Olive oil

Properties and processing for use in food

D. Boskou    Aristotle University, Thessaloniki, Hellas

1.1 Mediterranean world and the culture of the olive tree

Virgin olive oil is a staple food for the people living in the countries surrounding the Mediterranean Sea. The olive tree has probably been cultivated before recorded history and originates either from Iran and Mesopotamia or North Africa. It has contributed to the economy, cuisine, and health of the inhabitants of the coastal regions of Greece and the Greek Islands; Cyprus; Syria; Lebanon; the south of Italy, France, and Spain; and the coasts of North Africa. The culture of the olive tree, manifested in objects, pieces of art, medical prescriptions, rituals, and religious symbols has three aspects: the landscape, the use of the oil, and the symbolic importance of the tree and its fruit (Polymerou-Kamilakis, 2006). Greek mythology and the Old Testament provide information for the role of olive tree oil in everyday life and religion. Among the various myths, perhaps the most symbolic ones are the origin of the city of Athens and the flying of the dove from Noah’s ark. In ancient times the olive tree symbolized peace and friendship. The champions of the Olympics were crowned with a wreath of olive branches. Modern historians believe that the olive can be a marker and a compass to explore the history of cultures and civilizations.

Olive oil, the oil of the olive tree (Olea europaea L.), has been produced for over 6000 years. The natural oil is a “fruit juice” ready for direct human consumption and highly appreciated for its nutritional and sensory properties, dominant in the specialty foods arena. The production of high-quality virgin olive oil requires healthy and properly ripened olive fruit and a process control throughout the entire manufacture from olive tree and olive fruits to bottled oil. In the last 30 years, there has been a global interest in the use of olive oil in the diet and this is due to the awareness of the healthy virtues of a Mediterranean diet. The oil is now gaining popularity among consumers not only for its unique character and flavor but also because scientific research suggests important health benefits. Virgin olive oil is a typical example of a “natural” functional food, and its role in health is universally recognized (Stark and Madar, 2002; Covas et al., 2006; Castañer et al., 2012; Servili et al., 2014).

The growing enthusiasm for olive oil is mainly due to studies indicating that the Mediterranean diet plays a positive role in the prevention of certain diseases; in particular, coronary heart disease. New consumers who probably in the past considered this fatty material as part of an exotic dish, want now to extract healthful benefits from its fatty acid composition and the presence of antioxidants and other bioactive minor constituents. Today olive oil is produced in many countries, including areas outside the Mediterranean basin. Therefore, experts and authorities centered in the Mediterranean region meet regularly with authorities spread throughout other parts of the world to explore the elements of excellence in extra virgin olive oil, and discuss technical production issues, authenticity, organoleptic properties, and health.

1.2 Grades of olive oil: Definitions, standards, legislation

The quality and processing of several grades of olive oil are defined by Codex Alimentarius, the European Union Commission (EC), and the International Olive Council (IOC). Regulations and standards provide defined value ranges for physical and chemical properties and for composition of minor fatty acids, sterols, and other constituents, naturally present or due to processing.

In unrefined extra virgin and virgin olive oils the process does not go further than extraction by physical means, filtering (which is also a physical method), and packing. Producers of these two types of olive oil have to use fruits in excellent condition and manage all the factors affecting their quality. Due to their high cost, these two grades of olive oil are protected by strict regulation and international standards.

Definitions (Commission Regulation. 2568/91/EC, Commission Regulation 61/2011; EC, IOC Trade Standard,15/NC No 3/Rev. 7, 20131; Codex Alimentarius, STAN 33-1981)

Extra virgin olive oil. Virgin olive oil having free acidity, as a percentage of oleic acid, up to 0.8% and the other characteristics according to regulations in force. Extra virgin olive oil is the most flavorful and the highest quality grade. It is produced entirely by mechanical means without the use of any solvents, and under temperatures that do not degrade the oil.

Virgin olive oil. Virgin olive oil having free acidity, as a percentage of oleic acid, up to 2.0% and the other characteristics according to regulations in force.

Ordinary virgin olive oil. Virgin olive oil having free acidity, as a percentage of oleic acid, up to 3.3% and the other characteristics according to regulations in force. EC Regulations do not include this category.

Olive oil. Oil obtained by blending refined olive oil and virgin olive oil having free acidity, as a percentage of oleic acid, up to 1.0% and the other characteristics according to regulations in force.

Lampante olive oil. Virgin olive oil having free acidity, as a percentage of oleic acid, greater than 2% and the other characteristics according to regulations in force; virgin olive oil not fit for consumption but intended for refining or for technical use.

Refined olive oil. Olive oil obtained from virgin olive oil refining that preserves its natural triacylglycerol composition, having free acidity, as a percentage of oleic acid, up to 0.3% and the other characteristics according to regulations in force.

Crude olive-residue (olive pomace) oil. The oil extracted from olive pomace by means of a solvent having the characteristics according to regulations in force.

Refined olive residue oil. Oil obtained from crude olive residue oil by refining that preserves its natural triacylglycerol composition, having free acidity, as a percentage of oleic acid, up to 1.0% and the other characteristics according to regulations in force.

Olive residue oil. Oil obtained by blending refined olive residue oil and virgin olive oil having free acidity, as a percentage of oleic acid, up to 1.0% and the other characteristics according to regulations in force.

1.3 Composition of virgin olive oil

1.3.1 Fatty acids, triacylglycerols

The main fatty acids present in olive oil and their limits expressed as m/m% methyl esters are palmitic (7.5–20%), palmitoleic (0.3–3.5%), heptadecanoic (≤ 0.3%), stearic (0.5–5.0%), oleic (55.0–83%), and linoleic (3.5–21%). Other fatty acids, the limits of which can be used to check identity, are myristic ≤ 0.05%, heptadecenoic ≤ 0.3%, linolenic ≤ 1.0%, arachidic ≤ 0.6%, eicosenoic ≤ 0.4%, behenic ≤ 0.2% (for olive oil types) and ≤ 0.3% (for olive residue oils), and lignoceric ≤ 0.2%.

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