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Nagasaki Castella: A Japanese Sweet with European Roots

Hirano Kumiko [Profile]


A Piece of Cake

A few years ago I began regularly crossing the country from my main residence in Yokohama to live part time in Nagasaki. Spending long stints in the historic Kyūshū city, once the center of Japan’s foreign trade, has rekindled my appreciation of its famed kasutera sponge cake. Widely recognized as a symbol of Nagasaki’s role as the gateway of Western culture, the Portuguese-inspired sweet, known as castella in English, remains a steady draw for tourists and a vital revenue source for the local economy.

Judging from the enthusiasm of visitors to Nagasaki from neighboring Asian countries, castella is hugely popular in the Sinosphere. Members of Chinese tour groups commonly return to passenger liners docked at the city’s port weighed down with paper bags from well-known castella makers. Foodies from Taiwan and Hong Kong, too, can frequently be found peppering staff at Iwanaga Baijuken, a castella shop established in 1830, with questions about ordering from overseas and whether the specialty eggs used in the sweet are for sale.

Castella have even crossed over to neighboring countries. In Taiwan a growing number of chain and specialist stores offer “Japanese-style” and home-grown versions, and Hong Kong also has a locally produced rendition. The cake is such a part of local food culture that when a Taiwanese friend received a Nagasaki-style castella a few months back as a gift she asked me to explain how it differed from the kind she had grown up eating.

I had to admit that I did not know for certain, but the addition of raw milk stood out when I perused the ingredients list of a Taiwanese castella she emailed me.

Castella traditionally contain no dairy products or baking powder whatsoever. Older shops in Nagasaki continue to make the sweet by hand the old-fashioned way with just eggs, flour, starch syrup (mizuame), and sugar. To create the spongy texture, cooks whip the eggs, flour, and fine sugar into a frothy batter, then add mizuame to give the cake its delightful stickiness. A coating of coarse sugar is sprinkled in the bottom of the rectangular baking pan prior to pouring in the mixture, giving a pleasing crunchiness to the finished dish.

Castella is not native to Japan, but has evolved over the centuries in accord with local tastes and can now safely be considered a Japanese sweet. Traditional versions remain popular, but like the ubiquitous manjū sweet bun, which has been shaped into countless versions since crossing over from China hundreds of years ago, castella is continually evolving. Creative confectioners are constantly creating new varieties featuring exotic flavors like chocolate, honey, matcha, and strawberry. Just the other day I even found a store in Nagasaki offering castella made with collagen powder aimed at beauty-conscious patrons. Nagasaki-style purists still insist, though, that a cake must be made in the tried-and-true fashion to be called a kasutera.

The Road to Wagashi

The predecessor of the castella, a dish called pão de ló, was introduced to Japan by Portuguese missionaries in the sixteenth century. While making their rounds the priests would offer the luxurious sponge cake as a gift to prospective converts and sick church members. The confection proved to be so popular that Japanese traveling to Portugal to study propagated the recipe after returning to Japan.

Several theories exist as to the name kasutera. According to one it derives from the Spanish region of Castile, while another suggests it comes from the tendency of Portuguese chefs to shout castelo (castle) as they vigorously beat eggs for pão de ló into stiff, citadel-like peaks.

Pão de ló has a different shape and texture than its descendant, the Japanese castella.

Making castella was a demanding, labor-intensive process for early Japanese bakers. First ingredients had to be measured, mixed by hand into a foamy batter, and carefully poured into specially designed molds. Chefs then baked the cakes in make-shift ovens, small kiln-like structures heated with charcoal from above and below, while repeatedly prodding the mixture with a bamboo pick to keep air pockets from forming and to make sure it baked evenly.

Influenced by local tastes, later chefs introduced starch syrup to add a moist stickiness and coated the bottom of the pan with coarse sugar for a slight crunchiness contrasting the spongy texture of the cake. Creative developments like these gradually transformed the castella from a European edible into a Japanese sweet.

Shops like Fukusaya, a Nagasaki confectioner founded in 1624, continue to create castella in the traditional fashion. Each batch is made by a single baker who oversees each step in the process, from mixing ingredients to cooking.

  • [2018.06.05]

Nonfiction writer. Started writing after working in the publishing industry. Asian tea lover. Her 2000 work Tantan yūjō (Light Exquisite Feeling) won the Shōgakukan Nonfiction Grand Prize. As well as writing about various Asian countries, she is particularly interested in the period when Taiwan was under Japanese control. Works include Teresa Ten ga mita yume: kajin kasei densetsu (Teresa Teng’s Dream: A Chinese Singing Legend), Chūgokucha: fūga no uragawa (Chinese Tea: Behind the Elegance), Tōsan no sakura: chiriyuku Taiwan no naka no Nihon (Father’s Cherry Blossoms: Japanese Culture Fading in Taiwan), and Mizu no kiseki o yonda otoko (The Man Who Caused a Water Miracle).

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