Edible holograms could decorate or even authenticate food
Remember back in the mid-80s, when mass-produced holograms were such a big deal? Since then, they've become common on credit cards, currency and other items. Now, thanks to new research, you can actually eat the things.
First of all, why would anyone want an edible hologram? Well, along with simply being used for decorative purposes, they could conceivably also serve to show that a food item hasn't been tampered with, or to display its name and/or ingredients in a way that proves it isn't a counterfeit product.
Scientists have already successfully molded edible holograms into chocolate, although only certain types of chocolate worked, and a new mold had to be created for each hologram design. Seeking a more versatile alternative, researchers at the United Arab Emirates' Khalifa University of Science started out by mixing corn syrup and vanilla with water, then letting the solution dry into a film.
That film was then coated with a thin layer of a synthetic black dye. Utilizing a technique called laser interference patterning, most of that layer was subsequently etched away, leaving behind a series of nanoscale raised lines that formed what is known as a diffraction grating.
When light passes through that grating and reflects off the underlying corn syrup/vanilla film, the grating refracts the light in such a fashion that it appears in a rainbow-colored pattern – the visible colors change with the viewing angle. Additionally, the range and intensity of the colors can be altered by changing the spacing between the lines, or by varying the sugar content of the film.
Although the black dye already is non-toxic, the scientists now want to adapt the technology so it works with an actual food-grade dye.
The research, which is being led by Drs. Bader AlQattan and Haider Butt, is described in a paper that was recently published in the journal ACS Nano.
Source: American Chemical Society