Sunday, June 16, 2024

The Method of Determining Polycyclic Aromatic Hydrocarbons (MOAH) for Non-Specialists in Simple Terms and Some Basic Thoughts, after research and study from reliable sources, concluded in the article “Olive sector in the Crosshairs of the European Commission. Challenging the Hygiene and Quality of olive oil – pomace oil with MOAH” which gained significant attention, raising numerous questions on such a complex issue. The article expresses serious doubts about the expressed view that the main culprits for MOAH are olive oil producers in certain regions. It aligns more with the arguments of the Spanish stakeholders, suggesting that traces of MOAH are endogenous to the olive fruit, regardless of any human practices. It also explains why the proposed limit for MOAH would disrupt the entire agri-food chain, with olive millers likely to be most affected.

The crucial date of 27/2/2024 is approaching, set by the Commission as the deadline for member states and stakeholders in the agri-food chain to submit their opinions and proposals. The Commission’s proposal sets the limit at 2mg/kg for olive oil or pomace oil, with the likely implementation date being 1/1/2025. In other words, “yesterday”! reached out to representatives of the olive oil and pomace oil sector, who reserved their comments. Additionally, contacted Constantinos A. Demopoulos, Emeritus Professor of Foods Chemistry and Biochemistry at the National and Kapodistrian University of Athens, Greece and a member of the 4E, who has extensive experience, both theoretically and in the laboratory, on the subject.

Given the critical nature of the issue affecting the entire agri-food chain, olive oil including pomace oil, and the tight timeframes, we asked Professor Constantinos A. Demopoulos to focus his intervention on the following axes:

– What are the current techniques for the analysis and measurement of MOAH?
– How reliable can the proposed limit of 2mg/kg by the Commission be?
– What studies and research need to be conducted immediately to establish a quantitative limit for MOAH with the required scientific certainty and assess the potential risk to human health?

(Vassilis Zampounis)


Constantinos A. Demopoulos, Emeritus Professor of Food Chemistry and Biochemistry at the National and Kapodistrian University of Athens, Greece (NKUA), and member of the Scientific Society of Olive Encyclopaedists Non-Profit-Civil Society (4E).

If one wants to describe in simple terms the principle of the method for the analysis of MOAH, one could say the following:

In the sample to be analyzed, the fraction containing the set of compounds characterized as MOAH is separated using a chromatographic column (in HPLC), and then the existing compounds in the MOAH fraction are further separated from each other using a second chromatographic column (in GC). Specifically, the set of molecules of compounds characterized as MOAH from the first column (in HPLC) is divided into two parts that simultaneously pass through two identical GC columns (# 1 and # 2), hence the term two-dimensional chromatography (2D). From one GC column (# 1), the presence of various compounds (chemical molecules) included in the MOAH set is certified and recorded, and from the other GC column (# 2), data are provided regarding the chemical structure of each of the compounds that have been certified and recorded by column # 1. This data comes from the fragmentation of the molecule of each compound separated by GC column # 2, using mass spectrometry (MS) ionization technique, which certifies and counts the fragments (pieces) of the molecule of that compound.

That is, ultimately, fragments from the chemical molecules of the compounds present in the MOAH are obtained, and with appropriate software, it is determined whether these fragments could originate from Aromatic Hydrocarbon Mineral Oils with 1, 2, 3, 4, etc. rings.

All this becomes more understandable if we consider (with some simplification for non-specialists) that each chemical molecule taken after GC column # 2 is a complete puzzle picture and the fragments obtained from the fragmentation of the molecule with MS are the pieces of that puzzle picture. The software does the work that a player would do, that is, it adjusts the pieces to form the picture.

If puzzle picture # 1 and its pieces are present, the matter is relatively simple. That is, one can confidently answer whether a piece belongs to this picture. However, if pieces from a second puzzle are also mixed in, without having the corresponding picture # 2, then it is not excluded that a piece may fit both pictures and be counted as a piece of picture # 1.

Returning to chemical identification, the case of a puzzle with only its pieces is a case encountered in the laboratory.

In nature, things are more complex, that is, there are pieces from more puzzles, without always having the corresponding pictures of each puzzle. This is because, although we know a lot about the compounds present in nature, there are still many compounds whose existence we do not know.

Specifically, in a natural sample analyzed by this method, there are many fragments from each chemical molecule obtained from MS, but it is considered that all fragments originate from Aromatic Hydrocarbon Mineral Oils (which are considered as standard compounds for identification) and not from other possible existing compounds in nature whose existence is unknown.

These shortcomings are mentioned in scientific publications on the method of MOAH determination, that is, they are used as standard compounds for identification by various researchers, various proportions of oil fractions, something that is not exact but close to the truth. In addition, there are chemical molecules that result from various random breakdowns of mineral oil fractions, e.g., from heat for exhaust gases, etc.

Because we can only know the quantity of fragments that may originate from rings of Aromatic Hydrocarbon Mineral Oils, which are toxic compounds, the European Commission plans to set limits per quantity of olive oil or seed oil, specifically 2mg/kg.

In conclusion, the origin of the chemical molecules that give the determined fragments is not known, and it is not excluded that there may be compounds in nature that give these fragments but are not toxic.

Compounds with aromatic rings are widespread in nature and as their name suggests (aroma in Greek it means perfume) they provide aroma and color. In olive oil, there are phenolic compounds with 3 rings, as well as in sesame oil, but also 4 rings in red wine, which are anti-inflammatory and anti-atherogenic, as our research team has published for years. Similar concerns with indications from their experimental results have been expressed in publications by a Spanish team (R.B.Gomez-Coca, M. Del CarmenPerez-Camino, W. Moreda).

In conclusion, existing indications must be investigated and clarified, whether olive trees produce compounds that can be counted as MOAH. Especially if the core (the kernel) of the olive fruit inherently has such compounds, without any human processing from any bad practice, which would add MOAH. Therefore, the legislator cannot impose destructive restrictions on the economy of a sector vital to the Mediterranean countries of Europe and deprive the consumer of a food valuable for health, without being conclusively certain that there are no such natural endogenous compounds.


The present article-study is an original work by the authors Constantinos A. Demopoulos and Vassilis S. Zampounis, and is protected by copyright law. It was written with the aim of informing, and its dissemination is encouraged. However, the republication of this article, or any part of it, or the rewriting of its basic information and opinions, is allowed only under the condition of explicit reference to the original authors and

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