On May 10, Samy Kamkar posted on his Twitter account a chocolate that shimmers like a rainbow. He is not a chocolatier but Openpath's founder, which is an internet security company. He gained early notoriety in 2005 when he released a virus on the social media site, MySpace.
According to the New York Times, his inspiration for making the iridescent chocolate can be traced back a few years ago when he saw the same effect on a black plastic at a maker meet-up in Los Angeles.
Suddenly, a question popped in his mind about what else he could do this on. At first, he considered making an iridescent effect on hard candy but decided against it because it was too easy. Then finally, he thought of using chocolate because of its melty gooeyness that seems like a bigger challenge.
Two months later, Mr. Kamkar has created a repeatable technique.
Making the Shimmering Chocolate
Mr. Kamkar said that anyone could just do his technique at home. There is no need for any special ingredient since it is the surface texture producing the rainbow effect on the chocolate.
Using his 3D printer, Kamkar designed a 3D model for casting which included at its base, a saw-tooth wave pattern. Each of the grooves in the mold is a few micrometers wide, and when the chocolate is poured inside, it adapted the inverse pattern on the casting's surface.
Kamkar tempered the chocolate before putting it inside the mold. Tempering involves the melting and cooling of the chocolate in a calibrated sequence that allows certain crystalline structures to form and give the chocolate its excellent properties.
The second step involves putting the chocolate inside a vacuum chamber to avoid bubbles from forming, although Kamkar noted that this step might not be necessary. In his Twitter post, he showed mushroom-shaped chocolate that he thinks is magical.
I’m finally getting some decent results producing 100%-edible iridescent tempered chocolate. The colors are from the chocolate (not any ingredient or coating) diffracting light after being forcefully molded onto a diffraction grating in vacuum. pic.twitter.com/6wpbsIKh5C — Samy Kamkar (@samykamkar) May 9, 2020
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Diffraction Made the Chocolatey Magic
A principle in physics, diffraction happens when light interacts with a surface and is drawn or pulled apart. This concept was used in making these iridescent chocolates. It is somewhat similar to refraction, wherein white light is broken into many different colors or a rainbow when it passes through a prism.
Objects with many uniform lines and edges, such as Kamkar's chocolates, diffracted light and creates iridescence. The same process happens to produce a rainbow effect on the surface of a compact disc.
Dr. David Weitz, a physics and applied physics professor at Harvard University said that many insects and butterflies use a similar phenomenon to show off iridescent wings or bodies. For him, Kamkar's chocolate is the best-tasting diffraction that anyone will ever see.
Weitz also noted that the saw-tooth pattern Kamkar used is not at all important. Any pattern will do, from straight lines to curves, as long as the lines are uniform, parallel, and spaced in proximity to the wavelength of light.
Meanwhile, for two and a half years already, Swiss researchers have also been collaborating to create a marketable iridescent chocolate. However, this seems to be a challenge as many people do not believe that there are no additives added to the chocolate's ingredients. People think that they added plastic on top, which makes the chocolate shimmer.
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