Possible markers of olive oil “soft” deodorization by physical stripping

“Soft” deodorization can be reasonably achieved by two main methods, either separately or combined: physical stripping treatment and deodorizing “filtration”. Both techniques can be considered refining phases, and are not allowed for extra virgin olive oils defined as “oils obtained from the fruit of the olive tree solely by mechanical or other physical means under conditions that do not lead to alteration in the oil, which have not undergone any treatment other than washing, decantation, centrifugation or filtration, to the exclusion of oils obtained using solvents or using adjuvants having a chemical or biochemical action, or by re-esterification process and any mixture with oils of other kinds.” (EC Reg. No.1513/2001, Annex). The reason for their prohibition is because they are not aimed towards extraction ot to stabilization of the oil (such as a proper filtration procedure), but to the "correction" of a product, which otherwise would not be native, or no longer, extra virgin; they could, for example, be used to reduce defects of virgin or lampante oils, rejected for sensory scores from the extra virgin category. Physical stripping "soft" deodorization, addressed here, can remove off-flavours but fatty acid alkyl esters (FAAEs), recently related to the main sensory defects such as fusty-muddy, winey, and mouldy (Gómez-Coca et al., 2012) can be permanent markers (Pérez-Camino et al., 2008) that reveal an oil of low quality. Their determination, performed together with the quantification of waxes (EU Reg. No. 61/2011) is lenghty and laborious and as a consequence, other preliminary screening methods have been proposed, or ara being studied, including: a) FT-IR coupled by Partial Least Square (PLS) fast method (Valli et al., 2013a); b) Time Domain Reflectometry (TDR) and PLS multivariate statistical analysis (Valli et al., 2013b). “Soft” physical stripping deodorization may produce other observed or theoretical effects, which are being investigated as possible markers, such as: i) the appearance of anomalous sensory attributes (e.g. the so called “cardboard like”); ii) the modification of volatile compounds, such as their relative ratios (e.g. ratio between ethanol and E-2-hexenal); iii) the lowering of the amount of water in oils, due to the stripping effect (Bendini et al., 2009); iv) the diacylglycerols content and the proportional amount of free fatty acids.