Machine Production of Bawan (Taiwanese Meatballs): Starch Batter Wrappers and Forming

Bawan (肉圓) is a signature Taiwanese snack. The oil-poached bawan of Changhua and Beidou and the steamed bawan of Hsinchu and Pingtung each have their loyal fans. The reason bawan is hard to mechanize is that its wrapper is not a dough but a "starch batter."

What Is the Bawan Wrapper Made Of?

The common recipe for the bawan wrapper is based mainly on sweet potato starch, with added zailai rice slurry or zailai rice flour (在來米, an indica rice). It is mixed with water and stirred over heat so that some of the starch gelatinizes into a thick, translucent batter. Each maker uses different proportions: more sweet potato starch gives a chewier texture, while more rice slurry gives a softer one.

The traditional method is:

1. Oil a small dish (bawan dish) and spread a layer of batter in it.
2. Add the filling (pork, diced bamboo shoots, shiitake mushrooms, etc.).
3. Cover with another layer of batter and smooth it into a dome.
4. Steam it together with the dish until cooked, then remove it.
5. Steamed bawan is served directly with sauce; oil-poached bawan is then warmed in warm oil.

Can Bawan Be Made by Machine?

Yes, but along a different route from steamed buns and dumplings. An encrusting machine requires an outer material that "can be pushed and squeezed yet hold its shape"; bawan batter is semi-fluid before steaming and cannot stand on its own, so it cannot be wrapped into a ball like dough. Common approaches to mechanizing bawan are therefore:

• Metered filling: Depositing (dispensing) equipment injects the batter and filling into mold cups in sequence, effectively mechanizing the three actions of "spreading batter, adding filling, and covering with batter," and then the bawan are steamed in the mold cups. Among the options for encrusting machines on RHEON's Japanese website is a "depositor function option" (デポジター機能オプション), described as being used to dispense nearly liquid materials, which shows that metering semi-fluid materials is a separate technical route.
• Adjusting batter consistency: Pre-gelatinize the batter to a thicker consistency to increase its plasticity, then handle it with forming equipment. But once the consistency changes, the texture changes too.
• Partial mechanization: The batter and filling are portioned by machine, while laying them in dishes and covering with batter are still done by hand. Many shops start with this step.

How Does Sweet Potato Starch Batter Run on a Machine?

• Gelatinization must be consistent: Different heating temperatures and times give different consistencies, and the fill volume drifts accordingly. Batter-making conditions must be fixed for every batch.
• Temperature changes: Batter thickens and forms lumps as it cools, so if the work takes too long, it becomes hard to dispense.
• Settling: Starch batter settles when left standing, so the hopper needs stirring or circulation.
• Filling: Diced bamboo shoots and shiitake must be uniform in size, or metering will be inaccurate; the meat filling should be marinated and drained first.

Forming Before Steaming or Frying

• Steamed bawan: After forming, they are steamed directly in the mold cups or dishes; the wrapper only sets after steaming, and only then can they be removed.
• Oil-poached bawan: Likewise steamed first to set, removed and cooled, and then warmed in warm oil at the time of sale. The oil should not be too hot, or the wrapper will blister and burst.
• Frozen bawan: Steamed, cooled, and then blast frozen. Starch batter wrappers tend to turn white and hard after freezing, and the reheating method affects texture, so the recipe often needs separate adjustment. For frozen transport, under Article 8 of the Regulations on Good Hygiene Practice for Food (食品良好衛生規範準則), the ambient temperature of frozen compartments must not be higher than -12°C.

Hygiene and Safety

Starch batter has a high water content and is rich in starch, so residue left in dead spots in pipes and hoppers quickly turns sour. Disassemble and wash after work every day, and before doing so, stop the machine, cut the power, and apply lockout/tagout in accordance with Article 57 of the Occupational Safety and Health Facilities Regulations (職業安全衛生設施規則).

None of the models listed on Dong-Yih Machinery's website indicate bawan as a suitable product. If you have ideas for mechanizing bawan, see How to Judge Whether a New Product Can Be Made by Machine, or call 06-257-4644.

FAQ

Q: Can bawan be made with an encrusting machine?
A: Standard encrusting machines require an outer material that holds its shape, and bawan batter is semi-fluid before steaming, so it is usually mechanized by metered filling and steaming in mold cups.

Q: What starch is the bawan wrapper made of?
A: Usually mainly sweet potato starch, with zailai rice slurry or zailai rice flour, mixed with water and heated into a thick batter. Each maker uses different proportions.

Q: Why does the wrapper of frozen bawan turn hard and white?
A: Starch retrogrades after freezing, making the wrapper white and hard. Both the recipe and the reheating method affect the texture.

Q: Is oil-poached bawan deep-fried?
A: Oil-poached bawan is first steamed to set and then warmed in warm oil before sale; the oil should not be too hot.