**1. Introduction**

266 Olive Oil – Constituents, Quality, Health Properties and Bioconversions

Rodríguez, G.; Rodríguez, R.; Guillén, R.; Jiménez, A. & Fernández-Bolaños, J. (2007a). Effect

Rodríguez, G.; Rodríguez, R.; Fernández-Bolaños, J.; Guillén, R.; & Jiménez, A. (2007b).

Ruiz-Gutiérrez, V.; Sanchez-Perona, J. & Osada, J. (2009). Using refined oil from olive

Ruiz-Méndez, M.V.; López-López, A. & Garrido-Fernández, A. (2008). Characterization and

Taylor, J. C.; Rapport, L. & Lockwood, G. B. (2003). Octacosanol in human health. *Nutrition,*

Sáenz, M.T.; García, M.D.; Ahumada, M.C. & Ruiz, V. (1998). Cytostatic activity of some

Sánchez, P.; Ruiz, M.V. (2006). Production of pomace olive oil. *Grasas y Aceites*, Vol.57, No.1,

Singh, D. K.; Li, L. & Porter, T. D. (2006). Policosanol inhibits cholesterol synthesis in

Valavanidis, A.; Nisiotou, C.; Papageorghiou, Y.; Kremli, I.; Satravelas, N.; Zinieris, N. &

Vlyssides, A.G.; Loizides, M. & Karlis, P.K. (2004). Integrated strategic approach for reusing

Vol.19, No.2, (February 2003), pp. 192-195, ISSN 0899-9007

*Farmaco*, Vol.53, No.6, (June 1998), pp. 448-449, ISSN 0014-827X

*Technolog*y, Vol.224, No.6, (April 2007), pp. 733–741, ISSN 1438-2377 Rodríguez, G.; Lama, A.; Rodríguez, R.; Jiménez, A.; Guillén, R. & Fernández-Bolaños, J.

Mac-1 integrin , patent No. WO2005092354-A1

(March 2006), pp. 47-55, ISSN 0017-3495

(April 2004), pp. 2358–2365, ISSN 0021-8561

pp. 136-142, ISSN 0021-8561

8524

1438-7697

of steam treatment of alperujo on the enzymatic saccharification and in vitro digestibility. *Journal of Agriculture and Food Chemistry*, Vol.55, No.1, (January 2007),

Antioxidant activity of effluents during the purification of hydroxytyrosol and 3,4 dihydroxyphenyl glycol from olive oil waste. *European Food Research and* 

(2008). Olive stone an attractive source of bioactive and valuable compounds. *Bioresource Technology*. Vol.99, No.13, (September 2008), pp. 5261-5269, ISSN 0960-

pressings for retarding development of atherosclerosis; reduces levels of triglycerides and specific lipoproteins; and the number of leucocytes carrying the

chemometric study of crude and refined oils from table olive by-products. *European Journal of Lipid Science and Technology,* Vol.110, No.6, (June 2008), pp. 537-546, ISSN

compounds from the unsaponifiable fraction obtained from virgin olive oil. *Il* 

hepatoma cells by activation of AMP-kinase. *Journal of Pharmacology and Experimental Therapeutics,* Vol.318, No.6, (May 2006), pp. 1020-1026, ISSN 0022-3565

Zygalaki, H. (2004). Comparison of the radical scavenging potential of polar and lipidic fractions of olive oil and other vegetable oils under normal conditions and after thermal treatment. *Journal of Agriculture and Food Chemistry*, Vol.52, No.8,

olive oil extraction. *Journal of Cleaner Production*, Vol.12, pp. 603-611, ISSN 0959-6526

Extra virgin olive oil (EVOO) contains a wide range of bioactive compounds which give it its particular aroma and taste. It is a well-known key component in the traditional Mediterranean diet and due to its high levels of phenolics and unsaturated fatty acids, it is believed to be associated with good health and a relatively long life (De Faveri et al., 2008). The phenolic compounds have the ability to reduce the oxidative modification of lowdensity lipoproteins (Fitó et al., 2005), which play a key role in the development of atherosclerosis and coronary heart disease. Moreover, olive oil is very resistant to peroxidation (Najafian et al., 2009), a fact conferring great oxidative stability to the product (Bendini et al., 2006). The sustainable development of the agriculture and food industry is dependent upon powerful biotechnological tools which meet the demands of the new urbanized population. The improvement in the properties of EVOO is a good example of how useful the application of biotechnology to improve food quality is.

The olive oil extraction process is extremely important for its quality. During this step, the content of some components is significantly altered, depending on the extraction technique employed. A new process for the extraction of olive oil that has been studied is the addition of enzyme preparations during malaxation. This reduces the complexing of hydrophilic phenols with polysaccharides, increasing the concentration of free phenolic compounds in the olive paste and their consequent dissolution in the oil and waste waters during processing (De Faveri et al., 2008). The enzymes most used in the extraction of EVOO are microbial pectinases and cellulases, which hydrolyse the cell wall of the olive fruits, liberating the oil and phenolic compounds. This method has some advantages compared to traditional methods, giving higher oil and phenolic compound extraction yield. It also involves lower energy costs and possibly provides an oil with improved health properties

<sup>\*</sup> Corresponding Author

Genetic Improvement of Olives, Enzymatic Extraction and Interesterification of Olive Oil 269

A wide range of variation was observed for all the fatty acids, minor components and related characteristics evaluated by León et al. (2011). The fatty acid C18:1 was the predominant fatty acid in all the selections, with values ranging from 62 to 81%. Together with C16:0 and C18:2, it accounted for more than 94% of the total fatty acid composition, on average. The genotypes producing olive oils with high oleic acid percentages could be of particular interest for planting in low latitude locations, where the oleic acid content tends to be too low (Ripa et al., 2008). Of the minor components, α-tocopherol represented more than 90% of the total tocopherols, whereas the total polyphenol content varied widely from 67 to 1033 mg/kg. A wide range of variation was also obtained for stability, with values ranging from 16 to 195 h. The statistical analysis showed that genotypic variance was the main contributor to the total variance for all the fatty acids and ratios evaluated, with significant differences between the genotypes in all cases. In fact, the effect was significant for all the fatty acids, except C18:3, all the minor components and related characteristics evaluated, α-tocopherol and stability, but was lower for the other characteristics. Several studies have demonstrated that the quality of olive oil is greatly determined by genetic (cultivars) factors. For instance, in the Germplasm Banks of Catalonia and Cordoba, Tous et al. (2005) and Uceda et al. (2005), respectively, showed that more than 70% of the variation in the fatty acids (except for C18:3) and several minor components, such as the polyphenol content, bitter index (K225) and oil stability, was due to genetic effects. It should be noted that many other factors including pedoclimatic aspects, olive ripeness, olive harvesting methods and the olive extraction system have also been reported as quality indicators of virgin olive oil (Aguilera et al., 2005;

Ayton et al. (2007) found a stronger relationship between the polyphenols content and oil stability when individual cultivars were analyzed separately, which suggests that the relationship between induction time and total polyphenol content is different for each cultivar. In another study (León et al., 2011), the ranking of the cultivars was different for the polyphenols content and oil stability, which could suggest that not only the total polyphenol content, but also different polyphenol profiles in the different cultivars could have distinct antioxidant effects. Similar results have been reported for the analysis of the composition and oxidative stability of virgin olive oil from selected wild olives (Baccouri et al., 2008). The correlation between the different fatty acids also agrees with what was previously reported

Significant differences between the genotypes obtained for crosses between *Arbequina*, *Frantoio* and *Picual* were observed for the fatty acid composition, minor components and related characteristics. The multivariate analysis allowed for the classification of the genotypes into four groups according to their olive oil compositions. Further work will be required to determine the best selections to adapt to different environmental conditions, as well as the optimal harvesting periods in terms of optimal oil quality (León et al., 2011).

Ripa et al. (2008) evaluated oil quality, in terms of fatty acid composition and content in phenolic compounds, for many new genotypes previously selected in a breeding programme and cultivated in three different locations of central and southern Italy. The availability of data from many genotypes cultivated in all three locations allowed quantitative analyses of the genetic and environmental effects on the oil quality traits studied. The acidic composition varied greatly both with genotype and with environment, and so did the concentration in phenols, though the effect of genotype on phenols was not significant. The fatty acid

for olive cultivar collections and breeding progenies (León et al., 2004a).

Guerfel et al., 2009; León et al., 2011).

due to the liberation of the phenolic compounds. Microbial lipases can also be used to synthesize structured lipids from olive oil triacylglycerols.

This review discusses mainly the genetic improvement of *Olea europaea* to achieve higher quality EVOO, with lower production costs and greater productivity. Additionally, it reports on the use of enzymes to improve the extraction of virgin olive oil from olives and the enzymatic synthesis of lipids based on olive oil triacylglycerols.
