2. Presentation of flow diagrams

Edible vegetable oils are composed mainly (95 to 98%) of fatty acid triesters and glycerol (or triglycerides). These are susceptible to deterioration either through lipolysis by hydrolysis, which is the breakdown of lipids (leading to the release of fatty acids esterifying glycerol through hydrolysis of glycerides), or through oxidation (auto-oxidation, photo-oxidation, or enzymatic oxidation).

They also contain minor undesirable compounds, which will be removed during refining, such as: free fatty acids, phospholipids, oxidation products, flavors, waxes, pigments, metals (iron, copper), contaminants, heavy metals, pesticides, polycyclic aromatic hydrocarbons (PAHs), and mycotoxins.