Is it safe to cook in discolored stainless steel pots?
I sauteed some fresh cut veggies in a stainless steel wok and it has a rainbow tinge on the inner bottom? Is it safe to continue using this wok for future cooking?
Best Answer
If the pan has been always used in the kitchen and for cooking,
then is absolutely safe.
The phenomenon you observe is due to thin film interference. Is the same iridescence that we observe on soap bubbles or where a thin film of a greasy matter spread on a water surface.
In the pan case, the thin film causing the interference and the related coloured fringes is formed by metal oxides already present in the pan. Actually these oxides are exactly what makes the steel of the pan stainless and resistant to corrosion.
The phenomenon can be amplified if the pan has been overheated for instance while sauting to dryness.
The rainbow might be an annoyance but does not compromise your pan nor the quality of your food.
For those onto the physics and chemistry of this here are two possible starting links:
https://www.scientificamerican.com/article/why-doesnt-stainless-stee/
https://en.m.wikipedia.org/wiki/Thin-film_interference
In principle a thin layer of grease/oil can give the same effect. This is obviously not the case for a washed pan.
EDIT: As for OP mentioned a stainless steel pan I forgot to say that obviously also a non homogeneous thickness of reticulated fat can lead to fringes or spot in a seasoned iron pan.
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Quick Answer about "Is it safe to cook in discolored stainless steel pots?"
Mix oxygen and chromium, and you've got yourself a little rainbow show all to yourself. It's basically a thin protective layer that changes color when combined with air and high heat. But don't worry…it's completely safe. Here's how to pick a safe nonstick pan.Is it safe to use old stainless steel cookware?
Older cookware: Some old or badly burned stainless steel pans may allow chemicals to seep into food as well. And if you're scouring yard sales or second-hand stores for pans that are nonstick, beware that they may contain Teflon. In general, it's best to opt for newer cookware when replacing a pan.Why do stainless steel pans discolor?
Overheating or allowing cookware to boil dry can cause yellow, brown, dark purple, blue or rainbow tints on the stainless steel surface. Although harmless, these tints can spoil the appearance of the pan. To remove this discoloration, use a products like Barkeepers Friend\xae and a non abrasive cleaning pad.How do you get discoloration out of a stainless steel pan?
Simply wash your pan with vinegar and rinse with water to remove discoloration. Additionally, vinegar can be used to rid your pan of white calcium build-up stains. Make a mixture of one part vinegar to three parts water and boil in the affected pot or pan. Allow the mixture to cool, empty the pan, and wash as normal.Is black residue on stainless steel harmful?
It is essentially harmless, though certain industries that need a "clean" surface as determined by a "wipe test" get thrown into a panic.How to Clean Stainless Steel Pots and Pans
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