I've recently started taking shots of food as well. I don't have anything particularly great to show for my efforts yet, however I have noticed that you can keep shooting for a while before the food actually starts to appear unappetizing. Additionally, if it starts to look dry, you might just want to keep a spray bottle with water in it on hand to mist and keep things looking fresh. Keeping your food covered while you investigate previous shots and evaluate your next shots can help keep it looking fresher for a little longer as well. Granted, you won't get much more than 5-8 minutes of "perfect" looking food, but you can get decent looking food for a while...and since its just practice, perfection isn't necessarily the goal (that comes later! :)
One of the things I've learned in my efforts so far include the use of a polarizer. Fresh cooked food often exhibits a lot of pinpoint highlights that eat away at your dynamic range without offering any kind of useful return. By using a polarizer, you can adjust how much of those highlights you wish to keep, and you can greatly minimize them to the point where they help enhance your food without creating a bunch of tiny overblown highlights all over everything. Use of a polarizer might help you get more keepers earlier, and not run into the problem of dry, old, unappetizing looking food. Just keep in mind, you'll need to increase exposure if you use a polarizer, by 1-2 stops.