Could you be more specific about what the food was? I've heard a tomato-based sauce (like spaghetti sauce) can "sour" if you place it into the refrigerator while it's still hot, but I don't have any science to prove or disprove the idea.

-Grainlady

I think it has more to do with the volume (and to some extent the shape); a large pot of boiling stock, for instance, will take far longer to cool down to fridge temps than, say, a two cup flat Rubbermaid container.

The food safety folks talk about the 'danger zone' between 140 degrees and 40 degrees; the longer the food is in that zone, the more likely that germs will be able to reproduce and cause mischief.

Here is a link that might be useful: danger zone

This post was edited by arley on Wed, Jan 21, 15 at 8:55

It's been quite awhile since I saw that show and I can't recall what the item was, it might have been a tomato sauce but I can't say for sure. I'm pretty sure it was a large container of whatever it was.

"-----putting hot food into the refrigerator, he said it would cause it to sour."

I don't understand that. In general, chemical reaction increases with higher temperature, not lower.

A couple of things can happen with hot food in a refrigerator:\\

1. If the hot food is not covered, moisture will condense on the cooling coil (evaporative coil) and decrease freezer efficiency.

2. If hot food is put in the refrigerator, it can raise the temperature inside the refrigerator. A typical refrigerator has a compressor which can handle around 1500 BTUs per hour, and each gallon of water requires about 30 BTUs to cool down one degree F. But there is enough thermal mass from other foods to help cool the hot food down without much of a problem.

dcarch

The biggest concern with putting hot food in the refrigerator is indeed that danger zone. For any food product to remain safe is must be held above 140F or below 40F. The more time spent in the "danger zone" in between the greater the risk for spoilage and for contamination.

By putting a large volume of hot anything in the fridge and expecting it will cool faster, only raises the internal temp of the fridge and potentially, of the other food occupying that space, placing everything at a greater risk for being in the danger zone. Not to mention making the fridge work harder than it should.

The goal is to cool hot food as quickly as possible to roughly room temp, before refrigerating. At that point the refrigerator can effectively cool the food the additional way to below 40F. The jugs of frozen water is actually an excellent way to quickly cool your product without diluting it, before refrigerating.

Steve

I've never heard the "sour" bit before, so I started searching and found an article in the Chicago Tribune where an interviewee tried a batch of tomato sauce half right into the fridge and half not, and didn't find a difference in taste. Not definitive, but at least a test. :)

In this case, however, Ramsay might have meant "sour" as in spoil, rather than flavor.

I've heard that a kettle of sauce or soup will cool down faster at room temperature rather than put intact into the fridge. Supposedly an encapsulated hot core develops in the fridge which is insulated by the surrounding cooler stuff. That sounds like a good story, but I don't know enough physics to know if it's ridiculously stupid, sort of true but not functionally important, or spot on, and I don't have the inclination to test it. Another version says that the air between the food and cover stays too warm too long in the fridge and that's where the bacteria grow.

These might be the origins of what Ramsay said, but they might be myths.

In general, when the food is cool enough to handle, the best idea is to portion into small and/or flat containers, and refrigerate. If there's enough to worry about, do the ice chill. In food service, they usually put it in shallow pans.

Yes, I understand the food safety "danger zone" topic. I was only commenting about hot food going into a refrigerator will not cause the food to turn sour.

While I will not recommend anyone to do this, I do it all the time to leave a hot pot of food on the counter to cool overnight. I have been to many parts of the world where that is a fairly normal thing to do and no one got sick.

"-----I've heard that a kettle of sauce or soup will cool down faster at room temperature rather than put intact into the fridge.----"

That is a very tricky scientific statement.

It can be correct if you are talking about the RATE of cooling for a given same temperature because the refrigerator is better insulated.

It is not true if your are talking about pure temperature drop comparing in a room temperature environment vs. refrigerator temperature environment.

dcarch

Depending on how hot it actually is, I would worry about putting plastic water bottles into hot food. While the plastic may be "food safe" I don't think it's "hot safe" and I wouldn't want it swimming around in hot food. If you've ever put a water bottle in the dishwasher, you'll know what I mean. I'd rather put the pot in a sink of water with the ice filled bottles floating and stir it often to cool quickly, without risking leaching of plastic into the food.

I think the safest thing is to put a large volume into smaller containers and refrigerate. I know I read our health dept restaurant inspections and often there are demerits for hot food being refrigerated in too large a volume to cool quickly/safely.

Dcarch, could you please try that again... The root question is if the center of the mass will cool faster, say down to 70ð if the stock pot is on the counter or in the fridge. That's ceteris paribus, starting from a boil, moved off of the burner onto a solid (not trivet or rack) surface.

I wouldn't ever pt anything hot into the fridge as it will just warm up the fridge. I've never been ill from leaving something to cool down either.

"----Dcarch, could you please try that again... The root question is if the center of the mass will cool faster, say down to 70ð if the stock pot is on the counter or in the fridge. That's ceteris paribus, starting from a boil, moved off of the burner onto a solid (not trivet or rack) surface.--"

Watched water never boils, searing meat seals the juice, ------- Our observations can play games with us, unless conditions are exactly defined.

1. If I put one gallon of water at 212F in an empty refrigerator that is at 40F, and a one gallon of water at 212F in a room that is also at 40F, the water in the room will cool faster because the room is not well insulated, and has a much greater thermal mass to help cool the water down. In addition, evaporative cooling is greater in a bigger room.

2. If I put a one gallon of 212F water in a room that is at 85F, and a gallon of 212F water in a relatively full refrigerator which is at 40F, water in the room will at some point cooled to 85F, as will the one gallon in the refrigerator, but the refrigerator will cool the water down to 85F faster, based on the law of entropy and thermal conductivity, To understand this quicker is to do a reverse thinking. Food gets cooked faster using higher heat.

The entire industry of magic entertainment is based on one single fact that we are such lousy observers. :-)

dcarch

Thanks so much for the answer, Dcarch! Heat flow problems were my nemesis in college math. I could integrate them but I couldn't figure out how to set them up (they should have been in Physics. I wasn't taking Physics!).

What you've said makes excellent sense, and makes much more sense than the encapsulation hypothesis.

Re leaving it on the counter, there's a big difference between what's safe for home cooks in a clean kitchen, and what's safe in a many hands restaurant kitchen serving the public. You know if you've boiled your kettle for long enough to remove the bacteria, and stirred enough for it to have been hot all the way through. You know that you've washed your hands after touching bacteria sources. You know how clean your containers are. You know how much dirt blows in from outside. You know if you have pests, and most likely don't. You know who's going to be eating the food and if any have poor immune systems. None of these are sure things in a restaurant kitchen.

Not to mention the downside risk for a restaurant kitchen (food poisoning of lots of people will cause expense, lawsuits, loss of reputation, maybe some Health Dept hassles) is much greater than for a home kitchen, so it makes sense that they would have to be far more diligent about food safety.

I'm not sure about the science, as in the numbers involved.. but I do know the reasoning, as in how it works in laymans terms.

I'm going to use the example of stock. If you put a pot of super hot stock right into the fridge, a couple things happen.
One, you raise the general temp of the fridge- think of how your fridge kicks on when you stand in front of it with the door open on a hot summer day for too long. And in particular, you can raise the temp of any foods close to the pot. So the fridge is working overtime to compensate for a big heap of hot, and your hot pot is not cooling down as quickly as you think it might be.
Two, the pot. Since you usually put a lid on it instead of letting your pot steam up the fridge, you are trapping the heat that could otherwise escape out the top- think kind of like how your head radiates heat off the top, and what a difference there is between wearing a hat or not when it's cold out.
Then there is the danger zone of between 40-140. When you put that hot pot into the fridge, you are effectively creating a breeding environment, with the core staying at that cozy danger zone the longest. Think of how a bucket frozen solid of ice melts, outside in, with that ice water outside sort of acting like an insulator, where if you were dumping the melted water out, the ice block would melt faster. Same thing goes for your pot of stock, only there isn't any way to pour off the cooler stuff to let the hotter stuff cool down. That's why a lot of professional kitchens use ice batons that they plunge into the middle of a container of stock to cool it fast and from the middle. One can do the same thing at home with an ice bath surrounding the kettle and stirring the stock- adding salt to the ice bath brings down the cold even better, that's why they use it in home ice cream makers. If one has a snow bank on hand, they can use a snow bank too, lol.

Now take that to something thick like tomato sauce. On a round about description... did you know a home canner can't safely can packed pumpkin, even with a pressure cooker? That's because you can't get the internal temp high enough quick enough during processing- and you get the danger zone going on. The opposite effect is true with a thick liquid like tomato sauce and cooling- you have a hard time getting the chill down quick enough fast enough to avoid danger zone. Or a turkey carcass needs to be stripped of meat because the carcass holds the heat.

Then coupled with all of this is the time and temp abuse rule- up to four hours of room temp is ok for a lot of foods, but beyond that is abuse, inviting in foodborne pathogens. So letting food cool down a bit to room temp is ok, but letting it sit out for over four hours to get to room temp before putting it into the fridge to get cold is not. Since a lot of super hot bit pots of food take longer than four hours, that hits outside the mark, thus requiring the chill down before putting into the fridge.

So I've done a lot of research since this thread started. I was pleased to learn that the way I've been doing it is "right". (What I do is let sit until cool enough to touch (i.e. no spatter burns, and also cool enough not to worry about plastics), portion out into small, flat vessels (lots of surface area for cooling), let cool to merely warm, cover and put in fridge. Move to freezer once cooled.)

The more I've read about it, the more I'm convinced that Ramsay must have meant "sour" is in go bad rather than a flavor issue.

Gordon Ramsey actually said if a hot sauce is 'sealed' and placed in fridge, condensation causes it to go off. Never heard of that before though!

There is nothing wrong with placing hot food in a fridge. Cooling down first introduces harmful bacteria. Don't worry about 'warming' up a fridge! It will not happen!!!

Please clarify that last sentence.

It was an old belief that the condensation from covering hot food would "poison" the food. My MIL left her turkey on the counter, uncovered for about 6 hours...and her husband got sick the day after every thanksgiving

I've always heard that you should never put hot food in the fridge. Food cools very quickly- at least in my house lol brrrrr.

It all depends on many factors, but one is very important to many of you:

Studies have shown that temperature inside many home refrigerators are way above safe range. To put hot food inside an already too warm refrigerator is asking for trouble.

Make sure you have a very good thermometer and always check your refrigerator temperature.

dcarch

What? I think the OP was asking a question about food handling.
And college classes ( liberal arts) I attended stressed straight forward instructions not even mentioning the "do not's". Sort of like not telling children to put beans up their nose.

I wish someone had imparted that bean thing to me when I was a kid ...

I have worked in the industry for over 30 years, and I am in Instructor/Proctor for the National Restaurant Assn's ServSafe Food Safety Program. Here is the answer to why Chef Ramsey instructed as he did. If you place freshly prepared chili, soups, etc., in your cooling device, SEALED, it will sour within a few hours. (Not to mention that the individual should have known better)Thus, the practice to leave lids, Seran wrap, with a 1-2" gap, as to allow the steam to escape until it has properly cooled. This is common knowledge within the industry. However, best practices include breaking up large items into smaller items to expedite the cooling process along with ice baths. Remember! Below 70F within the first 2 hours and below 40F within four hours.

What does "sour" mean? How does chili or soup "sour"?

It means go bad in this context.

Yes, 'sour' means 'spoil'.

To speed up the cooling process the food should be placed in the blast of a fan. For an open pot the fan should be placed such that it blows at least partially on the top ie into the pot. The bigger the fan the greater and faster the air flow and the faster the cool down (higher heat transfer coefficient)*. For faster cooling arrange it so the fan blows over ice in some form like a couple plastic bottles of frozen water for example. Rotating the pot a couple times would speed it up too as would stirring the contents. I spect if you put a small fan in the refer this principle would hold. I should think a simple experiment with a gallon of water would be in order.

*Certainly the temp drop will be asymptotic to the ambient temp but the general slope of that curve will be greater with the fan than without. Additionally there would be no stagnant volumes.