Effect of Harvesting System and Fruit Cold Storage on Virgin Olive Oil Chemical Composition and Quality of Superintensive Cultivated ‘Arbequina’ Olives

Abstract

Storage at 3 and 18 °C of 'Arbequina' olives (Olea europaea L.) cultivated in hedgerows and harvested manually or mechanically (wine grape harvester) was tested. Fruit characteristics and oil quality were monitored. Mechanical harvesting caused internal fruit damage that induced its rapid softening and decay, but also facilitated obtaining higher amounts of oil, which suffered a rapid deterioration during fruit storage. This oil presented lower tocopherol and phenol contents and lower oxidative stability than the oil extracted from manually harvested olives, but showed similar fatty acid composition. Cold storage (3 °C) delayed all of these deterioration processes. It allowed maintaining the best commercial level of quality ("extra") in the oil from mechanically harvested olives for 10 days. This cold storage could be considered as an alternative to the increase in machinery for processing the growing olive production, due to both hedgerow cultivation and mechanized harvesting.

Responses of fruit physiology and virgin oil quality to cold storage of mechanically harvested ‘Arbequina’ olives cultivated in hedgerow

“…Thus, the weight losses in the fruit stored at 6 °C and the other two treatments of cold storage (2 and 4 °C) significantly differed in a period between 2 and 6 days, whereas these two latter treatments still showed no significantly different values in this parameter after 12 storage days. The weight loss values presented in this experiment confirm the results obtained by Yousfi et al (2012) with hedgerow 'Arbequina' olives which were also harvested and maintained at 18 or 3 °C, but considerably differ from the ones published by Castellano et al (1993) or Agar et al (1999), who found lower values for this parameter, respectively working with handpicked 'Picual' and 'Manzanilla' olives, stored at ambient or 5 °C. Yousfi et al (2012) also tested the changes in this parameter in handpicked 'Arbequina' olives during their storage, obtaining significantly lower values than those harvested by machine.…”

“…The weight loss values presented in this experiment confirm the results obtained by Yousfi et al (2012) with hedgerow 'Arbequina' olives which were also harvested and maintained at 18 or 3 °C, but considerably differ from the ones published by Castellano et al (1993) or Agar et al (1999), who found lower values for this parameter, respectively working with handpicked 'Picual' and 'Manzanilla' olives, stored at ambient or 5 °C. Yousfi et al (2012) also tested the changes in this parameter in handpicked 'Arbequina' olives during their storage, obtaining significantly lower values than those harvested by machine. However, these values were also notably higher than those noted for 'Picual' or 'Manzanilla' olives.…”

“…It seems clear that cold storage is more effective in avoiding post-harvest decay for hand-harvested 'Picual' olives than for machine-harvested 'Arbequina' olives. This negative effect on decay incidence during cold storage of hedgerow 'Arbequina' olives due to mechanical harvesting has already been reported by Yousfi et al (2012), who compared the behavior of handpicked or machine harvested olives during storage. The handpicked olives stored at 3 °C showed 6% decay incidence after 21 days, whereas the machine-harvested fruits already surpassed this value after 4 storage days.…”

“…In the following sample, the differences in this parameter between the three treatments of cold storage progressively increased. In a recent work carried out by our research team (Yousfi et al, 2012), using the same kind of olives, a significant difference in fruit decay incidence was found between cold (3 °C) and ambient storages from the first sampling date (4 days). Previously, Garcia et al (1996) observed a similarly rapid decay of hand-picked green 'Picual' olives from a traditional olive orchard (≤ 300 trees/ha) maintained at 12 ± 2 °C in comparison to cold stored olives at 5 and 8 °C, which did not show significantly different decay incidence until 14 storage days.…”

“…More recently, our research team (Yousfi et al, 2012) compared the cold storage of 'Arbequina' olives from hedgerow cultivation, either hand or mechanically harvested, for extending the period of delaying processing at the olive mill. Mechanical harvesting with a grape harvester machine significantly reduced the feasibility of the fruit stored at 3 °C, which only maintained the initial level of the commercial quality of the VOO extracted for a period of 10 days, compared to that noted for the olives harvested by hand, which maintained their best level for a period of at least 21 days.…”