Nut Oils

The oils of a number of nuts are prized for their flavor—walnut oil and coconut oil, for example—and several others as ordinary cooking oils (peanut oil, sunflower seed oil). Oils are extracted from nuts by two different means. “Cold-pressed” or “expeller-pressed” nut oils are made by crushing the nut cells and forcing the oil out with mechanical pressure. The nuts get hot from the pressure and friction, but generally don’t exceed the boiling point. Solvent-extracted oils are made by dissolving the oil out of the crushed nuts with a solvent at temperatures around 300°F/150°C, then separating the oil from the solvent. They are more refined than pressed oils, having fewer of the trace compounds that make oils both flavorful and potentially allergenic. Cold-pressed oils are generally used as a flavoring, refined oils as cooking oils. Nut oils have a stronger flavor if the nuts are roasted before extraction. Because they often have a large proportion of fragile polyunsaturated fatty acids, they’re more vulnerable to oxidation than ordinary vegetable oils, and are best kept in dark bottles in the refrigerator. The leftover solids—nut meal or flour— make a flavorful and nutritious contribution to baked goods.