The evolution in the olive oil extraction: performance, yield, and quality by comparing traditional and modern systems.
Extra-virgin olive oil has an unmistakable fruity flavor that develops different nuances and aftertastes, depending on the olives' varieties and the production area. Its high antioxidant content slows the oxidation of fatty acids and prevents the development of unpleasant flavors. High levels in phenolic compounds, tocopherols, carotenoids and monounsaturated fats give extra.virgin olive oil a greater stability with respect to other edible oils. As well as having a delicious taste, extra-virgin olive oil has health benefits: polyphenolic compounds give it anti-tumoral properties and act against age-related neurodegenerative processes.
To ensure that the product mantains its features as long as possible, you need to use an extraction technology which keeps the chemical and physical features unchanged and avoids the oxidation of the volatile compounds of extra-virgin olive oil.
Scientific research and technological progress in extraction systems demonstrate how much this topic is addressed at all levels: from the quality oriented consumer to the producer and to the research community. One of the most recent and interesting research projects on this topic is: "Effect of extraction techniques on the chemical-physical characteristics and volatile compounds of extra virgin olive oil," conducted by the Institute of Food Sciences of the National Research Council (CNR) in Avellino, and published in the Journal of Oleo Science (JOS), a monthly scientific journal published by the Japan Oil Chemists' Society. The project, which involved Maria Grazia Valape, Fausta De Cunzo, Francesco Siano, Marina Paolucci, Costantina Barbarisi, and Giancarlo Cammarota, highlighted how over the past 30 years, the continuous-cycle process has become the most widespread extraction system. The main advantage is the reduction of production costs and the increase in productivity, with a reduction in olive storage times, to the benefit of less oxidation, which begins already in the drupe, if its storage is prolonged over time.
The study focused on a specific type of centrifugation that, by eliminating the use of a final separator at the end of the process, has been shown to better preserve the chemical and nutritional features of extra virgin olive oil. It was observed how different extraction methods influence the chemical and physical features and volatile compounds, and how this correlates with the quality of extra virgin olive oil from the cultivar Ortice. The research compared: the traditional system, using hydraulic presses and vertical-axis separators; the "Pieralisi" continuous-cycle system, with a vertical-axis centrifugal separator at the end of the process; and the "Officine Meccaniche Toscane" continuous-cycle system with the Super-Decanter Euro X15 D.E., which does not require a vertical-axis separator at the end of the process.
The two continuos system extraction methods showed better free acidity values. In fact, in the traditional press system, both the oil and the vegetation water remain in contact until the separation by decantation. This procedure could favor the hydrolysis of triglycerides, resulting in an increase in free fatty acid levels. The two centrifugation systems also produced lower peroxide values, a benefit due to reduced oxidative stress. Total polyphenol content also followed the same trend. in particular it was predominantly seen in the extra virgin olive oil produced with the Super-Decanter Euro X15 D.E., which, overall, showed superior features when compared to the other two extraction technologies. Phenolic substances not only influence the stability of olive oil, but also contribute to its flavor and aroma, giving olive oil its typical spicy taste, a particularly appreciated feature by sensory analysis.
Even the yield in oil was the highest in the continuous cycle system with the Super-Decanter Euro X15 D.E.; in fact while with the traditional “Pieralisi” system, the percentage of oil extracted per weight of pressed olives was 17.2% and 18.6% in the continuous cycle “Pieralisi” system, the percentage of oil extracted through the continuous cycle system with the Super-Decanter Euro X15 D.E. stood at 19.8%; an interesting record, considering it was the the product which was enriched with superior organoleptic qualities. The volatile elements that enhance and emphasize the flavor of olive oil were found in significantly higher concentrations in the two centrifugation systems. Furthermore, scientific analyses conducted using the most modern technologies (electronic nose) have confirmed these results and highlighted how the gap is even greater if the comparison is made between the results obtained by extracting extra virgin olive oil with the traditional system and that produced using the continuous cycle plant with the Super-Decanter Euro X15 D.E.
