What Is The Difference Between Japanese Sponge Cake and Castella Cake?

by Flora Baker

Soft and springy, with a deliciously fluffy and bread-like texture, Japanese Castella cake is a quintessential snack food throughout the country. But what makes castella any different from a regular sponge cake – and is it anything like Japanese jiggly cake? 

Firstly, castella is more delicate than a typical Western sponge cake. Though the ingredients are similar, mainly focused around flour, sugar and eggs, castella cake tastes quite different. It’s very light with a mild sweetness and moist texture, thanks to the inclusion of either honey or mizuame (a thick, clear syrup made from starch which is often added to wagashi to give a glossy sheen). Because castella cake uses bread flour there’s an elasticity to the crumb which actually makes it behave a little like bread! 

But with a non-Japanese sounding name like Castella, where does this cake actually come from?

An International History of Castella, the Japanese Sponge Cake

The original creators of Castella cake are sadly lost to the depths of history, but it’s generally assumed that the cake’s recipe originated in Europe, most likely in the medieval kingdom of Castilla once belonging to present-day Spain. When Portuguese merchants reached Japan’s shores in the 16th century, they were accompanied by plenty of as-yet-unseen products and ingredients. Among them was a Portuguese cake called Pão de Castela, which lasted well on the merchants’ long sea voyages. It’s said that Portuguese missionaries had learned the recipe from Dutch traders and passed it along to the Japanese. 

A port was established in Nagasaki – at that time, the only Japanese port open for foreign commerce – and trading with Portugal began. During the 200-year-long isolation of the Edo Period, Nagasaki’s port of Dejima continued to trade with China, Korea and the Netherlands, which meant that Dutch sugar was still being imported and bakers could still experiment with making castella in Japan. 

The price of sugar was lowest in Nagasaki, which means that nowadays Nagasaki is still known as the Japanese home of Castella cake, and it’s the city’s signature export. There are three classic Castella stores that each have a long history creating the cake, and still use traditional manufacturing methods while baking. Though Castella cake is sold all over Japan, it’s highly recommended to try the rare versions in Nagasaki, which are well known for their unique flavors.  

If you were wondering about the non-Japanese sounding name, the clue also lies in its history. Pronounced ‘Kasutera’ in Japanese, the etymology of Castella comes from the Portuguese Pão de Castela, which means ‘bread from Castile’, that aforementioned ‘Castilla’ region of medieval Spain.


What Sets Japanese Castella Cake Apart – And How Do I Make It?

The uniqueness of Japanese Castella cake ultimately comes down to specific ingredients and the care taken in the preparation. Interestingly, there are no leavening agents used in castella cake! 

First you separate egg whites from their yolks, and whisk the whites over a hot water bath at a low speed. Add caster sugar, bit by bit, while continuing to whisk until you have soft peaks, like making meringue. Add the egg yolks one by one and whisk to a creamy consistency, then add your honey or mizuame. Instead of regular plain flour, you use sifted bread flour, which provides more aeration. After adding milk, tapping the mixing bowl hard against the table will burst any bubbles and give the cake a finer texture. You can also do this with a toothpick once the batter’s been poured into the cake tin.

Traditionally castella is baked in a bottomless square wooden frame for just under an hour, then cut into long rectangular slices and served with green tea or iced coffee – but as the slices are the perfect size for a portable snack, they’re often wrapped individually and eaten on the go. It’s also sold in long boxes and packaged beautifully, making a perfect gift for friends and family back home. 

There are plenty of other delicious cakes in Japan – like the beloved Japanese jiggly cake, a type of souffle cheesecake made extra fluffy and airy with plenty of beaten egg whites. If you haven’t tasted them yet, check out the castella cakes available in Bokksu’s marketplace, or try out a Japanese snack box subscription for the chance to try even more tasty snacks!

Now that you know the difference between castella and sponge cake, see what castella cake looks like!

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Author Bio

Flora Baker is a writer, blogger and author based in London, UK. She runs the award-winning travel website Flora The Explorer and has written for Coastal Living, Telegraph, and National Geographic Traveler.