Why Does Red Cabbage Turn Blue?

why does red cabbage turn blue

What Makes Red Cabbage Red?

Let’s start with why red cabbage is red. It’s all because of something called anthocyanins. Anthocyanins are a type of pigment, or color, that plants make. They can be different colors, but in red cabbage, they are mainly a type called cyanidin. Cyanidin gives the cabbage its rad red color. These anthocyanins don’t just make the cabbage look pretty. They also help protect the cabbage from harmful things, like bugs, and help the cabbage stay healthy (Yuan et al., 2009).

How Does Red Cabbage Turn Blue?

Now, how does this red cabbage turn blue? This is where things get interesting. These anthocyanins are pretty special. They can change color depending on something called pH. pH is a way to measure how acidic or basic something is. Think of lemon juice, which is very acidic, or baking soda, which is very basic.

When the pH is low, meaning it’s more acidic, the anthocyanins in red cabbage are red. But when the pH is high, meaning it’s more basic, these anthocyanins change from red to blue or green (Stoddard & McIndoe, 2013).

Why Does Cooking Change the Color?

You might have noticed that when you cook red cabbage, it sometimes turns a little blue. This is also because of pH. The water you cook the cabbage in is usually neutral, which means it’s not too acidic or too basic. But when you heat it up, some of the acid in the cabbage can evaporate into the air. This makes the cabbage less acidic and more basic, which can make the cabbage turn blue (Wang et al., 2021).

Why Does the Color Change Matter?

You might be wondering why we care so much about the color of our cabbage. Besides making our food look more interesting, the color of the cabbage can tell us something about its health benefits. The more anthocyanins a cabbage has, the more it can help protect our bodies from harmful things, like diseases. So, a bright red cabbage might be healthier than a blue one (Myojin et al., 2008).

Wrapping It Up

So there you have it! Red cabbage turns blue because of special pigments called anthocyanins. These anthocyanins change color depending on how acidic or basic their environment is. And when you cook your cabbage and some of the acid evaporates, your red cabbage can turn blue. But remember, whether it’s red or blue, your cabbage is still packed with good stuff that can help keep you healthy.

The Science Behind Anthocyanins

Anthocyanins are not just ordinary pigments; they are powerful agents that can change color based on the environment they are in. This is a form of adaptation that helps the plant survive in different conditions. But how do they do it?

Well, anthocyanins like cyanidin are made up of tiny particles that vibrate at different speeds. When the environment around them changes, like when it becomes more acidic or basic, these particles vibrate differently. This change in vibration can change the color we see. In the case of red cabbage, the color changes from red to blue when it becomes less acidic (more basic) (Stoddard & McIndoe, 2013).

The Role of Cooking in Color Change

When we cook red cabbage, we often use water. This water is usually neutral on the pH scale. As we mentioned earlier, anthocyanins change color based on how acidic or basic the environment is.

When we heat the cabbage in water, some of the acids that give the cabbage its red color can escape into the air. This changes the cabbage’s pH level, making it more basic. As a result, the anthocyanins change color from red to a bluish tone.

Remember, this doesn’t mean your cabbage is bad or unhealthy. It’s just the way anthocyanins work!

How Color Indicates Nutrient Levels

The colors we see in our foods are not just for show. They can tell us a lot about what nutrients are in our food. For example, the anthocyanins in red cabbage are not just responsible for its color. They also carry health benefits.

Studies have shown that anthocyanins can help protect our bodies from harmful things, like diseases. They do this by scavenging for harmful particles in our body and neutralizing them. The more anthocyanins a food has, the more health benefits it can offer.

In the case of red cabbage, a bright red color can indicate a high level of anthocyanins and thus more health benefits. So, while a blue cabbage is still healthy, a red one might offer more benefits (Myojin et al., 2008).

The Magic of pH

We talked a lot about pH, but what exactly is it? pH is a measure of how acidic or basic something is. Imagine a scale from 0 to 14. If something has a pH of 7, it is neutral, like water. If it’s less than 7, it’s acidic, like lemon juice. If it’s more than 7, it’s basic, like baking soda.

The pH of a food can affect not just its color, but also its taste and how it reacts with other foods. That’s why some recipes call for “balancing” the pH with ingredients like vinegar (acidic) or baking soda (basic). Understanding pH can help us understand our food better and even make us better cooks!


If you want to learn more about this, here are some resources you can check out:

  1. Malien-Aubert, C., Dangles, O., & Amiot, M. (2000). Color stability of commercial anthocyanin-based extracts in relation to the phenolic composition. protective effects by intra- and intermolecular copigmentation. Journal of Agricultural and Food Chemistry, 49(1), 170-176. https://doi.org/10.1021/jf000791o
  2. Myojin, C., Yamaguchi, T., Takamura, H., & Matoba, T. (2008). Changes in the radical-scavenging activity of shredded vegetables during storage. Food Science and Technology Research, 14(2), 198-204. https://doi.org/10.3136/fstr.14.198
  3. Stoddard, R. and McIndoe, J. (2013). The color-changing sports drink: an ingestible demonstration. Journal of Chemical Education, 90(8), 1032-1034. https://doi.org/10.1021/ed3007346
  4. Wang, J., Brennan, M., Brennan, C., & Serventi, L. (2021). Effect of vegetable juice, puree, and pomace on chemical and technological quality of fresh pasta. Foods, 10(8), 1931. https://doi.org/10.3390/foods10081931
  5. Yuan, Y., Chiu, L., & Li, L. (2009). Transcriptional regulation of anthocyanin biosynthesis in red cabbage. Planta, 230(6), 1141-1153. https://doi.org/10.1007/s00425-009-1013-4