Handbook of Olive Oil

Olive oil has capitalised on world demand for healthy vegetable oils in recent decades, its production trebling from 1 million tonnes in 1958/1959 to around 3.4 million tonnes in 2011/2012. Nowadays, production and consumption are spread much more widely across the world than just two decades ago, although they are still highest in the EU. The International Olive Council (IOC), an intergovernmental organisation responsible for administering the International Agreement on Olive Oil and Table Olives negotiated at United Nations commodity conferences, is responsible for establishing the designations and definitions of olive oil. The members of the IOC – currently 43 countries plus observers of other intergovernmental, governmental and non-governmental organisations – adopt international rules and standards to determine the quality of the products on sale and to monitor international trading. The methods recommended in the IOC trade standard have been developed in three ways. Some have been developed by the ISO or the International Union of Pure and Applied Chemistry (IUPAC), and their applicability to olive oil has been checked by the group of chemists representing the laboratories that collaborate with the IOC in studying methods of olive oil and olive-pomace oil analysis. Other methods have been developed by national bodies and approved by the IOC because they have been proven to be applicable to olive oil. Yet others have been drawn up in collaborative trials led by the IOC and approved after it has been demonstrated that their repeatability and reproducibility are acceptable; one example is the method for the organoleptic assessment of virgin olive oil.

The objective is to achieve the harmonious development of the world olive economy in terms of production, consumption and international trade. In recent years, trade has been increasingly stimulated by a growing awareness of the health-related properties of olive oil. In its campaigns to promote and expand world olive oil consumption, the IOC draws on the wealth of evidence of the effects of olive oil in preventing thrombosis and platelet aggregation and specific types of malignant tumours and the antioxidant effects of its minor components, as well as on other scientific research findings in the fields of nutrition, sensory assessment and gastronomy.

The main goal of olive oil orcharding is to produce large quantities of very high-quality olive oil efficiently and economically, every year. This chapter describes how olive oil, though influenced by thousands of years of history and culture, has been revolutionized by new agricultural practices and cultivars that have tripled production in the last 40 years. Producers all over the world are using supplemental irrigation, properly selected cultivars, higher-density plantings, efficient mechanical harvest, and modern processing techniques to produce very high-quality oil at a lower cost. A summary of Mediterranean and new-world production is outlined including the economics of some medium- and high-density orchard systems. The complex characteristics of cultivar, including vigor, precocity, alternate bearing, oil content, chemical composition, and flavor, are compared. The chapter also explores the influence on oil characteristics of climate and elevation, soils and tree nutrition, irrigation and rainfall, fruit maturity and time of harvest, pest damage and freeze injury, and crop load and pruning. As consumer demand for this healthy and flavorful food increases, researchers and farmers will need to work together to discover ways to further improve production efficiency and enhance olive oil quality.

The olive tree was known more than 5,000 years ago, and for many centuries it was still cultivated to obtain olive oil in the various civilizations that arose in the coastal territories of the Mediterranean and more inland areas of the Middle East, as the archaeological findings in many countries prove.

However, during the second part of the twentieth century, progress of the mechanical industry made it possible to improve the efficiency of machines working in the traditional pressing system, used since 1,000 B.C., but also helped the construction of the new centrifugal decanter, increasing the loading capacity of oil mills and the quality of virgin olive oil.

The quality of virgin olive oil (VOO) depends above all on the quality of olive fruits, but the technological operations carried out in oil mills are important for maintaining that quality and to avoid its reduction by using non-rational working conditions. To this end, olive fruits, waiting to be processed, must be stored for a short time and in good conditions using large plastic crates (bins) able to avoid the squeezing of drupes and, therefore, the alteration of their quality.

The processing of olive fruits begins with the leaf-removal and washing of the olive, necessary operations in order to remove from the olives all foreign materials, whether vegetable or non-vegetable, that might be harmful to the machinery or contaminate the product.

Then olive fruits are crushed to obtain the olive paste using a stone mill, with two or three (sometimes even four or six) granite millstones, in general cylindrical or, as happened in Spain, conical or truncated-conical. When an oil mill is equipped with a centrifugation system, olive crushing is generally carried out by a range of different metallic crushers, the most important of which are metallic crushers on fixed hammers and metallic crushers on discs. Olive crushing by stone mill is a nonviolent operation that helps to obtain an oil that is less bitter and pungent, whereas olive crushing by metallic crushers is a very violent operation that allows one to obtain an oil that has a high content of phenolic compounds and that is therefore more bitter and pungent.

The next operation is the malaxation of the olive paste, which is useful for increasing the size of oil droplets and the quantity of free oil and, as a consequence, the oil extraction yield.

After malaxation, the olive paste is ready for the extraction of oil by one of the following mechanical systems: traditional pressing, percolation or the new centrifugation system in two or three phases. The pressing system is a very expensive method, and at present the number of oil mills equipped with the aforementioned system is fast decreasing and such a system exists only in small oil mills. The percolation system is not very widespread, and at the present time oil mills have replaced it with the more modern centrifugation system.

In contrast, the continuous centrifugation system, in either two or three phases, is the most common in all the olive-producing countries because of its high loading capacity and the lower labor costs. In Spain, in particular, more than 95 % of the oil mills process olive fruits using a two-phase centrifugal decanter, whereas in Italy oil mills prefer to process olives using a three-phase centrifugal decanter and only a small percentage of oil mills use two-phase centrifugation. Moreover, it is interesting to note the new trend of large oil mills, which adopt the diagram of double oil extraction and the recovery of stone fragments of olive pomace to use as fuel.

The storage of VOO is also treated and the factors that are potentially harmful to its quality are described. The rational conditions for storing oil to avoid the risk of its oxidation are also suggested.

Finally, the two last sections deal with the rational use of the by-products of oil mills and sound control practices.

Virgin olive oil (VOO) is a natural product extracted from fresh olive fruits by physical means without any chemical transformation. Olive oil contains a mixture of triacylglycerols (TAGs) plus minor components that give the oil its properties and organoleptic characteristics. TAGs from olive oil are synthesized through a complex process that involves fixation of carbon dioxide, the production of sugars that are transported to the developing fruits, and their breakdown through glycolysis to produce intermediates that are imported into the plastids and finally converted to acetyl-CoA. In green fruits (like olive) a part of this carbon can also be fixed in the fruits themselves. The acetyl-CoA is converted to malonyl-CoA, which is used for fatty acid synthesis in cycles of elongation that take place within the plastids. The fatty acid products are converted to acyl-CoA derivatives, exported to the cytosol, and then utilized for lipid assembly in the endoplasmic reticulum. The TAG products are finally stored in oil vesicles that increase in size during fruit maturation. The aroma of VOO is caused by a variety of volatile compounds. This fraction is quantitatively small when compared with TAGs but determines the organoleptic quality of the oil. Analysis of olive volatiles reveals a high content of six-carbon aldehydes and alcohols typically synthesized by the lipoxygenase (LOX) pathway. This pathway involves the release of polyunsaturated fatty acids (linoleic and linolenic) from olive fruit cell membranes and their oxygenation by LOX activity. The resulting hydroperoxides are then cleaved by the enzyme hydroperoxide lyase to produce oxoacids and volatile aldehydes that can then be reduced to alcohols by the action of endogenous alcohol dehydrogenases. The relative activities of these enzymes during fruit maturation and olive oil processing determine the volatile composition of the oil. The more recent advances in these aspects of olive fruit metabolism are described in the review.

Olive is one of the most important fruit crops in the Mediterranean basin, where it has been cultivated since ancient times for its high-value oil and drupe consumption. Over the centuries numerous cultivars have been evolved by human intervention that possess desirable qualitative/quantitative traits or better adaptation to specific environments. In the past decade, the use of molecular markers has permitted significant advances in identifying centers of early olive domestication and routes of genotype diffusion. First-generation molecular marker techniques have been widely employed as powerful and versatile tools for cultivar identification, parentage analysis, evaluation of synonymy/homonymy, genetic diversity studies, genome mapping, and the construction of genetic linkage maps. Research so far points to a high degree of olive genetic variability in the Mediterranean basin that offers advantages for breeding in order to justify sustainable production of high-quality olive oil in a constantly changing environment. Next-generation high-throughput DNA technologies, like single nucleotide polymorphism genotyping platforms, are quite promising for the characterization of olive genetic plasticity and the development of quantitative trait loci markers. These high-throughput approaches will also reveal key components in the biosynthesis of bioactive molecules and antioxidants, crucial constituents of the exceptional olive oil quality. These strategies and outcomes could be used to improve olive cultivation and genomic selection within elite cultivars when combined for specific environmental niches. Complementary to these efforts, significant progress has been achieved toward understanding regulatory constituents, molecular mechanisms, and controlling circuits in fatty acid synthesis/modification and the triacylglycerol storage pathway in olive. Recently, key genes/enzymes in the olive lipoxygenase pathway have been characterized. These pathways have a major impact on the array of aroma compounds and eventually shape the typical characters of olive oil. Functional genome sequence analysis has started to elucidate molecular mechanisms governing important agronomical traits or providing tolerance to environmental constraints. This chapter serves as a synopsis of the resources in olive genomics and presents the state of the art on olive molecular biology studies underlying recent advances and “omics” approaches, possible drawbacks, and future perspectives.

any analytical methods have been proposed to characterize olive oil because of the numerous olive oil components. To organize such a heterogeneous group of methods, they have been clustered in accordance with the classical division of compounds into major and minor compounds and the unsaponifiable fraction. Thus, the methods for the group of major compounds are focused on the derivatization of fatty acids, the gas–liquid chromatography (GLC) of their methyl esters, the determination of trans fatty acids, and the main characteristics of the chromatographic techniques determining triacylglycerols, for example, columns, mobile phases, and detectors of HPLC and sample preparation, columns, injection systems, and detectors of GLC. The analytical methods and techniques for determining diacyl- and monoacylglycerols, free fatty acids, fatty acid alkyl esters, and waxes, among others, are described and analyzed with chromatograms in a section devoted to the ample and heterogenous set of minor components. The unsaponifiable matter clusters a set of natural or accidental constituents that fail to react with NaOH and KOH to produce soaps while remaining soluble in classic fat solvents (hexane, ether) after saponification. These compounds, which rarely represent more than 2 % of total olive oil composition, include many substances that are thought to be the olive oil fingerprint. Thus, a panoply of methods and techniques, some that are official standards and others that are in-house proposals, is analyzed and compared after describing the methodologies for unsaponifiable determination. The chapter also gives attention to methodologies and techniques designed for determining hydrocarbons that are present in olives or are a consequence of olive oil processing, such as squalene, n-alkanes, n-alkenes, and stigmastadienes, or resulting from external or inappropriate practices such as pesticides and polycyclic aromatic hydrocarbons. The methods for determining sterols (4-desmethylsterols, 4,4-dimethylsterols, and 4-monomethylsterols) are of special relevance because these compounds are related to olive oil authentication, varietal characterization, and identification of olive oil geographical origins, in addition to their importance as bioactive components. Finally, the chapter analyzes appropriate methods for the determination of a miscellany of compounds (e.g., tocopherols, sterols oxidation products, linear alcohols, triterpenic dialcohols) of interest in authentication, quality, and nutrition.

This chapter, which is divided into four blocks for a better comprehension by the reader, provides essential information about various chromatographic methodologies for the analysis of chlorophyll and carotenoid pigments responsible for the color of olive oil.

The first block is focused on the general aspects of chlorophyll and carotenoid pigments such as their distribution, location, structures, functions, and biological activities and, especially, the spectroscopic and chemical properties that one must know to carry out their identification.

In the second block, the authors carry out a critical description of the available current information on methodologies used for chromatographic analysis of pigments (chlorophylls and carotenoids) in virgin olive oil (VOO), including both those allowing the direct injection of diluted oil and those requiring an enrichment step using liquid-phase extraction (LPE) or solid-phase extraction (SPE).

The third block summarizes the current information about the presence of chlorophyll and carotenoid pigments in fruit and olive oil, besides their changes in profile and concentration associated with metabolism, or processing and storage conditions. The presence of exclusive pigments can be used as a marker of varietal VOO, and pigment ratios are suggested as chemical markers for determining the genuineness and correct processing. In addition, the changes in the pigment profile are shown to be a useful parameter to monitor the degradation, loss of freshness, or adulteration by colorants of VOO.

Finally, the fourth block describes the most recent researches related to kinetic studies of the thermodegradation of pigments, design of prediction mathematical models of the evolution of pigments over time, and future trends in the methods for the analysis of pigments.

Virgin olive oil (VOO) is consumed without a further refining process, thus retaining minor compounds that give rise to a fragrant and delicate flavor. Volatile compounds are responsible for VOO aroma, playing an important role in its sensory quality. A wide range of compounds, from qualitative and quantitative points of view, has been described in VOO aroma. Different routes are implicated in their production, and the biochemical pathways leading to the formation of volatiles, including the lipoxygenase pathway as the most relevant, are described. The preferred technique for the analysis of volatiles is gas chromatography, which requires an adequate sample preparation procedure, usually including a preconcentration step. The chapter considers the main drawbacks of the analysis of volatile compounds and describes the most commonly used method in the analysis of olive oil, from traditional to current procedures, such as solid-phase microextraction or headspace sorptive extraction. In the search for an alternative to the time-consuming chromatographic procedures, chemosensor-based methodologies have been implemented using various kinds of sensors, and the application of metal oxide semiconductor sensors, conducting polymer sensors, and acoustic sensors and their results are reviewed in the chapter. The establishment of the relationship between chemical compounds and sensory attributes is the most complex aspect of flavor study. The contribution of volatile compounds to the sensory quality of VOO is discussed. The relationship between volatile compounds and the basic sensory perceptions of VOO, by using the statistical sensory wheel, is treated in depth. The main reason for the presence of sensory defects is the formation of certain volatile compounds that can be produced by overripening of the fruit, oxidation of the unsaturated fatty acids, or attack by molds and bacteria, and the chemical compounds responsible for the main sensory defects detected in VOOs are discussed. The most recent results in the evaluation of sensory descriptors and the research on brain activity induced by pleasant and unpleasant VOO aromas are analyzed as well.

The overall acceptance of virgin olive oil (VOO) has always been related to flavor in all consumer studies, although for some authors taste outweighs odor. Bitterness, pungency, and astringency are the main VOO taste attributes, and they are related to the presence of secondary metabolites, which contain at least one phenolic moiety, conjugated or not. The VOO phenolic compounds originate from those encountered in the fruit but present differences both quantitative and qualitative. The systematic training of panelists for VOO sensory assessment is not always rigorous enough so that its scores often become an issue for disagreements between interested parties. The casual link between the concentration of phenols (total or individual) and the detection of sensory descriptors has not yet produced an objective procedure, based on analytical techniques, for VOO sensory evaluation despite numerous analytical procedures developed recently. The chapter presents in a critical way the major achievements of the application of different techniques (separation, spectroscopic, spectrometric, colorimetric) with regard to taste issues that had as a result the proposal of objective criteria for the evaluation of bitterness or astringency or overall taste. The importance of objective means to support health claims or quality characteristics on VOO labeling is stressed as a near-future need.

Spectroscopic techniques have emerged in food analysis as rapid and very useful tools for determining a great variety of chemical parameters. They provide elegant, fast, and easy-to-use solutions to tackle analytical challenges as well as a cost reduction. They offer the possibility to control a high number of parameters and properties simultaneously at the different steps of the food and feed chains and can be applied online. Huge instrumental and computer improvements have contributed to the development of near-infrared (NIR), mid-infrared (MIR), Raman, and fluorescence spectroscopies.

In this chapter, the theory and instrumentation currently used in infrared, Raman, and fluorescence spectroscopy for the analysis of oils is presented, as well as a complete description of data acquisition, interpretation of oil spectra, assignment of the most noteworthy bands, correlation between absorption intensities, and chemical indices and chemometric data treatment for quantitative and qualitative analyses. A review of the potential offered by the spectroscopic techniques is also included.

Extra virgin olive oil is considered a fundamental food constituent traditionally consumed in the Mediterranean area, while its consumption has extended gradually to other countries. This is due to its high sensory and nutritional quality and, most importantly, because of its protective effects against several illnesses. In the last few years intensive research has been conducted on the analysis of olive oil using nuclear magnetic resonance (NMR), giving particular emphasis to the quality assessment and authentication of this commercial commodity. This review presents a short account of the various NMR techniques and methodologies used for the analysis of olive oil. One-dimensional high-resolution multinuclear NMR spectroscopy of ¹H, ¹³C, and ³¹P nuclei gives complementary information about the major and minor constituents of olive oil, while the employment of two-dimensional NMR techniques offers the possibility of assigning unambiguously the ¹H, ¹³C, and ³¹P spectra of the various olive oil grades and unravel hidden resonances of complex spectra usually observed in the polar extracts of olive oils, either through bond or through space connectivity. Quantitative aspects of high-resolution NMR are discussed as well. The potential of the hyphenated NMR spectroscopy with a separation technique, such as liquid chromatography, for high-throughput experiments and recent developments and applications of low-resolution NMR in the field of relaxometry and diffusometry are discussed as well. A few recommendations are given about the NMR instrumentation that satisfies the minimum requirements for an efficient analysis of olive oil. Also, importance is placed on sample preparation including sample pretreatment usually needed if minor compounds (e.g., polyphenols) are investigated. The sections on spectral assignments and statistical methods used for metabonomic studies are kept very concise since the analysis of olive oils using NMR spectroscopy has been described in several good review articles mentioned in the introductory section. Two sections of this review are devoted to applications of NMR spectroscopy to quality assessment and authentication, giving emphasis to olive oil adulteration, geographical origin, and varietal classification. Despite the fact that NMR spectroscopy has made considerable inroads in the field of olive oil, several aspects need further consideration. Some of these new directions are discussed in the final section of this report.

Olive oil is characterized by its high quality, health benefits, and high price compared to other edible oils, which results in a permanent problem of adulteration. In that context, the purpose of olive oil authentication is oriented not solely to the detection of possible adulteration but to the genuineness certification of the product with regard to different authenticity issues, such as geographical origin, extraction system, and olive cultivar variety. The most recent authentication issues not only require advanced analytical solutions, but they are also in need of a multivariate mathematical procedure for extracting information from a complex set of chemical data. Thus, this chapter starts by providing a complete description of the main mathematical procedures used in olive oil characterization. The contents include several types of multivariate statistical analyses (cluster analysis, factor analysis, multidimensional scaling, discriminant analysis), expert systems, and artificial neural network. The second half of the chapter is devoted to a critical review of the different authenticity issues, starting with the agronomic and pedoclimatic characteristics that influence olive oil chemical composition. Other authenticity issues are olive ripeness, extraction system, and botanical variety. All these issues determine the distinctive properties of olive oil produced in different geographical zones. Thus, another issue analyzed in this chapter is the geographical identification of olive oils to be implemented in a traceability system. Different geographical zones (Italy, Spain, Greece, and other countries from the Mediterranean basin) are considered in the chemical description of their olive oils. Finally, the last two sections are centered on the authentication of olive oil categories and the detection of other edible oils.

Lipid oxidation has been recognized as the major problem affecting edible oils, as it is the cause of important deteriorative changes in their chemical, sensory, and nutritional properties. Autoxidation and photooxygenation, which are due to the presence of oxygen in air, are virtually inevitable. As lipids oxidize, they may form hydroperoxides, which are susceptible to further oxidation or decomposition into secondary reaction products such as aldehydes, ketones, acids, and alcohols. In many cases, these compounds adversely affect flavor, aroma, taste, nutritional value, and overall quality. Many catalytic systems can oxidize lipids. Most of these reactions involve some type of free radical or oxygen species. The oxidation may be produced either in the dark or in the presence of light, which have differences in their oxidation pathway due to the action of external variables.

Virgin olive oil is considered to be resistant to oxidative degradation due to a low content of saturated fatty acids, a high monounsaturated-to-polyunsaturated fatty acid ratio, and the presence of natural antioxidant minor components such as α-tocopherol and phenolic compounds. Nevertheless, oxidative degradation in olive oil is the most important cause of an unfavorable sensory perception. This chapter revises the oxidative deterioration of olive oil considering enzymatic oxidative deterioration, autoxidation, and photosensitized oxidation. The role of primary and secondary oxidation products and the effect of minor components during oil oxidation are also discussed.

Deep-fat frying is one of the oldest and most popular food preparation methods. Complex reactions happen during deep-fat frying, generating the formation of pleasant or unfavorable flavors and affecting the color, texture, and nutritional value of the fried foods. A revision of this aspect is reported in the chapter, which also describes the different processes and components formed.

The chapter describes the different analytical methods developed to measure the extent of oxidation by means of the quantification of the products formed or involved in this deteriorating process. The chapter also reviews the changes in the chemical compounds responsible for virgin olive oil flavor and the formation of off-flavors produced through oxidative pathways and discusses the sensory characterization of the volatile compounds responsible for off-flavors. Finally, the analysis of oxidation secondary products in olive oil is carried out using different kinds of sensors, usually disposed as a sensor array, which are connected to a pattern recognition procedure to discriminate between high-quality and oxidized/rancid oils.

This chapter begins by analyzing the main parameters for the definition of the quality of virgin olive oils (VOOs) – color, taste, and aroma. Then the most common tests used in sensory analysis – preference test, qualitative discriminant tests, and qualitative discriminant tests – are extensively analyzed and discussed, together with the panel test methodology specially developed for the assessment of virgin olive oil, which was adopted by the International Olive Council (IOC) as a trade standard and is in force within the European Union for classifying virgin olive categories (extra virgin, virgin, and lampante virgin). The specific vocabulary developed by IOC with the objective of describing positive sensory attributes and defective flavors is analyzed as well. Special attention is paid to describing the role of the panel leader, the criteria for selecting and training the tasters, the facilities needed to implement the method, and the profile sheets for the qualitative and quantitative evaluation of virgin olive oils by panelists. Finally the chapter describes a sensory assessment method recently adopted by IOC for evidencing the sensory peculiarities of VOOs produced in approved Protected Denomination of Origin (PDO) or Protected Geographical Indication (PGI) designations. The chapter ends with a brief presentation of the trade standards adopted by the California Olive Oil Council (COOC), the Australian Olive Association (AOA), and Olive New Zealand (ONZ).

This chapter describes the application of consumer methodologies to the study of extra virgin olive oil (EVOO). Due to the multivariate nature of consumer behavior, both qualitative and quantitative methods were employed to provide a more holistic view of the consumption behavior. A focus group technique showed that the diversity of the participants’ experiences with olive oil resulted in differences in existing perceptions regarding what constitutes an EVOO and the meaning of ‘extra virgin’ and determined how the combination of considered factors influenced purchase and usage motivations. A two-stage sorting task was conducted to identify American consumers’ opinions of 25 EVOOs based on visual assessments of the bottles. The majority of the consumers perceived the EVOO bottles similarly; however the two-state sorting task allowed consumers to provide additional criteria of their perception of the products. Means-end chain analysis on the interview data revealed common grounds for consumption and buying motivations with three different consumer segments. As part of the quantitative research methods, survey research was employed to identify consumer preferences and attitudes regarding EVOO. Univariate and multivariate approaches were employed to understand how hedonic scores are related to descriptive analysis measurements. Three segments were identified using cluster analysis; the three segments agreed in the rejection of bitterness and pungency. In general, the positive drivers of liking are nutty, tea, green fruit, and green tomato. Some consumers are less sensitive to the presence of defects in EVOO and tend to like defective oils.

This chapter describes the application of consumer methodologies to the study of extra virgin olive oil (EVOO). Due to the multivariate nature of consumer behavior, both qualitative and quantitative methods were employed to provide a more holistic view of the consumption behavior. A focus group technique showed that the diversity of the participants’ experiences with olive oil resulted in differences in existing perceptions regarding what constitutes an EVOO and the meaning of ‘extra virgin’ and determined how the combination of considered factors influenced purchase and usage motivations. A two-stage sorting task was conducted to identify American consumers’ opinions of 25 EVOOs based on visual assessments of the bottles. The majority of the consumers perceived the EVOO bottles similarly; however the two-state sorting task allowed consumers to provide additional criteria of their perception of the products. Means-end chain analysis on the interview data revealed common grounds for consumption and buying motivations with three different consumer segments. As part of the quantitative research methods, survey research was employed to identify consumer preferences and attitudes regarding EVOO. Univariate and multivariate approaches were employed to understand how hedonic scores are related to descriptive analysis measurements. Three segments were identified using cluster analysis; the three segments agreed in the rejection of bitterness and pungency. In general, the positive drivers of liking are nutty, tea, green fruit, and green tomato. Some consumers are less sensitive to the presence of defects in EVOO and tend to like defective oils.

Before describing analytical solutions, this chapter first provides definitions of authenticity and describes the official methods supported by the European Communities, International Olive Council, and Codex Alimentarius.

Because analytical results are not exempt from errors, validated analytical methods are essential for the quality performance of analytical laboratories. Thus, the chapter has a special section devoted to method validation (Cochran and Grubbs tests, precision, repeatability, and reproducibility limits), the definition of validation characteristics (selectivity, sensitivity, robustness, linearity, LOD, LOQ), the use in practice of accuracy values by means of procedures for comparisons between laboratories, the measurement of uncertainty, and general requirements for the competence of laboratories to carry out analytical tests, calibrations, and sampling. The entire section is based on ISO standards.

The last section of the chapter, which is focused on future trends and perspectives, analyzes the global meaning of authenticity, genuine olive oils with a chemical composition that does not conform to international standards, and that the new trade standards prevent a casual relation between chemical compounds and authenticity can be interpreted as causal.

Fat is a major contributor to energy intake in most Western diets, supplying 35–40 % of food energy. It is described as being energy dense because a gram of fat (9 kcal/g) yields more than twice as much metabolisable energy as a gram of either carbohydrate or protein (4 kcal/g). Most of the fat we consume in our diet is in the form of triacylglycerol (90–95 %), with cholesterol and phospholipids making up the bulk of the remainder.

Dietary advice invariably stresses the importance of fat reduction, yet fats have diverse roles in human nutrition. They are important as a source of energy, both for immediate utilisation by the body and in laying down a storage depot (adipose tissue) for later utilisation when food intake is reduced, they act as a vehicle for the ingestion and absorption of fat-soluble vitamins, and they have diverse structural and functional roles in the body. Cholesterol is also an essential component of cell membranes and is the precursor for synthesis of hormones.

This chapter describes the structure, digestion, transport and functional properties of dietary fat in the body and explains the basis of associations between fat consumption and chronic disease.

With different degrees of evidence, many of the health-promoting effects of the Mediterranean diet have been attributed to olive oil consumption. Apart from oleic acid, the particular minor components present in olive oil, such as hydrocarbons, tocopherols, fatty alcohols, triterpenic compounds, and polyphenols, some of which are known to be anti-inflammatory, make it the quintessential functional food. The World Health Organization (WHO) statistics (1960–1990) indicate that life expectancy increased in Mediterranean countries compared to that in more developed Western countries, an effect that was related to adherence to the Mediterranean diet, and it is highly likely that olive oil is at least partly responsible.

The cardioprotective effects of the Mediterranean diet were first linked to olive oil consumption in the Seven Countries Study. Since then, a wealth of evidence has shown that a number of contributory causes of myocardial infarction, including atherosclerosis development, hypertension, and hemostasis, are influenced by dietary olive oil in a beneficial way and that micronutrients present in the oil may be important for some of these effects. There is also evidence to implicate olive oil consumption in the relationship between adherence to the Mediterranean diet and a reduction in the incidence of Alzheimer’s and Parkinson’s diseases, although the evidence is less clear in the latter case. Moreover, epidemiological data suggest an inverse correlation between regular consumption of olive oil and cancer risk, and this is supported by animal studies.

Although the mechanisms by which olive oil and its components exert these effects are only just beginning to be addressed, the mounting evidence indicating their anti-inflammatory and antioxidant effects are likely to be the key elements, as inflammation and oxidation are commonly found during the initiation or progression of the many different pathologies in which olive oil has been found to be beneficial.

Not all olive oil production is classified by the categories of extra virgin and virgin olive oils, which can be consumed directly. The refining process allows the elimination of color, odor, or flavor of those oils that are unacceptable to consumers or to remove chemical compounds that might be toxic or have bad influence on the olive oil stability.

This chapter describes the different steps in the refining process, along with quality control measures of the whole process. The modifications of some of the most significant olive oil compounds resulting from the refining process are described in detail. Finally, the recovery and possible alternative uses for the byproducts of the refining process are discussed.

Olive oil authentication requires advanced analytical solutions and complete chemical information about olive oil samples of diverse origins with which gives support to trade standards and feed mathematical procedures for solving complex problems, such as the geographical provenance of a virgin olive oil or the detection of sophisticated adulterators, among others. This chapter provides a fine characterization of varietal olive oils from different producing countries by means of six series of chemical compounds (fatty acids, 4-desmethylsterols, 4,4′-dimethylsterols, 4-monomethylsterols, aliphatic alcohols, and hydrocarbons), which have in common that they are not affected by external parameters once olives have been processed.