By creating coloured calcium alginate hydrogels it is possible to create a new form of coloured coating that could find use in a wide range of applications, including food and dietary supplements.
Lead researcher D. Tyler McQuade told FoodNavigator.com that, although the technology was originally developed for non-food use, the food industry could benefit.
"I think that our advance is solely in the area of coatings. This could be used for coating candy or dietary supplements. If sugar were added to the coating it could be a candy itself," he said.
To test their technology, the researchers focussed on coating artificial turf. This was achieved by spraying an aqueous solution of calcium chloride (gelling agent), and then spraying sodium alginate with one per cent red food colour (McCormick). The sprayed solutions then combined into a coloured thin film.
While the researchers used the red food colour for these preliminary experiments, the range of dyes used could potentially be extensive.
"We have not done a complete survey of colours, but do not see any reason why the full FDA approved dye rainbow is not accessible," said McQuade.
Different concentrations of the gelling agent produced gels with different physical properties, report the researchers in the American Chemical Societys journal Biomacromolecules (doi:10.1021/bm060341q). For example, the film produced using a low concentration of calcium chloride (0.1 moles per litre) was brittle and easily removed, while the higher concentration gelling agent (2.0 moles per litre) adhered well and was difficult to remove.
Calcium alginate is already used in the food industry as a thickening agent, and sales of sodium alginate are reported to exceed $100m annually.
McQuade told FoodNavigator that the research has not yet received any interest outside of the turf spraying industry, but since the materials used in the preparation of these hydrogels are cheap, readily available and environmentally friendly this could interest the food and dietary supplements industries.
"We are still in the initial phases of discovery and we feel that there are many yet to be tapped applications," he said.
More research is unquestionably needed, but the take home message, said McQuade, is: "We think that this is an exciting new technology that has not been fully exploited."