Why Did My Banana Bread Sink? (+How to Fix)

In recent years the popularity of banana bread has skyrocketed, with more people than ever trying to create the tastiest and fluffiest banana bread possible. However, many new home bakers end up disappointed when they take out their amazing looking banana bread out of the oven, only for it to collapse immediately.. So why is that happening, and is there anything you can do to fix it?

A banana bread will sink due to an undeveloped gluten network which can be caused by overmixing the batter, using too much liquid, not using the enough leavening agent, or baking at the wrong temperature.

As you can see there are quite a few things that can go wrong, but fortunately all of them are easy to correct. So let’s go over each one of them and after that we will take a look at what you can do with a sunk banana bread. And let’s begin by taking a look at why your banana bread sank in the first place.

Why Your Banana Bread Collapsed

There are multiple reasons why a banana bread can collapse, but overall they all lead to the same problem, an undeveloped gluten network.

The gluten network forms when you combine water with flour and mix them together. When you do this you are strengthening the gluten network.

You can think of the gluten network as a series of pillars that hold the ceiling in a room. If the pillars are strong the ceiling will stay in place, if the pillars are weak, the ceiling will collapse.

Here is a close up picture of two banana breads,on the left one with a good, strong gluten network, and on the right one with a weak gluten network.

As you can see the bread with the strong gluten network has air pockets in it which were formed by the leavening agent (baking soda or powder), and they were kept in place by the string gluten network. While on the left there are no air pockets, since the gluten wasn’t strong enough to keep them in place, and as a result the bread sank.

So let’s see why exactly the gluten network in your bread didn’t develop properly.

Over Mixing the Batter

This is the most common reason why banana bread ends up sinking.

It’s generally believed that mixing something a little more is better than not mixing it enough. And to some extent that is true, but overmixing can be just as bad as undermixing.

When you overmix anything that is a combination of flour and water, no matter in what quantities, you make the gluten network in the mix stronger than it needs to be, and the final product will be either dense, hard or chewy, and the bread itself will collapse.

You can usually get a better picture of how this works when you are working with dough, since it’s solid, unlike batter. If you keep kneading the dough after it’s ready it will start to get a rubber like texture, and if you keep on going even after that your kitchen mixer will get completely stuck and you won’t be able to stretch it even with your hands.

The same thing happens with batter, but not to the same extent, since it has way less flour than dough.

Overmixing will cause an overdeveloped gluten network which won’t be able to expand and if they do it, they will tighten back up at the first chance, and this will make your bread sink.

So as soon as you notice that all the ingredients are mixed together you can stop. If you keep on mixing the banana bread will inevitably sink once it comes out of the oven.

Too Many Liquids

Banana bread is fluffy due to the gluten network that develops when mixing flour with liquids. If the gluten flour is too weak, the end result will be a bread that collapses onto itself.

Here is a picture showing the texture of two banana breads. The one on the left has a good gluten network, as you can see the air pockets in the bread. The one on the right doesn’t have any air in it.

As a general rule you technically want to have 70% liquid and 30% solid ingredients in the batter.

In the case of banana bread, it can be quite hard to get an exact percentage since we are using bananas which have both liquid and solid parts. But if you are using the bananas that are ripe enough you can consider them 50% solid 50% liquid.

So if your batter has too much liquid in it you might want to either add some flour or use less flour (or milk).

Using the Wrong Flour Type

Flour is separated into different categories using a rating system. One problem with the rating system is that it’s not uniform worldwide, a lot of countries have their own, including the US, and Italy, as well as France and Germany, and a few more. Here is the rating system, with the different names each country has for the flour types, and what that actually means.

In the US you will most likely see the US grading system, but it’s not uncommon to see some manufacturers use a different label just because 00 flour can sound fancier than pastry flour.

But regardless of what system you are using to rate the flour, you have to know that there are differences between a flour rated 00 and another rated 0. The biggest one is how fine the flour is 00 being the finest one of them all.

How fine the flour is ground will have a huge effect on how much water it can absorb and what texture the banana bread will have.

If a recipe calls for 100 grams of all purpose flour and you are using pastry flour, it’s like you will only be using around 80 grams of all purpose flour, and this difference will completely change the recipe.

Another big important difference is the protein content. The table that I showed you contains the average, but some flour will have more or less proteins, this is because different manufacturers have different grain sources, grown in different conditions. The amount of protein in a flour can greatly influence how much water the flour can absorb.

Different flour types can absorb different quantities of water. This is why I would suggest you stick to all purpose flour, also known as 0 flour, this is the type that is usually used for banana bread. Unless the recipe specifically calls for a different type of flour.

If you don’t have enough flour, or water in your batter, the final result will be an undeveloped gluten network, which means a bread that will collapse.

Not Enough Leavening Agent

Whether you are using baking soda or baking powder it’s very important that once you add it to the mix you immediately put the bread in the oven.

The thing that differentiates a dense and a fluffy banana bread is the air in the bread. And the way this air makes its way into the bread is through the leavening agent (baking soda or powder, in this case).

So if you mix the leavening agent, and then wait 30 minutes until you put the bread in the oven, all the gas that formed in the batter will escape.

And make sure to test your leavening agent before using it, if the agent is not good the bread will not grow correctly and it will sink.

For baking powder you can fill a glass with hot water and add a pinch of baking powder to it. If it bubbles immediately, it’s good. If not you need to get some new baking powder.

Baking soda will react to vinegar and lemon, so mix a little of both. If they don’t fizz as soon as they come into contact, then the baking soda has gone bad. This can happen due to humidity or or due to being unlucky and getting a bad batch. But in either case you need to get some new baking soda.

Wrong Baking Time and Temperature

In the case of baking time and temperature there are quite a few things that can go wrong.

But first. One of the biggest mistakes that beginners make is overlooking the fact that the oven needs to be preheated. This is important for a lot of reasons. One of them being that if the oven is not hot enough, the leavening agent won’t be able to do its job properly, and the result will be a dense banana bread that might look fully risen, but once it’s out of the oven it will collapse..

Another problem is that most ovens, after a while, will lose their precision, so while you might have set your oven to 350°F (175°C), but the oven there might actually be just 300°F (150°C). This is why I would recommend you to always use an oven thermometer.

The best way to avoid undercooking, or overcooking your banana bread is to use a toothpick and poke the bread. If the toothpick comes out with residue on it, it means that the bread still needs to spend a few more minutes in the oven. If it comes out clean, it means that the bread is ready. No matter what the timer might say.

How to Fix a Sunk Banana Bread

A sunk banana bread can be fixed, but you can’t really make it less collapsed at this point. This can only be done if you haven’t already put it in the oven. However there are still a few things that you can do with your sunk banana bread.

Banana Bread French Toast

And the first one is french toast. French toast is a dish of sliced bread (banana bread in this case) soaked in beaten eggs and milk or cream, then fried in a pan.

For this recipe it doesn’t really matter if your bread is dense or not. And if your bread is starting to get stale you can also use it for french toast.

So simply mix an egg with some milk or cream, add something to enhance the taste, like sugar and cinnamon, soak the bread slices in the mix one by one, then fry them in a pan with butter.

Banana Bread Croutons

Croutons are simply small pieces of bread that have been baked in the oven until they become crunchy. You can use them in salads, soup, or eat them as they are. My favorite way of making croutons is putting a very small piece of cheese on top of each one and letting it melt in the oven. I would definitely recommend you to try this.

And the best thing about croutons is that it doesn’t matter if your bread is dense or stale, you can use it either way.

Banana Bread  Ice Cream Dessert

Scoop some of your favorite icecream and put it on top of the banana bread, and wait 5 minutes so some of that ice cream will melt and make the banana bread easier to eat.

Final Thoughts

The overall problem of a collapsed banana bread is the gluten network, which can be either underdeveloped due to the lack of flour, or too many liquids. Or it can be overdeveloped due to mixing the ingredients too much. And in some cases due to baking it the wrong way, or using a bad levanting agent.

It is possible to use a sunk banana bread in other simple recipes like french toast or croutons, but it’s not possible to make it rise again after the bread is out of the oven.

But now you should never have any problem with sunken banana bread ever again.