Your Spice Grinder Is Probably Cooking the Spices While It Grinds Them

Treat the sections below as a sequence. With choosing and using a spice grinder, getting the early decisions right makes the later ones much easier.

What the heat is doing

A blade grinder works by smashing material at high speed, and most of the energy that does not break spice becomes heat. Held down continuously, the chamber can become uncomfortably warm to touch inside a minute. Volatile aroma compounds start leaving well below that temperature, so you are losing them during the grind.

Cardamom, fennel and pepper are the biggest losers, since their appeal is entirely in the volatile fraction. The powder that comes out smells strong because everything that escaped went into the air around you.

Grinding without cooking

Work in bursts of eight to ten seconds with several seconds of pause between them. Shake the grinder between bursts rather than running it longer, which also gives a more even particle size. Fill the chamber no more than half full, since an overloaded motor works harder and runs hotter for longer.

Chilling the spices in the freezer for ten minutes beforehand buys you a genuinely useful margin. The chamber should never be too hot to hold comfortably when you open it.

Blade against burr against mortar

Blade grinders are cheap, fast and produce an uneven grind with a wide range of particle sizes. Burr grinders give a far more consistent particle size but struggle with oily and fibrous spices. A stone mortar is slow, produces no heat at all and handles cardamom and pepper better than either machine.

For a chai kitchen a cheap blade grinder for batches and a mortar for daily crushing covers everything. Spending heavily on a single device is generally worse value than owning both of the cheap options.

The contamination problem

Spice oils soak into the plastic of a grinder body and stay there more or less permanently. A grinder that has ground cloves will contribute clove to everything that goes through it afterwards. This matters enormously if the same machine is used for coffee, since coffee picks up aroma readily.

Grinding a tablespoon of plain rice cleans the chamber reasonably well between different spices.

A dedicated spice grinder costs very little and removes the problem entirely rather than managing it.

What not to put in it

Fresh ginger, fresh turmeric and anything wet will clog a blade grinder and are jobs for a mortar or a blender. Very hard whole nutmegs can damage blades and are better grated on a fine rasp. Large cinnamon quills should be broken by hand first rather than dropped in whole.

In the pot, saffron should never go anywhere near a grinder, since threads are worth crushing between the fingers. Sugar ground with spices will absorb moisture and cause the whole blend to cake in the jar.

Maintenance that matters

Unplug it and wipe the chamber with a dry cloth after every use rather than washing it. Water in a blade grinder rusts the shaft and creates a damp environment that spoils the next batch.

By the second boil, check the blade for dullness occasionally, since a dull blade runs longer and hotter for the same result. Store it with the lid off so any residual moisture can evaporate rather than sitting in the chamber. A grinder used for spices and looked after this way will last many years for very little money.

The takeaway

Short bursts, a half-full chamber and a grinder that does nothing but spices.

A good glass is mostly fresh spice and the patience to let it boil twice.