**2. General description of olive plant**

Olive (*Olea europaea* L.) is the main cultivated species belonging to the monophyletic *Oleaceae* family that comprises 30 genera and 600 species, within the clade of Asterids, in which the majority of nuclear and organellar genomic sequences are unknown. The Olea genus includes 30 species and has spread to Europe, Asia, Oceania and Africa (Bracci et al., 2011). The wild olive or oleaster (*Olea europaea* subsp. *europaea* var. *sylvestris*) and the cultivated olive (*Olea europaea* subsp. *europaea* var. *europaea*) are two co-existing forms of the subspecies *europaea*  (Green 2002). Other five subspecies constitute the *Olea europaea* complex including *laperrinei*, present in Saharan massifs; *cuspidata*, present from South Africa to southern Egypt and from Arabia to northern India and south-west China; *guanchica* present in the Canary Islands; *maroccana* present in south-western Morocco; and *cerasiformis* present in Madeira (Green 2002).

The Mediterranean form (*Olea europaea*, subspecies *europaea*) includes the wild and cultivated olives is a diploid species (2n = 2x = 46) (Kumar et al., 2011). The origin of the olive tree is lost in time, coinciding and mingling with the expansion of the Mediterranean civilisations which for centuries governed the destiny of mankind and left their imprint on Western culture.

The common olive is an evergreen tree that grows up to ∼12m in height with a spread of about 8 m. However, many larger olive trees are found around the world, with huge, spreading trunks. The trees are also tenacious, easily sprouting again even when chopped to the ground. Sometimes it is difficult to recognize which is the primary trunk. The tree can be kept at a height of about 5m with regular pruning. Olives are long-lived, with a life expectancy of greater than 500 years (Kumar et al., 2011).

Most olive-growing areas lie between the latitudes 30◦ and 45◦ north and south of the equator, although in Australia some of the recently established commercial olive orchards are nearer to the equator than to the 30◦ latitude and are producing a good yield; this may be because of their altitude or for other geographic reasons.

The olive fruit is termed a *drupe* botanically, which are green in color at the beginning and generally become blackishpurple when fully ripe. A few varieties are green even when ripe, and some turn a shade of copper brown. Olive fruits consist of a carpel, and the wall of the ovary has both fleshy and dry portions. The skin (exocarp) is free of hairs and contains stomata. The flesh (mesocarp) is the tissue that is eaten, and the pit (endocarp) encloses the seed. Olive cultivars vary considerably in size, shape, oil content and flavor. Raw olive fruits contain an alkaloid that makes them bitter and unpalatable. A few varieties are sweet enough to be eaten after sun-drying (Wiesman, 2009).

Olive cultivars are basically classified into "oil olives" and "table olives," and oil cultivars predominate. Olive cultivars are also classified according to the origin of the cultivar – for example, Spanish, Italian, Greek, Syrian, Moroccan, Israeli, etc. The most popular cultivars are: Picual, Arbequina, Cornicabra, Hojiblanca and Empeltre in Spain; Frantoio, Moraiolo, Leccino, Coratina and Pendolino in Italy; Koroneiki in Greece; Chemlali in Tunisia; Ayvalik in Turkey; Nabali, Suori and Barnea in Israel and The West Bank; Picholin in France; Mission in California; and various varieties in Australia. The table olive cultivars include Manzanilla and Gordal from Spain; "Kalamata" from Greece; "Ascolano" from Italy; and "Barouni" from Tunisia (Jacoboni & Fontanazza, 1981; Weissbein, 2006).

Traceability of Origin and Authenticity of *Olive Oil* 167

Other techniques such as proton transfer reaction mass spectrometry (PTR-MS), nuclear magnetic resonance spectroscopy (NMR) or high performance liquid chromatography (HPLC) has also been addressed using different methodologies (Luykx & van Ruth, 2008). However, the chemical composition of *olive oil* may differ among seasons and growing areas. Several investigations concerning the origin and authenticity of *olive oil* have shown that chemical analyses per se are not sufficient to assure *olive oil* authenticity or to reveal *olive oil* region (Gimenez et al., 2010). Christopoulou et al., 2004 expressed that no single known parameter could detect the presence of hazelnut and almond oils in *olive oil* which have many chemical

Several Protected Denomination of Origin (PDO) *olive oil* regions have been established by legislation to ensure both producer's profits and consumer's rights. In this context, it is mainly the identification of the olive cultivar used for the oil production which is of importance for authentication (Luykx & van Ruth, 2008) since the contribution of cultivars is known for each designation (Gimenez et al., 2010). Different PDO labels such as "Oliva Cilento", "Colline Salernitane", and "Penisola Sorrentina", have been granted for the extravirgin *olive oil* produced in Campania, and some others are in the process of assignment.

According to the report of the International Olive Council (IOC) (the International *Olive oil* Council, IOOC, until 2006), Mediterranean countries account for around 97 percent of the world's olive cultivation, estimated at about 10,000,000 hectares. There are more than 800 million olive trees currently grown throughout the world, of which greater than 90 percent are grown for oil production and the rest for table olives. It is estimated that more than

Since the mid-1990s, Spain has consistently been the largest producer; in the year 2004/05 it produced 826,300 tons of *olive oil* and it is expected a sum of 2,948,000 tons for total world olive oil production in 2010/11. The main producer is still European Union (EU), with 2.1 million tons, of which 1.2 from Spain (-14% from the previous campaign), 336000 tons produced by Greece, 480000 tons by Italy, 67500 tons by Portugal, 65000 tons by Cyprus and 6000 tons by France. Out of EU, IOOC estimated a production of 193500 tons from Syria, 160000 tons from Turkey, 12000 from Tunisia, 150000 from Morocco, 48000 from Algeria, 24900 from Palestine,

19000 from Jordan, 18000 from Australia, 17500 from Argentina, and 15000 from Lybia.

(40000 tons), Syria (50000 tons), Tunisia (90000 tons), and Turkey (38000 tons).

648000 tons, with a 2.93% increase from the previous year (*IOC website*).

The world *olive oil* consumption (2010-2011) will reach 2.98 million tons, with a 3.65 %

IOOC has estimated that the world export will increase of 5.05% and reach 707000 tons, with EU (438000 tons) as the main commercial power, followed at great distance by Morocco

The import for the period between October 1st 2010 and September 30th 2011 is estimated at

The pattern of production of *olive oil* during these years shows big fluctuations from one year to the next; however, Spain, Italy and Greece remain the three largest *olive oil* producing countries, dominating the world annual *olive oil* production. This signifies a high level of uncertainty regarding production levels. In the year 2004/05, Spain, Italy and

characteristics (fatty acid profile, sterol composition, … ) similar to *olive oil*.

2,500,000 tons of *olive oil* are produced annually throughout the world.

increase from the previous campaign 2009-2010 (*IOC website*).

**4. World olive oil production** 

The large number of cultivars, added to the many cases of synonymous and homonymous name, makes particularly difficult the description and classification of olive varieties (Fabbri et al. 2009). Notice that two varieties are synonymous when they have different names but the same profile of fingerprinting, and two varieties are homonyms when they have the same name but different fingerprinting profiles.

The size of olive germplasm is controversial: about 1,250 varieties (or in some other references 1,275 cultivars, Sarri et al., 2006), cultivated in 54 countries and conserved in over 100 collections, were included in the FAO olive germplasm database (Bartolini 2008), also if this number is certainly higher because the lack of information on many local cultivars and ecotypes (Cantini et al. 1999). The most part of these cultivars comes from southern European countries such as Italy (538 varieties), Spain (183), France (88) and Greece (52) (Baldoni & Belaj 2009). Due to this richness of the germplasm, olive is an unusual case among horticultural crops and its biodiversity can represent a rich source of variability for the genetic improvement of this plant.
