I have a tupperware container that I use every week for pasta. Over the years, it’s gotten a slightly saucy tinge along the sides from the many helpings of pasta it’s had stored in it, and even the fiercest scrubbing with soap won’t get rid of it. What can I do? Hopefully something that’s not toxic as I’d like to continue to use it for food.
We have several containers that are years old that only get used for sauce/pasta. Never a problem.
It’s a stain, as long as you clean out all food residue, you’re good.
It’s in the plastic. It’s never coming out. Plastic is permeable and dye-able.
This stuff works.
Back in my restaurant days we used diluted bleach to clean the nylon cutting boards, and decruddify the coffee pots. . . Rinse well with ***hot ***water, and you’re good to go.
I understand the desire to have ‘clean’ food storage containers, but if you run it through the dishwasher with a hot dry, it’ll be nearly sterile.
I’ve always assumed there’s no solution to this - I mean, the formerly white plastic parts inside my dishwasher (the rotor arms etc) have taken on a distinctly orangey hue which I assume is from tomato sauces. If it manages to stain the dishwasher while it’s washing, then what hope do I have of getting out of anything else? 
Edit - just checked out that link… I wonder if “Cascade Plastic Booster” is available in the UK?
Edit 2 - looks like it has been discontinued. Any alternatives?
I use the cheap Aldi nappy soaker that uses sodium percarbonate as the active ingredient. It is the same thing as in expensive solutions and breaks down to hydrogen peroxide and soda ash in water. It is great on glasses. I fill them with water, throw in a little napicare plus and rinse them next day. They come up cleaner than any other way of cleaning them. Cleans most stuff really - I use it to scrub the tiles.
Make a paste of baking soda and water and thickly cover the stained area. Put a piece of plastic on top to keep the paste moist. Wait a few hours (maybe overnight) and rinse. The stain should be gone or greatly diminished. Or you could try a stong solution of Oxyclean and hot water. Mix up strong solution in much large vessel than the stained item. Soak for as long as the mixture is warm. Hope this helps.
I’ve had good luck setting the plasticware out in the sun for a day or so.
Very hot water, close to boiling, sometimes will get the stains out.
Are you just storing the pasta in it, or actually re-heating the pasta inside this in the microwave? If re-heating it, my experience is that the sauce has melted itself into the plastic, and can’t really be removed. Replace the tupperware (or continue to use it, but only for pasta).
oils and oil-like substances can be absorbed into some plastics. it is deep into the plastic and likely to stay. this behavior is put to good use in making oil booms for oil spills.
staining is common and probably is not a health risk just cosmetic and flavor. it may just be colorants and flavors. tomato, chili and basil will all stain and leave a residual slight smell. once a container material has been loaded for a long time with chili pepper you might get some mild taste later into mild tasting fruit. keep using the container for similar foods is probably good.
The platic booster stuff beowulff linked to does work. There are other names/brands they sell the stuff under.
Just load all your stained plastics in the dishwasher and run a cycle with the stuff.
I just use it for eating and reheating pasta (don’t even bother with plates, as I make portions large enough to be for dinner and then lunch the next day). I was kinda curious if I could get rid of it though just in case I wanted to use it to store cookies or something. I don’t have a dishwasher and don’t want to go out and buy fancy chemical cleaners just for this one container. I might try the baking soda thing, but if it’s actually melted into the plastic then I’ll just continue using it for pasta.