Learn the science behind:
What’s a better surprise than biting into your donut and discovering there’s a whole other filling inside?! Whether it’s a jam or creme patissiere, it gives your donut a whole extra dimension. But how do they get all that deliciousness inside your donut?
We’ve made donuts filed with some milk chocolate, a frozen raspberry and a smooth creme patissiere for this post. It helps you understand so much better how even a basic donut is made, so today we’re diving into the world of (filled) donuts, explaining all you need to know to make your own and understand how they’re made. What is the science that’s involved?
We’ll focus on yeast donuts
Within the donut world there are two main types of donuts: cake & yeast donuts. Most of the filled donuts tend to be yeast donuts which is why here we’ll be focusing on yeast donuts only. Also, yeast donuts tend to be a little easier to fill, but more on that later.
Yeast creates gas bubbles
Yeast donuts are made with a yeast dough. The yeast in the dough will create those air bubbles that you are looking for in a donut. You need those air bubbles to make your donut light and airy instead of a very dense fried dough ball.
Gluten are essential here
For the yeast to hold on to the air bubbles well you need to knead your dough very well, just like with a bread dough. During kneading you want to develop gluten. Gluten are the proteins in bread. by kneading the dough you ‘activate’ the gluten and align them all. If you knead by hand you will notice that the dough becomes smoother as you go, partially because of this alignment and organization of gluten molecules.
Benefit of developing these gluten is that the donut dough will be able to hold on to its shape once you’ve formed them. They don’t collapse as easily.
Yeast donuts take time
Once you have kneaded a yeast donut dough it will need to proof at least once, in most cases twice though. This is when the yeast becomes active and produces those gas bubbles in the dough (thanks to fermentation).
This step takes most time. If you are looking for a faster donut you may want to make some cake donuts instead. These do not use yeast but baking powder or soda to rise up.
Filing your donuts
The type of dough will impact how best to fill it. You can fill some doughs before baking whereas for others it’s best to do so afterwards.
Filling before frying
If you want to fill your donuts before frying you need a dough that is flexible and that you can pull apart and stretch. This is typically a characteristic of a yeast donut, another reason to use this type for your filled donuts.
Of course, it’s not just the dough that needs to be suitable. The filling you choose to put inside should either stay inside well (so not take up to much space and running the risk of it leaching out), or it should be fine to come in contact with some hot oil. Or, it might be a filling that you just can’t put in after frying (e.g. a whole raspberry or a block of chocolate). In the recipe at the bottom of the post we’ve opted for a small amount of filling that doesn’t leach out easily.
Filling after frying
Some fillings just aren’t worth the effort to try and put into your donut before filling. Jam & creme patissiere are probably the most obvious examples here. It really is just any filling that will turn even softer during frying and runs the risk of leaching out.
In these cases you want to fill your donut once it’s been fried. Also, you want to make sure the donut has cooled down back to room temperature. If not, the liquidy filling will still run out quite easily. Your best strategy for these types of fillings is to put your filling in a spiping bag of some sort and fill the donut by making a little hole in the side al the way to the middle in which you can add the filling.
A quick note on using tins
If you’re using a tin to bake your donut (so not frying it), you’ve got a whole other world of filling opportunities ahead of you. Some cool methods involve freezing your filling to give it a shape and then placing it in the center of your filling. Another option is to fill the tin half way, add your filling and then fill the rest on top.
Frying your donuts
Frying a donut with a filling can be more of a hassle than frying one without it. Here’s a few general guidelines:
- If you’re using frozen fruits or another very cold filling, it is best to give the dough enough time to warm up and get that filling up to room temperature. If you don’t do this it will be hard to cook the dough just around that cold filling. It will take long for the filling to warm up and as a result the center won’t have enough time to get cooked before the outside has turned sufficiently brown.
- As always, ensure the temperature of your oil is constant typically around 180C (=365F). This help ensure an even fry of all donuts.
- Really take care that you don’t loose any filling and if you do remove it from the oil to prevent it from burning.
Storing filled donuts
Any donut will turn old over time, but for filled donuts the process of getting old is just a little more complicated.
Filled donuts have an imbalance, especially if you’ve using a very moist (think fruit) filling. Since the center contains a lot of water and the dough doesn’t as much, the moisture will move from the center into the rest of the dough, making it soggy (this can be explained using the concept of water activity).
In the case of a chocolate filling though there barely is any migration of the moisture since chocolate itself doesn’t contain any moisture. Therefore, it will keep a little easier.
Some fillings (e.g. creme ones) need to be refrigerated to not spoil and keep their texture whereas others (e.g. that chocolate again) will cope well both in and out side of the fridge.
The masterclass episode from the Great British Bake Off
Want more donut inspiration? Serious Eats has a great long list of all sorts of donuts.
Food52, Erin McDowell, If you want to fill doughnuts with jam, pastry cream, apples… Read This!, Sep-16 2016, link
OMG Chocoalte Desserts, Vera Z., Nutella filled baked donuts, Apr-7 2018 link
The breakfast drama queen, Jelly doughnut mini muffins, Dec-12 2015, link