You’re not alone if you’ve wondered what those weird little dark lines in banana bread are. If you look around the internet, theories range from bugs to worms to chemical reactions.
What are the black lines in banana bread? Surprisingly, there are no scientific studies that directly address the question.
To help you solve the mystery, we’ve compiled some of the best answers we can find on the web.
Banana bread is made from mashed bananas. It often tastes moist and sweet.
Its main ingredients are flour, brown sugar, butter, and overripe bananas. Other recipes have eggs, lemon juice, baking powder, and shortening. And to enhance its flavor, some add raisins or nuts.
Here are the most popular answers we found:
Many believe the black strings are the banana fruit pulp’s natural fibers. These fibers supposedly turn a shade darker as the banana fruit ripens.
As we all know, the riper the banana, the better ingredient it becomes for banana bread.
Hence, the mature, darkened fibers on a banana bread batter appear as tiny black strings on baked banana bread.
Others think it takes sodium bicarbonate, or baking soda, as a leavening agent to change the color of the banana’s fibers.
Banana bread’s main ingredients—banana, brown sugar, butter, and flour—are all acidic. Moreover, a ripening banana becomes even more acidic as its carbohydrates break into sugar.
Adding alkaline baking soda to leaven the dough changes the acidic banana bread batter’s pH. This chemical reaction is responsible for changing the color of the banana’s fibers.
You may notice bananas can turn brown quickly when you peel, slice, chop, or mash them against each other. It’s especially true when you’re making banana bread.
Bananas contain the enzyme polyphenol oxidase (PPO) and substances called phenolic compounds. When both are exposed to air, oxidation occurs, producing the brown pigment melanin.
This phenomenon is called enzymatic browning. The banana’s browned fibers then show up as black strings in the baked banana bread.
The Maillard reaction occurs when you apply heat and moisture to proteins and sugars. The reaction produces substances called Maillard products.
These substances give a distinctive flavor to food, similar to steak and coffee’s charred taste.
In banana bread, the Maillard reaction produces Maillard pigments called melanoidins.
The melanoidins give the bread a rich flavor, aroma, and darkened color. The pigments may also be the cause of the black strings.
The commercial bananas we buy from the supermarket today are seedless. Yet, unfertilized seeds that look like little dots remain at the center part of the banana.
For some, these banana seeds are the black strings in baked banana bread. In fact, when you feed a baby mashed bananas, similar-looking black strings appear in its stool.
A few argue that these black strings are neither the banana’s fibers nor seeds. Instead, they’re the banana’s starch.
The banana cells have organelles called amyloplasts which contain starch.
When this starch is exposed to certain chemicals, like when you’re cooking banana bread, the starch turns into a black color. This then becomes the black strings.
You may ask: Is there a way to prevent the black strings from appearing? Are they even safe to eat? Does their appearance mean the banana bread is well-cooked?
The black strings are perfectly fine to eat. Seeing them doesn’t mean something went wrong with your cooking. However, others may not exactly like seeing black strings in their banana bread.
Gladly, there’s one way to lessen their chances of showing up. Instead of mashing the bananas manually, you can puree them. Here are some steps you can follow:
This method works better if your bananas aren’t overly ripe. So this might not work for those who want banana bread to have a fully rich flavor.
The usual method is to use a fork in mashing the bananas together. This time, you can puree the bananas using a food processor or a blender.
Puree them until the batter reaches a smooth and creamy texture. Use this batter in cooking the banana bread.
Banana bread is one of the most popular desserts today. It’s not just simple and easy to make, it’s undeniably tasty too.
That said, there are many theories about the black lines in banana bread. People think it could be the banana’s fiber, seeds, starch, or baking soda. While others believe it’s due to the chemical reactions, such as enzymatic browning and the Maillard reaction.
However, the black lines are still perfectly edible. You can eat them without worrying about your safety. If you do want to get rid of their sight, you can puree the bananas instead of mashing them.
I have a bachelor’s degree in Film/Video/Media Studies, as well as an associates degree in Communications. I began producing videos and musical recordings nearly 15 years ago. I am a guitarist and bassist in Southwest MI and have been in a few different bands since 2009, and in 2012 I began building custom guitars and basses in my home workshop as well. When I’m home, I love spending time with my three pets (a dog, cat, and snake) and gardening in my backyard.