Harvesting system and fruit storage affect basic quality parameters and phenolic and volatile compounds of oils from intensive and super-intensive olive orchards

This study evaluated the effects of different olive harvesting systems and fruit storage durations on quality of oils from both super-intensive (cv. Arbequina) and intensive (cv. Frantoio) olive groves. Four harvesting systems were used: gentle manual harvesting, manual harvesting with hand-held combs, facilitated harvesting with hand-held pneumatic combs, and mechanical harvesting with a straddle machine (in super-intensive grove) or a trunk shaker + reversed umbrella (in intensive grove). Gentle hand harvesting caused the least damage to the fruits, whereas the trunk shaker and the straddle machine caused the greatest damage. The damage increased with olive storage. Total polyphenols and single secoiridoid were all negatively correlated with the degree of fruit damage. Volatile compounds (aldehydes, alcohols, esters and ketones) were strongly affected by both the harvesting system and the olive storage. In both cultivars, increasing the mechanization level (from gentle hand harvest to the straddle machine or the trunk shaker) caused a decrease of total aldehydes and total esters, and an increase of total alcohols and total ketones. Moreover, there were negative relationships between the degree of fruit damage and the total C5 and C6 aldehydes and total esters and positive relationships between the degree of fruit damage and the total ketones. Overall, the results indicate that fruit damage explains most of the worsening of oil quality across harvesting systems and storage duration. This is the first study reporting a clear quantitative/ linear correlation between fruit damage and important components of oil quality, such as polyphenols and volatile compounds deriving from the lipoxygenase pathway.