Cooking For Engineers

[cbuck1]

I have a cleaning question regarding a plastic food storage container. I made a brisket with a sauce that was essentially tomato and onion-based. I thickened it with instant mashed potatoes. Afterward, I stored the extra sauce in a plastic container in the fridge for about a week, then transferred it to a smaller container for freezing.

The problem: There is a ring around the circumference of the container where the top of the sauce sat. It is palpable, which implies to me that it is probably due to potato starch. I have tried soaking it in soapy water and blasting it with very hot water. Nothing has worked. I can't scrub with steel wool without scratching the smooth plastic beneath it. Does anyone have any ideas?

[Dilbert]

oils / fats from the meat/sauce may have caused the plastic to swell -

let it dry thoroughly (slim hope there....)

if you can't scrape it off with a fingernail, it may be a permanent swelling / mark vs. a "deposit"

[Jim Cooley]

I've gotten strange marks like that after I've microwaved stuff in a plastic container. It's usually where an oily or sugary substance got so hot it melted the plastic a bit.

[cbuck1]