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How to solve deodorization frauds in extra virgin olive oil? The EU reply will be soon

Good news for the scientific research, in Europe, to counteract the fraudolent activities in the world of the extra virgin olive oil. A workshop in Madrid has outlined the challenges and the urgent needs

In April 2011, the EU Regulation n. 61/2011 (1) become operative and the content of fatty acids alkyl esters (FAAE) has become an official quality parameter for extra virgin olive oil. The methyl and ethyl alcohols, which are part of these esters, are formed as a result of enzymatic and fermentative processes which occur if the olives, before crushing, overripe or incorrectly stored, suffer damages to cellular structures. When this happens, in fact , the leakage of water can facilitate processes capable of generating many volatile substances, between those ethanol. It is no coincidence that the “viney-vinegary”, linked to the alcoholic, lactic and acetic fermentations, is one of the defects which downgrade the extra-virgin olive to virgin or lampante olive oil, depending on the intensity.

A content over the limit of the alkyl esters can assume, however, the insiders know it, at least two different meanings.

First case: downgrading of the category accompanied by other chemical or sensory non-conformities, precisely because the etiology of alkyl esters is linked to degradative or fermentative processes. In this case, it is frequent that the oil is also sensorially defected. The alkyl esters are here clearly markers of a lower quality of the product.

Second case: the oil has values ​​of alkyl esters higher than limit, but the sensory quality is unexceptionable. These analytical results may produce the suspect that, to avoid a sensory downgrading, the oil has been subjected to a fraudulent "stripping" correction of the volatile compounds. The alkyl esters are, in this case, markers for a not allowed treatment, known as mild deodorization. This stripping can remove volatile compounds but does not seem able, and future research will confirm or disprove, to remove the alkyl esters.

Currently the EU regulation sets a maximum limit on the total content of alkyl esters (sum of methyl and ethyl esters) of fatty acids at 75 mg kg-1, with the possibility to classify as "extra virgin olive oil" a product which, although presenting a total ester content of between 75 and 150 mg kg-1, has a value of the ratio ethyl/methyl esters less than or equal to 1.5.

On May 23, 2013, the IOC approved a revision of the trade standards (2,3), valid from the olive crop year 2013/2014, reporting a change in the limits of the alkyl esters. In particular, it will be evaluated only the content of ethyl esters, with a lowered limit, because this esters are due to fermentation processes, linked with incorrect storage or sanitary condition of olives, and not from the ripeness state of the fruits.

This document provides that the reduction of the content of ethyl esters will be gradual: it will be a limit of ethyl esters less than or equal to 40 mg kg-1 for the year 2013/14, less than or equal to 35 mg kg-1 for the year 2014/15 and less than or equal to 30 mg kg-1 from the season 2015/16 onwards.

To update the official methods for the quality and authenticity control of extra virgin olive oil, the archetype of excellence, therefore, subject to fraud and object of numerous chemical and sensory methods that have made the history of food analyses, the European Commission, together with the IOC and the Institute for Reference Materials and Measurements of the Joint Research Centre (IRMM JRC) organized a workshop in Madrid. This meeting, entitled "Olive oil authentication" was focused on the identification of future lines to renew the methods in use including the actual scientific knowledge and to set novel technologies to update EU Regulation 2568/91 and subsequent amendments.

The themes of work, on which some experts have grouped and presented their research activities, were dictated by two simple keywords: adulteration and deodorization.

Europe and the international scientific community must concentrate its efforts to solve, beyond the case of olive oil, fraud problems or reduce them, thus contributing to maintain quality and protect origin and added value.

I presented in Madrid the analytical determination of alkyl esters with methods, let me say, not-conventional, namely rapid and less laborious than "separative" methods. The short lecture, titled "Possible markers of olive oil "soft" deodorization by physical stripping", prepared with the valuable contribution of Enrico Valli and Alessandra Bendini and downloadable from the website of the European Commission (http://ec.europa.eu/agriculture/events/olive-oil-workshop-2013_en.htm), reported some analytical experiences carried out in the last years and some papers recently published or in press (4, 5). In particular, the considerations set out in Madrid retraced the effort, the planning and the evidences that an interdisciplinary group of food scientist and engineers of the Department of Agricultural and Food Sciences of the University of Bologna (http://www. distal.unibo.it) are carrying on in the direction of rapid diagnostics.

Some of these control methods are projected to be fast, cheap and non-destructive. Among those tested, the time domain reflectometry (TDR) and the spectroscopy in the near and mid-infrared (NIR, MIR), even if in a different stage of progress, look very promising and could complement the traditional separation techniques, to manage the quality control in a more sustainable and effective way, which may come to more accurate separative and quantitative determination only in really suspicious cases.

These are small steps toward a great job of revision and development of sensory and instrumental methods of analysis, evidence of a "resonance", or a strong will of collaboration, between national and international centers, enterprises and associations. This big revision is combined by the desire to affirm the research in Europe in collaboration with third Countries on a plot (olive oil authenticity) in which Europe has always been excellent, but on which there is a need a better coordination and times are ready to make an efficient network.

The Reg. (EEC) N° 2568 dates 1991, after twenty-two years the olive oil analytics deserves a great international boost, Europe is requiring it, to protect a precious common capital, in a logic of applied research, often funded by small contracts, that needs in order to be successful and convincing, the active involvement and participation of all actors of the “extra virgin olive oil” supply chain.

Bibliografy

1) Reg (EU) 61/2011 of 24 January 2011– Official Journal of European Union L23 27/1/2011.
2) COI Decision No DEC-20/100-V/2013, IOC, 23 May 2013.
3) COI/T.15/NC No 3/Rev. 7 November 2012.
4) Valli, E., Bendini, A., Maggio, R.M., Cerretani, L., Gallina Toschi, T., Casiraghi, E., Lercker, G. Detection of low-quality extra virgin olive oils by fatty acid alkyl esters evaluation: A preliminary and fast mid-infrared spectroscopy discrimination by a chemometric approach (2013) International Journal of Food Science and Technology, 48 (3), pp. 548-555.
5) Berardinelli, A., Ragni, L. Bendini, A., Valli, E., Conte, L., Gallina Toschi, T. Rapid screening of fatty acid alkyl esters in olive oils by time domain reflectometry (2013) Journal of Agricultural and Food Chemistry, 61 (46), pp. 10919-10924.

by Tullia Gallina Toschi
02 december 2013, Technical Area > Olive & Oil

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