How long can uncovered food at room temperature stay fresh?

It depends upon which type of food you are asking about. For instance, jerky can be left uncovered for weeks. Fake jerky (ie: meat that looks like jerky but still has juice inside of it like those dried sausage sticks) can not be left uncovered for more than a few hours. Some foods, such as dinky-twinkies - whicheven the insects won't touch - have been found to be edible still after months of having been left uncovered.

So basically, foods that are fresh tend to go bad after only a few hours. Processed foods can last up to about a day (or more in some cases), and food that has been hardened in some way (like jerky) can last weeks or even months uncovered.

Food that has been cooked falls into the first and second category depending upon what it is and how it was cooked. Most meals that are cooked at a restaurant (or even at home) can last between a few hours and about a day. Again, it depends upon what you are cooking and how it is cooked.

There is also the temperature to think about. What the food kept warm or allowed to cool. Food that is meant to be kept warm can begin to deteriorate faster if it is allowed to cool. And conversely, food that is supposed to be kept cold - if allowed to heat up - will go bad faster also (think ice cream).

Frozen foods that are allowed to heat up (or thaw out) and which are then re-frozen tend to begin going bad even if they are frozen again because they were exposed to the air outside of the freezer and thus any contaminates there were floating around in the air (or the surface the item was placed on) have gotten onto the food.

Next is - how clean is your food preparation area? If you keep it clean - HOW do you keep it clean? If you use something like Formulae-401 - that doesn't really make a sterile place for you to prepare food. There are a lot of cleaners out there that say they clean a surface but only a few of these actually sanitize the surface. Most do a great job of picking up grease, oil, butter, and other things that might be on the surface - but they don't kill the germs that linger behind. Only two things will kill germs (ammonia and chlorine) but of the two - only Chlorine disenfects and cleans. So keep a spray bottle around, clearly marked, with Chlorine in it. You can do this by just putting a cap full of bleach and then filling the bottle the rest of the way up with water. Use a clean paper towel, spray the surface you are going to work on and then just wipe up the excess moisture. Give it a minute or two to dry, and then go ahead and start preparing your meal. All of the fancy computer graphics in the world can not change the fact that only Chlorine will keep your counters clean and free of germs.

Finally, your nose. Your nose can smell when food has begun to go bad. So if nothing else - smell it. If it doesn't smell good - don't eat it. Just throw it out. Better to be safe than dead.