Why Does Lettuce Turn Pink?

by Charlie
Lettuce

If you’ve ever fished an old lettuce out of the back of the refrigerator and frowned at the unappealing color, you might be wondering why lettuce sometimes turns pink. After all, not many other foods go pink when they are going off, and there’s no apparent reason for lettuce to do so.

Why does lettuce turn pink? Lettuce turns pink because of oxidation. The process usually starts around the bottoms of the lettuce’s stems, and can spread up these, especially if given a few days to do so. The chlorophyll in the lettuce has been oxidized, and is no longer giving the lettuce that familiar green color.

Is Pink Lettuce Safe To Eat?

Pink lettuce is safe to eat, although it doesn’t look appetizing, and it’s not surprising if it doesn’t appeal to you! We are all familiar with the potential dangers of eating lettuce – the commonness of E. coli has made many of us wary about salads.

You can safely eat pink lettuce, however. The pink is not a sign of mold or bacteria; it’s just caused by a chemical change in the makeup of the lettuce’s leaves. You can put pink lettuce in your sandwich and you’ll be fine.

It’s worth taking note if your lettuce is turning pink, because it’s a sign that it is deteriorating. If you are going to eat it, you should do so quickly, and not let it hang around in your fridge for longer than necessary.

It may not taste as good anymore and it probably isn’t as healthy as a fresh lettuce, as some of the nutrients will have gone out of it, but it won’t do you any harm at all. As long as it is still crispy and hasn’t gone slimy, your lettuce is perfectly safe to eat.

What Makes Lettuce Turn Pink?

You might be wondering what specifically causes lettuce to oxidize and why your lettuce sometimes does this and sometimes doesn’t. Exposure to ethylene gas is the cause of the pink color. In stores, lettuces are often packed in sealed bags with higher levels of nitrogen and CO2 than in the surrounding air.

Once you open your lettuce, it is being exposed to more oxygen. The greater the airflow that occurs around it, the more likely it is to start oxidizing. Essentially, air is what makes your lettuce turn pink!

Storing your lettuce at high temperatures can also contribute to the pink color. This will cause the lettuce to “overmature” faster, and spoil its tempting green color, so if you’ve accidentally left your lettuce in a warm place, you’re more likely to see this pink.

Again, the pink won’t hurt you, so you can still eat the lettuce, even if this has occurred. It is always a good idea to wash salad leaves thoroughly before consuming them, however – even pre-washed salad. This will reduce your chances of eating something harmful.

How Can You Stop Lettuce From Turning Pink?

If you aren’t keen to eat that pink stuff, or you just want to prolong the life of your lettuce (who doesn’t want their salad greens to keep for as long as possible?), you need to address the two things that make lettuce turn pink in the first place.

That means, first of all, reducing the airflow around your lettuce. If possible, lettuce should be kept in a bag, so that the currents of air don’t increase the oxidization process too much. 

You can keep your lettuce in the bag you purchased it in, or try storing it in a Ziploc bag of your own. Alternatively, try a Tupperware, especially if you buy your lettuces loose and you’re trying to cut down on plastic. Leave the lid off or loose so that condensation can evaporate, and check your lettuce isn’t getting too wet, or it will rot.

Some people recommend wrapping lettuce in a paper towel before you store it, as this reduces the moisture on the leaves and may help to increase its lifespan. It will also cut down on airflow.

Look at where you are storing it in the fridge, too. Certain foods give off lots of ethylene gas, particularly fruits such as apples, bananas, and avocados, so try to keep your lettuce away from these.

Obviously, to deal with the temperature issue, you need to keep your lettuce in the fridge. Ideally, lettuce should always be stored at 40° F or lower, and should not be left out of the fridge for more than two hours. Put your lettuce away promptly when you have done a grocery shop, and after each use. This should help to reduce the appearance of the pink “rusty” look.

How Can You Tell If Lettuce Is Bad?

You might be wondering how you know if a lettuce is not safe to eat. While the pink itself is nothing to worry about, it is an indication that your lettuce is getting old or hasn’t been stored correctly, and that means other things could possibly be wrong with it. However, before you just toss it into your compost, check for these signs.

Sliminess indicates that lettuce has gone beyond its edible period. You should discard any lettuce that is slimy, and only eat leaves that are still firm and crispy.

A bad smell is also a sign that the lettuce should not be eaten. In general, we can tell when foods are no longer edible using our senses, so sniff produce that you are unsure about, and don’t risk eating your lettuce if it smells funny to you. If your lettuce is still good to eat, it shouldn’t smell of much.

Dark spots on the leaves are a further indicator of lettuce that shouldn’t be eaten. You should check the leaves of your lettuce, and if you notice brown or black spots, or discoloring around the edges, you probably shouldn’t eat it.

Final Thoughts

Lettuce turns pink when it is exposed to high temperatures and ethylene gas or too much oxygen. It’s a natural process that won’t do you any harm if you consume the lettuce, but you should aim to use pink lettuce up quickly, as this is a good sign that it won’t last much longer!

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