Caratteristiche di qualità e purezza degli oli d’oliva tra necessità di standardizzazione e variabilità naturale

Abstract. The improvement of the agricultural surface devoted to olive oil production, highlighted the strong influence of environmental conditions on the oil composition. In the meantime, the establishment of shared rules and standard of composition is mandatory to improve the worldwide trade of olive oils. Rules are established as Regulations that means mandatory rules (laws) within European Union, while outside UE, the Trade Standard by International Olive Council is the reference standard and at worldwide level, the Codex Alimentarius (established by FAO-OMS) is the World Trade Organization reference. The number of members of these three levels of international organization is different and an hard work is to find an acceptable compromised between countries quite different in terms of agricultural scenarios, environmental conditions, economic conditions and social organization. Standards relate to quality and purity characteristics, this classification is very important because while quality is a ranking parameter, purity is a cutting limit, this means that it is necessary to be very careful in admitting any exception in limits. The environmental differences between “traditional” geographic area of olive cultivation, that’s to say the Mediterranean basin and new areas of cultivation, mainly located in the South Hemisphere, in some cases strongly influence the oil composition, even in some characteristics whose limits are an important borderline to defend olive oil purity. Nevertheless, it’s an evidence that some authentic olive oils exist , that for some parameters exceed the established limits; the very hard issue is that these parameters are purity parameters and that the modification of a limit can open the door to faked oils. Linolenic acid content is an important parameter to highlight the admixtures with soybean oil, however, in some areas, the content of linolenic acid of authent ic ol ive oi ls exceeded the Codex Alimentarius limit; no agreement had been reached between main producing countries and new producing ones and nowadays the Codex Standard has no limit for this acid. Campesterol and Δ-7 Stigmastenol, too, are very useful to highlight the presence of several seed oils (the former) and Compositae oils (the latter), but some cultivar in some geographical areas where the presence of olive in the agricultural landscape is rather recent, present concentration of these sterols higher than the established limit (respectively 4,0% and 0,5%). In all these cases, the problem is not to expel from the market some production of genuine oils, in the meantime not leave any space to possible frauds. A solution had been to build some so called “decisional trees”, that are based on the principle of admit selected “anomalies” for one limit, in the meantime making the other more strictly, with the aim to avoid any possibility that the derogation of one limit can make faked oils not possible to b e distinguished by authentic ones. In this review, some of these cases will be described and critically discussed-.