Chocolate’s low melting point makes it delectable, but also a pain for shipping and storage.

M&M’s six-decades-old slogan “Melts in your mouth, not in your hand” might sound quaint to modern ears, but chocolate that won’t melt at warm temperatures while still maintaining its natural taste and texture may be the holy grail of the candy industry. And M&M-maker Mars is still on the hunt for chocolate that can fulfill M&M’s promise without its protective candy shell.

Mars, Inc. has recently filed an international patent for a more heat-resistant chocolate, according to the site Food Navigator. Chocolate typically melts around 86 degrees Fahrenheit, but the tests Mars conducted for its patent application were at 91 degrees, 95 degrees, and 100 degrees—all of which would represent a significant improvement. By comparison, in 2014, when Hershey’s was working on a heat-resistant chocolate, the target was reportedly 90 degrees or above.

Pieces of melting chocolate in melted chocolate sauce
Melting pieces of chocolate into a sauce.
| Credit: Westend61/Getty Images

The key to Mars’ innovation appears to be including what is repeatedly described as “a polyol with a boiling point of 105 degrees Celsius or higher.” A “polyol” is a type of compound with multiple hydroxyl groups. In the food industry, the most notable examples are sugar alcohols like sorbitol—though Mars would appear to have its eye more on glycerin in this case. Mars also specifies that this chocolate would be combined with innovative packaging to further its heat resistance.

It’s not clear when or in what form these products would be released, but in the past, the focus for heat resistant chocolates has been countries where consistently warm temperatures make shipping and storage problematic. As Mars explains in the patent, “What is a desirable trait from the consumer's point of view is not necessarily a positive attribute from the point of view of manufacturing, shipping, or handling... These concerns may be exacerbated in regions where economic circumstances are not favorable for the widespread use of refrigerated storage.”

And adding a bit of perspective on this innovation, Mars points to 17 other examples of patents around the globe for similar attempts at a chocolate and chocolate packaging that can stand up to high temperatures. It actually gives you a lot more respect for M&M’s good ol’ candy shell.