The oil obtained from the fruit of wild olive trees has excellent sensory, physicochemical and nutritional stability characteristics, according to an article published in the journal Antioxidants. The work, based on the analysis of the fruits of the wild olive trees of the integral nature reserve of the Medes Islands, reveals that the parameters of oil quality are within the values allowed by the International Olive Council (IOC).
The study represents a first approach to the characterization of albino wild olive trees in Catalonia, and is led by Rosa M. Lamuela, professor at the Faculty of Pharmacy and Food Sciences of the UB and member of the Biomedical Research Center in Obesity and Nutrition Pathophysiology Network (CIBERobn). It is also signed by experts from the Institute of Nanoscience and Nanotechnology of the UB (IN2UB), the Institute for Agri-Food Research and Technology (IRTA) and the Institute for Agricultural and Fisheries Research and Training (IFAPA). The UB's Scientific and Technological Centers (CCiTUB), among other research support infrastructures, have also participated in the research.
The olive tree: the wild variety of the cultivated olive tree
The wild olive tree ( Olea europaea L. var. Sylvestris ) ―a tree of the oleaceae family― is the ancestor of the cultivated olive tree ( Olea europaea L. subsp. Europaea ), the plant that is grown from of antiquity to obtain oil. Currently, the commercial use of the fruit of wild olive trees is a minority in the food industry, although in some peninsular regions it is occasionally used to make oils of high ecological quality.
Until now, not much information was available on the phenolic profile of wild albino olives. “The fruits of the olives are characterized by having a low oil content. However, they have unique characteristics as albino fruits with a high content of phenolic compounds that could have an effect within the parameters required by the European Union to have a health claim (protection of low-density lipoprotein particles or LDL in the face of oxidation) ”, explains Professor Rosa M. Lamuela, director of the Research Institute for Nutrition and Food Safety (INSA) —located in the Torribera Food Campus— and head of the Research Group of Natural Antioxidants of the UB.
In the Medes Islands, olive groves have adapted to conditions marked by the Mediterranean climate and the geological environment (water stress, salinity, etc.). "The phenolic profile of the oil obtained is higher than the one described so far in a genotype of wild olive trees in Algeria," says Lamuela. "Therefore, we are probably facing genotypes that could be used for food purposes and in programs to improve the traditional olive tree," adds the researcher.
The organoleptic properties of olive oil from olive trees are similar to those of commercial olive varieties. "This is due to the fact that the two oils have similar concentrations of oleocanthal and oleacin, two phenolic compounds responsible for perceptions such as spiciness and bitterness," say researchers Anallely López-Yerena (INSA-UB) and Antònia Ninot ( IRTA), first signatories of the article.
Wild olive trees: protect the natural heritage and promote local cultivation
The process of extracting olive oil has always been tried to optimize in order to maintain a balance between economic performance and oil quality. For twenty years, the renewal of olive groves has favored the use of some varieties, such as picual and arbequina, which dominate olive groves throughout the country. This practice excludes the agronomic use of many local varieties, which carries a high risk of loss of plant diversity.
In this scenario, the olive trees represent a potential example of resilience and adaptation to adverse agronomic conditions. Today, you can still find forests of wild olive trees in southern Spain (Andalusia), as well as genuine wild forms scattered retotespecially in disturbed areas or in abandoned fields― in the Valencian Country and Catalonia.
The new work is part of a program on cultivated biodiversity aimed at preventing the alarming loss of genetic diversity and promoting the use of local crops. Ongoing activities are aimed at prospecting and harvesting olive groves in Spain, in order to assess their genetic variability and study their potential application in future olive improvement programs.
“Protected areas, such as the Medes Islands, can help maintain the biodiversity of species and foods such as virgin olive oil. In the future, new studies will need to be promoted to improve the conservation of wild olive trees, the selection of genotypes with other sensory characteristics better adapted to certain environmental conditions, and the use of genetic material for reproductive purposes. In addition, this knowledge will help us to know better the history of the vegetal domestication of the olive tree for the crop », conclude the researchers Anna Vallverdú-Queralt and Julián Lozano-Castellón (UB, INSA, CIBERobn).
López-Yerena A, Ninot A, Lozano-Castellón J, et al. Conservation of Native Wild Ivory-White Olives from the MEDES Islands Natural Reserve to Maintain Virgin Olive Oil Diversity. Antioxidants. 2020;9(10):1009. doi:10.3390/antiox9101009
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