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technological innovation in the improvement of the mechanical extraction process in order to achieve higherquality VOOs.4) Servili M., Esposto S., Taticchi A., Urbani S., Selvaggini R., Montedoro GF. (2006) Technologicalstrategies in the mechanical extraction process to preserve natural antioxidants of virginolive oil. 4 th Euro Fed Lipid Congress. 1-4 October 2006, University of Madrid (UCIM),Spain. Pag. 22.Secoiridoids are the prevalent classes of hydrophilic phenols in Virgin Olive Oil (VOO), that also contains phenolicalcohols, phenolic acids, flavonoids and lignans. The biological activity of secoiridois and lignans has beendemonstrated towards human diseases prevention and improvement of the oil shelf life. They include aglyconderivatives of oleuropein, demethyloleuropein and ligstroside that are released into the oily phase during crushingfrom their glucoside precursors present in olive fruit. Secoiridoids concentration in VOO is largely affectedby the enzymatic degradation activity of polyphenoloxydases (PPO) and peroxidases (POD) during the mechanicalextraction process.The possibility to increase the secoiridoids concentration in VOO has been studied during processing by controllingthe enzymatic activities of PPO and POD. The oxidation control may be realized with different approachessuch as the reduction of the oxygen concentration in the olive pastes during malaxation using an inert gas (N 2 )and/or the olive stone removal, where most of the POD is concentrated, before crushing. HPLC diode-arrayanalysis on the phenolic fraction of the obtained oil samples showed that the secoiridoid concentration in virginolive oil can be preserved from enzymatic oxidation during mechanical extraction process by reducing oxygenconcentration in the pastes or by the extraction of virgin olive oil from stoned olive pastes.5) Servili M., Taticchi A., Esposto S., Urbani S., Selvaggini R., Montedoro G.F. (2007) Applicationof Head-Space sensors in the malaxation management to improve in virgin olive oil quality.Oils, Fats and Lipids from Science to Application 5 th Euro Fed Lipid Congress GothenburgSweden 16-19 september 2007 p 16.Sensory and healthy properties of Virgin Olive Oil (VOO) are highly related to its volatile and phenolic composition.The occurrence of these substances in the oil depends from various endogenous oxidoreductase activitiesof olive fruit that are activated during processing, such as PPO and POD, which promote hydrophylic phenolsoxidation during malaxation, and LPO that catalyzes the genesis of C5 and C6 saturated and unsaturated aldehydes,alcohols, and esters responsible for the desirable sensory notes of VOO. The malaxation process parameters,in terms of temperature, length and oxygen concentration, affect the all the mentioned enzymatic activitydetermining strong modifications in the VOO quality. The technological approach to the control of the enzymaticactivities has been attempted through the optimization of the malaxation temperature and the time of exposureof olive pastes to the air contact, using N 2 in order to reduce the oxygen concentration, according to thephenolic and aroma profile of VOO. Recently the CO 2 emission from malaxed pastes has been described as aninteresting mean to reduce hydrophilic phenols oxidation.In this work the monitoring of CO 2 and O 2 concentration modifications during olive paste malaxation in industrialscale has been carried out on several olive cultivars and in different atmosphere composition conditions. Theevolution of the volatile compounds has been followed by electronic nose application (MOS) directly in the malaxerchamber. Data acquired during malaxation were successively studied in relation to the composition of theolive pastes and oils obtained in terms of phenolic and volatile concentration, analysed by HPLC and HS-SPME-GC-MS, respectively. During the olive paste’s malaxation in oxygen containing atmosphere, the oxygen concentrationreduction was always observed; so far, the oxygen availability in the malaxer chamber seemed to influencevery slightly the extent of the CO 2 emission from the olive pastes. Furthermore, according to the increase ofthe oxygen level the phenolic concentration in the VOOs significantly decreased, showing that it affects the PPOand the POD activity; for this reason the oxygen depletion attainable in the sealed malaxing machines, due to theprogressive increase of the CO 2 , may represent a useful mean to preserve the phenolic compounds from theoxidative degradation. Results indicate that the monitoring of the chamber atmosphere during malaxation may bea very helpful technological innovation in the improvement of the mechanical extraction process in order toachieve higher quality VOOs.SISTAL - SOCIETA’ ITALIANA DI SCIENZE E TECNOLOGIE ALIMENTARIDipartimento di Scienze e Tecnologie Agroalimentari, Università degli Studi della TusciaVia San Camillo de Lellis, 01100 ViterboTel.: 0761- 35 74 94/7 , Fax: 0761- 35 74 98, e-mail: mmoresi@unitus.it356