Q&A: why are new and improved analytical methods for verifying olive oil quality needed?

Q: OLEUM will develop new and/or improved analytical methods for verifying olive oil quality and detecting fraud. Would it be more effective and faster to combat olive oil fraud by tightening regulatory thresholds for specific analytical markers? (e.g. lowering the threshold from 20 meq O2/kg of oil down to 15 or 10 meq O2/kg of oil for peroxides; from 0.8 to 0.6 for free acidity; or from 150 mg/kg to 50 mg/kg for alkyl esters)

This question is based on an enquiry from foodwatch Germany.

A: First of all, in order to fighting frauds in the olive oil sector it is highly desirable to foster a preventive action, thanks to a continuous increase in the analytical controls performed by the official bodies. On the other hand, food quality in general, and virgin olive oil quality in particular, is a complex concept where all the chemical parameters provide a partial indication of quality that is not complete or definitive. The discussion of reducing limits needs to consider the fact that the final objective is to obtain a product that is unquestionable in regard to each one of all the quality aspects. For example, peroxide value provides information from the oxidation status, ethyl esters of fatty acids provide some indication about fermentation and degradation in the olives, and free acidity provides information on hydrolysis reactions. All of them are different points of view of quality, and each one provides some indications that may be related with sensory quality to different degrees. For that reason, this ‘global perception’ of virgin olive oil quality is always introduced in the debate as an important factor.

In particular, peroxide value (PV) is just one useful parameters for describing the oxidative status of oils and fats, but it is not exhaustive. UV absorption is another very important assessment: K232 is even more sensitive than PV to signal early oxidation status, while K270 can be out of range later. PV usually shows the typical normal distribution curve. After a lag phase, peroxide levels increase until it reaches a maximum, after which the concentration decreases as they themselves undergo degradation. This means that even an oil with a high level of oxidation can show a relatively low PV, despite being very oxidised. It is true that a PV of 20 meq O2/kg of oil is very high, as good quality oils have less than 10 meq O2/kg oil or even, when freshly extracted, less than 5 meq O2/kg oil. However, the limit of 20 meq O2/kg oil has been established for all edible fats and oils within Codex Alimentarius, which also applies to olive oils. We agree that a lower limit is advisable for extra virgin olive oils, even if it requires measures to define how bottled oils are treated throughout a trade distribution chain that, often, does not respect basic conditions for avoiding oil oxidation (such as light on the shelf, heat during transportation and so on).

The current limit of free acidity (0.8 %) for extra virgin olive oil is, in fact, the result of a reduction of the previous limit (1.0 %), which was decreased more than one decade ago with the aim of stricter quality control. Today, there are ongoing discussions about whether to keep reducing the free acidity to lower values (e.g. 0.5 %) to be even stricter, since modern production lines are able to produce extra virgin olive oil with free acidity < 0.5%. Some regulations have already taken this action. However, it is important to keep in mind that this debate has to take place in the frame of an international regulatory context where a common definition of “extra virgin” category is desirable for facilitating the trade between countries. Harmonization of regulation is one of the current trends today, and this harmonization activity involves accommodating the current limits to the particularities of production in different places. That is why this discussion of lowering limits sometimes takes longer than expected in some cases.

Finally, regarding fatty acid ethyl esters, according to the Commission Delegated Regulation (EU) No. 2016/2095 of 26 September 2016 - amending Regulation (EEC) No. 2568/91 on the characteristics of olive oil and olive-residue oil and on the relevant methods of analysis-, the legal limit for classifying an olive oil as extra virgin is already set at ≤ 35 mg/kg. The sum of methyl and ethyl esters ≤ 75 mg/kg or 75 mg/kg < sum of methyl and ethyl esters ≤ 150 mg/kg (in case of the ratio methyl esters/ethyl esters equal or higher than 1.5) correspond to the old legal limit (Commission Regulation (EU) No. 61/2011).