the extra-virgin olive oil handbook (peri/the extra-virgin olive oil handbook) || the composition...

3The composition and nutritionalproperties of extra-virginolive oilManuela Mariotti1 and Claudio Peri21Department of Food, Environmental and Nutritional Sciences,University of Milan, Milan, Italy2University of Milan, Milan, Italy

Abstract

Chapter 3 gives basic information about the composition and nutritional propertiesof extra-virgin olive oil. As triglycerides make up 97 to 99% of extra-virgin oliveoil, the main chemical-physical characteristics of the oil depend on the compositionof the triglyceride moiety. However, the minor components give an invaluable con-tribution to sensory and health-promoting properties. It is mainly the presence ofthese components that differentiates extra-virgin olive oil from all other edible oils.

3.1 Triglycerides and fatty acids

Extra-virgin olive oil essentially includes two groups of chemical compounds:

• triglycerides: 97–99% wt

• minor components: 1–3% wt

Triglycerides mainly contain a monounsaturated fatty acid (oleic acid), a fairamount of polyunsaturated fatty acids (linoleic and α-linolenic) and a slight amountof saturated fatty acids (palmitic and stearic).

The minor components are a complex mixture of polar, nonpolar and amphiphilicsubstances: hydrocarbons, tocopherols, phenolic compounds, sterols, chlorophyll,carotenoids, terpenic acids, monoglycerides and diglycerides, free fatty acids, esters

The Extra-Virgin Olive Oil Handbook, First Edition. Edited by Claudio Peri.© 2014 John Wiley & Sons, Ltd. Published 2014 by John Wiley & Sons, Ltd.

22 CH03 THE COMPOSITION AND NUTRITIONAL PROPERTIES OF EXTRA-VIRGIN OLIVE OIL

and other volatiles. They contribute in a particular way to the sensory and health-promoting properties of extra-virgin olive oil.

Extra-virgin olive oil is separated from an aqueous medium so it still contains avery small, but essential amount of water. The water saturation threshold of extra-virgin olive oils is 300–400 mg per kg of oil, but they often have higher amounts,ranging from 300 to 1200 mg per kg of oil. Water is present in micro-droplets,less than one-tenth of a μm in diameter, impossible to separate by centrifugation.These microdroplets are associated with and stabilized by water-compatible, polaror amphiphilic substances of the minor components group.

Triglycerides belong to lipids, organic compounds that do not mix with water.They derive from the combination of three fatty acid molecules with one moleculeof glycerol. Glycerol is a short 3-carbon chain alcohol that serves as the frame towhich the three fatty acids can attach themselves with an ‘ester’ link. Fatty acidsconsist of chains 4 to 30 carbons long, with an acidic group at one end: it is thisgroup that binds to glycerol to make a glyceride. Natural fatty acids usually have aneven number of carbon atoms, as their synthesis in vivo is based on the assembly ofa variable number of acetyl-CoA, a 2-carbon molecule (O’Keefe 2008).

Figure 3.1 shows the structural formula of a fatty acid molecule (stearic acid). Itconsists of a long chain of 18 carbon atoms (C) with their four valence bonds. Twobonds create the basic connection of the chain, whereas the other two are saturatedby hydrogen atoms (H). At one end of the molecule there is a special group in whichthe carbon atom is linked to an oxygen atom (O) and to a hydroxyl group (OH). Theresulting COOH group is called the ‘acidic group’. At the other end, the carbon atomis linked to three hydrogen atoms forming a ‘methyl group’ (CH3).

The position of carbon atoms is usually identified by a number in the sequencethat starts from the acidic group and ends at the methyl group. The acidic groupis also called 𝛼 (alpha), the first letter of the Greek alphabet. The methyl group iscalled ω (omega), the last letter of the Greek alphabet.

Figure 3.2 represents the same molecule of Figure 3.1 but with a different graphi-cal convention, which is called the ‘skeletal’ formula. Carbon atoms are representedas black dots and hydrogen atoms, directly connected to the carbon atoms, are notindicated: each carbon atom is understood to be associated with enough hydrogenatoms to give the carbon atom four bonds. An even simpler representation is the

H H H H H H H H H H H H H H H H H

H

1

ω

α 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18

123456789101112131415161718

C

O

HO C C C C C C C C C C C C C C C C C H

H H H H H H H H H H H H H H H H

Figure 3.1 The structural formula of stearic acid.

3.1 TRIGLYCERIDES AND FATTY ACIDS 23

HO

O

Figure 3.2 The skeletal formula of stearic acid.

skeletal formula without the black dots. In this type of representation, it is impliedthat the carbon atoms are located at the corners and ends of the line segments.

Figure 3.3 shows how a molecule of glycerol combines with three molecules ofthe fatty acid (in this case stearic acid), giving a triglyceride molecule (in this case‘tristearin’) and three molecules of water.

In some fatty acids there are double bonds that derive from the elimination oftwo hydrogen atoms from two adjacent carbon atoms. Figure 3.4 shows a fatty acidderived from the stearic acid of Figure 3.2, by removing two hydrogen atoms fromcarbons 9 and 10, in the middle of the stearic molecule.

When double bonds are present, fatty acids are defined as ‘unsaturated’. Theunsaturated fatty acid represented in Figure 3.4 is the most important fatty acid ofolive oil and it is called ‘oleic acid’. It represents from 65 to 85% of all fatty acidsin olive oil.

HOOH +

OH3H2O

+

OH +

+

O

HO

O

HO

O

Figure 3.3 The triglyceride of stearic acid (tristearin).

O

HO− H

− H

Figure 3.4 The skeletal formula of oleic acid.


A very particular structural change that takes place in the presence of doublebonds is the bending of the fatty acid molecule, as shown in Figure 3.4.

The same fatty acid molecule can have several double bonds, as illustrated inFigure 3.5, in which four fatty acids are shown, all with 18 carbon atoms but with adifferent number of double bonds:

• stearic acid is a saturated fatty acid

• oleic acid is a monounsaturated fatty acid (acronym: MUFA)

• linoleic and α-linolenic acids are polyunsaturated fatty acids (acronym: PUFA)with two and three double bonds, respectively.

Double bonds are the most reactive position in a fatty acid molecule, especiallyif multiple double bonds are ‘conjugated’, which means ‘separated by a single CH2group’, which is the case with both linoleic and α-linolenic acid. Double bonds canreact with oxygen, thus spurring the oxidative spoilage of oil, or they can react withhydrogen, thus re-establishing a saturated condition.

If one double bond of a natural PUFA is saturated by chemical reaction with twohydrogen atoms, the resulting unsaturated fatty acid has a linear structure. Therefore,if a double bond of α-linolenic acid is transformed into linoleic acid by saturationof a double bond, the resulting linoleic acid has a linear structure. Similarly, if anatural linoleic acid is transformed into oleic acid by saturation of a double bond,the resulting molecule of oleic acid has a linear structure (Figure 3.6). In order todistinguish these forms, all natural forms of unsaturated (and bended) fatty acidsare identified with the prefix cis-, while all trans-formed, artificial, unsaturated fattyacids are identified with the prefix trans-.

However having an equal number of carbon atoms and the same number of doublebonds, trans-isomers have physical, chemical and biological characteristics that aremore similar to saturated fatty acids than to unsaturated fatty acids. Thus, trans-oleicacid is more similar to stearic acid than to cis-oleic acid.

Trans oils increase the risk of coronary heart disease by raising the level of LDLcholesterol and lowering the level of ‘good’ HDL cholesterol. The presence of trans-isomers in an extra-virgin olive oil is a clear sign of fraud and can be easily detectedthrough analytical methods that are common practice nowadays.

Due to the bending of the molecule, the ‘cis’ structure makes it more difficult forthese fatty acids to solidify into compact crystals, so at a given temperature unsatu-rated fatty acids are softer than saturated fatty acids. In other words, unsaturated fattyacids have lower melting points in comparison to saturated fatty acids. Table 3.1shows the four C18 fatty acids that are present in olive oil. Despite the fact thatthey have very similar molecular formulas and molar masses, they have differentdegrees of unsaturation and very different melting points. It is especially worth not-ing that stearic acid, a saturated fatty acid, has a melting point that is much higherthan the human body temperature (37 ∘C or 98.5 ∘F) and therefore is solid in thebody, whereas all the others are unsaturated fatty acids and have a melting pointlower than the body temperature and therefore are liquid in the body.

3.1 TRIGLYCERIDES AND FATTY ACIDS 25

HO

O

O

HO

HO

O

HO

O

(a)

(b)

(c)

(d)

Figure 3.5 The molecules of stearic acid (a), cis-oleic acid (b), cis-linoleic acid (c) and cis-α-linolenic acid (d).

Lipid oxidation is influenced by many factors: the presence and concentrationof oxygen, temperature, light and metal catalysts, but, most of all by the degree ofunsaturation and the presence of conjugated double bonds.

The velocity of oxidative reactions is more than proportional to the number ofdouble bonds as is evident by comparing the data in Table 3.2.


(a) (b)

HO

O

HO

O+ H+ H

Figure 3.6 Transformation from cis-linoleic (a) to trans-oleic acid (b) by hydrogenation.

Table 3.1 Melting points of C18 fatty acids.

Fatty acid Molecular formula Molar mass Melting point (∘C) Melting point (∘F)

Stearic acid C18H36O2 284 69 ∘C 156.2Oleic acid C18H34O2 282 13 ∘C 55.4Linoleic acid C18H32O2 280 −5 ∘C 23α-linolenic acid C18H30O2 278 −11 ∘C 12.2

Table 3.2 Relative velocity of oxidativedegradation.

Fatty acid The relative velocityof oxidative reactions

Stearic acid 0Oleic acid 1Linoleic acid 64α-linolenic acid 100

3.2 The nutritional role of olive oil triglyceridesand fatty acids

Oils and fats are the nutrients with the highest caloric value (9 kcal/g). Excess fat inthe diet results in accumulation of fat in the adipose tissue. This aspect of their nutri-tional contribution, however, is only partial. In fact, they have essential structuralroles in the skin, retina, nervous system (the brain is the body’s organ with the highestconcentration of lipids), and biological membranes. They are precursors of hor-mones and the vehicle for the absorption of liposoluble vitamins (Kritchevsky 2008).

It is interesting to observe the percentage distribution of fatty acids in olive oil inTable 3.3. Polyunsaturated fatty acids with 18 carbon atoms (linoleic and α-linolenicacid) play crucial roles in cell structure and function. They cannot be synthesized

3.2 THE NUTRITIONAL ROLE OF OLIVE OIL TRIGLYCERIDES AND FATTY ACIDS 27

Table 3.3 Distribution (%) of the fatty acids in the triglycerides inolive oils.

Fatty acids Percentage of totalfatty acids in olive oil

Monounsaturated fatty acids, oleic acid 65–83Saturated fatty acids 8–14Polyunsaturated (ω-6), linoleic acid 6–15Polyunsaturated (ω-3), α-linolenic acid 0.2–1.5

by the body and therefore must be part of our diet; hence, they are referred to as‘essential fatty acids’ (EFA). Nutritional studies have shown that they have preven-tive effects on cardiovascular diseases and nutritionists have identified them as ω-6(linoleic acid) and ω-3 (α-linolenic acid) depending on the position of the first dou-ble bond in their molecule, counting from the ω end (Figure 3.5). However, thesetwo important fatty acids are metabolically and functionally distinct, and often haveopposing physiological functions in cell membranes. In some cases it has been foundthat their high reactivity and susceptibility to oxidation may represent a health risk.Therefore, a suitable balance of these essential fatty acids is important for goodhealth and normal development. The ratio of monounsaturated to polyunsaturatedfatty acids, and in particular ω-6 to ω-3 fatty acids in olive oil, is close to the optimalratio recommended by nutritionists.

Most of all, the profile of olive oil fatty acids is characterized by the abundantpresence of oleic acid, whose characteristics and functions are summarized inthe box below.

Oleic acid

The data in Tables 3.1 and 3.2 demonstrate the unique characteristics of oleicacid compared to the other C18 fatty acids. Like the other unsaturated fatty acids,it has a melting point that is lower than the human body temperature, an essentialrequisite for preventing accumulation on artery walls (atherosclerosis) and forguaranteeing cell membrane fluidity. At the same time, it is much more resistantto oxidation than the other unsaturated fatty acids. This is essential for prevent-ing oxidative damage to critical cell structures.

These characteristics make oleic acid an almost ideal food component andparticularly useful in a number of biological functions, for example: (i) loweringblood pressure; (ii) ensuring the free flow of blood by reducing the clogging andhardening of arteries; (iii) lowering the levels of low-density lipoprotein (LDL)or bad cholesterol, while increasing the levels of high-density lipoprotein (HDL)or good cholesterol; (iv) strengthening cell-membrane integrity and helping torepair cells and damaged tissues; (v) fighting cancer, especially breast cancer;(vi) relieving symptoms of asthma and (vii) an ingredient in cosmetics, servingas a moisturizer, giving soft, supple skin.


3.3 Minor components and antioxidants in extra-virginolive oil

Free radicals are highly reactive oxygen species. They are formed in the body duringnormal metabolism and, at a higher rate, upon exposure to environmental factorssuch as cigarette smoke and pollutants, or as a consequence of disease and traumaticevents.

If free radicals are not intercepted and neutralized, they can cause serious damageto essential molecules such as DNA, protein, polyunsaturated fatty acids, especiallythose in the phospholipids of cell membranes, and lipoprotein. As a consequence,free radicals are closely associated with a range of disorders including cancer, arthri-tis, atherosclerosis, Alzheimer’s disease, diabetes, and aging. The body reacts tooxidative threat with internal defence mechanisms and with molecules derived fromfood (tocopherols, carotenoids, phenolic compounds).

Since the discovery of the health benefits of the Mediterranean diet (Willet et al.1995), interest in health protection from the daily consumption of extra-virgin oliveoil has increased enormously (Visioli et al. 2002; Covas et al. 2006; Cicerale et al.2009; Viola and Viola 2009; Pelucchi et al. 2010). This has also stimulated studies onthe relationship between the health-promoting properties and quality of extra-virginolive oils (Lavelli 2002; Servili and Montedoro 2002).

3.3.1 Hydrocarbons

Hydrocarbons are organic compounds that contain only carbon and hydrogen atoms.The major hydrocarbon in olive oil is squalene (skeletal formula in Figure 3.7); itsname derives from the fact that it is extracted from the liver oil of sharks (in Latinsqualus).

Squalene is a triterpene hydrocarbon that exerts antioxidant activity by reactingwith oxygen radicals and oxygen-reactive species, thus protecting the skin againstUV rays (something like a biological filter). Squalene has also been cited for itsimmune-stimulating properties and for its antineoplastic effects on colon, breast andprostate cancers.

Olive oil is a major source of squalene in the diet. Extra-virgin olive oil contains200–700 mg of squalene per 100 g of oil, while refined olive oil contains about 25%less. Other useful hydrocarbons are present in extra-virgin olive oil, as for exampleβ-carotene (pro-vitamin A), even if in small quantities.

Figure 3.7 Squalene.

3.3 MINOR COMPONENTS AND ANTIOXIDANTS IN EXTRA-VIRGIN OLIVE OIL 29

HO

O

Figure 3.8 α-tocopherol.

3.3.2 Tocopherols

Tocopherols are fat-soluble alcohols that function as vitamin E, especiallyα-tocopherol (spacial formula in Figure 3.8), a very important antioxidant.Alpha-tocopherol is uniquely able to intercept free radicals and prevent chainreactions of lipid destruction at the cell membrane level. It also protects low-densitylipoprotein (LDL) from oxidation. Oxidized LDL is implicated in the developmentof cardiovascular diseases. Extra-virgin olive oil contains 150 to 250 mg/kg ofα-tocopherol with an optimal vitamin E-to-polyunsaturated fatty acid ratio of1.5–2.0.

3.3.3 Phytosterols

Sterols are unsaturated alcohols present in the fatty tissues of plants (phytosterols)and animals. Although these compounds represent a minor part of lipids in vegetableoils, their quantification can be useful to establish the origin of an oil and to revealintentional adulterations. The amount in extra-virgin olive oil varies from 100 to250 mg/100 g of oil, of which 90–95% is β-sitosterol (spacial formula in Figure 3.9).Cholesterol is absent.

In addition to their cholesterol-lowering actions, mounting evidence suggests thatphytosterols act against cancer of the lung, stomach, ovary and estrogen-dependenthuman breast cancer. In vitro studies using cell culture models have shown thatβ-sitosterol may have anticarcinogenic effects with regard to cancer of the prostate,colon, breast and stomach.

HO

H

H H

H

Figure 3.9 β-sitosterol.


The total sterol content and determination of the amount of individual sterols(cholesterol, brassicasterol, campesterol, stigmasterol, Δ-7-stigmastenol, andβ-sitosterol) gives an indication of authenticity (see Table 2.4 in Chapter 2).

3.3.4 Phenolic compounds

These compounds are increasingly attracting the attention of researchers. Themost important are the 5-hydroxytyrosol and its elenoic acid ester, oleuropein(Figure 3.10), the latter being an exclusive constituent of olive leaves and olive oil.

The sugar part of the oleuropein molecule is removed by enzymatic digestionduring the malaxing operation, thus producing oleuropein aglycones. These com-pounds are partially soluble in oil and therefore they pass from the olive paste tothe oil. This is a critical step for olive oil quality because these compounds have ahigh antioxidant potential and a bitter taste, which is a typical and positive sensoryattribute of extra-virgin olive oils.

Oleuropein and its metabolite hydroxytyrosol have powerful antioxidant activityin vitro and in vivo associated with anti-inflammatory action. Oleuropein, in par-ticular, has several pharmacological properties. Other simpler phenolic compoundspresent in lower amounts, such as caffeic acid, vanillic acid and ferulic acid havea protective effect on α-tocopherol and lignans, a class of phenols with protectiveeffects against colon and breast cancer.

In summary, from the recent and extensive scientific literature, the following bio-logical activities have been attributed to the phenolic compounds of extra-virginolive oil: (i) direct antioxidant activity; (ii) protection of α-tocopherol antioxidantactivity; (iii) binding of metal ions that favours radical formation; (iv) inhibition ofplatelet aggregation; (v) reduction of plasma cholesterol levels; (vi) inhibition ofLDL oxidation; (vii) increased immune activity; (viii) anti-inflammatory activity;(ix) decreased cancer growth; (x) anti-allergic activity; (xi) skin protection.

(a)

(b)

OH

OHHO

O

O

O

O

HHO

HOOH

OH

OH

OHO

OO

Figure 3.10 5-hydroxytyrosol (a) and oleuropein (b).

3.4 THE COLOUR AND ODOUR COMPONENTS OF EXTRA-VIRGIN OLIVE OIL 31

Evaluation of the phenolic fraction and its composition provides importantinformation in terms of oil quality, stability and nutritional value. The mostreliable method is based on high-performance liquid chromatography (HPLC)(Servili et al. 1999). Interesting information can be obtained from chemical orenzymatic methods for assessing antioxidant potential (Lavelli 2002). These are,however, complex and time-consuming methods, also requiring sophisticatedanalytical equipment and therefore they cannot be used as process control tools.In fact, evaluation of the phenolic content of extra-virgin olive oil can be used tocharacterize milling batches or to establish blending proportions, or to correlate anolive maturity index to the quality profile of the oil. A very commonly used methodis based on the Folin–Ciocalteau colorimetric assay of total phenolics, which issimple but necessitates a well-equipped laboratory. Recently, the use of portable,easy-to-use, rapid analytical apparatuses has spread with success for online controlduties among olive oil producers and millers. However, the problem of setting up arapid and precise method of phenolic compounds analysis of olive oil that is in goodagreement with the more reliable HPLC method, is still open (Garcia et al. 2013).

3.4 The colour and odour componentsof extra-virgin olive oil

The colour of extra-virgin olive oil ranges from green to yellow due to the prevalenceof chlorophyll or carotenoids, respectively. The green colour of early-harvested oliveoil, which is particularly intense in oil from some cultivars (e.g. Correggiolo), is veryappealing to many consumers. Chlorophyll is a molecule very sensitive to light, andcareful storage to protect the oil from oxygen and light helps maintain the greencolour for a longer time. A rapid loss of the green colour is a sensitive indicator ofpoor storage conditions.

The odour of extra-virgin olive oil is a much more complex subject. Over a hun-dred volatile compounds have been identified by gas chromatography and massspectrometry in extra-virgin olive oil: aldehydes, alcohols, esters, hydrocarbons,ketones, furans and others. Only a few of them have a real impact on the perceivedodour, like, for example, those derived from hexanal (green, grassy), trans-2-hexenal(green, bitter), and 1-hexanol and 3-methylbutan-1-ol, which are the major volatilecompounds of olive oil. Other, mostly unknown molecules, which are present invery low concentrations (in the range of parts per billion), are responsible for theodour and flavour notes that characterize extra-virgin olive oils. They arise fromcomplex relationships between the genetics of the olive tree (cultivar), the originin terms of soil and climate, and the conditions of the milling process. Notes oftomato leaf or ripe tomato, green or ripe olive, artichoke, fresh almond, apple, cit-rus, freshly mown grass and many others give an essential contribution to the sensoryprofile of the extra-virgin olive oil. They may be considered as the most importantaspect of quality in the culinary arts and for consumer appreciation. In the end, these


components, which are unknown, are very difficult to identify and to explain in termsof fruit genetics and metabolism, but they have the greatest impact in differentiat-ing excellent from common oils and hence in the commercial success of an oil ora brand.

3.5 Conclusion

It can be concluded that extra-virgin olive oil is a complex, unique food with signif-icant nutritional and health-promoting properties:

1. Unlike any other edible oil, it contains phenolic compounds with a high antiox-idant potential. Most of these compounds are an exclusive metabolic productof the olive tree and the olive fruit.

2. Concerning the nonpolar antioxidants, extra-virgin olive oil is a rich mixturecontaining squalene, α-tocopherol, β-sitosterols and other minor compoundssuch as β-carotene. They play different and synergistic antioxidant roles.

3. The polar and nonpolar antioxidants in extra-virgin olive oil assure recip-rocal protection from oxidation. Thus, polyphenols are known to protectα-tocopherol and simple phenolics to protect the more complex phenolicmolecules from oxidation. This is what is defined as in vitro antioxidantactivity, whereas the in vivo antioxidant activity consists in fighting andinactivating free radicals in the body. The second property is closely connectedto the first.

4. The fatty acid mix of olive oil triglycerides also has interesting properties, asfor example, an optimal ratio of monounsaturated-to-polyunsaturated, of ω-6-to-ω-3 fatty acids.

5. The abundant amount of oleic acid assures a high resistance of olive oil tooxidation and further strengthens the health-promoting properties of olive oil.

The complexity of the overall picture should discourage an oversimplification ofthe functions and benefits of olive oil. Focusing on phenolics without consideringthe nonpolar antioxidants would be a mistake. Emphasizing the presence of oleicacid without giving appropriate weight to the presence of polyunsaturated essentialfatty acids would also be a mistake. In general, trying to extract and isolate somehealth-promoting components to make pills or concentrated solutions is a dramaticunderestimation of the importance of equilibriums and synergistic effects that makethe natural product an unmatched source of pleasure and health.

A good extra-virgin olive oil is a tasty, healthy ingredient in the diet. An averageconsumption of 20 g per day of a very good extra-virgin olive oil can, and, in fact,should be part of the diet from infancy to old age, as suggested by the Mediterraneandiet pyramid.

REFERENCES 33

Balance is everything

‘Balance is everything’ was one of the mantras that were used by John Wooden,the best basketball coach ever (Hill and Wooden 2001). He used to summarizethe concept as follows: ‘I must have offensive balance, defensive balance, squadbalance, emotional balance, mental balance, balance, balance, balance.’ JohnWooden did not just talk about the need for balance in basketball; everything inhis life suggested that he lived this value as well.

Balance is certainly a critical feature of good diet and nutrition, as an unbal-anced diet is the most common mistake and risk in nutrition.

Extra-virgin olive oil is a very special case and almost a prototype of therequirements for balance:

• In a good olive oil there is an almost perfect balance of MUFA and PUFA, allof them at concentrations perfectly suited for the human diet. There is alsoan almost perfect balance of PUFA and α-tocopherol, maximizing vitamin Eeffectiveness.

• In an excellent extra-virgin olive oil there is a balance of hydrophilic andlipophilic antioxidants, which is the most convincing cellular basis of theirsynergy and effectiveness.

• Referring to the previous point, excess water should be avoided, as it is acondition for oil spoilage, but, at the same time, water is needed to guaranteethe presence of precious minor polar compounds, with a useful biologicalactivity and an essential role in sensory quality. Balance is the condition.

• Oxygen and oxidative damage must be avoided, but some oxidation is nec-essary for the formation of particular flavour compounds. Processing underinert gas has proved to maximize the antioxidant concentration, but it impairsflavour formation. Thus, an optimal balance of health and flavour is a matterof balancing oxygen availability/oxygen exclusion in the olive oil process.

• Olive harvesting should be carried out not too early and not too late. Thebalance between oil yield and oil quality requires an optimal choice of theharvesting time.

Dealing with complexity and excellence always requires balance and oliveoil is a most convincing case in point.

References

Cicerale, S., Conlan X.A., Sinclair A.J. and Keast, R.S.J. (2009) Chemistry andhealth of olive oil phenolics. Critical Reviews in Food Science and Nutrition 49(3), 218–236.


Covas, M.I., Ruiz-Gutièrrez, V., De La Torre, R. et al. (2006) Minor componentsof olive oil: evidence to date of health benefits in humans. Nutrition Reviews64 (10), 20–30.

Garcia, B., Coelho, J., Costa, M. et al. (2013) A simple method for the determinationof bioactive antioxidants in virgin olive oils. Journal of the Science of Food andAgriculture 93, 1727–1732.

Hill, A., Wooden, J. (2001) Be Quick – But Don’t Hurry, Simon & Schuster,New York.

Kritchevsky, D. (2008) Fats and oils in human health, in Food Lipids: Chemistry,Nutrition and Biotechnology (eds C.C. Akoh and D.B. Min), CRC Press, BocaRaton, FL.

Lavelli, V. (2002) Comparison of the antioxidant activities of extra-virgin olive oils.Journal of Agricultural and Food Chemistry 50 (26), 7704–7708.

López-Miranda, J., Pérez-Jiménez, F., Ros, E. et al. (2010), Olive oil and health:summary of the II international conference on olive oil and health consensusreport, Jaén and Córdoba (Spain) 2008. Nutrition, Metabolism and Cardiovas-cular Disease 20(4), 284–294.

O’Keefe, S.F. (2008) Nomenclature and classification of lipids. In Food Lipids:Chemistry, Nutrition and Biotechnology (eds C.C. Akoh and D.B. Min), CRCPress, Boca Raton, FL.

Pelucchi, C., Bosetti, C., Negri, E. et al. (2010) Olive oil and cancer risk: an updateof epidemiological findings through 2010. Current Pharmaceutical Design 17,805–812.

Servili, M., Baldioli, M., Selvaggini, R. et al. (1999) High-performance liquid chro-matography evaluation of phenols in olive fruit, virgin olive oil, vegetation water,and pomace and 1D- and 2D-nuclear magnetic resonance characterization. Jour-nal of the American Oil Chemists’ Society 76 (7), 873–882.

Servili, M. and Montedoro, G. (2002) Contribution of phenolic compounds to vir-gin olive oil quality. European Journal of Lipid Science and Technology 104,602–613.

Viola P. and Viola, M. (2009) Virgin olive oil as a fundamental nutritional componentand skin protector. Clinics in Dermatology 27, 159–165.

Visioli, F., Poli, A. and Galli, C. (2002) Antioxidant and other biological activitiesof phenols from olive and olive oil. Medicinal Research Reviews 22, 65–75.

Willet, W.C., Sacks, F., Trichopoulou, A. et al. (1995), Mediterranean diet pyramid:a cultural model for healthy eating. American Journal of Clinical Nutrition 61,1402S–06S.

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