble vitamin D2 as a model hydrophobic ingredient, the, reported that the micelles could be "useful as nano-vehicles for entrapment, protection and delivery" of sensitive ingredients, Efrat Semo said, whose work appears in the journal Food Hydrocolloids this fall.

"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," wrote Semo.

Food manufacturers are increasingly turning to encapsulation technologies as a way of achieving much-needed differentiation and enhancing product value, and more research of late has begun to look at nanoencapsulation as a natural way to encapsulate and deliver nutrients.

The protein casein makes up about 80 per cent of the protein content of cow's milk (30-35 grams per litre) and is found naturally in the form of spherical micelles with diameters ranging from 50 to 500 nanometres. The stability of these micelles during processing also makes them a very attractive nano-encapsulator, indicated the authors.

The research, funded by the German-Israel Foundation, achieved non-covalent binding of the vitamin (Sigma-Aldrich) to sodium caseinate (Miprodan 30, 93.5 per cent protein, MD Food Ingredients) by adding the vitamin drop-wise to a sodium caseinate solution. The researchers used a rehydrated commercial sodium caseinate powder. This was done "in order to extend the commercial applicability of the method," they said.

Semo and co-workers report that the average casein micelle (CM) diameter was 147 nm, and this increased slightly to 156 nm when vitamin D2 was added. Only 27 per cent of the vitamin added was incorporated into the nano-capsules, they said.

A paper entitled “Micellization of Bovine-Casein Studied by Isothermal Titration Microcalorimetry and Cryogenic Transmission Electron Microscopy” was published in April by Department of Biotechnology and Food Engineering and Russell Berrie Nanotechnology Institute, Technion-Israel Institute of Technology, Haifa, 32000 Israel, and Department of Food Science and Technology, University of California, Davis, California 95616, USA

Cited authors include: Irina Portnaya, Uri Cogan, Yoav D. Livney, Ory Ramon, Karin Shimoni, Moshe Rosenberg and Dganit Danino