Lumps and undissolved powder after mixing: causes and checks

Symptoms

• Visible lumps or gel balls in the batch or on filters.
• Powder floating on the surface and not drawn down.
• Viscosity or solids lower than the recipe target.
• Longer mixing times than before to get a smooth batch.

Likely causes

• Powder added too fast. More powder than the mixer can wet and disperse at once forms clumps.
• Wrong liquid level. A level too low exposes the mixing head and pulls in air. A level too high reduces the vortex that draws powder in.
• Liquid temperature. Some powders, such as gums, starches and proteins, need a specific temperature range to disperse and hydrate.
• Order of addition. Adding a thickener before other powders, or into a liquid that is already viscous, makes dispersion harder.
• Worn rotor and stator. Wear increases the gap between rotor and stator and lowers shear.
• Damp or caked powder. Powder that took up moisture in storage can enter the mixer already lumped.

What to check, in order

1. Compare the powder addition rate with the recipe and with a good batch.
2. Check the liquid level and temperature at the moment powder is added.
3. Check that the mixer runs at the recipe speed when powder enters.
4. Check the order of addition. Pre-blending a thickener with sugar or another dry ingredient often helps.
5. Inspect the powder for caking, and check storage conditions.
6. At the next stop, check rotor and stator wear against your service documentation.

When to call a TPS engineer

Call a TPS engineer if lumps remain after addition rate, level and temperature are correct, or if you plan a new recipe or ingredient.

Ask LiveAccess

Ask with the ingredient, batch size, liquid temperature and mixer type, or a photo of the lumps. In the app you can also find a high shear mixing expert in the Expert Network and chat or call them.

This guide gives general checks. Settings, limits and procedures differ between machines: always use the values in your service documentation and your site procedures.