Impact of harvesting method and storage on quality phenolic profile and fatty acid composition of olive fruit (Olea europaea L.)

This study investigated the biochemical and quality changes in mechanical and hand-harvested olive fruit of the cultivars 'Istrska belica' and 'Leccino' during storage. It investigated changes in phenolic compounds and fatty acid composition, analysed using HPLC and GC methods, to understand how different harvesting methods, affect olive quality during storage. The results showed that harvesting methods had different effect on fruit quality, which became more pronounced during storage. Hand-harvested olives maintained better fruit integrity, delaying slower degradation, whereas mechanically harvested olives showed greater damage at harvest, leading to accelerated biochemical changes. At harvest, 'Istrska belica' olives responded immediately to mechanical damage by accumulating phenolic compounds such as tyrosol (increased by 43 % from 18.3 to 26.1 mg/kg FW), verbascoside (33 % from 792 to 1049 mg/kg FW), hydroxytyrosol (55 % from 27.1 to 42.0 mg/kg FW), compared to manually harvested fruits, together with an increase in certain fatty acid compositions (palmitic (67 % from 11.2 to 18.7 mg/100 g FW), palmitoleic (96 % from 0.5 to 1.0 mg/100 g FW), stearic (49 % from 4.2 to 6.3 mg/100 g FW), and linoleic acids (44 % from 6.5 to 9.3 mg/100 g FW), probably due to membrane damage. In contrast, 'Leccino' fruits showed minimal metabolic differences compared between harvesting methods. During storage, the phenolic content of mechanically harvested 'Leccino' olives initially increased due to stress-induced metabolic activity, but significantly decreased after 16 days, indicating fruit deterioration. Meanwhile, hand-harvested 'Leccino' olives maintained stable phenolic and fatty acid profiles. During storage, mechanical harvesting of ' Istrska belica ' caused the degradation of oleuropein (for 21.9 %) and other phenolic compounds, while oleuropein degradation products such as tyrosol, elenolic acid, demethyloleuropein increased, whereas hand-harvested fruit maintained stable content of six phenolic compounds and four fatty acids. • 'Leccino' and 'Istrska belica' responded differently to harvesting methods during storage. • Mechanical harvesting caused more fruit damage, resulting in faster metabolic changes. • 'Istrska belica' showed a stronger phenolic response to mechanical harvesting. • Mechanical harvesting of 'Leccino' olives led to faster degradation of oleuropein. • Hand-harvested olives showed slower degradation and longer preservation of quality.