I was just told not to put my paper lunch bag (a small shopping bag) in the refrigerator because paper (and cardboard, too) traps the warm air inside it and prevents to cool air from properly circulating. The person who told me this insists it’s a well-known fact, but it doesn’t make any sense to me. Why would air in a paper cool any slower than air in a half-full, two-litter soda bottle? Why would a bag disrupt the convection any more than a tupperware container? Or is this entire notion bunk?
Is it true I shouldn't put a paper bag in the refrigerator because it will create a pocket of warm a
The concise answer: your informant is a moron.
Bunk, unless the bag is really blocking the cold-air vent.
Thank your friend. I will put my house in a paper bag and then not have to heat it this winter!
P.S. Hogwash!
I have heard a great number of old wives’ tales but never encountered this one before today.
If a paper bag were in some way less efficient than other containers I can assure you the difference would be much smaller than the effect you cause by opening the door to check if the items are cold yet.
Two problems with it, apparently:
- It is not well-known at all.
- it is not a fact.
It’s bunk.
That is, a paper bag will offer some insulation against the cold air, but all that does is slow down the time it takes to cool your food to the refrigerator’s temperature. And of course, the same thing happens (at slightly different cooling rates) with tupperware, tin foil, cellophane, etc.
Paper isn’t a very good moisture barrier though, so your food will dry out faster than it would in a sealed plastic container, for example. Refrigerators, like air conditioners, make the air inside dryer, as in, less humid. But if you’re just keeping your lunch cold for a couple hours, it won’t be an issue.
Ether should not be stored in the refrigerator. In or out of a paper bag.
I’ve actually wondered this about the styrofoam cups used by Sonic, and if that’s why their slushies still seem to melt in the freezer.
But a paper bag? There are more holes in that than in a plastic baggy, and they still get cold on the inside.
You might want to open the top of the bag to facilitate the cold air getting into it and cooling the contents faster.
But agree, your coworker is an idiot.
It is probably true that a warm sandwich in a paper bag in the refrigerator would cool down slightly slower than the same sandwich sitting on a paper plate in the refrigerator. My WAG is that sandwich on a plate would reach 35 degrees F in about 40 minutes but the sandwich in a paper bag might take 50 minutes. BFD.
Now, if you put the sandwich in a plastic bag, wrapped it in foil, put that inside a paper bag, put that paper bag inside another plastic bag, wrapped it in foil again, repeat this process about 8 times, then I bet it would take hours for the sandwich to get down to 35 degrees F.
IMHO, a bigger problem than short-lived pockets of warm air is the fact that a sandwich in a paper bag will dry out faster than a sandwich in a plastic bag. Plastic keeps in moisture but paper doesn’t. This effect is noticeable after just a few hours.
Your Slushy is already slushy ie. it contains enough heat that there is liquid above freezing temperature. I think the styrofoam cup WILL block the cooling effect except on the top surface. So it may progress to some equilibrium with slightly more liquid at a lower temperature before it starts to freeze solid.
This is true, but as others have said, the affect should be so minimal as not to matter.
Under some circumstances though, it can be an issue. If you have a large pan of sauce for example, and you put it in Tupperware and then the fridge while it is still hot, the sauce in the center of the tub may take hours to cool. That is long enough for things to start growing. With the sauce, you are better of letting it cool on the stove some before you put it in an airtight container in the fridge.
No, it will always cool faster in the fridge than on the stove, even the inside. The reason to cool large hot dishes before refrigerating them is so that you don’t warm up the other, smaller items in the refrigerator too much.
Are you sure about “always”? If you have sauce sitting in a pan, it is presenting a large surface area to the air and the steam can carry away the heat. As soon as you put it in a container you have added an insulating layer of material, plus you have trapped in the moisture that could have carried away some heat. You have also (assuming a typical Tupperware type container) greatly reduced the surface area of the sauce through which the heat can escape.
I have no idea about the specifics of the OP but had a recent surprise myself. I started taking bottled water with me in the car to work. I took 3 500 ml bottles, 2 had been frozen over night. I carried them to my car in a plastic bag and put it on the passenger seat. I took out the unfrozen bottle to drink on the way to work. On arrival I chucked the empty bottle in the bag and put one of the frozen bottles in the cup holder.
On the way home, 8 or 9 hours later I drank the now defrosted bottle. As traffic was slow I finished it and reached for the other bottle in the bag. Although it had only been sitting in a polyester bag, left open the contents were still about a third ice. I have tried the same thing a few times with the same results. Where I park is open to the elements although it is a multi level car park and the bottle left out of the plastic bag is not even cool by the time I use it.
So I am open to testing any weird insulation effects as I couldn’t have predicted this one.
Okay, yeah, surface area considerations aside, it will always cool faster in the fridge versus in the same container on the counter. But I don’t think glass or Tupperware versus paper will make that much difference in heat loss unless you’re actually using a thermos.
And I’d say I move my food from a more compact pan to a more spread out dish at least half the time. So going from pan to container isn’t a guarantee of having more surface area and thus faster cooling.
My WAG? The bottle inside the polyester bag created a small pocket of chilled air in a contained area. The bag acts as a small cooler. The bottle in the cup holder did not. It could not cool the entire vehicle cabin before equalizing temperature.
Where is the plastic bag left? The difference may not be that one bottle is in a plastic bag and the other not, but that one bottle is in the drinksholder, exposed to sunlight through the windshield, and the other is in a shady spot.
My refrigerator installer told me that a way to make your fridge more efficient would be to place open paper bags in it. The walls of the paper bag make a dam that keeps the cold air from spilling out every time you open the door to look for pizza. My guess is that cardboard or plastic bins would work the same.