Israeli team conquers cloudy drinks problem with new nutraceutical nano-encapsulation method

14-Mar-2012 - Last updated on 20-Mar-2012 at 08:03 GMT

Figure shows the increased curvature effect by conjugating oligosaccharide onto the hydrophilic domains of casein (Picture Copyright: Food & Function)

Israeli researchers have developed a way to enrich transparent beverages with nutraceuticals using nanocapsules, protecting them from degradation at a low pH and ensuring their shelf life, while solving the challenging problem of cloudiness.

Lead author of the recent study in Food and Function, Dr. Yoav D. Livney, told BeverageDaily.com: “The conjugates are most suitable for sport drinks, iced tea, mineral water, and soft drinks. They might work well also for beer and hot drinks, though we have not simulated these conditions yet.”

For the study, Livney and his student Gilad Markman, from Technion Israel Institute of Technology, Faculty of Biotechnology and Food Engineering, formed conjugates made of casein (CN), and the oligosaccharide maltodextrin (MD), and co-assembled them with hydrophobic nutraceuticals (HNs) vitamin D and green tea extract epigallocatechin gallate (EGCG) to enrich clear beverages.

“To date, no method for the nano-encapsulation of HN, based on protein-saccharide conjugates, has been reported to form loaded particles small enough to maintain a clear aqueous beverage,” the authors wrote.

They added:“We have managed to controllably form Maillard reaction conjugates of CN and MD, without forming melanoidins, and utilised them for the encapsulation and protection of HN, including vitamin D and the more water-soluble EGCC.”

Compared to controls based on an unconjugated CN-MD mixture and unencapsulated vitamin D, advantages of conjugate vitamin D particles included: smaller particle diameters and a more transparent solution, while conjugates conferred better protection to both vitamin D and EGCG than the unconjugated CN-MD mixture.

Greater colloidal stability

Greater colloidal stability was another advantage over the CN-MD mixture, Livney and Markman added – allowing for the formation of nanoparticles below 30nm when mixed with vitamin D – as was better protection against degradation at a low pH and during shelf life.

Entrapment efficiency was found to be 90%, measured using Nile red (NR) a fluorescent model for a hydrophobic nutraceutical, the presence of which was assessed via spectrophotometry and spectrofluorometry.

The lack of NR release from nanovehicles during simulated gastric digestion also suggested potential as an enteric coating for the delivery of bioactives to the intestine, the authors said.

Livney told BeverageDaily.com: “The conjugates (formed by the Maillard reaction) solubilise and protect the encapsulated nutraceuticals against deterioration, e.g. by oxidation (Maillard reaction products have antioxidant properties), during processing and product shelf life.

“Additional benefits may include masking of undesired flavors of the nutraceutical, making the beverage more palatable. Moreover, the encapsulation may protect acid-sensitive bioactives against the harsh stomach conditions, and only release them in the small intestine."

Innovative research

Protein–polysaccharide conjugates (PPCs) formed by the Maillard reaction had been used before, Livney said, as emulsifiers, e.g. egg proteins-polysaccharide conjugates (Kato et al. 1994) and as encapsulation materials, e.g. beta carotene in casein-dextran conjugates (X.Y Pan et al. 2007)

“However our work is apparently the first to report the formation of PPC nanocapsules forming clear aqueous systems while encapsulating water-insoluble nutraceuticals,” he added.

Asked whether regulatory hurdles, such as the EU’s Novel Foods Regulation, might prove a barrier to the emergence of new products using nanovehicles, Livney said that such barriers were important “for assuring safe implementation of such novel products and food materials”.

“Nevertheless, it is important that such regulations are enforced wisely, taking into account that not every product new in Europe is new to the world (e.g. some products have been consumed safely for centuries elsewhere),” he added.

“In general, my approach is to base the nutraceutical-delivery vehicles we develop on natural, or naturally forming, food components, which have a long history of safe consumption,” Livney said.

Market potential

So when did Livney believe that nanotechnology could really take off, in regard to delivering nutraceuticals and vitamins via beverages?

“I believe it is already happening, but the prudent approach requires that it will take time to assure safe implementation of novel nanoparticle-containing beverage products. Some natural nanoencapsulators, like gum arabic, have already been applied for years in flavour encapsulation in beverages.

“Popular beverages, including bottled water are potentially excellent platforms for delivering health-promoting compounds to large populations. Therefore I think we would witness more and more nanoencapsulated nutraceutical containing products (including foods and beverages) in the coming few years,” he added.

Title: ‘Maillard-conjugate based core-shell co-assemblies for nanoencapsulation of hydrophobic nutraceuticals in clear beverages’

Authors: G.Markman and Yoav D.Linvey (Israel Institute of Technology).

Source: Food & Function, 2012, 3, 262. doi:10.1039/c1fo10220f