Brown Fruit

From childhood on, professionals and parents encourage kids to include fruit as a part of a healthy diet. I remember being taught the ever changing food table, recommended daily servings, and hearing, ‘An apple a day keeps the doctor away.’ In an effort to reach my fruit quota for the day, I would sometimes pack an apple in my lunch for school. If I cut the apple in the morning, by the time I got ready to eat it, it would be all brown. After making observations such as the smell and texture of the fruit, I made the decision that the fruit was still good to eat, despite it’s rotting color. Just as Andrew taught us about risk, I weighed the cost of eating the fruit:

Eating the apple The apple is bad and I get sick. The apple is fine and I get the nutrients from the apple.
Not eating the apple The apple is bad and I avoid getting sick. The apple is fine and I miss out on the nutrients.

I ate the apple because I decided it would be worth the risk. Because science builds upon knowledge that already exists, I also decided to eat the apple because I had seen people eat an apple that turned brown after being cut, and not get sick.



Typically, when naturally bright foods turn brown, it is bad news. Why does this not hold true for apples? According to Lynne McLandsborough, it all has to do with something in apples called o-quinones. Once an apple is cut and interacts with the air, certain enzymes oxidize compound that react with the o-quinones, which cause the brown color.

Another fruit that I notice has a similar reaction is avocado. I had not had much experience with avocados until much later in life compared to apples. I noticed their browning when I opened a container of guacamole that had been made the day before. The top layer of the dish was all brown. In this case, my sister encouraged me it was not bad, but I chose not to eat the brown part. The risk of eating the guacamole seemed bigger to me because I was not as familiar with that food. I could not make any observations that would confirm or deny the quality of the fruit as I did with the apple.



Avocados appear to be a much different fruit compared to apples, but Compound Interest explains how the browning occurs in a similar way. In avocados, the enzyme polyphenol oxidase, once in contact with oxygen, helps quinones form polyphenols. The polyphenols are the mechanism that causes the brown color.

I took the risk and ate the browning fruit, but many other people do not. Anastasia Bodnar  explains how scientists have created modified apples to avoid the browning color. It will be interesting to see how produce may transform in the next few years to get rid of or reduce browning in fruits such as apples despite its harmlessness.

5 thoughts on “Brown Fruit

  1. Derek William Drotman

    After reading your blog I instantly became interested in why fruits turn brown. I know there has been many times in my life where I went to grab an apple, banana or leftover guacamole and was immediately disturbed when I saw the brown color. Personally I think the freshness and color of a fruit makes me crave fruit over ordinary food . After reading this article, I learned bruised fruit isn’t necessary healthy because the cell walls are broken which allows nutrients to exit the fruit. When the microbes enter the fruit and turn it brown it can cause salmonella and E-coli which are some dangerous diseases. I wish you extended your blog and talked about why other fruits bruise and turn brown

  2. Danielle Megan Sobel

    I would’ve never thought to write about this for the blog, so it was really interesting to read about. I personally have no problem eating browned apples (sometimes brown guac freaks me out a little), but I can understand why people don’t– it’s different from the norm. I know other fruits go through changes like this as well. For example, bananas turn brown when left un-eaten for too long after they have been cut. Here is an article which explains the same reaction about the enzymes in apples and avacados, but also in bananas! I wonder what other fruits have this reaction happen to them?

  3. Kaitlyn A Kaminski

    Hi Erin,

    I never thought about this topic…good choice and explaining this. I love my avocados and have an obsession with them! My roommates all make fun of me because I eat them too much, but I just love them so much! I am glad to see their is a reasoning behind their color. I understand the pain of avocados turning brown as well as apples and I am over the moon that scientists are trying to make something that will improve the coloring- let’s hope it’s safe! Here’s an article on pear’s coloring-, I thought you might enjoy this!

  4. Matthew Porr

    I have often noticed that after a while my apple slices would turn brown while they were in my lunch bag waiting to be eaten. I’m not sure if I would weigh the risk of eating a brown apple but I do know that the browning was due to oxidization. While watching the food network, I received a tip that putting lemon juice on freshly cut apples would deter the brown color. I’m not exactly sure the mechanism behind this but It probably has something to do with a chemical in the lemon juice bonding with the o-quinones which stops the oxidation from occurring.

  5. Claudia Lynn Hatch

    This was a very strong blog. This is a topic I have always wondered why my apples brown so quickly, and now I know. I am someone who will still eat the apples, but the guacamole always worried me. I think you had very solid sources to help reinforce your points and I thought the blog was very well written. I also liked that you used concepts from class to help your reader better understand your topic. This article helps further explain the issue and also gives you some helpful tips on how to naturally keep your apples from browning.

Leave a Reply