Olive has been grown traditionally for centuries in countries of the Mediterranean basin. However, the increase in olive oil consumption related to the perception of its health-related benefits (Waterman and Lockwood, 2007) has led, in the last two decades, to the intensification and expansion of olive cultivation, inside and outside of Mediterranean countries. According to the Food and Agriculture Organization of the United Nations (FAO), at present there are 9.4 million hectares of olive orchards in the world, most of which are still located in the Mediterranean basin (FAO, 2012). Traditionally, olives are not irrigated, but recently water application has been recognized as constructive to 1) increase yields of olives in regions with traditional rain-fed olive production (Moriana et al., 2003), 2) allow cultivation in high-density olive orchards, and 3) expand olive production into regions where there is not enough rainfall to support the crop (Connor, 2005). Today, 25% to 30% of the olive orchards supplying fruit to the oil extraction industry receive some level of irrigation (Lavee, 2011).
It has been claimed that the greatest deterioration of olive oil quality is due to poor handling of the olives between harvest and processing (Olias and García, 1997). These fruit may develop all kinds of degenerative processes in a short period of time. The resultant oils tend to show hydrolytic and oxidative deterioration, evident by their high FFA and PV content (García and Yousfi, 2006). Therefore, many studies have explored the proper way to store olives before processing to maintain good oil quality. Olive oil extraction is often not well synchronized with crop harvests because of limited labor and machinery available for harvest, and the number and size of oil extraction facilities (Agar et al., 1998). Therefore, short-term storage of olive fruit before oil extraction can provide a buffer which will enable more efficient use of both harvest facilities and the mill.
Several papers have been published on the effects of storage length and conditions on the resultant oil’s quality. However, they generally examine manually picked fruit (Agar et al., 1998; Clodoveo et al., 2007; Dourtoglou et al., 2006; García et al., 1996; Kyriakidis and Dourou, 2002; Youssef et al., 2011) or give no indication of the harvest method (Inarejos-García et al., 2010; Kalua et al., 2008; Kiritsakis et al., 1998; Yousfi et al., 2009). Moreover, there is generally no indication of whether the fruit originated from rain-fed or irrigated orchards (Agar et al., 1998; Clodoveo et al., 2007; Dourtoglou et al., 2006; García et al., 1996; Inarejos-García et al., 2010; Kalua et al., 2008; Kiritsakis et al., 1998; Yousfi et al., 2009; Youssef et al., 2011), although we may speculate that those which are not indicated originated from rain-fed orchards. There are almost no such studies of fruit originating from modern, irrigated, and mechanically harvested orchards, although these are becoming more and more common in olive oil producing countries.
Olives from irrigated trees demonstrate an apparent sensitivity to mechanical wounding, which subsequently leads to increased free acidity and peroxide level, and decreased total phenol content in the oil (Ben-Gal et al., 2011; Dag et al., 2008; Patumi et al., 2002). Therefore, their storage capacity might be limited in comparison with fruit originated from traditional rain-fed, manually picked orchards. Olive storage is important to balance the rates of harvest with those of oil extraction in the mill. The objective of the current work was to evaluate the effect of storage temperatures and duration on extracted oil quality from commercial, mechanically harvested orchards.
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