Pie is a good example: fruit pie tends to keep for a good while at room temperature. I have found many sites which stridently claim this not to be the case, and many grocery stores that leave their bakery pies at room temp for about three days (even psycho Mrs. Cookwell says 2 days is fine). I'm siding with the grocery stores. Nut pies tend to last longer still, because they're drier: the presence of dairy and eggs is counteracted by the higher concentration of sugar.
Likewise cake, though it can vary depending on your frosting...The more things besides fat and sugar in your frosting, the more it needs to be refrigerated. In most cases cake will stay edible longer than you'd want to eat it. Again, grocery stores only bother to refrigerate decorated cakes, or ones with cream cheese icing.
Most store bought condiments are fine at room temperature. Obviously not mayonnaise, or anything creamy, but ketchup, mustard, A-1, worstershire...They last a good long time unrefrigerated. Likewise soy sauce, fish sauce, and some of the more popular asian condiments.
I've never seen a pepper sauce (e.g. Tabasco) that needs refrigeration, and they'll last for years, though the color starts going off after a while.
There is no bacterial risk to leaving fruits and vegetables out, but this will dramatically increase the rate of spoilage. The exceptions are root vegetables, and bananas. Root vegetables will last a long time in a cool dark place, so just lump 'em in your garage if you're not going to eat them in the next week or two. And bananas will go south at the same rate regardless (though you can freeze them for future banana bread).
Fresh eggs (like, straight from the chicken) will last a couple of weeks without refrigeration (make sure they're not fertilized, or you may wake up to find baby chickens in your kitchen). The rule of thumb is "Every day unrefrigerated is like 5 days refrigerated." Once eggs are cracked, you should use them immediately.
I'd trust store bought eggs left out on the counter to eat, though its not good to let refrigerated eggs get warm again. Eggs have a wide array of natural antimicrobial tendencies, though the processing store bought eggs go through removes some of this. (citation). An easy way to test for internal contamination is to see if the egg floats in water. If it floats, toss it.
Bacon grease keeps a long time unrefrigerated, as does any sort of fat really, as long as it's strained and filtered. With fats you're more worried about them going rancid, which is a function of light and air (its a type of oxidation), so store your fat in a dark place, in a sealed container. (citation)
Butter can last several days unrefrigerated (it should be covered). I'd say as much as a week, but I have no way of knowing because it never lasts that long. It's much more likely to oxidize (see above) and go rancid than to pick up a significant bacterial colony.
There are four methods for thawing frozen foods which are recognized as safe:
- In a refrigerator
- In the microwave
- Under cool running water
- As part of the cooking process
These four methods all meet the criteria that they minimize the amount of time the food spends in the danger zone (40-140 F, 4-60 C) where bacteria can grow.
The pros and cons of the following often-recommended methods are also reviewed:
- Leaving food on the counter overnight
- Thawing in a bowl (or sink) of water
- On a metal pan or with a "miracle thaw" device
In the refrigerator
Thawing food in the refrigerator is slow; it can take a day to thaw several pounds (a kilogram or two), and even more time for larger foods like a whole frozen turkey.
The advantage is that the refrigerator is at a safe temperature, and bacterial growth is already inhibited, so there is little risk.
This is probably the preferred method for many foods, if you have the time.
In the microwave
Thawing in the microwave is fast, but it has several disadvantages:
It requires a lot of attention, turning or rotating the food to get even coverage from the microwaves; for items like ground beef, you might even need to scrape off the thawed portions and continue defrosting the frozen portion.
It is easy to accidently go to far and start cooking the food, especially if it has an odd shape or small pointier parts sticking out (like wings on a chicken).
For this reason, microwave thawing is best done only for foods like soup or stew, where you can stir them and if one part boils a small amount while another part is frozen, no harm is done.
Under cool running water
This one is most surprising, but it is true: the fastest way to thaw food safely is under cool running water (at or below 70 F / 21 C), like the cold water from your tap.
The reason is that that water has an extremely high capacity for carrying heat, and the forced convection from running water ensures that it transfers heat from the food item as rapidly as possible. In the Good Eats episode What's Up Duck, Alton Brown thawed several frozen ice duck sculptures by various methods. The one under cool running water was almost completely melted, even when the one in the oven at 200 F was still fairly recognizably bird shaped.
It is important that the water be running, to ensure strong convection. You can do this by setting the food in the sink under a very small stream of water.
If the food should not get wet, you can put it in a zip-type bag or similar to keep it dry. Try to remove as much air as possible, to get the best contact between the water and the food (through the bag).
This is the best method for forced, rapid thawing (at least when microwaving is not appropriate or inconvenient), but it is probably less convenient that the refrigerator method. You also have to monitor the food, and remove it when it is thawed, or it will come to the ambient temperature of the water, which is probably in the danger zone.
As part of the cooking process
Some foods can be cooked starting from the frozen state, thawing and then cooking in one operation.
Among the ones most suitable for this are are smaller or thinner items, such as:
- Cookie dough lumps
- Hamburgers
- Chicken parts
- Pizza
- Stew meat
- Frozen, chopped vegetables
- Frozen stock (at least in smaller quantities)
Bad idea: on the Counter overnight
This is a bad idea, especially for meats and other highly perishable items. You have no control over the temperature the surface of the food will reach, and it may begin to spoil at the surface before the center is thawed.
Bad idea: In a bowl (or sink) of cold water
Again, a bad idea. Without the convection, the thawing speed is reduced. There is also no source of newer, cooler water, so the temperature of the water itself will rise.
Some parts of the food may reach dangerous temperatures before it is fully thawed. Also, if you don't check the food frequently, the temperature can get into dangerous territories, facilitating spoilage.
Risky: On a cast iron, stainless steel or other metal pan, or a "miracle thaw" device
This method is most often used with thin foods like steaks or frozen hamburgers.
Physics are with you, as the specific heat capacity and conductivity of the metal are very high (higher even than water). The large surface area of the metal acts like a radiator or heat sink in reverse, conducting heat away from the food more rapidly than air alone would.
This method is not approved by health codes for commercial use, and carries some risks. You need to monitor the food closely, and cook it or move it into the refrigerator as soon as it is thawed. Failure to do so will allow the food to spoil, and the conductivity of your metal will become your enemy, more quickly bringing the food to ambient temperature.
While this method is not officially sanctioned, you may choose to assess its risks for yourself.
See also:
Best Answer
The recommendations (in the US at least) are based on a risk model, which takes into account a number of factors:
Some of these factors are statistical (frequency, economic, for example), and some are measured (growth, aspects of severity). For the measured aspects, a large number of methods are employed, including animal testing, human histories, and toxicology reports (including LD measures).
Primarily, most home cooks should follow the FDA guidelines as the recommendations take into account the supply chain and common outcomes for most pathogens (for a given food). It's important to note that live pathogens are not the only risk in food safety, also toxins (as produced by the pathogens) are an important factor depending on the specific life form. These toxins are not mitigated by cooking (generally), and some pathogens are not completely mitigated by heat or cold. The risk is related to the combined risks, time, and supply chain.
The FDA site contains the regulations, methods, and sampling guidelines for various stages of food production and food safety.
This is not my speciality, but I did teach food safety many years ago (please refer to the current guidelines and methods for current recommendations).
References: