Effect of extraction systems and cultivar on the quality of virgin olive oils

Abstract

This research was carried out to compare the effects of two industrial scale processes (super press and triple phase systems) and a traditional Tunisian family-sized operation with laboratory milling for two varieties of olives: Chemlali and Chemchali. Analyses of the effect of the extraction system, on the oils' characteristics, revealed statistically significant differences in some parameters, mainly in antioxidant compounds (P < 0.05). Major fatty acids presented significant differences (P < 0.05) with respect to the cultivar kind (55.93% vs. 72.21%). Oxidative stability of Chemchali was nearly two times higher than Chemlali (94.58 vs. 50.37 day kg )1 ). Results appear to confirm the general consensus that Chemchali oils are of much higher quality compared with the tolerable quality of Chemlali. The traditional method is a valid form of producing high quality oil with very high stability (48.87 and 109.07 day kg )1 for Chemlali and Chemchali oil, respectively). However, industrial mills showed that triple-phase scale could cause considerable loss in polyphenols. Finally, olive oil quality is mainly dependant on the quality of the olives and on the extraction method.

Influence of Extraction Techniques on Physicalchemical Characteristics and Volatile Compounds of Extra Virgin Olive Oil

“…1 . The range of polyphenol content for Ortice cultivar is higher than that obtained with any extraction system 22,27,40 , but in agreement with the Database of Italian monovarietal oils 41 .…”

“…Inside the decanter s rotating conical drum is a coil rotating a few rpm slower, pushing the solid materials out of the system. The separated oil and vegetation water are then rerun through a vertical centrifuge, working around 6000 rpm and separating the small quantity of vegetation water still contained in oil and vice versa 27 .…”

“…In addition, the characteristics and operating parameters of the systems have been shown to affect both extraction yield and the quality of the extracted oil 23 26 . In the last 30 years, centrifugation has taken over and has become the most widespread extraction technique, inasmuch entails a reduction in the manufacturing costs and, at the same time, allows high production and shortens the storage time of olives before processing, with beneficial effects on the final product 27 . Moreover a particular centrifugation typology, considered also in our study, a patented device that does not need any vertical centrifugal separator at the end of the process 28 31 is described as the one that is able to better preserve the chemical-nutritional characteristics of extra virgin olive oil.…”

Effect of Processing Systems on the Quality and Stability of Chemlali Olive Oils

“…These results are in agreement with those obtained by Gimeno et al 10 . However, Issaoui et al 11 have found that there are differences in fatty acids composition that are significantly remarkable.…”

“…However, the disadvantages of this method are the large amount of liquid wastes and the addition of lukewarm water to dilute the olive paste. This addition decreases the levels of phenolic compounds in the oil owing to their high solubility in the aqueous phase 11 . The liquid wastes from the three-phase centrifugation in some countries are reused instead of fresh water.…”