Olive oil is an important constituent of the Mediterranean diet with proven health benefits due to its chemical composition, which is rich in unsaturated fatty acids and phenolic compounds that contribute to its organoleptic and nutraceutical properties. According to previous studies, climate change affected the olive tree phenology, increasing growth, anticipating flowering and ripening processes, accompanied by a reduction in yield and fruit quality [3-5]. The present investigation aimed at studying the effect of a thermal increase on the metabolite profile of olive fruits. Changes in the metabolite profile at 4 ºC above ambient temperature was performed on field trees (cv. Picual) by using a UPLC-MS/MS approach. For the above ambient temperature treatment, a temperature-controlled Open-Top-Chamber, equipped with heating and ventilation devices was employed [5]. Twenty fruits per tree (3 trees per treatment) were sampled at 3 ripening stages [6]; green, turning red and purple. Metabolites were extracted from olive pulp using aqueous and organic solvents [7], being the extracts subjected to UPLC-qTOF analysis. Metabolite identification was carried out by MS/MS spectra with different databases (PlantCyc, Plant Metabolic Network, KEGG, MassBank and FDA) using Progenesis QI algorithm. A total of 1162 and 9877 annotated compounds were found in negative and positive mode, respectively. Around 10 % of the total were confidently identified (compounds present on 2/3 replicates but not in blank, with fragmentaion score and present on Quality control or Standar phenolics mixture). Qualitative and quantitative differences have been found between treatments (AT and AT+4ºC); differential metabolites corresponded to the lipid and phenol chemical families, these compounds being responsible of the organoleptic and nutritional properties of the olive oil.
References
[1] Casini L., et al., 2014. Nutrition & Food Science, 44(6):586-600.
[2] Poole S. and Blades M. 2013.The Mediterranean diet – a review of evidence relevant to the food and drink industry. Nutrition & Food Science, 43(1):7-16.
[4] Tupper N.,2012. Spanish olive oil under constant threat from climate change. Olive Oil Times, Oct-26.
[3] Dag A. et al., 2014. Optimizing olive harvest time under hot climatic conditions of Jordan Valley, Israel. Eur. J. Lipid Sci. Technol, 116:169-176.
[5] Benlloch-González M. et al., 2018. An approach to global warming effects on flowering and fruit set of olive trees growing under field conditions. Scientia Horticulturae, 240:405-410.
[6] Roca M. and Minguez-Mosquera M.I. 2001. Changes in chloroplast pigments of olive varieties during fruit ripening. Journal of agricultural and food chemistry, 49(2):832-839.
[7] Valledor, L. et al., 2014. A Universal Protocol for the Combined Isolation of Metabolites, DNA, Long RNAs, Small RNAs, and Proteins from Plants and Microorganisms. Plant Journal 79(1): 173-180.
