Quality control in processing drying oils

Abstract

A brief history of linseed oil, its production trends, uses and prospects for the future are discussed. Methods of processing, effects of process variables on oil quality, how quality is measured and how it is maintained are the main topics of this paper. Although linseed oil production declined steadily for many years after World War II, it has stabilized in recent years and shortages of petroleum products could cause a return to linseed oil in the form of water emulsion. Brief references to other drying oils will be included. Quality control begins with seed quality and includes storage, cleaning, processing and degumming. Refined oils described include alkali-refined, blown, heat-bodied and chemically modified oils. Present quality control methods are described. Problem methods such as the “foots” test for degummed oils are described. Recent developments used on occasion included liquid chromatography, thin layer chromatography (TLC), ultraviolet (UV) and infrared (IR) spectroscopy, but the most predominantly used technique has been gas chromatography (GC). Recent developments in capillary GC and fused silica columns have improved separations and reduced analysis times. Near infrared reflectance shows some promise for future quality control work.