Centenarian olive trees of Côa Valley region: rediscovering the past to valorise the future

Funder

Organizational Unit

Publications

Characterisation of olive oils from the Douro Valley, Portugal: study of the volatile fraction and its relationship with sensory characteristics

Publication . Silva, Kevin; Rodrigues, Nuno; Pereira, J.A.; Ramalhosa, Elsa

In recent years, the demand for olive oils from the Douro region (Portugal) has increased in line with wine. Thus, it is essential to characterise these olive oils to evaluate them. Therefore, this work describes the sensory and volatile profiles of olive oils produced in the Douro region. These were mainly identified as ripe fruity. Among the olfactory and gustatory sensations, the attributes of dried fruits, tomato, apple, tomato leaves, banana, and lavender stood out. Regarding volatile compounds, the following were detected in all samples: (E)-2-hexenal, (Z)-3-hexen-1-ol, (E)-2-hexen-1-ol, (Z)-3-hexen-1-ol acetate, 1-hexanol, and 2-methyl-4-pentanal. Moreover, it was impossible to separate the olive oils by sub-regions. In conclusion, studying the volatile fraction and their relationship with sensory attributes are essential to guarantee the genuineness and identity of these olive oils with a view to their future appreciation.

2022Journal article

Open access

FTIR-chemometric analytical methodology as a tool for clustering oils from centenarian olive trees grown in the Côa Valley region

Publication . Pascoal-Ferreira, P.; Peres, António M.; Silva, Kevin; Santamaria-Echart, Arantzazu; Barreiro, M.F.; Pereira, J.A.; Baptista, Paula; Rodrigues, Nuno

The centenarian olive trees are part of the historical and cultural heritage of the Côa Valley region where a significant number of these specimens can be found. They have high importance in olive grove heritage; however, their genetic and phenotypic diversity is still poorly studied. Recently, Fourier Transform Infrared (FTIR) spectroscopy start to be widely used in several studies in the food field, becoming a powerful analytical tool for the analysis of edible oils and fats. This technique has numerous advantages, allowing a fast and non-destructive analysis, and requiring minimal sample preparation. In this context, FTIR has been applied to classify and identify different fats, detection of virgin olive oils adulteration, determination of trans fatty acids and evaluation of oil mixtures' composition in foods, all this based on the spectral profiles. Considering that there is a great diversity of centenarian olive trees in which the varieties are unknown, the objective of this work was to use the FTIR technique to identify groups of olive oils with similar chemical characteristics, thus reducing the time and required amount of samples for analysis.

2021Conference object

Open access

FTIR-chemometric analytical methodology as a tool for clustering oils from centenarian olive trees grown in the Côa Valley region

Publication . Pascoal-Ferreira, P.; Peres, António M.; Silva, Kevin; Santamaria-Echart, Arantzazu; Barreiro, M.F.; Pereira, J.A.; Baptista, Paula; Rodrigues, Nuno

The centenarian olive trees are part of the historical and cultural heritage of the Côa Valley region where a significant number of these specimens can be found. They have high importance in olive grove heritage; however, their genetic and phenotypic diversity is still poorly studied. The identification of olive tree varieties is not an easy task, being required a morphological characterisation complemented with genetics, making this identification a time-consuming and expensive procedure. Recently, Fourier Transform Infrared (FTIR) spectroscopy start to be widely used in several studies in the food field, becoming a powerful analytical tool for the analysis of edible oils and fats1. This technique has numerous advantages, allowing a fast and non-destructive analysis, and requiring minimal sample preparation. In this context, FTIR has been applied to classify and identify different fats2, detection of virgin olive oils adulteration3, determination of trans fatty acids4 and evaluation of oil mixtures' composition in foods5, all this based on the spectral profiles 6. Considering that there is a great diversity of centenarian olive trees in which the varieties are unknown, the objective of this work was to use the FTIR technique to identify groups of olive oils with similar chemical characteristics, thus reducing the time and required amount of samples for analysis. Therefore, FTIR was applied to 99 olive oils from centenarian olive trees in the Côa Valley region. FTIR analysis was carried out using an MB300 FTIR from ABB (Zurich, Switzerland) operating in attenuated total reflectance (ATR) mode using a horizontal cell equipped with a diamond crystal. The spectra acquisition was done using 32 scans/min at a resolution of 4 cm-1, being the reading range comprised between 4000 and 500 cm-1. Spectra were acquired and treated using the software Horizon MB version 3.4. The background was acquired every two consecutive assays. Finally, raw transmittance data (in %) of the different olive oils were used for the statistical analysis. A hierarchical clustering dendogram was applied to evaluate the possibility of grouping the 99 olive oils studied according to the full FTIR spectra by computing the distance (dissimilarity) among the olive oils, using the Euclidean distance Ward method for matrix computation. The dendogram (Figure 1) allowed identifying dissimilarities based on the olive oils’ FTIR spectra, enabling to establish 4 main clusters, for a 2nd node cut establishing responding to a distance around 35. Since FTIR spectroscopy is sensitive to different aspects including the olive variety and considering that all the olive oils were extracted under similar conditions and from olives harvested in the same geographical regions, the observed variations can be tentatively attributed to the olive variety or to a similarity of the oils’ chemical composition. The clustering analysis allowed partitioning a large dataset of olive oils into smaller groups based on similar spectra characteristics, enabling the future practical and feasible evaluation of selected oils belonging to each of the 4 established clusters, avoiding the need to evaluate each one of the 99 olive oils.

2021Conference object

Open access

Oliveiras Centenárias: Vale do Côa

Publication . Rodrigues, Nuno (Coord.); Baptista, Paula (Coord.)

Redescobrindo o passado para valorizar o futuro o projeto OLIVECOA teve por objetivo caracterizar o património olivícola ancestral da região do Vale do Côa, tendo em conta a sua importância no passado, do ponto de vista económico, histórico, cultural e paisagístico, para a sua valorização atual e futura. Para tal estabeleceu-se um consórcio liderado pelo Instituto Politécnico de Bragança (IPB), através do Centro de Investigação de Montanha (CIMO), com a Faculdade de Farmácia da Universidade do Porto, através da Requimte, e a Fundação Côa Parque. Com a informação gerada por esta equipa multidisciplinar foi possível criar este catálogo que aqui é apresentado. Foram estudadas 150 oliveiras centenárias divididas em oito parcelas na região do “Vale do Côa” onde se registou cada planta e que é aqui apresentado. Em cada planta foi feito o registo biométrico do tronco e da copa, feita a caracterização morfologia da folha, fruto e endocarpo (caroço) para gerar informação à cerca das oliveiras da região. Foram colhidas azeitonas de cada planta e extraído azeite que também foi estudado. Procedeu-se, juntamente com os agentes locais, ao levantamento de histórias e lendas que incluam a oliveira nas parcelas selecionadas. Apresenta-se a informação gerada, destacando algumas plantas pela sua beleza, e/ou pela composição nos seus produtos.

2024Book

Open access

Olive oil sensory analysis as a tool to preserve and valorize the heritage of centenarian olive trees

Publication . Rodrigues, Nuno; Peres, António M.; Baptista, Paula; Pereira, J.A.

In inland areas of Portugal and some regions of the Mediterranean basin, olive production is based on traditional olive groves, with low intensification, local cultivars, aged plants, and centenarian trees. These plants play a key role in the ecosystem, contributing to carbon sequestration and possessing a high genetic diversity, particularly important for selecting cultivars more resistant to climatic changes. Appreciation of the value of this genetic diversity implies genetic, morphological, and physicochemical characterization of centenarian trees, which is expensive and time-consuming. Sensory evaluation is also of utmost importance. Thus, in this study, centenarian olive trees were selected in the Côa Valley region, a UNESCO World Heritage site. The descriptive sensory profile of their extracted olive oils was established and used to cluster the oils, using hierarchical clustering analysis, and consequently the olive trees, into five groups with similar intensities of perceived olfactory–gustatory attributes. Each cluster revealed olive oils with unique sensory patterns, presumably due to similarities of the olive trees, confirming the potential of the proposed screening approach. The identification of sensorially homogeneous oil-tree groups would reduce the number of specimens needed for subsequent morphological, genetic, and chemical characterization, allowing a cost-effective and robust future evaluation procedure.

2022Journal article

Open access