by Lorenzo Cerretani, Food Technologist
and Silvia Minetti, Biologist
An organic olive oil is the one obtained from the extraction process from olives grown with organic farming systemsdefined internationally “organic”.
I community regulations, as is known, harmonize the procedures for the production of food obtained through the systems at European level of organic agriculture, such as organic extra virgin olive oil. Therefore, in these cultivation systems it is foreseen to resort to “traditional” practices, essentially preventive, intervening with adequate cultivation techniques that forbid the use of synthetic chemical products.
At this point, entering more into the context of interest relating to extra virgin olive oil, it is useful to point out the main differences that it is plausible to find between an oil obtained from organic farming and that obtained from conventional farming. The ban for organic farming on the use of synthetic chemical products in technical means that perform the functions of fertilizers, herbicides, insecticides and fungicides reassures us of the absence of residues of these molecules in extra virgin olive oil. On the contrary, an extra virgin olive oil obtained from a conventional agricultural regime can contain just one or more chemical molecules at the same time (cocktail effect), provided that each of these is below the maximum limit allowed in the finished product. On the cocktail effect relating to the simultaneous presence of more than one pesticide residue (always within the limits established by law for each of these) there are numerous recent studies which warn of the risks to human health.
In oils obtained from cultivated olive trees under organic farming they are not present residues of synthetic moleculesi.e. chemical molecules. In fact, in organic farming for the protection of crops, if necessary, we intervene with natural substances of vegetable or mineral origin expressly authorized and listed in the European regulation. Similarly, in organic farming regimes, it is possible to use natural fertilizers, such as manure, other composted organic substances (cuttings, etc.) and green manure. Therefore, one first answer to the meaning of organic oil we can supply it: it is an oil that does not contain residues of chemical molecules of synthesis used in defense of the crop which, albeit in limited and regulated quantities, can be present in the oils produced from olives grown with conventional systems.
Beyond the presence of chemical residues of pesticides, another aspect that characterizes organic extra virgin olive oils is linked to the natural physiological processes of the plant grown with organic cultivation systems. In fact, as is known, all plant species, and therefore also the olive tree, have a secondary metabolism of interaction that is active mainly for the purposes:
• plant protection;
• attraction of pollinators and animals that can contribute to the spread of the species;
• of competition between the plant itself and the adjacent ones.
Therefore, if the defense interventions foreseen in conventional agriculture in a preventive manner through the use of synthetic molecules (chemicals) represent for agricultural producers a guarantee instrument for production in quantitative terms, on the other may limit some physiological processes which lead the plant to synthesize naturally secondary metabolites such as, for example, molecules that play a role of "defence", "attraction" as well as "competition". Among the latter secondary metabolites, natural compounds with an antioxidant as well as health-promoting action are often found, of which the fruit of the olive tree it contains some very characteristic ones. Among the secondary metabolites of the olive fruit, for which important antioxidant and health-promoting activities have been found, we mention not only the more common tocopherols and carotenes but also the more peculiar biophenols. These secondary metabolites initially present in the fruit of the olive pass, after the extraction process, to the extra virgin olive oil and within the group of characteristic biophenols there are numerous derivatives of oleuropein such as, for example, the well-known oleocanthal.
In the scientific literature there are numerous researches that have focused attention on effects of organic extra virgin olive oil on human health. One of the first studies conducted with the aim of comparing the qualitative characteristics of conventional and organic oils was published by some Spanish researchers in the distant 1999. The authors analyzed the characteristics of organic and conventional oils obtained from olive trees grown in the same field but applying different cultivation systems: natural fertilizers and natural substances for the "model plot" cultivated with organic farming methods and synthetic fertilizers on the contrary. and chemical pesticides for the conventional system. To defend the olive trees from adversity, the researchers had applied numerous natural tools in the "biological model": against the parasite “Prays” a treatment with the organism was used Bacillus thuringiensis; against the fly (Bactrocera oleae) natural pyrethrins were used; similarly the Bordeaux mixture was applied as an additional defense system and finally Opius concolor szpl e Chrysopa carnea steph have been released as beneficial insects predatory of the fly and Prays respectively. This well-structured and well-developed research has shown that the oils obtained from the organic farming model were significantly better in terms of quality compared to conventional ones.
The qualitative difference was evaluated at different stages of olive ripening. Organic oils always showed a significantly lower acidity compared to conventional products, but above all it is interesting to consider the significance of the difference in oxidative stability, i.e. the measurement which highlights the lower oxidizability for the more resistant oils. The organic oils they always showed a greater oxidative stability, an indication of both greater shelf life over time and better performance in high temperature cooking processes. In fact, it is evident from the numerous correlation studies, that these differences of stability are attributable to one greater presence of biophenolic antioxidant compounds. The latter evidence is confirmed by the sensory characteristics evaluated by the researchers: the organic oils were significantly characterized by a more green fruity as well as from bitter e more intense spicy compared to the corresponding conventional oils.
A more recent publication of the 2014 is related to a study conducted by Italian researchers who in an area of central Italy compared the characteristics of the oils obtained through the organic farming system with those obtained from conventional farming applied to two varieties of olives which are very common on the Italian peninsula: Leccino and Frantoio. The results of the research showed analogy with the previous one conducted years earlier by the Spanish researchers. In fact, Italian research has shown that the oils obtained from the cultivation of olive trees with the regime of organic farming they were characterized by a greater and significant content of antioxidant compounds biophenolics and sensory characteristics associated with the latter or were more bitter and more spicy.
As it is now known to professionals, but also to the most attentive consumers, the sensory characteristics of extra virgin olive oils and in particular the olfactory and gustatory characteristics are determined by the presence of specific compounds present in the oil in small quantities. THE volatile compounds which are mainly formed during the phases of extraction of the oils from the olives are responsible for olfactory characteristics. Instead, i biophenolic compounds whose content depends primarily on the characteristics of the olives such as variety, harvest time (ripening of the fruit), cultivation practices as well as the transformation process are responsible of the sensory characteristics related to the notes bitter and spicy. An oil richer in biophenolic compounds will be more bitter and spicier. It is no coincidence that some US researchers, investigating the spicier biophenol of extra virgin olive oil, or oleocanthal, have identified a functional analogy with ibuprofen. Oleocanthal is the name of the natural antioxidant compound present in extra virgin olive oil which is one of the main culprits for the spicy scent and is a natural anti-inflammatory.
In summary, to provide a second answer regarding the meaning of organic oil, we can state that scientific research suggests that theorganic extra virgin olive oil ha beneficial effects on health thanks to his higher content of biophenolic compounds and antioxidants.
Bibliography
Gutiérrez, F., Arnaud, T., Albi, MA (1999). Influence of ecological cultivation on virgin olive oil quality. JAOCS, Journal of the American Oil Chemists' Society 76 (5), pp. 617-621.
Rosati, A., Cafiero, C., Paoletti, A., Alfei, B., Caporali, S., Casciani, L., Valentini, M. (2014). Effect of agronomic practices on carpology, fruit and oil composition, and oil sensory properties, in olives (Olea europaea L.). Food Chemistry 159, pp. 236-243.
Beauchamp, GK, Keast, RSJ, Morel, D., Lin, J., Pika, J, Han, Q., Lee, C.-H., Smith, AB, Breslin, PAS (2005). Ibuprofen-like activity in extra virgin olive oil. Nature, 437(7055), pp. 45–46
