Once your plastic food container is as clean as it will get with a normal washing, you may have to take some extra steps to remove the stains. There are several things that you can try. Start with whichever is easiest for you and go from there.
Leave the container out in the sun: Just like the sun can bleach your hair, it may be able to bleach the stains out of your plastic food containers. Just leave the container out on the deck, porch or doorstep for several hours (at least two or three, though it may take longer) and the stain will fade or disappear completely. Remember to wash it again after you bring it inside, and don’t put it outside if it’s going to rain. If there’s nowhere for you to put the plastic food container outside, sitting it next to a window under direct sun is a good option.
Use bleach: If the bleaching powers of the sun aren’t working, try the bleaching power of Clorox, or any other brand of bleach for that matter. Bleach is great for lightening the appearance of stains.
To use this method, make a diluted bleach solution with one part bleach and one to two parts water. Fill your plastic food container with the solution and let it soak for about half an hour. After it’s done soaking in the solution, give the containers a good scrubbing with hot water and dish soap. Use a sponge or kitchen brush if you need to. Then, dry your plastic food containers with a dish towel.
Oxidize it: The benefits of oxygen for cleaning stains cannot be denied. You can harness this power by filling your plastic food containers with hot water and dropping in two denture cleansing tablets. Let the containers sit for about ten minutes and then wash as normal. Alternately, you can buy a bottle of oxygenated cleaner from your local home improvement store and follow the directions on the label.
Limescale: If you get a build-up of white mineral deposits on your plastic food containers, you can remove them with white vinegar. Soak a paper towel with white vinegar and press the paper towel over the deposits. Let it soak for about an hour, then scrub off the stains. Repeat the process as many times as needed for the limescale to be removed.
Deodorizing: If your plastic food containers are stained and they still stink, try cleaning them with baking soda. Just mix about a teaspoon of baking soda with a cup of water and scrub the containers with the resulting solution using a kitchen brush or sponge. Alternately, you can try undiluted vinegar, which cleans just about everything.