Which oil for which dish
A simple guide to cooking with groundnut, gingelly and coconut oil.
What “cold-pressed” really means
Wooden chekku, rotary expeller and refined oil: three ways oil is made.
Almost every oil bottle now says “cold-pressed”, and the word has stopped meaning much. Here is how the three main methods differ.
A wooden chekku is a large mortar carved from vaagai or tamarind wood, with a heavy wooden pestle that turns slowly, about 6 times a minute. It crushes the seed gently, and the oil stays below about 45 °C. It is slow: one chekku presses around 15 kg of groundnut in an hour and a half.
A rotary expeller is a steel screw press. It is much faster, and friction heats the oil to 70 or 80 °C. Many brands labelled “cold-pressed” use expellers with cooling, which is better than refining but not the same.
Refined oil is pressed hot, then the rest of the oil is pulled out of the seed cake with a solvent called hexane. The oil is bleached and deodorised until it has almost no smell or taste.
If you want to know which you are buying, ask the seller where the mill is, and visit if you can.
