Blueberries can turn green in your muffins, and that’s okay.

Why'd my blueberries turn green?


It happens even to the best of them, moist and sweet homemade blueberry muffins, made with care and love, but that end up with unsightly green blobs of what should have been pretty purplish blueberries. The taste is the same, but the color of the blueberries wasn’t expected. That, my friends, is anthocyanin‘s fault. But actually, to be more precise, the pH of the muffin batter also has a role in this story.

What is anthocyanin?

I guess I should actually say “anthocyanins,” plural because actually anthocyanins are a family of similar compounds. They are the antioxidants in plants, like leaves and berries, and they are responsible for much of the color you see on the tables at the farmer’s markets, from red cabbage and purple corn to many different types of berries, cherries, and grapes. The anthocyanins are not to be confused with the carotenoids (like beta-carotene): carrots get their orange color (and even purple color) from beta-carotene, while blueberries get their violet-blue tones from cyanidin 3-glucoside (an anthocyanin).

Why do anthocyanins change color?

Anthocyanins are actually really good pH indicators: they change color depending on if they are in an acidic, neutral, or basic (alkaline) environment. The color changes observed vary from one anthocyanin to another, but for cyanidin 3-glucoside, the anthocyanin found in blueberries, the color varies from red to violet to blue or even green (from low, acidic pH to higher, alkaline pH). A change in pH entails a small change in the structure of anthocyanins, like cyanidin 3-glucoside, thereby affecting how anthocyanins absorb/reflect light rays: they change colors.
Effect of pH on blueberry color | Jance Lawandi @ kitchen heals soul


What do anthocyanins have to do with the color of the blueberries in my muffins?

The answer is easy: does your recipe have a lot of baking soda, with the hopes of giving those muffins lots of oomph and volume? If there aren’t enough acidic ingredients in your recipe to balance out that alkaline baking soda, then your muffin batter will be basic (alkaline)… your blueberry muffins will probably have splotches of green berries, instead of violet.
Bowl of blueberries | Jance Lawandi @ kitchen heals soul


If your favourite blueberry muffin recipe yields the best muffins you’ve ever tasted, but the blueberries end up an unfortunate green, know that it’s not the end of the world, but if that green color bothers you, make a note. In the next batch, consider adding in a little extra vinegar (or buttermilk, or whatever acid that is called for in the recipe) to balance out the extra baking soda, or you could even use a touch less baking soda in the next recipe.

Here’s a recipe for yummy honey blueberry muffins on Kitchen Heals Soul.

, , , , ,

7 Responses to Blueberries can turn green in your muffins, and that’s okay.

  1. Mallory @ Because I Like Chocolate July 12, 2014 at 12:29 am #

    You have made this all sound so simple! I love these posts when you take your chemistry background and apply it to food and cooking. It’s something different from what the rest of the food blogging world is doing and I find it quite refreshing!

  2. Stephanie July 13, 2014 at 7:04 pm #

    ooooh so interesting! The muffin recipe I use doesn’t turn green, but I’ve had some very good cake-like versions of the blueberry muffins where I pondered the greenish blobs (briefly.. before shoving the whole muffin in my mouth, because I’m a lady)

  3. Vina December 26, 2014 at 9:35 am #

    Thank you for explaining the reason for the color change! My favorite cookie to bake is raspberry white chocolate and always turn green. The green with the red raspberries makes for a perfect Christmas cookie, but I’ve gotten used to people asking “why are they green?” and now I have an answer!

  4. Dave August 9, 2016 at 6:37 am #

    So, does it kill you if you eat it? I mean.. I don’t want to have cyanide in my cake.

    • Janice August 10, 2016 at 12:07 am #

      Hi Dave,
      Cyanide is not at all the same as anthocyanins, and the anthocyanins found in blueberries certainly won’t kill you (I think the human body just metabolizes and excretes them). No worries!


  1. Banana & cardamom buttermilk loaf cake | Kitchen Heals Soul - May 2, 2017

    […] Apparently I was wrong. The banana chunks greyed a little around the edges. Conclusion: I really need to get a pH meter or even some pH paper to verify the pHs as I go. Or maybe I need to work more on my banana browning theory (or rather my banana greying theory in this case). I could also do a test like I did with blueberries to show the impact of pH on blueberry colour. […]

  2. Carrot focaccia | Kitchen Heals Soul - May 9, 2017

    […] get their colour from anthocyanins (yes, the same family of compounds that are responsible for the colour of blueberries), while yellow carrots get their colour from xanthophylls. The orange carrots are loaded with […]

Read previous post:
gingerbread granola - granola sweetened with molasses and gingerbread spice mix, with candied ginger and lots of nuts
Gingerbread granola

  It's important to have a recipe for something that makes an easy, homemade holiday gift that friends and family...