We did a study on insulated bags many, many years ago and we found that a single, 12-inch, cheese only, boxed pizza could be held for up to just under 30-minutes before dropping to 140F, when two boxed pizzas were placed into a double bag the time increased to approximately 45-minutes. Like I said, this was done a long time ago, bags have changed, and insulation in the bags has probably changed (hopefully for the better) but this should give you some idea of what might be expected in bag performance when it comes to keeping a delivery pizza hot. On a personal note, I don’t find the temperature of the pizza to be a major issue where quality is concerned, instead it is the softening and toughness of the crust that distinguishes a DELCO pizza from a dine-in pizza, this is the reason why I always encourage DELCO customers to place their pizza into a 400F oven for a few minutes when they get it home, it helps to dry out the pizza and refreshen the crust for a more enjoyable dining experience.
Tom Lehmann/The Dough Doctor