The food may not come out how you want it,also it is never healthy to eat cold food that needs to be hot.Same with hot food.If cooked food reaches temperatures warmer than 40 degrees Farenheit or...
foil keeps things either hot OR cold by reflecting heat -- either from the meat, or from the air around the foil.In other words, the foil slows the transfer of radiant heat.
It doesnt the air is sucked out of the pack and replaced by nitrogen.As aluminum foil acts as a complete barrier to light and oxygen (which cause fats to oxidise or become rancid), odours and...