Depending on the food composition, different extraction procedures,
mainly based on classical solvent extraction (EFSA, 2012),
have been applied in mineral oils extraction from cereal and
cereal-based products. In the case of dry foods with a low fat content,
solvent extraction with hexane was first applied in extraction
of superficial contamination, such as that migrated from the packaging
(Vollmer et al., 2011). In the case of wet samples, solvent
extraction (with hexane overnight) was preceded by a dehydration
step (preferably carried out with anhydrous sodium sulphate).
Later, it was recognised that overnight extraction with hexane
did not allow for complete extraction of the mineral oil, also in
some dry foods. In 2011, Biedermann-Brem and Grob described a
solvent-based approach for exhaustive extraction of mineral oil
from wet samples. It involved sample equilibration (1 h) with ethanol
(added in amount at least 10-fold that of the water present in
the sample), followed by overnight extraction with hexane after
ethanol removal. As the ethanol extract contains some mineral
hydrocarbons, it was then recombined with the hexane extract
and added with water (twice the hexane volume) to separate the
hexane from the ethanol–water mixture.