Oct 27, 2012 11:44 AM
Discussion

### oven temperature versus temperature of what's in the oven

This may seem like a silly question, because I think the answer is illogical (at least to me), but I cannot find the answer. If you put a pot of soup in an oven to cook "low and slow," will the temperature of the contents of the pot ever equal the temperature of the oven? If I set the oven to 200 degrees so the soup will cook just below the boiling point, will the soup temperature get to 200 degrees, or must I set the oven temperature higher?

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1. The ambient temperature in the oven is 200 degrees, and the soup inside will eventually reach that temp as well. Definitely start the boil on the stove top, then transfer to the oven to maintain that low boil.

1. re: letsindulge

That's correct, and I'll add that the temp of the food will never get hotter than the ambient temp in the oven. There are proponents of roasting meats at the desired temp of the finished dish, so usually from 125-180. This guarantees that the meat will never overcook, and can remain in the oven beyond the time when it's done. The concern of some is that the meat may sit in the "danger zone" for too long, so many people who use this method sear the outside first, since if there are bacteria they are on the surface and this will kill them. I have achieved tender, juicy roast beef and turkey by this method, of which Adele Davis was the most famous proponent.

2. However, if you set the oven temperature to 400 degrees, the soup would never reach that temperature. But it's a good question.

7 Replies
1. re: todao

But if the answer is correct, that eventually the temperature of what is in the oven will be the same as the ambient temperature of the oven, then why would it not reach 400 degrees in a 400 degree oven?

1. re: HRR

By the time it got to 400 degrees it wouldn't be soup; it would be a solid. Water turns to steam at 212 degrees and the steam will leave the oven via the vent system. When the soup is dried it will continue to increase (albeit slowly) in temperature but the solids left to reach that temperature could not be referred to as soup. Charcoal, perhaps. Soup, no.
Running the oven for long periods of time to achieve a low and slow result for cooking soup can be quite expensive. Purchasing a slow cooker could, in the long run, be a better choice.

1. re: todao

Thanks. So it seems the posts above are in fact not correct if the goal is to cook soup. I don't know what "the" correct temperature is, or how to determine it, but it seems that once there is something other than water added to the pot, the temperature has to be higher than the boiling point of water, and too high, the water will cook out. Right?

Along the lines of a slow cooker, do you know at what temperature a slow cooker is set? Wouldn't that be the appropriate temperature at which to set the oven?

1. re: HRR

You are overthinking this. Yes, if the heat is too high the soup will boil away and burn, just as would happen on the top of the stove. Set the oven just below 212, and your soup will simmer happily. That's not to say that you can leave it in there for days on end without checking or adding water. Steam (water loss) happens below 212., just to a lesser degree. Your only major concern is that you get the ingredients hot BEFORE putting the soup in the oven, because it would take a (possibly dangerous) long time for cold ingredients to come to 200 degrees. Cooking soup in the oven is really no different than braising a piece of meat or a stew.

Slow cookers vary as to temp. Newer ones allow exact temp settings but old ones can have only the choice of high or low, and do not indicate the degrees that means.

1. re: HRR

Slow cookers don't really have a standard for high and low temperatures. I doubt that you'll find any two that are identical in temperature range. Most, in my experience, cook at about 190 - 200 on low and 225 - 300 on high. But those are thermostat temperatures, not food temperatures. Depending on how they're made the food may or may not achieve those temps. You'll need to use a good digital thermometer to find out just how hot your cooker gets. Keep in mind that the amount of food in the cooker will affect how quickly it will reach optimum temperature and how stable the temp. will be throughout the cooking process.
If you're slow cooking food (regardless of the environment - oven or slow cooker) you want to get it to its preferred cooking temperature as quickly as reasonably possible. When I use my slow cooker I generally start it with a small amount of liquid in the bottom while I heat the recipe on the stove to it's preferred cooking temp., then put the recipe in the slow cooker and cover it up until the food finishes cooking.

" I don't know what "the" correct temperature is, or how to determine it, but it seems that once there is something other than water added to the pot, the temperature has to be higher than the boiling point of water, and too high, the water will cook out. "

Not necessarily. Foods cooked in liquids don't have to reach the boiling point of water to cook. It just takes longer to cook them. The lower the temperature, the longer it takes to cook. But foods should never be cooked at a temperature below which food borne pathogens are destroyed.
The rate at which water "cooks out" (evaporates) depends on many factors. The amount of water, its total surface area, ambient temperature, even ambient humidity are among the issues to be considered. All things being even however, water evaporates more quickly at high temperatures than at lower temperatures. You can watch it evaporate (turn to steam) when it reaches the boiling point. Keeping the food covered preserves moisture and therefore reduces (but does not eliminate) evaporation.

1. re: HRR

Most slow cookers do not regulate temperature but have only two or three power settings. Temperature is limited by the boiling point of water. The "high" setting will reach it faster than the "low" setting.

Some more expensive slow cookers may have temperature regulation.

1. re: HRR

GH is exactly correct. Most slow cookers (>99%) are build with preset heating power. So it has no temperature regulation or temperature feedback.

2. < If you put a pot of soup in an oven to cook "low and slow," will the temperature of the contents of the pot ever equal the temperature of the oven? If I set the oven to 200 degrees so the soup will cook just below the boiling point, will the soup temperature get to 200 degrees, or must I set the oven temperature higher?>

I think pretty much everyone answers are correct. If you do set your oven at 200°F, then the soup will eventually reaches 200°F. It may take awhile depending on the size of the soup, the container…etc. However, water boils at 100°C (212°F), so liquid water will turn into steam at this temperature. You can see exactly the same phenomena on your stovetop. It is not entirely impossible to get the soup above 100°C (212°F) because soup (with additional ingredients beside water) has a slightly higher boiling point than water, but it is not significantly higher.

1. From a science perspective:

If you put a cold item in a hot environment, they will eventually reach the same temperature. The time it takes will vary, depending on the size of the cold item, the relative temperatures, and the material it's made of (a cold piece of metal heats really fast, water takes longer).

So at 200 F, the soup will also reach 200 F, but may take a long time.

Water, however, has a phase change at 100 C, where it goes from liquid to gas - liquid water normally can't exist at a temperature > 100 C . So an open pot of pure water in an oven at a temperature hotter than 100 C will come to a boil, and then boil off, just like a pot on the stove.

Soup is not pure water, though. It will also come to a boil, but at a temperature *higher* than 100 C, because of the other stuff in it (in a similar manner, a pot of strong salt or sugar water will boil at a temperature higher than 100 C). The less liquid the soup is, the higher the temperature it can reach (in general) and the longer it will take for the liquid to boil off.

The interior of the soup could possibly reach a temperature higher than its boiling point, though, if the steam can't escape fast enough and it's not in equilibrium. With pure boiling water it's easy for the steam to escape, so the water doesn't get higher than 100 C.

Water evaporation also occurs at temperatures lower than 100 C, so even at temperatures lower than this, the water will gradually evaporate (a cup of water left on the counter will eventually dry up, unless you live in a really humid environment).

If you put a lid on the pot in the oven, however, you can change the pressure inside the container, which changes the boiling point of water. The 100 C boiling point is only for sea level pressure. At high altitudes water boils at a much lower temperature, while increasing the pressure with a lid (or pressure cooker) will increase the temperature.

1. Actually, if you set your oven to 200 degrees F, the soup can reach higher than 200 degrees F simply because your oven cycles on and off and the internal temperature of your oven cycles higher and lower than the set temperature (see graph below).

5 Replies
1. re: 1POINT21GW

This is correct. The temp cycles above and below the set temp with the set temp being the average.

1. re: 1POINT21GW

But not higher than boiling point regardless of the oven temp.

1. re: chefj

Not unless you pressurize it. :P Heh heh heh.

1. re: Chemicalkinetics

It would still be the boiling point, but the boiling point would be higher.

1. re: GH1618

Smart. That's true. What about "superheating"?

http://en.wikipedia.org/wiki/Superhea...

:P

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