Cardboard in the oven...?

July 29, 2005 9:49 AM

I bought a package of frozen eggplant parm at Trader Joe's, and the cooking instructions are to place the package (made of cardboard) directly into the oven...

The instructions specify not to place the package within, I think, 7 inches of any heating element in the oven. But still, it seems counterintuitive to place a cardboard package in a hot oven. Can anyone tell me why this is safe? Or has anyone ever prepared packaged food like this?

posted by amro to Food & Drink (23 answers total)

Best answer: We buy Trader Joe's spinach pie all the time. It is also in cardboard and has a sheet of parchment on the top. It is cooked at 400 F. Never seen it even scorch.
posted by Mayor Curley at 9:53 AM on July 29, 2005

Best answer: Because the cooking instructions specify a temperature below 450? Paper (and presumably cardboard) will not burn below 451.
posted by boo_radley at 9:53 AM on July 29, 2005

See, literature does have a practical real-world purpose.
posted by smackfu at 9:56 AM on July 29, 2005

if it's damp, it's unlikely to get much above 100C, so you're safe whatever the temperature of the oven (within reason) unless you cook it for so long it dries out (what's parm anyway?)

you can make a "waterbomb" from paper, fill it, and place it on an electric cooker element and it will not burn until the water has boiled away.
posted by andrew cooke at 10:12 AM on July 29, 2005

Response by poster: andrew cooke - parm = parmigiana
posted by amro at 10:15 AM on July 29, 2005

well i had to google what parmigiana was, but that looks pretty tasty! thanks.
posted by andrew cooke at 10:22 AM on July 29, 2005

The book Fahrenheit 451 was so titled because it's the temperature at which paper burns.
posted by banished at 11:01 AM on July 29, 2005

My mom made one of those about a week ago. It works fine. Below 450 it's guaranteed not to burn, plus it has a gloss that's probably a good insulator. If it didn't, then some of the moisture would get into the cardboard as it defrosted and reduce its burning point further. So no, extremely unlikely, though don't try to cook it at 500 in a pinch or anything.
posted by abcde at 11:12 AM on July 29, 2005

Ok, just a note here, the idea that paper burns at 451F is completely ridiculous, there are as many temps at which paper will combust as there are types of paper.
posted by Cosine at 11:15 AM on July 29, 2005

Perhaps not -completely ridiculous- since we're okay with saying that water boils and freezes at 100C and 0C when in fact that is varied by its purity as well as your altitude. Admittedly there's a difference between a processed bit of tree and a molecule but I don't think failing to provide extensive qualifiers is unreasonable.
posted by phearlez at 11:23 AM on July 29, 2005

In other news, behold the mysteries of science! Boil water in a paper cup! But how you say?
posted by Pollomacho at 11:29 AM on July 29, 2005

Response by poster: The book Fahrenheit 451 was so titled because it's the temperature at which paper burns.

Ah, now smackfu's comment makes sense to me!
posted by amro at 11:33 AM on July 29, 2005

Have you never reheated pizza or at least looked at the reheat instructions on the side of the box?
posted by oh pollo! at 11:41 AM on July 29, 2005

phearlez - I still disagree, there is an accepted standard for what "water" is, pure clear water at sea level boils at 100, simple. Because there is no such agreed upon standard for paper I still say it's ridiculous, there are as many temps for paper to combust at as there are types of paper, the 451 is utterly meaningless.
posted by Cosine at 11:54 AM on July 29, 2005

Response by poster: oh pollo! - I have never reheated pizza in the box, and never felt the need to examine the box closely.
posted by amro at 11:59 AM on July 29, 2005

Have you never reheated pizza or at least looked at the reheat instructions on the side of the box?

Reheat pizza? You're not the kind of person that reheats fried chicken too, are you?
posted by Pollomacho at 12:43 PM on July 29, 2005

Wondering where Andrew is from... I'm a bit surprised that someone needed to Google "Parmigiana"

Yum.. getting hungry just thinking of a chicken parm sandwich coming out of the oven at any number of pizza joints here in NYC.
posted by hpsell at 12:53 PM on July 29, 2005

the uk. (we do have italian restaurants, but i'd never heard of that. sorry!)
posted by andrew cooke at 1:16 PM on July 29, 2005

Cosine: please show your work.
posted by boo_radley at 1:38 PM on July 29, 2005

Actually it's funny that you should say that, in high school I was part of a group that tested this for a science class, I don't have the data (would be a little weird if I did) but that class was what makes me refute that claim to this day.
posted by Cosine at 1:53 PM on July 29, 2005

In defense of Cosine, this says the ignition temperature of corrugated cardboard is 427 C, or 800 F.
posted by Galvatron at 4:15 PM on July 29, 2005

my mother, and her mother before her, would wrap the tins that they baked christmas cake in with brown paper. i have no idea why, but it didn't catch fire.
posted by andrew cooke at 4:20 PM on July 29, 2005

Andrew - they probably wrapped the cakes in paper to keep the cakes from drying out too quickly. It's also a hold over from the days of wood or coal stoves, and kept the ashes/clinkers out of the cakes.

Amro - it's perfectly safe. There's enough moisture in the food inside the box to keep it from igniting. It's also difficult to ignite paper/cardboard with indirect heat. Too close to a heating element or an flame, it ignites fairly easily, but you have to sit a hot iron on a piece of paper for a *long* time before the paper begins to degrade, and I don't ever remember having the paper ever burst into flames.

I have a quick bread recipe that calls for lining the pan with waxed paper (which burns a lot faster, and ignites at a lower temperature, than cardboard). My grandmother and my mother and I have been making this recipe for nearly 60 years, and I don't ever remember a problem with the paper igniting.
posted by jlkr at 6:19 PM on July 29, 2005