Olive oil is continually touted by regulators and watchdogs as one of the highest risk products for food fraud and adulteration. Agroisolab offers several tests to assist suppliers and retailers in product authenticity.
When poor harvests occur in the main olive oil-producing countries, the demand for olive oil doesn’t drop. Regulators commonly report suspicions that producers are finding ways to ‘stretch’ what they currently have to meet demand or take advantage of the high price when the rest of the market is hampered by a poor harvest.
One of the ways unscrupulous producers may be stretching out their olive supply is by simply buying more olives from outside of their normal appellation. A producer may be producing ‘Greek’, ‘Spanish’ or ‘Italian’ labelled oils, but they may be using olives bought from outside the declared country.
There are many challenges in the authenticity of olive oils - some are general to all oils and some are specific to olive oils. Isotope testing can directly help with some of these challenges and may be able to indirectly spot other issues. Here are a few examples:
Dilution of raw input olives with olives from other origins
Dilution of olive oils with olive oils from other origins/qualities
Dilution of olive oil with other vegetable oils
Dilution of olive oil with prohibited oils (e.g. waste oil, animal feed oil, mineral oil)
Origin analysis includes the following countries:
Random testing programs
Random testing programs allow for a different verification method to conventional traceability systems which are based on paper trails. By checking whether a product is or isn’t consistent with its declared origin can give insight into current traceability practices to improve them, can highlight other authenticity issues, and can give valuable evidence that supply chains are functioning as they should.
Agroisolab believes many of the risks in olive oil can be first detected using tests focusing on geographic origin. If there are clear issues with the geographic provenance of an oil, this normally calls for further investigation. However, if there are also concerns related to specific issues such as entry of petroleum hydrocarbons in olive oils Agroisolab can focus on these areas in more detail.
Want to know more about the risks related to olive oil authenticity?
We've put together a report containing the latest knowledge on olive oil origin testing using stable isotope ratio analysis.
Download the Agroisolab olive oil report here:
Archiving samples from producers
In order to ensure consistency of products from suppliers, particularly in high-risk products such as olive oil, Agroisolab recommends archiving samples from producers from each batch supplied. This significantly enhances origin testing work as it enables a 1:1 analysis in addition to verifying the general geographic origin claims made on the oil. In this situation, the product should match the reference sample with very high confidence.
Archiving helps overcome the following challenges:
• Authentication against the broad origin (e.g. Italian) and the local origin (e.g. Puglian)
• Ensuring that consistent input materials are used to make the retail product
• Ensuring what you buy from a producer is the same as what is on sale in your shop
To demonstrate the principle that European olive oils can be distinguished by their stable isotope ratios, we have put together some maps showing the general trends in the stable isotope ratios of European olive oils. These maps were made using data measured by Agroisolab from authentic samples sourced by Agroisolab GmbH and MaxFry GmbH. Please note that the maps are only designed to give a general overview of the trends in isotope ratios in olive oil and won't necessarily reflect detailed local variance.
Hydrogen isotope ratios in European olive oils
Hydrogen isotope ratios in olive oil originate from the rainwater the olive trees use to create sugar via photosynthesis. Sugars are subsequently metabolised into fatty acids and other lipid compounds and placed into the fruits of the olive tree. The above map shows the mean values of hydrogen isotope ratios in olive oils across Europe. ‘Red’ denotes that there is relatively more of the heavy isotope (hydrogen, 2H or ‘D’), ‘Blue’ denotes that there is relatively less heavy hydrogen. As hydrogen isotope ratios are dependent on temperature, latitude, altitude and the ‘continental effect’ it is no surprise that there is a similarity between some areas. [Click the map below to expand].
Oxygen isotope ratios in European olive oils
As hydrogen and oxygen are related to each other through groundwater as described by the GMWL, it can be expected that there will be relatively similar geographical patterns in oxygen stable isotope ratios and hydrogen stable isotope ratios. However, as oxygen ends up in lipid compounds (e.g. fatty acids, TAGs) in slightly different metabolic pathways to hydrogen there are also some differences. Whereas the hydrogen isotope map showed some general similarity between hydrogen isotope ratios in Portuguese olive oils and Cretan olive oils, the oxygen isotope ratios show clear differences between the two origins. [Click the map below to expand].
Carbon isotope ratios in European olive oils
Carbon ratios reflect the local climate. As Southern European countries all share a similar ‘hot’ climate it is easy to see similarity on the above map. The opposite is also true, colder Northern regions have olive oils with more depleted carbon isotope ratios. [Click the map below to expand].