Why do Bananas Turn Brown?

Have you ever picked a perfectly ripe yellow banana from the bunch only to see it quickly turn brown? As you ask yourself where those bright yellow hues have gone, discover the scientific answer behind why bananas turn brown. Uncover the hidden truth and find out to keep your favorite fruit lasting longer! Read on to find out more.


Bananas are a popular fruit, enjoyed all over the world. But have you ever wondered why bananas turn brown? This article is here to explain the science behind this phenomenon and provide insight into why bananas ripen, discolor, and eventually spoil.

By understanding the chemical reactions taking place in a banana as it ages, we can gain an appreciation for how this tasty treat is affected by time and temperature. So let’s take a closer look at what causes bananas to turn brown!

Why do Bananas Turn Brown

What Causes Bananas to Turn Brown?

Have you ever noticed how quickly bananas turn brown? This is a common phenomenon that many of us have experienced. But why does this happen?

The answer lies in an enzyme called polyphenol oxidase (PPO). PPO is found in the skin of the banana and when it comes into contact with oxygen, it begins to break down the cell walls of the fruit, leading to a discoloration known as browning. Temperature can also accelerate this process by increasing PPO activity. In addition, ripe bananas are more prone to browning due to their higher sugar content.

Bananas don’t necessarily have to turn brown; they can be prevented from discoloring by introducing an acidic element such as lemon juice or vinegar which interferes with the oxidation process caused by PPO.

Alternatively, covering them in plastic wrap or storing them in cold temperatures slows down their ripening and prevents further discoloration.

In summary, bananas turn brown due to an enzyme called polyphenol oxidase (PPO) found in its skin which interacts with oxygen and causes cell walls inside the fruit to break down.

This process can be inhibited through acidity or cold temperatures which slow down its ripening rate.

The Chemical Reactions Behind Browning Bananas

When a banana begins to turn brown, it is due to a complex chemical reaction. This reaction occurs when the enzyme polyphenol oxidase (PPO) comes into contact with oxygen and phenolic compounds in the banana peel.

When this happens, it causes an oxidation process resulting in the release of certain chemicals such as quinones and catechol that cause the fruit to darken. Ultimately, this process is what causes bananas to turn from yellow to brown as they age.

The amount of time it takes for a banana to turn brown will depend on its ripeness when picked, its variety and how it’s been stored after harvesting. Generally speaking, unripe bananas will take longer than ripe ones due to their higher PPO levels; however, storage conditions such as temperature can also contribute significantly towards the speed of browning.

Common Ways to Prevent and Slow the Browning Process

Bananas are a popular fruit, but they are also prone to browning. Browning is caused by the enzymatic breakdown of certain amino acids, producing melanin and other compounds that cause the banana to turn brown. To prevent or slow this process, there are a few common techniques that can be used.

The first technique is to store bananas in the refrigerator. The cold temperature inhibits the enzymatic activity of the enzymes responsible for browning, thus slowing down or preventing discoloration from occurring.

Additionally, storing bananas in an airtight container will reduce their exposure to oxygen which can further slow down their spoilage rate.

Another way to prevent or slow banana browning is by coating them with lemon juice or pineapple juice before storing them. The acidic properties of these juices inhibit enzymatic activity and help preserve the freshness of bananas for longer periods of time.

Additionally, adding a bit of honey helps keep them moist and prevents excess moisture loss which can contribute to discoloration as well as spoilage over time.

Finally, wrapping each individual banana in plastic wrap will help reduce its exposure to air while still allowing it some room for respiration during storage.

This method also helps keep moisture inside while preventing bananas from coming into contact with oxygen-rich environments where oxidation can occur more quickly than usual leading to accelerated spoiling rates and premature browning over time


In conclusion, it is clear that the process by which bananas turn brown is a complex one. While certain environmental factors can speed up this process, the main cause of browning is enzymatic oxidation.

This chemical reaction occurs when enzymes in the banana react with oxygen in the air, resulting in a change of color and texture.

By understanding why bananas turn brown, we can take steps to slow down or even prevent this process from occurring.

Whether it be storing them away from sunlight or keeping them at cooler temperatures, there are numerous approaches to preserving the freshness of our favorite yellow fruit.

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