Heat Tolerance of Parchment Paper
I have a roll of Wilton parchment paper that says it's safe up to 400 degrees. Does anyone know what happens to the parchment if it's heated higher than that? Does it transfer unsafe chemicals to the food? The reason I ask is because I saw an episode of America's Test Kitchen where they use a parchment sling to lower no-knead bread into a Le Creuset pot that's been preheated to 500 degrees and I wondered how they could bake parchment at 500 degrees for 40 minutes without having it burn. Are there brands of parchment that have a higher heat rating?
FWIW, Silpat is rated to 480 degrees and can't be placed directly on the floor of the oven or on a pizza stone.
I use parchment on my pizza stone at 550 degrees all the time. I've never had a problem except that it gets charred, and when it gets charred, the edges kind of disinigrate, but the paper under the pizza is fine. I would think that over 400 it's just subject to burning. But I've never had a problem....
I do the no knead bread sling into a preheated 550 degree oven often and have no problems either. Ditto for pizza. The edges turn brown and crumble just like jenhen2 described but I've never had a fire or anything like that.
FWIW, I use parchment paper from either Smart & Final or a restaurant supply house. I buy full sheets in bulk, cut them and it's much less expensive than others.
I would guess the paper under the bread never gets to 500 degrees. The bread itself acts as an insulator, and you take it out long before the bread reaches 500 degrees. I find the exposed pieces of parchment paper burn away, but the pieces that are directly touching a cookie sheet or the cookies doesn't burn.
Even if we take the fire hazard out of the equation, the paper is treated with silicone. Do you know what happens to the silicone at high temps? Is it dangerous from a food safety perspective?
i'm no scientist but i doubt parchment leeches chemicals into the food. i use parchment for everything and the only thing that happens at high temps is scorching around the edges. i know it might be different, but i can definitely taste silpat in certain foods, which is why i stay away from it. i can even smell it in the oven. don't know if that's normal or not.
but with parchment, i've never "tasted" it in cooked foods. even bland or "blank slate" type foods like bread or mild cakes.
i did however use a sloppily-parchment-lined baking sheet to roast some veggies a few years ago at a temp of about 475 and it did begin smoking in the oven. luckily i smelled it in time to pull the thing out. it was on its way to going up in flames. so be careful! i think limiting the amount of parchment "around the edges" of your food is the best bet no matter what temp. now i always use aluminum unless baking.