Why Does Lettuce Turn Pink? Understanding the Science Behind the Phenomenon

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## **Why Does Lettuce Turn Pink? Understanding the Science Behind the Phenomenon**

You’ve bought a fresh head of lettuce, stored it carefully, and a few days later — surprise — the edges or veins are turning pink. It looks strange and maybe even a little unappetizing. But what causes lettuce to change color like this? Is it still safe to eat? And how can you prevent it?

Let’s explore the science behind pink lettuce and what it really means for your salad bowl.

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### **The Phenomenon: What Is “Pink Rib” or “Pink Lettuce”?**

When lettuce starts developing a reddish or pinkish tint, particularly around the stem, ribs, or edges of the leaves, it’s often referred to as “pink rib.” This color change is most noticeable in crisphead types like iceberg or romaine, but it can happen to almost any variety.

It’s not mold, and it’s not a sign of rot — it’s a natural reaction that occurs post-harvest.

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### **The Science Behind the Pink Color**

The pink discoloration is the result of **oxidation**. Once lettuce is harvested (or cut), it begins to go through physiological stress. During this process:

* The **plant cells are damaged**, allowing enzymes and oxygen to interact.
* This interaction triggers the production of **anthocyanins** and **polyphenol compounds**, which can cause the tissue to turn pink, red, or even rusty brown.
* The color change often begins at the cut ends or leaf veins, where exposure to oxygen is greatest.