Vegetable Filling (Cabbage, Chinese Chives, Napa Cabbage): Dewatering and Water Release

Cabbage dumplings, chive dumplings, and napa cabbage and pork buns are among the most common dishes in Taiwan, and also the fillings that cause the most problems on machines. The reason is simple: leafy vegetables are naturally high in water, and once chopped, their cells are broken; as soon as they meet salt, water keeps running out.

Should Vegetables Be Dewatered First?

Leafy vegetables with high water content, such as cabbage and napa cabbage, generally need to be dewatered first. The common method is to chop them, toss them evenly with a little salt, let them sit for a while so the water seeps out, and then remove the water with a dewatering machine or by squeezing. For vegetables with lower water content and finer texture, such as Chinese chives and bok choy, many factories do not salt them first; instead, they toss them with oil after cutting and mix them with the other filling ingredients only at the end, so the chives are not drawn out by the salt and do not discolor.

How far to dewater depends on the product: too little and they release water, too dry and the vegetables taste like pulp and lose their sweetness. A practical approach is to fix the dewatering time and pressure and compare the finished texture across a few batches.

What Problems Does Water Release Cause?

When vegetable filling releases water, a chain of problems follows on the machine:

• The filling becomes runny, flowing back and dripping during feeding, so each piece has a different amount of filling.
• The wrapper gets soaked, and the dough becomes soft and sticky and tears easily during encrusting.
• The seal will not hold: dumplings open up when boiled and buns leak juice from the bottom.
• Poor quality after freezing: the water in the filling forms ice crystals that run out again on thawing, and the wrapper tends to crack.

What's more, vegetable filling does not release water just once and stop; the longer it sits after mixing, the more it releases. So mixed vegetable filling should not sit in the work area too long; it is best to mix small amounts more often and top up frequently.

What Can Be Added to Lock in Water?

There are several common ways to lock in water, which can be combined:

1. Toss with oil first: Toss the chopped vegetables with vegetable oil, lard, or sesame oil first; the oil coats the surface of the vegetables and slows water release.
2. Add salt and seasoning last: Salt draws water out, so many recipes season the meat filling first and mix in the vegetables only just before going on the machine.
3. Rely on the stickiness of meat filling: Once meat filling is mixed until sticky, it can hold some of the water, and the vegetable-to-meat ratio also affects how much water is released; see Meat Filling (Adding Water, Mixing, Stickiness).
4. Add binders: Absorbent ingredients such as starch, breadcrumbs, and chopped glass noodles can soak up excess water. If food additives are used, they must stay within the scope permitted by regulations; see Using Dough Improvers, Emulsifiers, and Additives.
5. Chill before going on the machine: Low temperatures slow water release; see Filling Temperature.

How finely the vegetables are chopped also matters: coarse stems jam the feed and puncture the wrapper, while chopping too finely makes them release water more easily. The balance point must be found by testing; see Filling Viscosity, Particle Size, and Water Content.

Dong-Yih Machinery's DY-201 Automatic Steamed Bun and Mantou Machine can make vegetable buns, meat buns, and more. For how to adjust your vegetable filling recipe for machine production, please call 06-257-4644.

FAQ

Q: Should the cabbage in cabbage dumplings be dewatered first?
A: Yes. After chopping, add a little salt and let it sit to release water, then remove the water with a dewatering machine or by squeezing.

Q: What happens when vegetable filling releases water?
A: The filling becomes runny, the wrapper gets soaked and tears easily, the seal will not hold, and the product is more likely to crack after freezing.

Q: Do Chinese chives also need to be salted to draw out water?
A: Many factories do not salt them; instead, they toss them with oil after cutting and mix them with the seasoned meat filling just before going on the machine, to avoid water release and discoloration.

Q: What can I add to keep vegetable filling from releasing water?
A: Toss with oil first, add salt last, rely on the stickiness of the meat filling, add absorbent ingredients such as starch or breadcrumbs, and chill before going on the machine.