Can Pizza Be Left Out Overnight?

This type question is always answered with the same old, predictable answers promising certain diseases or death in no more than 2 hours! Sometimes it's okay to be cautious and sometimes, it's necessary. Beef stew, beef gravy or chicken salad, as well as beef stew, beef broth, chicken salad, chicken salad, sliced meat, and cabbage rolls. But it doesn't cover all of these foods. It can't stand up to close inspection, biological science, or a hundred years worth of evidence. It is second only to the horrible obsession with "expiry dates", which can lead to the waste of perfectly good food.




Pizza isn't so dangerous as people think. Let's break it down ......

The crust is yeast-based bread. Only bacterial growth is of interest in this substrate type is in the middle of larger loaves still warm from the oven (not cooled fast enough), and where calcium propionate was not used. Sometimes we get thermoduric Bacillus subtilis (or B. mesenteric) in bread. This causes a stringy, proteinaceous thread, called "ropey loaf". However, the crust of pizza is too thin and will cool down to room temperature quickly.

The tomato sauce is acidic enough to inhibit the growth of the bacteria we are looking at. Cheese has low pH levels due to lactic fermentation and low water activity (Aw). These bacteria types are not compatible with vegetables, such as onions and peppers. Semi-dry pepperoni is low in Aw because of high NaCl and moderate amounts of nitrate/nitrite. Pineapple is low in pH, while anchovies are very salty (again, very low Aw). The only food that could pose a problem is ham. Even here, the danger is of it being chopped and fiddled with by unwashed hands. It could have been a source of Staphylococcus Aureus, which is one of few organisms that can grow well on ham (because of its ability to grow at an average Aw of 0.86). If the temperature was used before it was cooked, it could have produced Staph entryotoxins, which would have survived the baking process/temp.

Problem area: Pre-cooking growth in the ham and toxin-production in the ham. Would Staph have been able to survive the baking? It's highly unlikely. It can't withstand those temperatures. Any Staph pre-formed toxins would be unchanged. We also encounter heat-resistant pathogens such as Clostridium perfringens and Bacillus cereus that could survive the heat. Clostridium perfringens, Bacillus cereus) don't have the food or substrates that would support their growth.

What about after-baking, post cooling, contamination via faecally hands, or coughs & sneezes You could do it, but bacteria would have little chance to grow due to the Aw again

How about Norovirus contamination after baking? (Viruses are highly infectious and don't 'grow on food. However, very few virus particles are required. It is unlikely, based on the current knowledge about Norovirus.

Can we protect against Norovirus? Refrigeration doesn't help here. Serve hot, get everyone to wash their hands before touching the pizza and perhaps serve the whole group on paper plates.

Unrefrigerated pizza left unattended overnight poses very low risk of food-borne illnesses. This is evident by the extremely low incidence of food-borne illnesses in which pizza was implicated.

Q: can pizza dough be frozen?

You can freeze pizza dough in any amount, no matter how large or small. The dough can be frozen for up to 3-4 months. Once it thaws overnight, you can use it.

Q: can pizza boxes go in the oven?

Yes, you can. You can heat your pizza as long as the box isn't too big. The cardboard could catch fire if the oven temperature is too high. Heating pizza in the oven can be dangerous and it can also alter the flavor of your food.