I bought some cheese-covered bread at the store a few days ago. It was sold at room temperature, and we are keeping it at room temperature at home. I have no concerns about the safety of this practice, but I am not sure why. What distinguishes the cheese-covered bread from, say, a grilled cheese sandwich (which most people, I think, would deem unsafe after sitting at room temperature for a day)? (Or cheese-covered pizza, or cheese enchiladas, or any number of other cheese-related foods.)
Another example: Eggs. If I cook some eggs on the stovetop, you would think it is crazy to leave them out at room temperature and eat them a day later. But if I cook some eggs as part of a cake batter or other baked good, it is deemed perfectly safe to leave the food at room temperature for quite some time.
(I know none of these things can be store indefinitely at room temperature. But why can some things safely sit out for a few days, while others are considered safe for only a few hours?)
Well, it has to do with how quickly something spoils. For one reason or another, baked goods (like breads and such) will “keep” for longer out on a counter than things that have more moisture content. Part of this has to do with moist conditions encouraging growth of bacteria, mold, and other things that aren’t necessarily good for you to ingest. However, due to the dry nature of many baked goods (like bread), they may not be as tasty or have the right wet/dry ratio that made them taste good within a few days of making them. Fruits with peels also do well out on the counter because the [edible, but not commonly eaten] peel not only forms a barrier, but also releases gases that ripen the fruit and other fruits around it. (Sitting out on the counter, it does less damage to other fruits than in a bag. However, the fruits off-gas less when they’re in the fridge.)
Personally, I like to keep most of my foods in the fridge so that they maintain the 38-40F refrigeration safety range when I’m not eating them. Dairy products are mostly mandatory fridge-dwellers in my house because they spoil easily and milk changes into other dairy products fairly quickly if left at room temperature with the right conditions. Most of what gets left out of the fridge are things that don’t spoil quickly or aren’t very good with the cold temperatures of the fridge.
What appears to be the major difference between foods that can be left out and ones that must be refrigerated has to do with not only the original storage methods used, but the contents of the item. While it may be perfectly safe to store your cheese-coated bread on the counter, you’re also aware of when it starts to turn unsafe to eat via mold spores and other signs of decomposition.
Geeze, when I was in college, pizza only a day old was considered fresh out of the oven and eating three day old pizza wasn’t unknown.
The main difference I see here is the difference between mold and bacteria. Bread and cheese get moldy. The mold may be nasty, but it won’t kill you. The toxins given off by the bacteria in spoiled mayonaise will. Different bugs.
But what about differing treatment for differing cooked cheese products? Is it incorrect to say that, for instance, a grilled cheese sandwich should not be eaten after it has been sitting on the counter for two days? Compare, for instance, to the cheese bread I bought about four days ago, which I plan to eat with my lunch today. Or am I crazy to be eating the cheese bread?
It has to do with the amount of moisture in the food. Cheese bread has dried cheese on it; bacteria will not grow well there. The grilled cheese sandwich has a lot of moisture inside, and so it will not last nearly as long.
Food poisoning pathogens need four things to reproduce and render food dangerous to eat; food, moisture, warmth and time.
Food, in terms of the bacteria that cause food poisoning, usually refers to proteins (there are exceptions, such as Bacillus cereus, which feeds on carbohydrate, usually in cooked rice).
So foods like bread, crackers don’t contain enough protein or moisture to be a risk when left at room temperature for an extended period. Salami contains lots of protein, but little moisture, so it keeps well at room temp. Whereas raw meat and fish, uncooked cake batter, cooked meat mixed with mayonnaise, contain enough moisture and protein to support rapid bacterial growth at room temperature.
Of course, a lot of things say “Refrigerate after opening.” When you buy them, they’re sealed after having been cooked or otherwise sterilized, but once you open them, you let in bacteria, mold spores, etc., that can then multiply if the food is left at room temperature.
(Which makes me wonder: how was the OP’s cheese bread packaged?)
