I have made these bags with both corn and rice. I thought the corn one was a bit rough. I made one of each, heated them both at the same time for 1 minute, took them out, placed them on the counter, then measured them at 5 minute intervals for 30 minutes. The rice bag held the temp. the best. But I know a lot of people swear by the corn, so you might want to experiment like I did. Besides, I now have a 40 pound bag of corn--going to give it to a best friend to feed her chickens. LOL