Residue olive-oil

EC Council (1991) Characteristics of Olive Oil and Olive Residue Oil and on the Relevant Methods of Analysis, Regulation 2568/91. 

Crude olive-residue oil is the oil obtained by treating olive pomace with solvents any oils obtained by re-esterification processes or through mixtures with oils of other kinds are totally excluded. The characteristics of the oil correspond to those fixed for this category in Annex I to EC regulation 2568/91 and amendments. 

These two pentacyclic triterpenes are found concentrated in the skin of the olive fruit. Extraction processes employing only physical means results in an olive oil with a low concentration of the two triterpenic diols, their highest limit having been fixed at 4.5% of the overall sterol concentration for oils 1-6. Olive-residue oils obtained by organic solvent extraction of pomace contain large amounts of uvaol and erythrodiol, their official limits respectively being >4.5 and >12% for olive-residue and olive-residue refined oil (see Table 2.2). 

Beside olive-residue oil the two triterpene diols can be found in grapeseed oil, a finding that could be an element to account for in the event of suspected sophistication. 

Long chain aliphatic esters, commonly called waxes, are components of epicuticular waxes of the olive fruits (Bianchi and Vlahov, 1994). Whilst in virgin olive oils the wax concentration is negligible, in olive-residue oil the wax content is considerable. Thus, the presence of long chain esters in olive oil is evidence of the presence of solvent extracted olive oil, also commonly called sansa olive oil. The detection and quantification of waxes in olive oil is an official method. As shown in Table 2.2, virgin olive oils fit for consumption must contain less than 250 mg/kg of waxes the limits are 350 mg/kg for categories 4,5 and 6, whilst for olive-residue oil the amount is expected to be over 350 mg/kg. 

EC (European Community) (1991) EC Council Regulation 2568/91 Characteristics of olive oil and olive residue oil and on the relevant methods of analysis. 

In the pressure system, the paste is pressed to release an oily must (oil and water from the olives). The liquid separates from the solid phase through drainage. A cake (pomace) is formed between the mats and this is dried and used for the production of olive residue oil. Oil and water are further separated by centrifugation (see Figure 9.1). 

The raw oil extracted from the husks is dark green, with high acidity and a bad flavour. It has to be neutralised, bleached, and deodorised before it is edible. Due to the solvent extraction, olive-residue oil contains some minor constituents at higher levels than those found in olive oils (waxes, sterols, erythrodiol and uvaol). This is the reason for designating pomace oil as a distinct product. 

Olive pomace oil. This oil, which is a mixture of refined olive residue oil and virgin olive oil (except lampante), has a maximum acidity, in terms of oleic acid, of 1.5 g/100 g. 

It is clear from the tables that olive oils, and especially virgin olive oil, are strictly regulated. This is related to their high prices, and to the fact that natural olive oil has always been the subject of fraud by mixing less expensive vegetable oils and olive residue oil. 

---