Learn the science behind:
New year’s celebrations have resulted in a lot of, once-a-year snacks, all over the world. In the Netherlands, you’re bound to find a pile of oliebollen in most homes. But, aside from this typical staple, don’t discount its fruity alternatives, of which apple beignets is jus tone!
Apple beignets are deep-fried apple slices coated with batter and eaten with lots (and lots) of icing sugar. The combination of soft, warm, mushy apples, with a slightly crisp batter and crunchy sugar and cinnamon, is delicious. The challenge is balancing soft and crisp, because those two tend to be one another’s enemies! So, let’s have a look at how to ensure the crisp stays crisp, whereas the fruit remains juicy.
Finding that contrast ; crunchy + juicy
Whether you’re deep-frying apples, fish (e.g. kibbeling), chicken, or tempura, you’re always looking for that contrast. A crunchy outside, and juiciness within. It’s a delicate balance and revolves all around water content.
In order to make that outside crunchy, it should be quite dry, with very little moisture. It is well known that taking moisture out will make something crunchy (e.g. when crisping up chicken skin). The heat of a deep fryer can accomplish exactly that. The high heat of a fryer, generally around 160-180°C (320-355°F) ensures moisture evaporates. All those bubbles in the hot oil? Those are mostly made out of evaporated water.
However, a juicy inside should contain a good amount of moisture. The moisture is what helps keep the center soft and squishy.
Designing a good apple beignet crunch
A good apple beignet has quite a thin layer to cover a slice of apple. No thick, crunchy layer, instead, it’s more of a delicate crispy layer, just slightly less crispy than that of a good tempura.
Keep in mind that when ‘designing’ a good crunch on your fried food it should work well with the center. A piece of chicken is a lot stronger and has more of a bite, than a soft hot piece of apples. If you’d use the crunch of a fried chicken on an apple, it would be way too crunchy compared to the center. The reverse is true as well, a delicate thin crunch might work well on a soft piece of apple, less so on a sturdy piece of chicken.
Not too viscous
Knowing that your apple beignet needs a more delicate style crunch, you’d want to start with quite a liquid, thin batter. A thick batter will result in a thicker layer on the fruits, breaking the balance between batter and center. It’s also why you wouldn’t add additional crunch, such as corn flakes, the cornflake crunch would almost be too much for the center.
Add some lightness
A batter becomes crunchy when it’s dry enough. A thick solid layer is hard to dry out. The moisture will have to travel all throughout. If you have a large center that won’t be as much of a problem, you have a long frying time to accomplish this. In the case of a more delicate apple beignet that isn’t really an option.
A layer with a lot of air bubbles crunches up more easily. These air bubbles provide a good way for moisture to escape. It is why you often find some way of adding air bubbles to a batter. A common way to do so is by using carbonated water (or carbonated soft drinks, or beer). The gases in these drinks produce little air bubbles. If you leave a batter for a long time they’ll escape from the batter, but a batter is viscous enough to hold onto those bubbles for a little while longer.
Another way to add some air is by adding some baking powder or baking soda. These will both react at higher temperatures, forming carbon dioxide bubbles. Your final batter won’t contain large holes, but it’ll contain a lot of smaller bubbles that help just that little extra to crisp it up.
Choosing your apple
As is the case for apple pie, choosing a good apple can make or break your beignet. Some apples just don’t soften as well as others do. Also, we like an apple with a little bit of an acidic flavor to counteract all that sugar and frying. A good way to test your apple would be to bake one in the oven and taste how it turns out. That way you don’t have to start your fryer and batter while choosing an apple you’ll enjoy.
Slicing the apple
This might not seem that important, but it’s probably one of the most influential decisions you’ll make while making apple beignets! Slice it too thin and your whole apple beignet will be crunchy. All the moisture will be able to escape during frying and you’ll end up with a crisp.
The opposite is true as well, slice it too thick and the apple will not cook properly. Also, you might not like the ratio anymore. We stick to approx. 1-1,5cm (0.4-0.6 inch) thickness, it’s a good balance between crunch and soft.
Can you use other fruits?
Yes, although apple beignets aren’t apple beignets anymore without the apple ;-), you can use the same technique to deep fry other fruits. When deciding on a fruit, choosing one that will hold its shape when heated. Don’t use berries for instance, they’ll disintegrate. Instead, use fruits that still have a ‘bite’ to them when they’re warm.
Pineapple is one of our favorites, but we’ve also seen recipes using pears or even bananas (be careful with not overcooking the banana).
Sign up to our weekly newsletter to be updated on new food science articles.
Why you should eat apple beignets quickly!
Thermodynamics though, does not like this big difference in moisture content. A dry outside with a moist inside, that is bound to give problems. Moisture will want to travel from the high to the low moisture area (more specifically, from high to low water activity). It’s why you’d better eat most fried foods right after they come from the deep fryer. As soon as that food comes out, no more moisture evaporates leaves the outside and the moisture from the center will migrate into the coating.
It’s why you should eat those apple beignets straight from the deep fryer, or soon after. Yes, they’ll still taste ok a few hours later, but they’ll definitely be less crunchy and more soggy overall! Not because they contain any more moisture, but because the moisture has been distributed differently.