Walnut oil is edible and is generally used less than other oils in food preparation, often due to high pricing. It is light-coloured and delicate in flavour and scent, with a nutty quality. Although chefs sometimes use walnut oil for pan frying, most avoid walnut oil for high temperature cooking because heating tends to reduce the oil's flavour and produce a slight bitterness. Walnut oil is preferred in cold dishes such as salad dressings.
There are two types of walnut oil commercially available: cold pressed and refined. Cold pressed walnut oil is typically more expensive due to the loss of a higher percentage of the oil. Refined walnut oil is expeller pressed and saturated with solvent to extract the highest percentage of oil available in the nut meat. The solvents are subsequently eliminated by heating the mixture to around 400 °F (200 °C). Both methods produce food grade culinary oils. Walnut oil, like all nut, seed and vegetable oils will undergo rancidification accelerated by heat, light, and oxygen.
Over 99% of walnut oil sold in the USA is produced in California.
Some woodworkers favour walnut oil as a finish for implements that will come in contact with food, such as cutting boards and wooden bowls because of its safety. People who mix oil & wax to formulate wood finishes value walnut oil as an ingredient because of the edibility of both ingredients. The oil typically is combined with beeswax in a mixture of 1/3 oil to 2/3 beeswax.