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Why Does Cabbage Turn Black? (And Is It Safe to Eat?)

Kristie Leong M.D. is a family practitioner who believes in the power of nutrition and a healthy lifestyle to prevent and fight illness.

You bought a fresh head of cabbage at the farmer’s market and stored it in the refrigerator, but when you take it out to use, you notice that parts of your lovely green head have turned gray, brown, or black. You might wonder why this happens and whether black or darkened leaves is safe to eat. Let’s dig a little deeper.

Why Cabbage Turns Black

Darkening of cabbage occurs when oxygen reacts with iron in the leaves. Oxidation is a process that donates oxygen to another chemical compound. When this happens, it causes a color change. While some types of cabbage are more prone to darkening than others, there are ways to keep this from happening.

Store Cabbage Properly to Keep It From Turning Black

Since cabbage has a lower water content relative to other leafy greens, it has a long storage life. It will last up to three weeks in the refrigerator if you store it properly. Since cabbage darkens due to oxidation, you want to protect the leaves from air exposure.

To reduce darkening, place it in a plastic bag and seal it tightly, so air doesn’t come into contact with the leaves. You can also use cling wrap but will need a few layers to keep air away from the leaves.

Is Black Cabbage Safe to Eat?

If the black to dark gray color only affects certain parts of the cabbage, like the outer leaves, you can remove those leaves before preparing your recipe. As long as the rest of the cabbage looks bright and green and there are no signs of rotting, you can safely eat it.

Black Spots on Cabbage

Sometimes cabbage has black spots on it, rather than larger black areas due to oxidation. Discrete black spots can be caused by a fungal infection that affects cabbage leaves as well as other vegetables. One of the most common fungi that causes black spots is Alternaria.

Although the term fungus might sound ominous, the fungi that affect cabbage are usually not harmful to humans. They’re more of a cosmetic issue. However, there’s some concern that if cabbage leaves with black spots from fungi get too hot, they could form mold toxins. These could theoretically trigger allergic reactions in susceptible people. You can avoid buying cabbage with black spots by carefully inspecting cabbage before you buy it.

According to Cook’s Illustrated, cabbage can also develop tiny black spots called “’pepper spots.” These spots, which are no larger than specks of ground black pepper, arise from improper growing conditions such as improper soil pH, overfertilizing, and low light conditions. They tested cabbage with these tiny spots and found there was no difference in taste between leaves with and without these spots.

When to Throw It Away

Always inspect cabbage closely before eating it. Besides the risk of consuming rotting food, cabbage with the following features won’t taste good.

  • It has a strange smell. The aroma usually comes from the breakdown products of bacteria and indicate the leaves are rotting.
  • It feels wet or mushy,

Tips for Selecting Healthy Cabbage

  • Look for cabbage that is firm, with no soft spots, holes, or bruises.
  • Avoid those with yellowing leaves.
  • The outer leaves should be green and free from blemishes.
  • If it has been cut open, make sure that the interior leaves are white and crisp.
  • Check the weight. It should feel heavy for its size and be firm to the touch. A lighter head indicates that it has been picked before it was fully grown.

Spending a little extra time choosing a head of cabbage will help you get the best quality and flavor.

Final Words

Areas of darkening and blackening on the outer leaves of cabbage are usually due to oxidation from exposure to light and air. Storing it properly helps reduce this darkening.

If there are black spots on the leaves, it’s usually due to fungus or “pepper spots” from improper growth conditions. For quality purposes, it’s best to remove any areas that are dark or have black spots and enjoy only bright, green healthy leaves.

References

This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.