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Food Processing And Health

Thin residues

Finished oil

Thin residues

Pomace (-50% humidity)

Mill

Pump

Mixer

Olive paste

Decanter

Decanter

Water

Pomace (-50% humidity)

Filter

Centrifuge

Residual water

Pomace

Pomace

Dryer

Finished oil

Exhausted wastewater (alpechín)

Finished oil

Dryer

Pomace (<50% humidity)

Pomace (<50% humidity)

Figure 2. Scheme of three- and two-phase centrifugal processes for olive oil extraction.

such as fatty acids, triacylglycerols, squalene, sterols, tocopherols, alkanes, aliphatic alcohols, waxes, erythrodiol and uvaol, and stigmastadiene.

Fatty Acids. The International Olive Oil Council (IOOC) has established the normal ranges for the different fatty acids in olive oil. Gas chromatography has been used to measure these fatty acids, and this is the most common analytical technique for the assessment of the quality of olive oil (64). Among the different types of fatty acids, special attention should be paid to trans fatty acids. Trans fatty acids are not present in crude olive oils; however, they are formed during bleaching and deodorization. In addition to gas liquid chromatography, other techniques, such as infrared and nuclear magnetic resonance spectroscopy, high-performance liquid chromatography (HPLC), and supercritical fluid chromatography, have been applied to the detection of trans fatty acids (64).

Triacylglycerols. The triacylglycerol profile can provide information about the origin of the olive oil and its adulteration with other oils. Several methods are available for the determination of triacylglycerols, including high-temperature capillary gas chromatography and reversed-phase HPLC (65,66).

Squalene. Squalene content is very high in olive oil. Adulteration of olive oil decreases its content. Moreover, the refinement of olive oil induces squalene isomerization. Therefore, adulteration of olive oil with refined oil can be detected by the presence of these isomers using gas liquid chromatography (67) or HPLC (68).

Sterols. Large quantities of stigmasterol suggest adulteration with soybean oil. The ratio of beta-sitosterol (high in virgin olive oil) to campesterol + stigmasterol has been used for the detection of adulteration with seed oils.

Table 5. Price Ranges for Different Edible Vegetable Oils

Oil

Price ($/kg)

Extra virgin olive oil

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