To mill or grind?
A mill is the gold standard because it gives you much better control over particle size. But milling creates heat, and heat is the enemy of delicate aromatic oils, so keeping the spices cool matters. Particle size then controls how quickly those flavours extract: smaller particles extract faster, larger particles more slowly.
Buy whole spices rather than pre-ground. If possible, go to a good spice merchant rather than a major supermarket. Most spices on Australian supermarket shelves are extremely old and of low quality.
In our factory, we have a purpose-built milling line. We mill within 2–4 hours of production to preserve aroma compounds. Our pin and hammer mills run at 8,000–14,000 RPM, while we keep the spices below 40°C to help protect volatile aromatic oils.
At home or in a café, use a pin or hammer mill if you have one. Otherwise, a $40 spice or coffee grinder can do a solid job too. Work in small batches and don’t let the grinder or spices get excessively hot.
Fresh ginger, however, needs to be treated separately.
Fresh ginger
Fresh ginger gives warmth, brightness and lift, while dried ginger gives a more concentrated burn and lingering heat.
Fresh ginger is typically avoided by many commercial chai companies because it introduces moisture and increases shelf-life complexity, meaning the finished chai needs more careful processing and refrigerated storage. But the complexity it brings is unrivalled. If you choose to use it, go for mature fresh ginger for greater depth and longer heat.
At the Somage factory, we process fresh ginger separately using a Robot Coupe food processor.
At home or in a café, a good food processor will do the same. You want a coarse mince, not a purée or juice. Wash the ginger first and cut off any dark or spoiled parts.