Extracting oil from olives requires solvents and residues of halogenated solvent can sometimes leave a toxic taint in the product. European Union rules restricted the acceptable levels of these residues for the sake of public health but new sensitive and precise analytical procedures are needed to allow strict quality control and regulatory testing to be carried out.
Now, Spanish researchers have turned to chemical informatics to help them optimise the extraction-analysis process. Bromoform, chloroform, ethylene dichloride, trichloroethene, tetrachloroethene, dibromochloromethane, and bromodichloromethane are all employed to extract crude olive-pomace oils from the solid residue obtained in the pressing of olive oils. The EU limits the residues of these solvents to 0.1 milligram per kilogram for individual compounds and double than that for total content. “These solvents have a great negative influence on both the quality of oils and human health,” José Luis Gómez-Ariza of Huelva University told SpectroscopyNOW, “They are all considered to be possible carcinogens and, therefore, human exposure to such compounds should be minimized.”