Low-Copper Products vs. Copper Fungicide: Implications for Oxidative Stability of Virgin Olive Oil
Natalija Bulaš1, Maja Jukić Špika1,2, *, Luka Čotić1, Mirella Žanetić1,2, Gvozden Dumičić1, Jakša Rošin1, Elda Vitanović1
1Institute for Adriatic Crops and Karst Reclamation, Put Duilova 11, 21000 Split, Croatia (maja@krs.hr)
2Centre of Excellence for Biodiversity and Molecular Plant Breeding, Svetošimunska 25, 10000 Zagreb, Croatia
Abstract
The quality of virgin olive oil (VOO) is largely determined by its oxidative stability and oxidation products, affecting shelf life, sensory properties, and nutrition. Fungicides play a key role in olive disease control, with copper-based ones being effective but raising concerns about soil accumulation and oil quality. Alternative solutions should be sought to reduce the use of copper. This study therefore investigates the effects of different copper-based products on the quality indicators of VOOs; acidity, analytical oxidation parameters, phenols and oxidative stability.
The experiment was carried out in two harvests on Oblica olive trees treated with products with differed Cu content (1%, 12% and 37.5%), and with a control treatment. After harvesting, the oils were obtained by laboratory oil mill and the VOOs were chemically analyzed. In the first year, differences were limited to the peroxide value, which was either the same as in the control (12% Cu) or lower than control, but not significantly different from each other. Phenols ranged from 300 to 700 mg/kg, showing no significant differences between treatments. A tendency to decrease the peroxide value and K₂₃₂ was observed in the VOOs originating from trees treated with low-copper product.
Higher oxidative stability was found for VOOs extracted from treatment with higher Cu content. Results support sustainable disease control in olives, preserving oil quality while reducing copper use.
Key words: Virgin olive oil quality, Oxidation Products, Phenolics, Sustainable agriculture
