Virgin olive oil composition and its effect on human health

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1 237 Virgin olive oil composition and its effect on human health Artwork provided by A.K. Kiritsakis This article is by Apostolos K. Kiritsakis, a professor at the School of Food Technology and Nutrition, at Highest Technological Educational Institution of Thessaloniki, Sindos Thessaloniki, Greece, and Konstantinos A. Kiritsakis, a graduate of Aristotle University of Thessaloniki, Greece, where he majored in food science. Olive oil, a natural monounsaturated oil, contains several unsaponifiable constituents, such as phenols, tocopherols, sterols, pigments, squalene, and aroma and flavor compounds that may play a significant role in human health. Due to its monounsaturation and to the presence of natural antioxidants, olive oil is resistant to oxidation. Furthermore, the presence of phenols seems to prevent lipid oxidation within the body, regulating the formation of free radicals, which interfere with DNA and cause cell destruction. The aroma and flavor compounds of olive oil, as well as the pigments chlorophyll and pheophytin, facilitate stomach secretion and as a result the absorption of natural antioxidants and other useful constituents of olive oil by the body. Studies have suggested that the high consumption of olive oil in Mediterranean countries is related to low rates of cardiovascular heart disease (CHD) and of breast cancer, and to long life expectancy. M AIN OLIVE OIL CONSTITUENTS Olive oil contains triacylglycerols composed mainly of the monounsaturated oleic acid. The oleic acid content ranges from 55 to 83% (Table 1) depending on the area where the olive trees are grown and the degree of olive fruit maturation. Oleic acid is a fatty acid that is oxidized to a lower degree than polyunsaturated fatty acids, such as linoleic and linolenic. In addition, oleic acid reduces serum low-density lipoprotein (LDL)- cholesterol, which is involved in the formation of atherosclerotic plaque, and Table 1 Fatty acid composition of olive oil Acid Content (%) Oleic Palmitic Linoleic Stearic Palmitoleic Linolenic < 0.9 Myristic < 0.1 Arachidic < 0.6 Behenic < 0.2 Lignoceric < 0.2 Heptadecanoic < 0.3 Heptadecenoic < 0.3 Eicosenoic (gadoleic) < 0.4 Sources: International Olive Oil Council (IOOC) (1997) increases or maintains the level of the high-density lipoprotein (HDL)-cholesterol. The latter is removed from arterial cells, thus avoiding the development of atherosclerosis. Olive oil also contains small quantities of free fatty acids, mono- and diacylglycerols, hydrocarbons, tocopherols, sterols, phenols, pigments, aroma compounds, unidentified resinous components, and other minor constituents. The presence of mono- and diacylglycerols is related in part to incomplete oil biosynthesis in the olive fruit but is mainly attributable to enzymatic hydrolysis of the oil. When diacylglycerols are present, olive oil is of low quality. The unsaponifiable fraction constitutes only a small fraction ( %) of the total oil. However, its constituents may play a very important role in human health. The hydrocarbon squalene, which is metabolized in the body, is the major constituent (up to 40% by wt) of olive oil unsaponifiables (Figure 1). Olive oil contains the greatest concentration of squalene among vegetable oils, varying from from 2,500 9,250 µg/g, whereas other edible oils contain µg/g. Other hydrocarbons, such as polycyclic aromatics (phenanthrene, pyrene, fluor-

2 238 Table 2 Volatile constituents identified in virgin olive oil Aliphatic hydrocarbons Hexane Octane Nonane Isopentane 2-Methylpentane Aromatic hydrocarbons Ethylbenzene Naphthalene Ethylnaphthalene Dimethylnaphthalene Acenaphthene Alcohols Methanol Ethanol Isopropanol Isobutanol 3-Methylbutanol 2-Methylbutanol Pentanol Hexanol Heptanol Octanol Nonanol trans-2-hexenol cis-3-hexenol 2-Phenylethanol Aldehydes Acetaldehyde Butanal 2-Methylbutanal 3-Methylbutanal Propanal Pentanal Hexanal Heptanal Octanal Nonanal trans-2-pentenal cis-3-hexenal trans-2-hexenal trans-2-heptenal trans-2-octenal trans-2-nonenal trans-2-decenal trans-2-undecenal 2,4-Hexadienal 2,4-Heptadienal (two isomers) 2,4-Nonadienal 2,4-Decadienal (two isomers) Benzaldehyde Ketones Acetone 3-Methylbutan-2-one Pentan-3-one Hexan-2-one Octan-2-one Nonan-2-one 2-Methyl-2-hepten-6-one Acetophenone Ethers Methoxybenzene Dimethoxybenzene Furan derivatives 2-Propylfuran (two isomers) 2-Pentyl-3-methylfuran Thiophene derivatives 2-Isopropenylthiophene 2-Ethyl-5-hexylthiophene 2,5-Diethylthiophene 2-Ethyl-5-hexyldihydrothiophene Esters Methyl pentanoate Methyl hexanoate Methyl octanoate Methylbutyl acetate Methylpropyl acetate 2-Methylpropyl-2-methylpropanoate Methyl salicylate Ethyl acetate Ethyl butanoate Ethyl benzoate Ethyl heptanoate Ethyl octanoate Ethyl nonanoate Ethyl decanoate Ethyl phenylacetate Ethyl cyclohexanoate Hexyl acetate cis-hexen-3-enyl acetate Octyl acetate Terpene alcohols 1,8-Cineole Linalol α-terpineol Sources: Fedeli (1977), Blekas and Guth (1995), Kiritsakis (1998) anthrene, 1,2-benzanthracene, chrysene etc.), also are found in olive oil. Olive oil contains the tocopherols α, β-, γ-, and δ- (α-tocopherol accounts for almost 88%), which act as natural antioxidants in the body. Olive oil contains α- tocopherol in the range of ppm. The tocopherol content of olive oil depends on several factors such as olive fruit maturation, fruit storage before processing, and the conditions encountered in the olive oil mill. The high temperatures of the water used in the olive oil mill destroy tocopherols. The ratio of vitamin E (α-tocopherol) to polyunsaturated fatty acids, which in olive oil is mainly linoleic acid, is ideal. Thus, the potential for oxidation and the formation of free radicals, which causes cell destruction, are eliminated. Olive oil also contains sterols, which show antioxidant activity. The main sterols found in olive oil are β- sitosterol, 5-avenasterol and campesterol. Stigmasterol, cholesterol, 24-methylene-cholesterol, 7- campesterol, 5,23-stigmastadienol, sitostanol, 5,24- stigmastadienol, 7-stigmastenol, and 7-avenasterol are also present in olive oil but in smaller quantities. The oxidative stability of virgin olive oils shows a good correlation with their concentrations of total sterols, β- sitosterol, and 5-avenasterol. Olive fruit contains simple and complex phenolic compounds. Phenolic compounds are polar components that contain one or more aromatic hydroxylated rings. These water-soluble compounds, which are lost in the wastewater in an olive oil mill, may give a bitter taste to olive oil. However, a significant part of these compounds passes into the oil during olive fruit processing to increase its oxidative stability and considerably improve its flavor. Phenolic compounds are present in significant amounts (<350 ppm) in virgin olive oils, but to a very low degree in refined olive oil because they are destroyed during the refining process. Generally, phenolic compounds are of fundamental importance to the quality and nutritional properties of virgin olive oil. The main phenols originate from the degradation of the glucosides oleuropein and ligstroside. The subsequent hydrolysis of these compounds leads to the formation of simple phenols such as 3,4-dihydroxyphenyl ethanol (hydroxytyrosol) and p-hydroxyphenyl ethanol (tyrosol). Figure 2 shows the structures of various phenols and their degradation into tyrosol and hydroxytyrosol in olives and in extra virgin olive oil. Hydroxytyrosol, tyrosol, and some phenolic acids are found in olive oil. The total phenol content of olive oil and the specific composition of the phenols depend on

3 239 the altitude where the olive trees are grown, on the harvesting time, and on the processing conditions encountered in the olive oil mill (Figure 3). The use of high amounts of water eliminates the presence of phenols in the oil. Hydroxytyrosol is the most potent antioxidant of olive oil and olive oil mill waste water, and its presumed biological activities have stimulated research on its potential role in cardiovascular protection. The administration of hydroxytyrosol extract from olive oil mill wastewater has been found to be associated with an increase in plasma antioxidant capacity, protecting against the oxidation of LDL-cholesterol. Tyrosol, another phenolic antioxidant of olive oil, binds to human LDL in vitro, and phenolic compounds bound to LDL are likely to protect LDL from oxidation, thereby delaying atherosclerotic processes. Recent studies have shown that extra virgin olive oil, because of its greater content of phenols compared to refined olive oil, prevents LDL oxidation to a higher degree (Figure 4). The color of virgin oil is mainly related to the presence of chlorophyll and pheophytin. Carotenoids also make a contribution to the color of olive oil. The presence of these constituents in olive oil depends on several factors, such as cultivar, soil, climate, fruit maturation, and conditions encountered during olive fruit processing. Olive oil pigments such as chlorophyll and pheophytin protect the oil against oxidation in the dark, and carotenes protect it from photo-oxidation. Olive oil pigments, and especially aroma compounds, facilitate oil absorption (see below) by the human body. Aroma and flavor are distinctive features of olive oil compared to other edible oils, and they are generated by a number of volatile compounds (Table 2) present at extremely low concentrations. Their formation occurs in olive fruit via a series of enzymatic reactions (Figure 5). During processing of olive fruits in the olive oil mill, the malaxation (mixing) time of the olive paste and especially the temperature of the water negatively affect the intensity of aroma attributes of the oil. These factors reduce the amount of volatile compounds displaying pleasant sensations and increase those reducing the oil s attractive perceptions. Temperatures around 30 o C and malaxation periods ranging from 30 to 35 minutes are recommended conditions for retaining the aroma constituents of the oil. Generally, the volatile profile of virgin olive oil is influenced by olive cultivar, fruit maturity, cultivation practices, and processing conditions in the olive oil mill. Olive oil is well assimilated by the human body. In particular, the volatile aroma components of the oil, as Figure 1. Relative content of unsaponifiables in olive oil Figure 2. Structures of olive oil phenols, degradation pathway to tyrosol and hydroxytyrosol (Vissers et al., 2001) Figure 3. Effect of altitude and harvest date on phenol content of olive oil. D, December; F, February; A, April.

4 240 Figure 4. Effect of olive oil on low-density lipoprotein oxidation in vitro (EV = extra virgin; CAE = cafeic acid equivalents) (Olias et al., 1993) Figure 6. Diagram showing where free radicals may attack in cell membrane, nucleus (Viola, 1997) Figure 5. Formation of compounds from 13-hydroperoxides of linoleic acid by enzymatic process well as the pigments chlorophyll and pheophytin and other microcomponents, facilitate the absorption of oil in the human body. When the aroma and the taste of food are good, then gastric fluid secretions in the stomach are facilitated. Increase in the digestive activity promotes assimilation. The high assimilation of olive oil in the human body facilitates the absorption of phenols and other antioxidants present in the oil, preventing lipid tissue oxidation. cholesterol and HDL, and a reduction of LDL-cholesterol. The accumulation of free radicals, as a result of oxidation in the body, causes serious problems in human health. More specifically, free radicals destroy the polyunsaturated fatty acids of the membranes and the integrity of DNA (Figure 6). These phenomena facilitate the aging process, cause damage to the liver, and even induce cancer formation. The body is protected from free radicals by radical scavengers such as tocopherols and phenols. The latter, which are present in significantly greater amounts in virgin olive oil than any other type of oil, prevent the destruction of living cells. Greeks and Italians, who consume large quantities of virgin olive oil, have an intake of almost 25 grams of phenols per day, which is a significant amount for preventing oxidation of lipids in the tissues. It is interesting to note that the lower incidence of CHD in Mediterranean countries has been attributed to a diet rich in olive oil, fruits, vegetables, legumes, and grains. The presence of natural phenolic antioxidants in these foods may prevent LDL-cholesterol oxidation. In conclusion, oleic acid and mainly the unsaponifiable constituents of olive oil, such as phenols, tocopherols, pigments, squalene, sterols, aroma, and other compounds, acting individually or exhibiting synergistic activity, are probable contributors to good health. R OLE OF OLIVE OIL IN HUMAN HEALTH Recent studies have shown that LDL-cholesterol oxidation promotes atherosclerotic plaque formation. Diets rich in olive oil, on the other hand, showed a stable ratio between total B IBLIOGRAPHY Blekas, G., and H. Guth, Generation, Analysis and Process Influence, in Food Flavors, edited by G. Charalambous, Elsevier Science B.V., Amsterdam, The Netherlands, 1995, pp

241 Cert A., W. Moreda, and M.C. Perez-Camino, Chromatographic Analysis of Minor Constituents in Vegetable Oils, J. Chromatog. A 881:131 148 (2000). Covas, M.I., M. Fito, R.M. Lamuela-Raventos, N.

5 241 Cert A., W. Moreda, and M.C. Perez-Camino, Chromatographic Analysis of Minor Constituents in Vegetable Oils, J. Chromatog. A 881: (2000). Covas, M.I., M. Fito, R.M. Lamuela-Raventos, N. Sebastia, C. De La Torre-Boronat, and J. Marrugat, Virgin Olive Oil Phenolic Compounds: Binding to Human Low Density Lipoprotein (LDL) and Effect on LDL Oxidation, Int. J. Clin. Pharm. Press 3/4:49 54 (2000). Fedeli, E., Lipids of Olive, Prog. Chem. Fats Other Lipids 15:57 74 (1977). Fito, M., M.I. Covas, R.M. Lamuela-Raventos, J. Vila, J. Torrents, C. De La Torre, and J. Marrugat, Protective Effect of Olive Oil and Its Phenolic Compounds Against Low-Density Lipoprotein Oxidation, Lipids 35: (2000). García, A., M. Brenes, F. Martínez, J. Alba, P. García, and A. Garrido, High-Performance Liquid Chromatography Evaluation of Phenols in Virgin Olive Oil During Extraction at Laboratory and Industrial Scale, J. Am. Oil Chem. Soc. 78: (2001). Visioli, F., D. Caruso, E. Plasmati, R. Patelli, N. Mulinacci, A. Romani, G. Galli, and C. Galli, Hydroxytyrosol, as a Component of Olive Mill Waste Water, Is Dose- Dependently Absorbed and Increases the Antioxidant Capacity of Rat Plasma, Free Rad. Res. 34: (2001). Vissers, M.N., P.L. Zock., S.A. Wiseman, S. Meyboom, and M.B. Katan, Effect of Phenol-rich Extra Virgin Olive Oil on Markers of Oxidation in Healthy Volunteers, Eur. J. Clin. Nutr. 55: (2001). Readers may contact the senior author at the School of Food Technology and Nutrition, Department of Food Technology, Technological Education Institition (TEI), Sindos Thessaloniki, Greece (phone: or ; fax: or ; kiritsak@food.teithe.gr). The 2002 Annual Meeting & Expo in Montréal, Canada, is scheduled to have two sessions on the topic of olive oil. Kiritsakis, A., Olive Oil Second Edition, From the Tree to the Table, Food and Nutrition Press Inc. Trumbull, CT, Kiritsakis, A., Flavor Components of Olive Oil. A Review, J. Am. Oil Chem. Soc. 75: (1998). Olias, J., A.G. Perez, J.J. Rios, and J.C. Sanz, Aroma of Virgin Olive Oil: Biogenesis of the Green Odor Notes, J. Agric. Food Chem. 41: (1993). Trade Standards Applying to Olive Oil and Olive Pomace Oil, COI/T.15/NC No. 2, Rev. 6, International Olive Oil Council (IOOC), Madrid, Spain, Trichopoulou, A., and E. Vasilopoulou, Mediterranean Diet and Longevity, Br. J. Nutri. 84 (Suppl. 2):S205 S209 (2000). Uccela, N., Olive Biophenols: Biomolecular Characterization, Distribution and Phytoalexin Histochemical Localization in the Drupes, Trends Food Sci. Technol. 11: (2001). Viola, P., Olive Oil and Health, International Olive Oil Council, Madrid, Spain, 1997.

ANNEX. to the COMMISSION DELEGATED REGULATION

ANNEX. to the COMMISSION DELEGATED REGULATION EUROPEAN COMMISSION Brussels, XXX [ ](2016) XXX draft ANNEX 1 ANNEX to the COMMISSION DELEGATED REGULATION amending Regulation (EEC) No 2568/91 on the characteristics of olive oil and oliveresidue oil