Machine Production of Filled Tangyuan and Small Tangyuan

Tangyuan (湯圓) may look like simple balls, but their wrapper is made of glutinous rice, which is sticky, soft, and hardens when left to sit, making it notoriously difficult for encrusting machines. Demand is also heavily concentrated around the Winter Solstice and the Lantern Festival, and many businesses want machines to get through the peak season. Understanding the material first helps you avoid buying the wrong equipment.

Can Filled Tangyuan Be Made with an Encrusting Machine?

Yes. The structure of filled tangyuan (sesame, peanut, red bean, etc.) is "a ball with a wrapper around a filling," which is exactly the shape encrusting machines excel at: the glutinous rice dough and filling are fed separately, co-extruded into a rope, and cut and sealed at the outlet to form balls.

Note that one of the key design points of encrusting machines is handling "sticky" materials. The products listed on the website of Japan's RHEON include glutinous rice confections such as daifuku, gyuhi, and goma dango (ごま団子, sesame balls); the product list for the KN551 on its U.S. website also includes Sesame Balls and Mochi Ice Cream. This shows that wrapping filling in glutinous rice dough is a mature application for encrusting machines, but glutinous rice recipes vary greatly from maker to maker, so actual performance on the machine still needs to be tested.

Problems with Glutinous Rice Dough on a Machine

1. Stickiness: Glutinous rice dough sticks to the hopper, conveyor, and cutting device. A common solution is to use anti-stick dusting flour (such as cooked glutinous rice flour or corn starch) and connect dusting equipment after the outlet. The peripherals on RHEON's Japanese website include a "hygienic brushless flour coater" (サニタリーブラシレス粉付機, for dusting formed products) and a "flour remover" (手粉払い機, for removing excess dusting flour).
2. Inconsistent firmness: The amount of water added to the glutinous rice flour, and whether cooked dough is added (known as 粿粹: a small portion of the dough is cooked first and then kneaded back in), both change extensibility. Too soft and it slumps; too firm and the seal tends to crack.
3. Hardening: Glutinous rice starch retrogrades and hardens over time, so the dough should be used within a certain time after it is made and should not sit in the hopper too long.
4. Filling firmness: Sesame and peanut fillings often contain lard or butter and soften at higher temperatures. A common approach is to chill the filling until it can hold its shape before running it on the machine.

What Machine Makes Unfilled Small Tangyuan?

There are two mainstream methods for unfilled red and white small tangyuan:

• Divide, then round: The glutinous rice dough is extruded into a rope, cut into measured short pieces, and then rolled into balls with a rounding device or drum.
• Rolling (yao tangyuan): The traditional yuanxiao (元宵) method: filling or small base pellets are placed in a rotating drum or sieve basket and sprinkled with water and glutinous rice flour so the surface "rolls" larger layer by layer. The texture produced this way differs from kneaded tangyuan.

The red and white small tangyuan common in Taiwan mostly have the texture of kneaded dough rolled into small balls, so dividing plus rounding comes closer.

The products listed on Dong-Yih Machinery's website for the DY-528MS Taro Ball and Sweet Potato Ball Dividing Machine include mochi, taro balls, and sweet potato balls (蕃薯圓), with an output of 3,000–12,000 pieces/hour at 10 g–30 g per piece or heavier. Tangyuan are not among the products listed on the website; to find out whether your glutinous rice tangyuan can run on the machine, please bring your ingredients and call us.

Points for Frozen Tangyuan

• Blast freeze as soon as possible after forming, so the glutinous rice wrapper does not slump or stick together at room temperature.
• The surface of frozen tangyuan dries and cracks easily, so packaging must be sealed.
• 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.

For mochi and daifuku, see Machine Production of Mochi and Daifuku; for taro balls, see Machine Production of Taro Balls and Sweet Potato Balls.

FAQ

Q: Can sesame tangyuan be made with an encrusting machine?
A: Yes. Filled tangyuan are balls with a wrapper around a filling, exactly the shape encrusting machines excel at. The glutinous rice recipe and filling firmness need to be adjusted through test runs first.

Q: What should I do if the glutinous rice dough is too sticky and keeps sticking to the machine?
A: Common approaches are to adjust the water content, add cooked dough, use cooked glutinous rice flour or corn starch as anti-stick dusting flour, and connect dusting equipment after the outlet.

Q: What machine is used for small tangyuan?
A: Small tangyuan with a kneaded texture are mostly divided and then rounded; yuanxiao-style rolled tangyuan are rolled in flour layer by layer in a drum. The two have different textures.

Q: Can Dong-Yih's machines make tangyuan?
A: Tangyuan are not among the products listed on Dong-Yih's website. The DY-528MS listing includes mochi and taro balls; for tangyuan, please call 06-257-4644.