Edible wax lets you get the last drop out of the bottle

The formula for a non-toxic, non-stick coating that lets loose every last drop of tomato sauce from the bottle has been cracked.

Colorado State University materials scientists have created a ‘superhydrophobic’ coating that easily slicks away viscous liquids like syrup, honey and tomato sauce.

The research team, led by Arun Kota, assistant professor in the Department of Mechanical Engineering and the School of Biomedical Engineering, have published detail about synthesising and testing coatings made from beeswax and carnauba wax in Applied Materials and Interfaces.

Superhydrophobic coatings are not new, but they’re typically fabricated with fluorocarbons. These materials, while generally safe in low doses, are labelled as “emerging contaminants” because of their potential decomposition into perfluorooctanoic acid, a known human toxin, according to the paper.

The use of coatings in food-related applications is regulated by the Food and Drug Administration and the FDA recently banned three perfluorinated compounds (PFCs), which are used in food packaging for grease-proofing pizza boxes and other items.

“Companies are very specific about toxicity levels in these products, which is why they don’t get into the market very easily,” Kota said of hydrophobic coatings. However, the edible waxes used in the latest liquid-repellent coating are non-toxic and so particularly suited to food packaging.

One of Kota’s students came up with the idea of trying to make such a coating out of beeswax. Its chemical properties are similar to non-sticky fluorocarbons, but even at extremely high doses, they are safe to ingest. The researchers came up with a way to spray the coating onto a surface by first dissolving the wax.

Their coating allows a wide range of aqueous liquids to bounce and roll away. They tested a long list of substances, including Lipton green tea, Gatorade, pancake syrup, Coca-Cola, orange juice, milk and coffee. They used common polystyrene cups for their demos.

There is room for improvement in the mechanical durability of their coatings, which currently can’t withstand harsh and abrasive environments, according to the paper.