Unrefined oil from the extractor has a pronounced color, flavor and aroma normally removed by refining. Refined oil is standardized, bland, and odorless. However, unrefined oils have certain advantages over refined oils. Many oils (such as evening primrose oil) are naturally rich in antioxidants that are significantly reduced by refining. Unrefined oil is more stable, with a longer shelf life, and contains natural antioxidants that may provide additional health benefits. The natural flavor and aroma of unrefined oils can also be a selling point for use in health food and culinary applications.

Refining techniques fall into two categories: physical refining and chemical refining. Physical methods of refining include filtering, winterization, and deodorization. Chemical methods of refining include de-gumming, neutralization, and bleaching. Both techniques are, of course, suitable for use with food-grade products. Some customers, however, may wish to obtain a natural oil product, so physical refining methods are more appropriate.