The dynamic changes in olive fruit phenolic metabolism and its contribution to the activation of quiescent Colletotrichum infection.

Anthracnose, the most critical disease affecting olive fruits, is caused by Colletotrichum species. While developing olive fruits are immune to the pathogen regardless of the cultivar, the resistance level varies once the fruit ripens. The defense mechanisms responsible for this difference in resistance are not well understood. To explore this, we analyzed the phenolic metabolic pathways occurring in olive fruits and their susceptibility to the pathogen during ripening in two resistant cultivars ('Empeltre' and 'Frantoio') and two susceptible cultivars ('Hojiblanca' and 'Picudo'). Overall, resistant cultivars induced the synthesis of aldehydic and demethylated forms of phenols, which highly inhibited fungal spore germination. In contrast, susceptible cultivars promoted the synthesis of hydroxytyrosol 4-O-glucoside during ripening, a compound with no antifungal effect. This study showed that the distinct phenolic profiles between resistant and susceptible cultivars play a key role in determining olive fruit resistance to Colletotrichum species.

Influence of genetic and interannual factors on the fatty acids profile of virgin olive oil.

Among olive oil nutritional benefits, it is worth mentioning its fatty acids composition with predominance of monounsaturated fatty acids (MUFAs). We have evaluated the influence of the cultivar and interannual factors on the fatty acids profile of virgin olive oil samples obtained from 45 and 71 cultivars along three and two consecutive crop seasons, respectively. The cultivars were classified in two groups according to the fatty acids composition: (1) high content in MUFAs and moderate content in saturated and polyunsaturated fatty acids (SFAs and PUFAs, respectively) and (2) moderate content in MUFAs and high content in SFAs/PUFAs. We also observed variations in the fatty acids content with the climate conditions, which can significantly alter the saturated and unsaturated profiles. Thus, a significant decrease in MUFAs and an increase in SFAs/PUFAs concentrations was found when the precipitation accumulated within the June-October period was reduced.

The secoiridoid profile of virgin olive oil conditions phenolic metabolism.

The European Food Safety Authority highlights the beneficial effects of olive oil phenols, mainly, secoiridoids. Nevertheless, the metabolism of secoiridoids in humans has not been fully elucidated. This research evaluated the metabolism of secoiridoids in humans after intake of olive oils with diverse phenolic profiles. For this purpose, three extra virgin olive oils (EVOOs) were ingested by six volunteers at scheduled meals, and urine samples were collected the following morning for subsequent LC-MS/MS analysis. Using untargeted analysis, urinary metabolites revealed representative patterns associated with the various olive oil phenolic contents in absolute and relative terms. We were able to identify metabolites obtained through phase I, phase II, and microbial metabolism with discrimination between tyrosol and hydroxytyrosol derivatives. Metabolism of phenols is differentially activated as a function of the olive oil secoiridoids content, and this proof-of-concept study shows how urinary metabolites represent olive oil phenolic content.

Influence of genetic and interannual factors on bioactive compounds of olive pomace determined through a germplasm survey.

Olive mill wastes, generated in the extraction of virgin olive oil (VOO), are of important concern for the industry owing to the produced volume and polluting load, mainly associated with the presence of organic compounds. Among them, it is worth mentioning bioactive compounds, mainly phenols and triterpenes, which could be potentially isolated for further use in the cosmetic, pharmaceutical, or food industries. This research analyzed the olive pomace after extraction of VOO from fruits harvested of 43 international olive cultivars during three consecutive seasons. The cultivar was identified as the most determinant factor to explain the variability in the relative concentration of phenols and terpenic acids in the extracts. In addition, the characterization of olive pomace extracts allowed clustering cultivars according to the profile of bioactive compounds. Finally, we identified the components responsible for the observed discrimination that was explained according to biosynthetic metabolic pathways.

Influence of genetic and interannual factors on the phenolic profiles of virgin olive oils.

Phenolic compounds in virgin olive oil (VOO) contribute to its health properties, organoleptic features and oxidative stability. In this study, a total of 44 olive tree cultivars categorized by the International Olive Council to be among the most internationally widespread varieties were exhaustively and homogenously evaluated by analysis of the VOO phenolic profile during three consecutive crop seasons. Differences among cultivars resulted in up to 15-fold variations in the total phenol concentration. The 'cultivar' factor contributed the most to the variance (66.8% for total phenolic concentration) for almost all the phenols. However, the 'interannual variability' factor and the interaction 'cultivar x interannual variability' exhibited significant influences on specific phenols. According to the phenolic profile of the VOOs, we determined the presence of three groups of cultivars marked by the predominance of secoiridoid derivatives, which supports the phenolic profile as a criterion to be considered in olive breeding programs.

The decrease in the health benefits of extra virgin olive oil during storage is conditioned by the initial phenolic profile.

Phenols are responsible for the only health claim of virgin olive oil (VOO) recognized by the European Commission EU 432/2012 and the European Food Safety Authority. In this research, we studied the decrease in the phenolic content of 160 extra VOOs (EVOOs) after 12 months storage in darkness at 20 °C. Phenolic concentration was decreased 42.0 ± 24.3% after this period and this reduction strongly depended on the initial phenolic profile. Hence, EVOOs with predominance in oleacein and oleocanthal experienced a larger decrease in phenolic content than oils enriched in other phenols. Complementarily, hydroxytyrosol and oleocanthalic acid increased significantly in aged EVOOs, which allowed their discrimination from recently produced EVOOs. These changes are explained by degradation of main secoiridoids during storage due to their antioxidant properties. Hydroxytyrosol and oleocanthalic acid can be considered markers of olive oil ageing, although they can also provide information about quality or stability.

Changes in the composition of the polar fraction of Persian lime (Citrus latifolia) during fruit growth by LC-QTOF MS/MS analysis.

Citrus possess a large number of bioactive compounds mainly studied in ripe fruits. Few studies have focused on evolution of metabolites during fruit growth. In this study, fruits were sampled from weeks 1-14 of the ripening process. Polar extracts were obtained from all collected samples and analysed by liquid chromatography-tandem mass spectrometry. Analysis of variance applied to the dataset indicated that the relative concentration of 394 out of 423 molecular entities changed significantly during maturation. Principal component analysis showed a clear separation among samples from different weeks and revealed the main compounds responsible for differentiation. Additionally, 72 metabolites were tentatively identified and changes in their relative concentration during growth were individually analysed. The observed trends in relative concentrations of representative metabolites during the growth process are discussed.

Characterization of lemon (Citrus limon) polar extract by liquid chromatography-tandem mass spectrometry in high resolution mode.

Eighty four metabolites (32 flavonoids, 15 amino acids, nine carboxylic acids, six coumarins, six sugars, five phenolic acids and 11 unclassified compounds) have been tentatively identified in a polar extract from lemon, without reference standards, based on their liquid chromatography-quadrupole-time-of-flight MS/MS spectra and the comparison with databases. Despite information in databases for some families of plant compounds is poor, tentative identification based on MS/MS information (mass of the precursor ion and their fragments, together with neutral mass loss) was possible with the help of known fragmentation patterns for the given families of compounds. Both positive and negative ionization modes and at least two collision energies were always applied to obtain as much information as possible from each molecular entity, thus helping for identification. As the tentatively identified metabolites are the same regardless of the organism they belong, their fragmentation patterns are useful for identification with independence of the sample nature.