Bika Ambon

Bika Ambon is an Indonesian sweet made by combining tapioca flour, eggs, sugar, coconut milk and other ingredients, then fermenting and baking the mixture. Many elongated holes run through the cut face, and the yellow crumb is soft and springy to the bite. Although its name includes “Ambon,” the place where it is especially known as a local specialty is Medan, a city in North Sumatra.

The holes in the cross-section are traces of a batter that held bubbles

Bika ambon is made differently from a sponge cake, in which eggs are whipped so that they hold air alone. When a pourable batter combining tapioca or other starch, milky-white coconut milk, eggs and a sweetener is fermented by the action of yeast, small bubbles appear on the surface, and many holes remain after baking.

Besides tapioca, the starch extracted from cassava, some versions use sago starch. The two are not different names for the same plant. There are also recipes (sets of ingredient proportions and methods) that add wheat flour, and the choice of flour is tied to the springiness of the finished sweet and the handling of the batter.

Nor is fermentation something that can simply be extended. As fermentation progresses, the bubbles increase, but if it goes on too long, the smell of yeast and bitterness can become strong. The progress of fermentation is judged according to the temperature and the activity of the yeast.

Bika ambon from Medan. Elongated air holes line the cut surface. Photo: Midori, 2011-01-20, location unknown. Original image / CC BY 3.0. Reduced-size version from the source, no additional processing.

Not only making bubbles, but letting them rise

Whether the elongated holes come out evenly depends not only on creating bubbles through fermentation but also on a batter and a way of heating that allow the bubbles to escape upward during baking. In the method of the cook Leslie Tay, developed through repeated test batches, heat is applied from below to a free-flowing batter, leaving long trails where the bubbles traveled upward. If the top sets first, a thick layer forms that blocks the bubbles from rising, making it harder for thin holes to run all the way to the top.

In this method, the eggs are not whipped vigorously; the fermented batter is stirred, allowed to settle and skimmed of surface bubbles before heating. This is because fine bubbles collected on top also cause a dense layer. The method also includes a release step of warming the mold and coating it with oil, and a finish in which only the top is browned after the whole has been cooked. By treating the whipping of the eggs, fermentation, heating from below and final browning as separate steps, it aims for a cross-section with long holes.

Infusing the milk with aroma before adding yeast

The coconut milk is flavored with pandan, makrut lime leaves, lemongrass and the like. In one example using aromatic leaves, the coconut milk, sugar and leaves are warmed, and the temperature is lowered before the yeast is added. This procedure separates the heating that extracts the aroma from the temperature range in which the yeast works.

The batter, mixed with the flour and eggs, is left to rest and is baked once it has fermented and bubbles have appeared. Because tapioca tends to sink to the bottom, there is also a method of gently stirring it again before pouring it into the mold. Some recipes call for removing it from the mold and letting it cool before cutting, rather than slicing it thinly straight after baking.

The browned surface and the yellow, hole-filled interior differ in texture. Besides being baked as one large square sheet, it is also made in round molds and small molds. Even when the holes in the cross-section and the springiness are shared, the shape and the size of a slice are not uniform.

Figure: Chairy and Jhanghiz Syahrivar, “Bika Ambon of Indonesia: history, culture, and its contribution to tourism sector” (2019), Figure 2. CC BY 4.0. Image reproduced without modification. Original paper / License.

Green, pandan-flavored bika ambon. Air holes are visible in the cut surface. Photo: Agus Damanik, 2022-10-28, location unknown. Original image / CC BY-SA 4.0. Reduced-size version from the source, no additional processing.

Where does “Ambon” come from?

One theory holds that bika ambon got its name because it was sold on Ambon Street in Medan. In that account, a woman of Chinese descent made the sweet, and the street’s name became attached to it. Another theory says that merchants from Ambon brought it to Medan, where it became popular locally. These, however, are stories that explain the present name; no ledger from the time of its invention or contemporary production record confirms any single theory.

“Bika” is also linked to the name of a sweet called bingka. In Medan, far from the island of Ambon that the name bika ambon calls to mind, a fermented sweet full of holes became a local specialty.

From fermented palm sap to a sought-after souvenir

Methods of making bika ambon have been handed down that use palm sap called nira, or tuak, made by fermenting it. Today, methods using baker’s yeast have also spread, and halal, the Islamic dietary code, also carries great weight in the choice of ingredients.

When it became a souvenir sweet in Medan can be traced, bit by bit, through the memories of its makers. In 2002, Kaen, a shop owner on Mojopahit Street, said it was already a sweet eaten at home in the 1950s. In the same report, shop owner Ratna said she began selling it at Petisah Market in 1979 and moved to Mojopahit Street in 1987. According to Kaen, another family also moved from the market to the same street in 1985. What these accounts convey is not the year the sweet was invented, but the process by which a sweet of homes and markets came to gather on a shopping street that travelers also visit.

At that time, Ratna’s shop used fermented nira in its batter. As religiously appropriate choices of ingredients came to be expected, Zulaikha’s shop, which entered the trade in 2003, made its products with halal in mind and broadened its customer base by also increasing the range of flavors. Old methods of fermentation and new demands for ingredient labeling overlap in the commerce of the same city.

Shops selling it cluster on Mojopahit Street, where travelers buy it in boxes. Flavors such as pandan, durian and chocolate are also made. This sweet, cut from one large sheet, has come to be used both on family tables and as a souvenir to take home and share.

Glossary