Technological Aspects of Olive Oil Production

Abstract

Additional information is available at the end of the chapter http://dx.doi.org/10.5772/52141 IntroductionVirgin olive oil (VOO) is obtained exclusively by mechanical extraction from the olive fruit and can be consumed crude without any further physical-chemical treatments of refining. Its sensory and health properties are intimately linked to its chemical characteristics, in particular to several minor components, which are strongly affected by the operative conditions of oil processing and can thus be considered as analytical markers of the quality of oil processing.VOO contains different classes of phenolic compounds, such as phenolic acids, phenolic alcohols, hydroxy-isochromans, flavonoids, secoiridoids and lignans. The phenolic acids together with phenyl-alcohols, hydroxy-isochromans and flavonoids are present in small amounts in VOO (Montedoro et al., 1992). Secoiridoids which, in combination with lignans, are the main hydrophilic phenols of VOO, include the dialdehydic form of decarboxymethyl elenolic acid linked to 3,4-DHPEA or p-HPEA (3,4-DHPEA-EDA or p-HPEA-EDA) an isomer of the oleuropein aglycon (3,4-DHPEA-EA) and the ligstroside aglycon (p-HPEA-EA). The main lignans found in VOO are (+)-1-acetoxypinoresinol and (+)-1-pinoresinol (Brenes et al., 2000;Owen et al., 2000). Both secoiridoids and lignans affect the quality of the sensory and health properties of VOO (Servili et al., 2004a), determining bitter, pungent sensations.Many compounds, mainly carbonyl compounds, alcohols, esters and hydrocarbons, have been found in the volatile fraction of VOO.The C6 and C5 compounds, especially C6 linear unsaturated and saturated aldehydes alcohols and esters represent the most important fraction of volatile compounds found in high quality VOOs.The C6 and C5 compounds, produced from polyunsaturated fatty acids by the enzymatic activities exerted by the lipoxygenase (LOX) pathway and their concentrations, depend on the level and the activity of each enzyme involved in this LOX pathway.Olive Germplasm -The Olive Cultivation, The pathway (Figure 1) begins with the production of 9-and 13-hydroperoxides of linoleic (LA) and linolenic (LnA) acids mediated by lipoxygenase (LOX). The subsequent cleavage of 13-hydroperoxides is catalysed by very specific hydroperoxide lyases (HPL) and leads to C6 aldehydes, of which the unsaturated aldehydes can isomerize from cis-3 to the more stable trans-2 form. The mediation of alcohol dehydrogenase (ADH) reduces C6 aldehydes to corresponding alcohols, which can produce esters due to the catalytic activity of alcohol acetyl transferases (AAT).Furthermore, an additional branch of the LOX pathway (Figure 1) is active when the substrate is LnA. LOX would catalyse the formation of stabilized 1,3-pentene radicals, which can either dimerize leading to C10 hydrocarbons (known as pentene dimers), or can react with a hydroxy radical, producing C5 alcohols. The latter can be enzymatically oxidated to corresponding C5 carbonyl compounds. These compounds are responsible for the most important s...

Chemical and Sensorial Characteristics of Olive Oil Produced from the Lebanese Olive Variety ‘Baladi’

“…In fact, it was demonstrated that the 2-phases decanter preserves more of the phenolic compounds in comparison to the 3-phases decanter where the added water causes large amounts of phenols to be eliminated with the olive mill waste water [42] (12,16). Moreover, the high amount of O 2 dissolved in the pastes during the process of press and sinolea systems due to contact with the air result in a loss of phenolic compounds due to the activation of endogenous enzymes, polyphenoloxidase and peroxidase, that oxidize the phenolic compounds and consequently reduce their concentration in the produced oil [14].…”

“…The selection of the processing systems could have a significant effect on the oil oxidation due to the exposure to air oxygen in the press and sinolea systems and the use of mats in the press system. These inconveniences in the aforementioned systems were completely overcome in the modern systems including the 2-and 3-phases [14,15]. However, the 3-phases system might result in a decrease in the phenolic and aromatic compounds leading to lower oxidative stability due to the use of water that could dissolve the hydrophilic phenols that will be removed with the olive mill waste water [16].…”

Bioactive Compounds of Portuguese Virgin Olive Oils Discriminate Cultivar and Ripening Stage

“…Moreover, PPO seems to be the most relevant enzyme involved in phenolic oxidation in the milling process, while POD enzymes are mainly active in the malaxation process [17]. Therefore, the study of the influence of enzymatic activity on EVOO phenolic compounds profile changes is a current research challenge [18,19] since EVOO processing should include, as a main objective, the improvement of sensory and nutritional properties [20].…”

Improvement of Olive Oil Mechanical Extraction: New Technologies, Process Efficiency, and Extra Virgin Olive Oil Quality

“…Every crusher exerting different mechanical action to break down the olive tissue elicits several effects due to variation induced in the olive paste, in terms of temperature, granulometry of fragments, and exposure to atmospheric oxygen. These variations play a crucial role for endogenous enzymatic activities, affecting the final amount of the EVOO as well as its phenolic and volatile profile [27,28]. During this phase, in fact, the entire heritage of olive fruit endogenous enzymes (cellulases, hemicellulases, pectinases, polygalacturonases, lipase, β-glucosidase, polyphenoloxidase (PPO), peroxidase (POD), and lipoxygenase (LOX)) is activated and involved in the subsequent phases of the extraction process and the formation and transformation of phenolic and volatile compounds in EVOO [29,30].…”

“…Several studies carried out on the distribution of olive fruit endogenous enzymes in its constitutive parts (pulp, stone and seed) have shown that the seed is particularly rich in POD, while the phenolic compounds are most concentrated in the pulp [28,32]. In particular, in olive pastes and the produced oil the decrease of phenols is due to their oxidation catalyzed by the POD and the PPO together.…”