Returning to the subject of another 'god food' for just a moment......
Chocolate can keep and taste pretty good in your backpack. The story started in 1943 with the Hershey's Tropical Bar:http://amhistory.si.edu/militaryhistory ... .asp?ID=42
This bar was probably 'enhanced' with the addition of paraffin to achieve the heat-resistant quality. It wasn't too bad. I had a few of these issued to us when I was out in New Mexico many years ago, and they are chocolate-ish, but not the real thing.
Hershey's came up with a better formula for the Gulf War in the 1990s. It's called the "Desert Bar'. One description reads as follows:
"The chocolate that "melts in your mouth, not in the sand", the Desert Bar is a heat-resistant chocolate bar developed in 1990 by Hershey Foods, Inc. for U.S. troops assigned to the Persian Gulf during the Gulf War, and later, for inclusion in MRE rations. Chocolate has long been a U.S. military staple, but it doesn't do very well in high heat environments. Normal chocolate bars are made mostly of sugar and cocoa held together by cocoa butter, a fat which melts at around 35°C. This is critical to the taste experience of chocolate, because the cocoa butter melts easily at body temperature and serves as a carrier to deliver the other flavors to your taste buds. Without cocoa butter, chocolate wouldn't be chocolate, so replacing it with something that doesn't melt is not an option. Hershey solved the problem by creating a method to seal the cocoa butter in a matrix of tiny bubbles built from the other ingredients in the bar. At desert temperatures, the cocoa butter still melts, but since it is no longer what is holding everything together, the whole thing doesn't turn into a gooey mess like a regular bar would. The texture and taste are a little bit different than normal chocolate, but still pretty good."
It was available to consumers for a year, but now they're gone, discontinued in 1992.
Maybe somebody here can come up with their own "Playa Chocolate Bar" and post their results.