Refined oil quality is evaluated primarily by traditional quality parameters such as a low residual free fatty acid content, a high oxidative stability, a light color and a bland odor and taste. In addition, high quality food oils need to contain low trans fatty acid levels, high amounts of natural antioxidants (tocopherols) and very low or no (process) contaminants such polycyclic aromatic hydrocarbons (PAH), pesticides, dioxins, polychlorinated biphenyls (PCB), 3-monochloropropanediol (3-MCPD)- and glycidyl esters (GE).
Increased attention from consumers together with new (EU) regulation that imposes stricter limits for several contaminants are forcing edible oil refiners to continuously optimize their refining processes. In the bleaching process, activated carbon is now systematically used for the removal of light PAH. A reduction of the heat load during deodorization is obtained by applying dual temperature deodorization, all or not in combination with a packed column stripper while more powerful vacuum systems (chilled barometric vacuum system or dry ice condensing) are implemented for a better stripping .
Lowering the heat load during deodorization surely has a positive impact on the reduced formation of process contaminants (TFA, GE), while a deeper vacuum gives improves stripping of volatile contaminants (pesticides, PCB, light PAH), but all these process improvements has to be adopted in a smart way to ensure that the refined oil still has a light color (enough heat bleaching), a good oxidative stability (not too much stripping of natural anti-oxidants) and a good shelf life (good deodorization).
In conclusion, optimizing the refining process conditions is such a way that all traditional and nutritional quality parameters can be met at the same time is a real challenge and requires a very good understanding of the impact of the various process parameters on the individual quality parameters.