Dough Mixers: Types, Mixing Time, and Safety

What Types of Mixers Are There?

The first machine for making buns, mantou, and dumpling wrappers is usually a mixer. There are three common types:

• Vertical (planetary) mixer: The mixing head rotates on its own axis while orbiting around the bowl, and can be fitted with a hook, paddle, or whisk, so it can handle dough, fillings, and beaten eggs. Suitable for shops with many products in modest volumes and for small and medium-sized factories.
• Spiral mixer: A spiral hook rotates in a fixed position while the bowl also turns, so the dough is continuously drawn into the hook and kneaded. Suitable for doughs of medium water content; common in bakeries and the steamed bun and mantou trade.
• Horizontal mixer: The mixing shaft lies horizontally in a trough and can handle large amounts of dough at once, usually paired with tilting discharge; used in large factories.

Mixing Time and Gluten

When flour and water are mixed, the proteins in the flour absorb water and form gluten; the longer the mixing, the more complete and elastic the gluten network. But longer isn't always better:

• Under-mixing: The dough surface is rough and breaks easily, buns can't hold their shape after proofing, and dumpling wrappers tear easily.
• Over-mixing: The gluten breaks down, the dough becomes sticky and loses elasticity, and it's harder for machines to form.
• Temperature rise: Friction during mixing warms the dough, affecting subsequent fermentation. Many bakers use ice water or adjust the water temperature to control this.

Buns and mantou are fermented, so the gluten must be able to hold gas; dumpling wrappers need bite without too much spring-back. Every shop's recipe, flour, and water content differ, so there's no fixed mixing time. The practical approach is to first find the end-point condition for your recipe (for example, how thin a membrane the dough can be stretched into), record the speed and time, follow those records for every batch, and fine-tune based on the finished product.

How to Choose Capacity

The capacity listed on a mixer's specs might be the "bowl volume," the "flour capacity," or the "dough capacity," and these are very different, so when comparing brands, always ask which one it is.

When choosing capacity, think about it this way:

1. First calculate the total amount of dough used per day, then divide by how many batches you'll mix per day.
2. The lower the dough's water content (the firmer it is), the heavier the load on the machine, so the amount it can mix usually needs to be discounted.
3. The mixer's output must keep up with the forming machine that follows. If the forming machine is waiting for dough, or the mixed dough sits too long, quality suffers.

Safety Precautions

Mixers are among the food factory equipment most prone to entanglement accidents. An occupational safety alert issued by Hong Kong's Labour Department in 2023 recorded a case in which a food factory worker fell into the bowl of an electric mixer and was fatally crushed by the rotating mixing arm. It recommended that employers carry out risk assessments, install effective guards, mark out danger zones, and switch off and lock the power supply during inspection, maintenance, and cleaning.

Taiwan's Occupational Safety and Health Facilities Rules (職業安全衛生設施規則) set clear requirements for this kind of equipment:

• Article 76: Openings of grinders and mixers must have covers, enclosures, or fences at least 90 cm high to prevent workers from falling in; where contact between the opening and moving parts is dangerous, enclosures are also required.
• Article 77: When removing contents from a mixer, unless there's an automatic discharge device, the machine must first be stopped.
• Article 57: When machinery is being cleaned, oiled, inspected, repaired, or adjusted, operation and feeding must be stopped, and the machine must be locked out and signs posted to prevent others from starting it accidentally.
• Article 279: Where workers' hair or clothing could be caught, appropriate clothing and headwear must be worn.

Build a few habits into daily operation: never reach into the bowl to scrape dough while mixing; confirm the guard or safety interlock switch works; tie up long hair and wear a cap, and keep cuffs snug; and always cut power and lock out before cleaning. For detailed procedures, see Cleaning Safety: Stop, Cut Power, Lock Out.

FAQ

Q: How long should bun dough be mixed?
A: It depends on the recipe, flour amount, and machine model, so there's no fixed time. Find the ideal condition for your dough, record the speed and time, and follow that for every batch.

Q: The mixer spec says 25 kg. Is that flour or dough?
A: Makers state it differently; it could be flour capacity, dough capacity, or bowl volume. Ask the maker to clarify before buying.

Q: Can I reach in to scrape the bowl while it's mixing?
A: No. Under Article 77 of the Occupational Safety and Health Facilities Rules, the mixer must be stopped before removing contents, and scraping the bowl should also be done only after stopping.

Q: Does Dong-Yih sell mixers?
A: Dong-Yih Machinery's business focuses on automatic encrusting and forming machines, portioning and cutting machines, and steamed bun and mantou machines. For matching peripheral equipment, call us at 06-257-4644.