Ancient olive trees as a source of olive oils rich in phenolic compounds

Abstract

Olive oil phenolic compounds are receiving increased attention due to its influence on sensory characteristics and to scientific evidences of positive health effects. In this work, 28 ancient olive trees were selected and, during four consecutive seasons (2014-2017), oils were extracted and their phenolic fraction characterized. Hydroxytyrosol and tyrosol secoiridoids were the predominant groups, with contents between 32 and 496 mg of tyrosol equivalents/kg. Based on principal component analysis it could be concluded that the individual phenolic contents enabled the unsupervised grouping of olive oils by crop year. Furthermore, linear discriminant analysis allowed achieving sensitivities greater than 90%. It was shown that some specimens consistently allowed obtaining oils with high phenolic contents (≥500 mg tyrosol equivalents/kg). The identification of centenarian specimens for breeding based on their potential to produce oils with high levels of healthy compounds is of utmost interest, contributing to preserve the genetic heritage.

Impact of the malaxation temperature on the phenolic profile of cv. Cobrançosa olive oils and assessment of the related health claim

“…As shown in Table 1, the IOC chromatographic method (HPLC-DAD) allowed establishing the phenolic profiles of the cv. Cobrançosa olive oils extracted, which were found to be similar to those previously reported for other Portuguese olive oils (Rodrigues et al, 2019;Peres, Martins, Mourato, Vitorino, & Ferreira-Dias, 2016). In this study, phenolic compounds of 5 different groups were detected and quantified.…”

“…Oppositely, hydroxytyrosol, tyrosol, vanillic acid, p-coumaric acid and ferulic acid were the less abundant phenolic compounds (0.1-2.8 mg/kg). The low amounts of the phenolic alcohols are in agreement with the studies of Peres et al (2016) and Rodrigues et al (2019) for Portuguese olive oils and could be tentatively attributed to the freshness of the olive oils (5 months after extraction) since hydroxytyrosol and tyrosol contents increase along the storage time due to the hydrolysis of secoiridoids (Brenes, García, García, & Garrido, 2001), as well as to the different olive cultivars studied.…”

“…Phenolic compounds were analytically extracted according to the protocol of the IOC (International Olive Council, 2017), with minor modifications as previously described by Rodrigues et al (2019). Briefly, to 0.4 g of olive oil, 25 μL of a methanol/water (80/20 v/v) solution containing syringic acid (0.15 mg/mL; Sigma-Aldrich), used as an internal standard, were added, being then vortexed for 30 s. Then 2.5 mL of the same methanol/water solution were added, and the solution vortexed for 30 s, followed by the addition of 2.5 mL of hexane, aiming a better elimination of fat, being again agitated for 5 min in a horizontal mechanical shaker (Edmund Bühler GmbH).…”

Application of an electronic tongue as a single-run tool for olive oils’ physicochemical and sensory simultaneous assessment

“…As previously described in detail by Rodrigues et al [33], the olive oils were extracted in a pilot plant with an Abencor analyzer (Comercial Abengoa S.A., Seville, Spain), from olives collected, during the 2017 crop season, from one farm with centenarian trees (> 250 years). The olive grove is located near Mirandela (N 41°29′26.628′′; W 7°1 5′31.219′′), in the northeast of Portugal.…”

“…However, since the aim of this work was to evaluate the capability of an E-tongue to quantitatively assess olive oils characteristics, determined using different techniques (e.g., titration, UV/Vis spectrophotometry, colorimeter, liquid chromatography and sensory panel evaluation), only the parameters that showed wide dynamic ranges were considered. So, in summary, the parameters/attributes evaluated in this study are given in Table 1 together with the experimental data range and the references [2][3][4][5]20,[33][34][35][36][37] describing, in detail, the analytical procedures used. Furthermore, according to the EU regulations and IOC recommendations [2][3][4][5] all olive oils were classified as extra virgin olive oils (EVOO)…”