Castella: The First Authentically Japanese Cake (Arguably)

While Japan is famously fond of its desserts, it's no secret that most of the cakes and pastries beloved in the country are based on Western confectionery. Creamy and light roll cakes are a variation of swiss roll; strawberry shortcake is a classic Western cake, even if it has been adapted to suit Japanese sensibilities better by being lower on sugar content, and you’ll have an easier time finding Mont Blanc chestnut cake or German Baumkuchen in Japanese bakeries than you would in their native countries.

But the one pastry that started Japan’s obsession with cake is arguably the one that has the fewest ties with Western cuisine. In fact, the original Japanese version was so different from its progenitor from the get-go that we’d go as far as to describe it as the first authentically Japanese cake that shares little but ingredients with Western cakes.

We’re talking about the famous Castella (or, as it's called in its native Japan, Kasutera).

This claim, of course, can be argued over and argued ardently. After all, even the name itself is an ironclad proof that the cake was created under the Western influence (the name Castella comes from Portuguese Bolo de Castela, “cake from Castille”). 

But when put beside each other, the “original” and Japanese Castella have very little in common. The curious thing is that it was like that from the beginning, unlike most other Western cakes that came to Japan in their original form and took years to be adapted to their current, distinctly Japanese form. 

It would be like saying Japanese Shokupan originated from French Baguette just because they’re both bread. 

At Yummy Bazaar’s online store, you’ll find a great Castella cake selection in various flavors, from the original taste the purists consider the only valid option to rich chocolate to signature matcha and the unexpected cheese (don’t be surprised, the Japanese are famously fond of adding cheesy flavor to their desserts, they’ve done so to Baumkuchen as well, for example). 

What is Castella Cake?

Castella is a Japanese take on Western sponge cake. As is typical with Japanese pastries, it’s lighter, airier, and less sweet than its Western counterpart. 

The interesting thing about Castella is that it’s not always classified as cake, per se. More often than not, you’ll find on a list of Wagashi: traditional Japanese confectionary served with green tea, along with mochi, dango, and Yokan jelly. More likely than not, this has to do with how old it is: bread (including sweet buns) and cake only started becoming a regular part of the Japanese diet at the end of the 19th century. Until then, most confectionaries were considered Wagashi. There simply wasn’t a separate category for cake, especially considering there weren’t many types of it going around. 

Another aspect that might have played a part in Castella technically not being considered a pastry in the beginning, is that it contains no shortening (no butter or oil) or leavening agent (like baking powder, baking soda, or even salt). The original Castella cake was made with four ingredients: bread flour (for its higher gluten content that adds elasticity to texture), sugar, eggs, and Mizuame, with the egg foam solely responsible for raising the batter. 

Mizuame is a Japanese sweetener with a thick, liquid jelly-like consistency. It’s traditionally made by mixing glutinous rice with malt and having starch in the rice convert to sugar. In most modern recipes, Mizuame is often substituted either with honey, corn starch syrup, or a mixture of both.

The Japanese Castella cake has a lot of visual similarities to classic sponge cake. The main difference is the dark brown crust on the top and the bottom of Castella. But the texture and flavor are another matter entirely.

What is the Difference Between Castella Cake and Sponge Cake Then? Is it Just the Name?

What separates Japanese Castella cake from Western sponge cake into its own distinct thing (aside from darker crust which, frankly speaking, is sometimes characteristic of Western sponge cake, as well, if not a strict requirement like with Castella) are texture and flavor.

The solid dark brown Castella crust encases a lighter and creamier inside. Due to the use of Mizuame (or the corn starch syrup in the modern varieties), Castella has a more moist texture than Western sponge cake. It’s closer to chiffon cake than sponge cake, with a smooth and bouncy texture, though it’s still somewhat denser than the former. If chiffon cake is somewhere between a sponge cake and butter cake, we could argue that Castella cake is somewhere between a sponge cake and chiffon cake.

What Does Castella Cake Taste Like?

The original Castella is very light on sweetness, so much so that it may even seem somewhat bland to Western sensibilities. It’s mellow and pleasant without being overwhelming to the palate. It’s commonly enjoyed either by itself, with a cup of green tea (as is traditional with Wagashi), or with some whipped cream for extra flavor (as whipped cream is considered light enough not to overwhelm the cake). 

Modern Castella varieties often include additional flavorings that add a bit more strength to the cake. As mentioned above, Honey Castella is common (though it’s considered a separate variety) and has a little more sweetness to it than the original. Chocolate Castella is one of the most popular varieties and has a more robust flavor due to the generous use of cocoa. And unsurprisingly, matcha-flavored Castella is another widespread option. It has a more earthy and nutty flavor than the original, with just a hint of bitter undertones.

An Abridged History of Castella Cake:

The original Castella cake recipe was developed using Nanban confectionery (i.e., desserts imported by the Europeans during the years 1568-1600, a period now known as Azuchi-Momoyama). 

Its primary source of inspiration is supposedly Portuguese Pão-de-Ló, a type of sponge cake that was often packed for long seafaring bouts by the sailors, as it could be stored for long periods without going bad.

That said, it should be mentioned that the Japanese Castella shares little in common with pão-de-ló, from the texture to flavor. The original pão-de-ló was more dense and crumbly, more bread-like than a cake; the modern version is more creamy, with a pudding-like consistency. It’s traditionally flavored with citrus peel like that of lemon or orange and brandy. The two cakes differ so vastly that pão-de-ló would be nowhere near the top guess if one didn’t know where to look for Castella's inspiration.

However, there’s no denying that European confection was quite popular in what is modern Nagasaki prefecture during Oda Nobunaga’s rule. Oda saw the arrival of Portuguese missionaries as an opportunity to undermine his Buddhist rivals. He continuously considered Buddhism a threat to his power throughout his rule and saw the popularization of a new religion as a useful tool to solidify his stance. He encouraged and supported the spread of European products, including pastries, and is said to have enjoyed European bread himself (he was famously a big tea connoisseur, so it’s possible he did indeed enjoy sweets with it). 

According to the tales, Portuguese priests would share the original pão-de-ló with their church visitors and potential converts, and it quickly became one of the most popular European treats, especially with the rumors of the Daimyo enjoying Western pastries going around. 

After Oda Nobunaga’s death, the Nanban trade quickly declined and was entirely forbidden in 1614. But by that time, the Castella cake had already become a staple Japanese dessert, especially in Nagasaki, which is considered the prime Castella destination to this day. During the Edo Period, Castella was considered a product for elites due to the high cost of its ingredients (most notably sugar). There’s a tale about the Tokugawa Shogunate presenting the Emperor of Japan's envoy Castella as a treat, which says a lot about the cake’s reputation.

Since then, it has remained one of the most famous Japanese pastries worldwide and has influenced other Japanese desserts. For example, the famous filled pancake Dorayaki? Not a pancake at all, but two thin layers of Castella cake, stuck together by a sweet filling. 

It has even seen a new variation pop up, inspiring another national dessert the same way some Western cakes have inspired Japan to create its own.

Taiwanese Castella Cake: No, It’s Not the Same as Japanese Castella

While classic spongy Japanese Castella is famous all over East Asia, its Taiwanese version is slowly starting to catch up with its popularity. While finding it outside Taiwan is a bit harder these days, in the 2010s, Taiwanese Castella has definitely seen a significant boost in name recognition.

The beginning of its story is not a kind one: classic Castella came to Taiwan between 1895 and 1945, during the Japanese colonization of the country. Certain Japanese staples like takoyaki, tempura, Oden, sushi, etc., also became Taiwanese staples over the years. 

The Japanese influence on Taiwanese own cuisine can be overrated. While Japanese restaurants are prevalent in Taiwan, Taiwanese cuisine itself remains largely separate, with a few distinct exceptions like tempura-frying, teppanyaki-style cooking, increased beef consumption, or, yes, the Castella cake.

Here’s the kicker: just like modern Japanese pastries differ from their Western counterparts, Taiwanese Castella cake differs from its Japanese parent. Taiwanese Castella is even airier and mellower than Japanese. It has a jiggly souffle-like texture and a soft, custardy center. It can be said that Taiwanese Castella has more in common with Japanese Cheesecake than it has with Japanese Castella.

How Long Does Castella Cake Last?

Castella cakes are most frequently sliced into long thin rectangles and packed in boxes before being sold. If packed in air-tight packaging, the Castella cake can maintain freshness for up to 8 months when properly stored, even if they contain no preservatives. Freshly baked bakery Castella is almost always preservative-free, but even among commercial manufacturers, there are a few with recipes that call for no stabilizers, with the shelf life entirely dependent on air-tight packaging.

However, more often than not, manufacturers do resort to adding some kind of stabilizer to the cake to keep it not only viable for an extended period of time it’ll spend on convenience store shelves but maintain its flavor qualities without degrading until the packaging is opened. 

Each Castella producer has its own recipes, so do check the packaging for both the ingredients and the expiration date, as it can differ from manufacturer to manufacturer due to the differences in recipes and packaging material. Generally, though, most pre-packaged Castella cakes seem to last between 8 and 12 months until their packaging is opened.

How to Properly Store Castella Cake to Maximize its Shelf Life:

The easiest way to keep the cake fresh and maintain its flavor qualities is to keep the Castella in a refrigerator, regardless of the package being opened or sealed. Once open, the Castella is suitable for consumption for an additional 5 to 7 days (for best results, wrap it in aluminum foil after opening the package).

If you don’t think you can consume it fast enough, there’s no need to get rid of the cake right away. Like most other pastries, Castella cake can be frozen. Wrap it in paper or, better yet, place it in an airtight container, and your Castella will be suitable for consumption for about additional 3 months.

Do keep in mind, though, that its texture and flavor quality will degrade over time. Don’t expect the thawed Castella to fully maintain its texture, even if it's frozen for only a short period. Thawing will turn the texture more rubbery and dense. Avoid using the microwave for thawing, as it’ll make the cake drier. Let it thaw in a fridge overnight, and lightly reheat in the pan the next day, if necessary.

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