I Stored Tomato-Based Foods in a Plastic Container: Is That Doomed?

It’s a conundrum that many of us have struggled with. We all want to do our part to help the planet and reduce food waste – yet we know that once the leftover spaghetti touches the inside of that plastic food container, it will be consigned to a life of orange-colored abandonment in the back of the kitchen. the closet until we can justify throwing it away and buying a new one.

For me, proud Brit that I am, it’s usually leftover baked beans that get me a cropper. Rather, it has reached the point where I have dedicated containers reserved for this purpose, and woe betide anyone who comes near my pristine boxes of food that has even a sniff of tomato. A quick look at Reddit proves I’m not alone.

But does it have to be this way? Why do tomato-based foods discolor plastic so much, and is there a reliable way to get the stains out? Well, here at IFLScience we like to try to answer the big questions, and these were certainly questions that came to mind as I decided which container would be the next to be sacrificed to the baked bean gods.

Why do tomatoes stain plastic containers?

With several years of adult plastic container ownership under my belt, I wasn’t embarrassed to hear that the answer to this question could be found in some good old high school chemistry class.

Tomatoes contain a bright red pigment called lycopene. Among its many redeeming qualities — it has been linked to a number of health benefits, from sharper vision to better erections — lycopene is hydrophobic. The plastics typically used to make food storage containers are also hydrophobic and porous, which is the perfect combination to encourage lycopene to stick to them and never let go.

Another reason why this is such a headache in the kitchen is that cooking tomatoes to make sauces, soups, and all the other fancy things you want to keep in a container actually increases their lycopene content.

As Dr Emma Davies writes for BBC Science Focus, its hydrophobicity explains why removing the lycopene stains with soap and water is a non-starter – and the high temperatures in dishwashers can actually make the problem worse.

By the way, hydrophobicity also explains another annoyance associated with plastic containers: how difficult they are to dry. Writing for Cosmos, Ellen Phiddian explains that water on a plastic surface is in larger droplets, slowing evaporation.

How do you clean stained plastic?

We’ve identified lycopene as the nasty culprit, and we know hot soapy water is unlikely to be up to the challenge, but are there any cleaning tips that do work?

To avoid some of the inevitable comments: There is of course a simple way to avoid this problem, namely by not using plastic in the first place. For example, microwave-safe glass containers are readily available and more resistant to stains. But if you do find yourself with a sad, orange-colored container, there may be a way to save it.

Good Housekeeping suggests that if you tackle the stain immediately, applying some vegetable oil before washing can help remove the stain. If that’s not enough, they recommend a good scrubbing with baking soda paste before washing as normal.

With almost every major problem plaguing humanity, a five-minute search on TikTok will turn up a plethora of people claiming to have The Answer™, and stained plastic containers are no exception. The good folks at The Spruce Eats took a look at a TikTokker hack using plain dish soap and paper towels and found it to be surprisingly effective.

You simply pour warm water and a little dish soap into your stained container before adding a torn paper towel, securing the lid and shaking vigorously. Apparently it only takes about a minute for the stain to disappear. Microbiologist Jason Tetro explained to The Spruce Eats that it’s the combination of agitation and oil absorption through the paper towels that makes this hack effective.

A more old-fashioned option for tough stains, as recommended by the American Cleaning Institute, is soaking in a mild bleach solution.

All of these methods sound like they’re worth a try, and they’re certainly preferable to giving up and throwing away your container – our planet really doesn’t need any more plastic pollution.

But reader, it is time for confession. I’m afraid we can’t directly confirm whether any of these hacks worked for us. After completing my bean storage duties, my sacrificial plastic container was washed in the sink along with the rest of my dishes and, well, you can see the results:

hand holding a blue plastic food storage box against a gray work surface

It’s like it never happened.

Image credit: ©IFLSience

Not a spot to be seen. Is it because the container is colored? Did I accidentally buy stain-resistant plastic containers? Would any other tomato-based food have weathered so successfully? Maybe those are questions for another day.

Fact-checkers confirm that all ‘explainer’ articles are correct at the time of publication. Text, images and links can be edited, deleted or added at a later time to keep the information current.

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