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Virgin olive oil (VOO) represents the main source of lipids in the Mediterranean diet, its phenolic fraction being one of the main contributors to the health-promoting properties of this diet. Phenolic composition of VOO is directly related to the content of phenolic glycosides present in the olive fruit, which undergo a series of modifications during the oil extraction process. The vast majority of these phenolic glycosides comprise phenylethanoid derivatives of tyrosol and hydroxytyrosol whose metabolic origin are the hydroxylated aromatic amino acids 4-hydroxyphenylalanine (tyrosine) and 3,4-dihydroxyphenylalanine (L-DOPA). However, the synthesis of phenolic compounds in plants has traditionally been linked to the action of the phenylalanine ammonia-lyase (PAL) enzymes on the non-hydroxylated aromatic amino acid phenylalanine, thus constituting the first step in the biosynthetic pathway of different families of phenolic compounds known as phenylpropanoids. In this research, the implication of PAL in the conformation of the phenolic profile of olive fruit and VOO has been studied through the combined analysis of phenolic composition, PAL activity and gene expression in the mesocarp of the fruit from olive cultivars whose oils have very contrasting phenolic contents. According to the data, the role of PAL would be restricted to the most advanced stages of the fruit ripening process, controlling the channeling of phenylalanine towards the synthesis of phenylpropanoids, mainly anthocyanins, and thus reducing the metabolisation of tyrosine and L-DOPA towards the synthesis of phenylethanoids. Consequently, it is advisable not to use the selection of olive cultivars based on molecular markers related to PAL genes in olive breeding programs aimed at obtaining cultivars that give rise to oils with improved functional properties.

The phenolic components of virgin olive oil (VOO) are key to the organoleptic and functional quality of this emblematic food of the Mediterranean diet. Olive breeding for improving VOO phenolic fraction, including both phenolic compounds with secoiridoid structures and tocopherols, depends largely on the identification and characterization of the key genes determining the biosynthesis of these compounds in the olive fruit as well as those that transform these phenolic components during the oil extraction process. However, there is very little knowledge about the key genes/enzymes controlling these metabolic processes. In this work, the role of olive polyphenol oxidase (PPO) in the metabolism of olive phenolic compounds has been studied. Three PPO genes have been identified from a transcriptome obtained from six olive cultivars with highly contrasting phenolic contents. These genes were expressed in Escherichia coli and the functional identity of the recombinant proteins verified using olive phenolic substrates. The OePPO1 and OePPO2 proteins exhibit diphenolase activity, while OePPO3 is a tyrosinase that not only possesses diphenolase but also monophenolase activity, able to catalyse the hydroxylation of tyrosol to form hydroxytyrosol. The role of these PPO genes in the metabolism of phenolic compounds in the olive is analysed and the potential use of this information for olive breeding is discussed.

Fusarium oxysporum f. sp. fragariae and Macrophomina phaseolina are soilborne fungi leading impactful economical losses to strawberry growers worldwide. Symptoms caused by both pathogens are very similar and include vascular discoloration, wilting, stunting, and dieback of plants, but no fruit damage. An extraction of phenolic and volatile compounds was performed on strawberry fruits from three different cultivars while being grown in a plant growth medium infested by each pathogen. Inoculated plants showed higher content of certain phenolic compounds which have antifungal and antioxidant activity and may have a positive impact on strawberry shelf life. On the other hand, root and vascular infections caused by F. oxysporum and M. phaseolina were able to significantly alter strawberry aroma by reducing or increasing the content of specific volatile compounds which also have an important impact on fruit quality. The changes induced in the aroma profiles of the three strawberry cultivars do not only have organoleptic and economic implications for strawberry growers but play an important role in the plant defense system against pathogens. The results indicate a potential of this line of research to develop new tools for the detection and control of soil pathogens.

The stability and robustness of long-term anaerobic digestion process of fruit and vegetable waste (FVW) generated in Mediterranean wholesale markets were assessed, monitoring potential inhibitory volatile organic compounds (VOCs) such as volatile fatty acids (VFAs) and/or monoterpenes. Particle size (4 and 10 mm) and organic loading rate (OLR) were evaluated during the experimentation. Anaerobic digestion remained stable at OLR of 1.0 g VS L−1 d−1 (VS, total volatile solids) regardless of the feedstock particle size. At this OLR, methane yield was 254 ± 8 and 229 ± 11 mL CH4 g VS−1 for 4 and 10 mm, respectively. As the OLR increased above 1.0 g VS L−1 d−1, the system rapidly destabilized, and a high accumulation of VFAs was observed. In parallel of to the VFAs accumulation, other VOCs such as fenchone also reached concentrations that contributes to the destabilisation of the process. The destabilization process at an OLR of 3.0 g VS L−1 d−1 also resulted in a drastic reduction in the relative abundance and species diversity of methanogenic archaea in all digesters.

The phenolic compounds containing hydroxytyrosol are the minor components of virgin olive oil (VOO) with the greatest impact on its functional properties and health benefits. Olive breeding for improving the phenolic composition of VOO is strongly dependent on the identification of the key genes determining the biosynthesis of these compounds in the olive fruit and also their transformation during the oil extraction process. In this work, olive polyphenol oxidase (PPO) genes have been identified and fully characterized in order to evaluate their specific role in the metabolism of hydroxytyrosol-derived compounds by combining gene expression analysis and metabolomics data. Four PPO genes have been identified, synthesized, cloned and expressed in Escherichia coli, and the functional identity of the recombinant proteins has been verified using olive phenolic substrates. Among the characterized genes, two stand out: (i) OePPO2 with its diphenolase activity, which is very active in the oxidative degradation of phenols during oil extraction and also seems to be highly involved in the natural defense mechanism in response to biotic stress, and (ii) OePPO3, which codes for a tyrosinase protein, having diphenolase but also monophenolase activity, which catalyzes the hydroxylation of tyrosol to form hydroxytyrosol.

Los componentes fenólicos más importantes del aceite de oliva virgen (AOV) son los derivados secoiridoideos, en cuya estructura se combinan un resto terpénico y uno fenólico. El contenido de estos compuestos en el AOV está condicionado por el contenido de glucósidos fenólicos secoiridoideos presentes en la aceituna, que son posteriormente modificados durante el proceso de extracción del aceite. Los principales glucósidos fenólicos de la aceituna, oleuropeína, ligustrósido y demetiloleuropeína, se conocen genéricamente como feniletanoides debido a la presencia de tirosol (Ty) o hidroxitirosol (Hty) en sus estructuras químicas. La biosíntesis de estos dos alcoholes fenólicos parece ser el factor limitante para la formación y acumulación de glucósidos secoiridoideos en la aceituna. En este trabajo se discute la relevancia de algunos genes/enzimas identificados y caracterizados en nuestro grupo en relación con el metabolismo del Ty e Hty como la aldehído aromático sintasa (AAS), fenilacetaldehido reductasa (PAR) o una tirosinasa (TYR) recientemente caracterizada, y se discute su posible utilidad como marcadores moleculares para la selección de variedades de olivo con contenidos fenólicos mejorados en sustitución de otros utilizados tradicionalmente como la fenilalanina amonio liasa (PAL).

El aceite de oliva virgen extra (AOVE) cuenta en su composición con un gran número de compuestos minoritarios relacionados con sus propiedades saludables, entre ellos, los compuestos fenólicos. Dichos compuestos están asimismo relacionados con la estabilidad y propiedades organolépticas del AOVE, siendo, por tanto, constituyentes de primordial importancia con respecto a la calidad comercial. La composición fenólica del AOVE depende en gran medida de la composición inicial en dichos componentes de los frutos, que posteriormente sufre una serie de transformaciones enzimáticas durante el proceso de extracción en la almazara. En el presente trabajo se compara la variabilidad del contenido y composición en fenoles en frutos recolectados en dos épocas en seis variedades (‘Arbequina’, ‘Coratina’, ‘Hojiblanca’, ‘Koroneiki’, ‘Martina’ y ‘Picual’) cultivadas en condiciones contrastantes con clima mediterráneo de Córdoba y subtropical de Tenerife, con el objetivo de estudiar la influencia de los factores genético y ambiental en la composición fenólica de los frutos. En todos los casos se ha observado un descenso acusado del contenido total de fenoles en la fecha de recolección más tardía (Figura 1), descenso que afectó de manera similar a todos los grupos de compuestos analizados que no variaron significativamente su proporción en las dos fechas analizadas (Tabla 1). El contenido total de fenoles estuvo significativamente influenciado por ambos factores: variedad, con los valores más altos en ‘Coratina’ y localidad, con valores más altos en Tenerife, sin que exista interacción entre ambos factores (Tabla 2, Figura 1). En cuanto a la composición fenólica, en general se observó un efecto genético (variedad) más importante que el ambiental para todos los grupos de compuestos (Tabla 2). En particular, aunque no hubo diferencias significativas entre variedades para los tres grupos principales de compuestos fenólicos (derivados de hidroxitirosol, derivados de tirosol y flavonas), sí

The COVID-19 pandemic represents a valuable opportunity to carry out cohort studies that allow us to advance our knowledge on pathophysiological mechanisms of neuropsychiatric diseases. One of these opportunities is the study of the relationships between inflammation, brain development and an increased risk of suffering neuropsychiatric disorders. Based on the hypothesis that neuroinflammation during early stages of life is associated with neurodevelopmental disorders and confers a greater risk of developing neuropsychiatric disorders, we propose a cohort study of SARS-CoV-2-infected pregnant women and their newborns. The main objective of SIGNATURE project is to explore how the presence of prenatal SARS-CoV-2 infection and other non-infectious stressors generates an abnormal inflammatory activity in the newborn. The cohort of women during the COVID-19 pandemic will be psychological and biological monitored during their pregnancy, delivery, childbirth and postpartum. The biological information of the umbilical cord (foetus blood) and peripheral blood from the mother will be obtained after childbirth. These samples and the clinical characterisation of the cohort of mothers and newborns, are tremendously valuable at this time. This is a protocol report and no analyses have been conducted yet, being currently at, our study is in the recruitment process step. At the time of this publication, we have identified 1,060 SARS-CoV-2 infected mothers and all have already given birth. From the total of identified mothers, we have recruited 537 SARS-COV-2 infected women and all of them have completed the mental health assessment during pregnancy. We have collected biological samples from 119 mothers and babies. Additionally, we have recruited 390 non-infected pregnant women.

The quality of virgin olive oil (VOO) is largely determined by the technology used in the industrial process of extracting the oil. Technological innovations within this field aim to strike a proper balance between oil yield and the optimal chemical composition of VOO. The application of pulsed electric fields (PEF) that cause the electroporation of the plant cell membranes favors a more efficient breakage of the olive fruit tissue, which in turn could facilitate the extraction of the oil and some of its key minor components. Pilot-scale and industrial extraction tests have been conducted to assess the effect of PEF technology on the oil extraction yield and on the organoleptic and functional quality of VOO. The best results were obtained by combining the PEF treatment (2 kV/cm) with short malaxation times and a low processing temperature. Under these conditions, PEF technology could decisively improve the oil yield by up to 25% under optimal conditions and enhance the incorporation of phenolic and volatile compounds into the oils. The PEF treatment neither affected the physicochemical parameters used to determine the commercial categories of olive oils, nor the tocopherol content. Similarly, the sensory evaluation of the PEF-extracted oils by means of a panel test did not detect the appearance of any defect or off-flavor. In addition, the intensity of positive attributes (fruity, bitter and pungent) was generally higher in PEF oils than in control oils.

Mechanical treatments can be simple and feasible methods for enhancing the anaerobic digestion of lignocellulosic substrates. This work aims to relate the direct effect of five different mechanical treatments, i.e., variation in the size and number of particles, with the variations in the chemical composition and, subsequently, the effect over the anaerobic digestion of residual raspberry extrudate, which was used as a model substrate. A high variation in the number of particles and the particle size distribution was achieved depending on the mechanical treatment applied, reaching the highest number of particles for the treatments with knife mills and mortar (around 8000 particles per gram). The higher number of particles was related to higher solubilisation, including phenolic compounds and sugars. The combination of knife mills and mortar pretreatment, which presented the highest number of particles, resulted in a 66% more of polyphenols in comparison to the raw substrate. However, the presence of anthocyanins was higher in mechanical treatments with less effect. The enhancement of the anaerobic digestion was clearly related to the increment in the number of particles of small size after the mechanical treatments. The highest methane yield coefficient (236 ± 11 mL CH4/g volatile solids) was achieved for the raspberry extrudate treated with knife mills.

Hydroxytyrosol derivatives are the most important phenolic components in virgin olive oil due to their well-demonstrated biological activities. In this regard, two phenyl acetaldehyde reductase genes, OePAR1.1 and OePAR1.2, involved in hydroxytyrosol synthesis, have been identified from an olive transcriptome. Both genes were synthesized and expressed in Escherichia coli, and their encoded proteins were purified. The recombinant enzymes display high substrate specificity for 2,4-dihydroxyphenylacetaldehyde (3,4-DHPAA) to form hydroxytyrosol. The reaction catalyzed by OePAR constitutes the second, and last, biochemical step in the formation of hydroxytyrosol from the amino acid L-3,4-dihydroxyphenylalanine (L-DOPA) in olive. OePAR1.1 and OePAR1.2 enzymes exhibit high thermal stability, similar pH optima (pH 6.5), and high affinity for 3,4-DHPAA (apparent Km 0.6 and 0.8 µmol min−1 mg−1, respectively). However, OePAR1.2 exhibited higher specific activity and higher expression levels in all the olive cultivars under study. The expression analyses indicate that both OePAR1.1 and OePAR1.2 genes are temporally regulated in a cultivar-dependent manner. The information provided here could be of interest for olive breeding progr

Virgin olive oil (VOO) is one of the most emblematic products of the Mediterranean diet. Its content in phenolic compounds is strongly associated with the antioxidant and health-promoting properties of this diet. VOO's phenolic profile is determined mainly by the phenolic compounds present in the olive fruit, so knowing their content allows for a fairly precise estimate of the antioxidant and functional properties of the corresponding oil. In this sense, a convenient, green, and sensitive spectrophotometric method was developed for the quantitative determination of total phenolic compounds in olive fruits. The method is based on an easy-to-use extraction procedure of olive fruit phenolics using dimethyl sulfoxide and quantification with the Folin-Ciocalteu reagent. Oleuropein proved to be a suitable reference compound for quantification, displaying a good linear response (r = 0.9996) over the concentration range of 0.58-6.48 mg/mL, with a variation coefficient of 0.42% and limits of detection and quantification of 0.0492 and 0.1490 mg/mL, respectively. The method was validated using a wide array of fruit samples representative of the Olea europaea L. genetic diversity. The results obtained with this spectrophotometric method, expressed as mg/mL of oleuropein, showed a good correlation with those obtained with the fruit samples analyzed by high performance liquid chromatography, with an r value of 0.9930 and a slope value of 1.022, confirming its reliability. Thus, this method can become a very useful simple tool to estimate the total phenolic content of olive fruits, especially when working with numerous samples such as in olive breeding programs or in commercial olive production, in which it is especially useful to know the phenolic state of the fruit and thus determine the optimal harvest date or the most appropriate agronomic treatment to increase the functional properties of the olive fruit and the olive oil.

[EN] In the present work, we compared the phenol content and composition of fruit from the ‘Arbequina’ cultivar in four Mediterranean (in Andalucía, Southern Iberian Peninsula) and two Sub-Tropical (Canary Islands) locations throughout the harvest period. Two Mediterranean and two Sub-Tropical locations were maintained with drip irrigation, while the remaining two Mediterranean locations were in dry farming. Water availability and harvest date seemed to play more important roles than air temperature on the phenolic content and most of the studied components. The variability associated with location was a result of the high values observed in the two Mediterranean locations in dry farming, with respect to the other four maintained with drip irrigation. Few differences were found among the four drip-irrigated locations, despite the fact that two were Mediterranean and the other two Sub-Tropical. In addition, a sharp decrease was observed during the harvest period for phenolic content and most of the phenolic compounds., [ES] En el presente trabajo se compara la variabilidad del contenido y composición en fenoles de la variedad de olivo ‘Arbequina’ en cuatro localidades con clima Mediterráneo y dos con clima Sub-Tropical. Dos de las localidades mediterráneas y las dos Sub-Tropicales contaban con riego por goteo, mientras que las dos mediterráneas restantes estaban en secano. La disponibilidad de agua y momento de recolección parece ser un factor más importante que la temperatura del aire en el contenido y composición de fenoles del fruto. La mayor parte de la variabilidad asociada a la localidad estuvo causada por los altos valores encontrados en las dos localidades mediterráneas en secano, respecto a las otras cuatro localidades en regadío. Solo pequeñas diferencias se encontraron entre las cuatro localidades en regadío, a pesar de que dos eran mediterráneas y las otras dos sub-tropicales. Además, un descenso acusado del contenido de la mayoría de los fenoles analizados se ha observado conforme avanzaba la fecha de recolección.

Strawberry fruit has a short postharvest shelf life because it is very perishable and susceptible to several pathogens that quickly reduce the quality of the fruit. A large part of Huelva's strawberry production is exported, so the shelf life of the fruit is one of the main factors that determines the quality of the fruit when it reaches its destination. The aim of this work was to explore the relationship between postharvest shelf life and the agronomic and quality traits in different strawberry genotypes during several seasons. For this, the postharvest shelf life, early and total yield, soluble solids content, fruit firmness and the content of sugars and organic acids were quantified during four consecutive seasons (2016-2019). First, the relationships of the shelf life with the other variables were explored through a principal components analysis (PCA). Subsequently, the variables that showed a stronger association with the shelf life were analysed in more detail by correlation and linear regression analysis. The PCA showed a positive relationship of the shelf life with the acid content and with fruit firmness measured with penetrometer and subjectively. Specifically, the correlation between the shelf life and firmness (measured with a penetrometer and subjectively) and the total acid was 0.59, 0.48 and 0.53, respectively. In conclusion, the variables of firmness and acid content can be useful to select genotypes in a strawberry breeding program with an increased shelf life.

Extra virgin olive oil (EVOO) chemical composition is characterized by high content of monounsaturated fatty acids and minor compounds including phenols, sterols, tocopherols, squalene and volatile compounds. These components are related to EVOO quality in terms of healthy properties, shelf life alteration due to susceptibility to oxidative degeneration and sensory properties. In this work, the variability of 66 different chemical compounds, oxidative stability and sensory attributes of EVOO was analyzed in order to study the relationships among them and the effect of cultivar, growing location and their interaction on their expression. Partial least squares (PLS) regression models allowed accurate prediction for EVOO stability on the basis of the chemical composition of the oils, with marked positive influence of oleic acid and 3,4-DHPEA-EA phenol content on stability values, while poor prediction results were obtained for sensory attributes. Cultivar and location showed limited effect on the sensory properties of EVOO, even though the same factors provide significant effect for the rest of chemical compounds and stability. These results should be taken into account in breeding programs aimed to obtain new cultivars with improved EVOO characteristics and to determine the best cultivar to be planted in each environment.

Phenolic compounds are generally accepted as key components of virgin olive oil with a great impact on its organoleptic and health promoting properties. However, olive phenolic components are not commonly used as quality traits in olive breeding programs mainly due to the difficulties of evaluating a large number of new genotypes with very little oil production at the early stages of breeding. In the present work, we describe and optimize a fast and reliable method for the extraction and further analysis of the main phenolic compounds found in olive fruit. The analytical methodology has been validated with the two most relevant olive varieties grown in Spain, 'Picual' and 'Arbequina', which possess very different phenolic profiles. The significant correlation found between specific phenolic compounds, or groups of phenolic compounds in the olive fruit analyzed with this method, and the phenolic content of virgin olive oil suggest that this method may be a very useful predictive tool which could prevent the selection of olive genotypes whose oils will never reach an optimum phenolic content.

Olive breeding has traditionally focused on the agronomic traits but the increasing number of scientific proofs supporting the positive impact of virgin olive oil (VOO) consumption on human health has made the functional quality of this product to be considered as an olive breeding target, particularly regarding the phenolic fraction of VOO. The presence of phenolic compounds in VOO is based mainly on the content of phenolic glucosides initially present in the olive fruit tissues and on the activity of hydrolytic and oxidative enzymes acting on these glucosides during the VOO extraction process. Thus, data on olive fruit phenolic composition would be of interest in olive breeding programs with the aim of obtaining new cultivars with improved functional quality. Taking into account that the main phenolics in olive fruits are essentially similar to those found in olive leaves, the objective of the present work was to carry out a comparative study of the phenolic fraction of fruits and leaves in selected cultivars characterized by having different contents of phenolic compounds in the oils to find out if the early selection of olive seedlings could be possible through an analysis of the phenolic compounds of their leaves. Results of the study showed that there is no correlation between the level of the fruit and leaf phenolics for the different olive cultivars. In addition, no significant correlation was found between the content of tyrosol and hydroxytyrosol derivatives in the leaves of the different olive cultivars over time as it does in the case of the fruits during the ripening process. These preliminary data pointed out that although the biosynthesis of the major olive phenolics is carried out through similar biochemical pathways, they seem to be regulated differently in the different organs of the plant.

Verticillium wilt, caused by the defoliating pathotype of Verticillium dahliae, is the most devastating soil-borne fungal disease of olive trees, and leads to low yields and high rates of tree mortality in highly susceptible cultivars. The disease is widely distributed throughout the Mediterranean olive-growing region and is one of the major limiting factors of olive oil production. Other than effects on crop yield, little is known about the effect of the disease on the content of volatile compounds and phenolics that are produced during the oil extraction process and determine virgin olive oil (VOO) quality and commercial value. Here, we aim to study the effect of Verticillium wilt of the olive tree on the content of phenolic and volatile compounds related to the sensory properties of VOO. Results showed that synthesis of six and five straight-chain carbon volatile compounds were higher and lower, respectively, in oils extracted from infected trees. Pathogen infection affected volatile compounds known to be contributors to VOO aroma: average content of one of the main positive contributors to VOO aroma, (E)-hex-2-enal, was 38% higher in oils extracted from infected trees, whereas average content of the main unpleasant volatile compound, pent-1-en-3-one, was almost 50% lower. In contrast, there was a clear effect of pathogen infection on the content of compounds responsible for VOO taste, where average content of the main bitterness contributor, oleuropein aglycone, was 18% lower in oil extracted from infected plants, and content of oleocanthal, the main contributor to pungency, was 26% lower. We believe this is the first evidence of the effect of Verticillium wilt infection of olive trees on volatile compounds and phenolics that are responsible of the aroma, taste, and commercial value of VOO.

The phenolic composition of virgin olive oil (VOO) is strongly determined by the content and distribution of secoiridoid phenolic glucosides present in the olive fruit. Among them, oleuropein is the most abundant in olive mesocarp and is characterized by containing an hydroxytyrosol residue in its chemical structure. Hydroxytyrosol-containing molecules are those that exhibit the most important biological activities in virgin olive oil. In this regard, we identified an aromatic aldehyde synthase gene (OeAAS) from an olive transcriptome, which was synthesized, expressed in Eschrichia coli, and purified its encoded protein. The recombinant OeAAS is a bifunctional enzyme catalyzing decarboxylation and amine-oxidation reactions in a single step. OeAAS displays strict substrate specificity for l-DOPA to form 2,4-dihydroxyphenylacetaldehyde, the immediate precursor of hydroxytyrosol. In addition to the biochemical characterization of the enzyme, the expression analysis carried out in different olive cultivars and ripening stages indicate that OeAAS gene is temporally regulated in a cultivar-dependent manner. High correlation coefficients were found between OeAAS expression levels and the phenolic content of olive fruits and oils, which supports a key role for OeAAS in the accumulation of hydroxytyrosol-derived secoiridoid compounds in olive fruit and virgin olive oil.

Virgin olive oil (VOO) is the main source of lipids in the Mediterranean diet and one of the main contributors to its proven protection against diseases associated with chronic inflammation states. This oil is rich in antioxidant compounds such as tocopherols, which together constitute the vitamin E stock of the oil. The purpose of the present work was to conduct a study on the diversity of the contents of vitamin E in the olive species (Olea europaea L.), and to know how the season climatic conditions and the degree of fruit ripening stage influences the final content of this vitamin in VOO. Data showed that the content of vitamin E in VOO is highly dependent on the olive cultivar, displaying a wide variability (89–1410 mg tocopherol/kg oil) in the olive species, and that is also dependent, to a lesser extent, on the crop year climate and the stage of fruit ripening. In addition, the suitability of cultivar crosses for breeding programs to obtain new cultivars with improved vitamin E content in VOO has been assessed. Our findings demonstrated that a single cross of olive cultivars may provide sufficient variability to be used in the selection of new cultivars.

Virgin olive oil is unique among plant oils for its high levels of oleic acid, and the presence of a wide range of minor components, which are responsible for both its health-promoting properties and characteristic aroma, and only produced when olives are crushed during the industrial process used for oil production. The genetic variability of the major volatile compounds comprising the oil aroma was studied in a representative sample of olive cultivars from the World Olive Germplasm Collection (IFAPA, Cordoba, Spain), by means of the headspace solid-phase microextraction/gas chromatography–mass spectrometry–flame ionization detection (HS-SPME/GC-MS-FID). The analytical data demonstrated that a high variability is found for the content of volatile compounds in olive species, and that most of the volatile compounds found in the oils were synthesized by the enzymes included in the so-called lipoxygenase pathway. Multivariate analysis allowed the identification of cultivars that are particularly interesting, in terms of volatile composition and presumed organoleptic quality, which can be used both to identify old olive cultivars that give rise to oils with a high organoleptic quality, and in parent selection for olive breeding programs.

The wide olive genetic patrimony has revealed high variability for most of the agronomic and oil quality traits of interest in olive growing. Few studies, however, have addressed the interaction of this variability with the environment, a subject of particular interest considering the natural high instability of the Mediterranean climate and the challenge of the predicted climate change. The current work presents results on the interaction between genotype and environment from multi-environment trials of olive cultivars and breeding selections, planted in different edaphoclimatic conditions of Andalusia, Southern Peninsular Spain and Canary Islands. For most of the agronomic and oil quality characters evaluated (flowering phenology, flower quality, pattern of oil accumulation, fatty acid composition and phenol content and composition), significant genotype and environment effects have been observed. For example, olive cultivars grown in Tenerife under much milder winter temperatures than in the Iberian Peninsula showed substantially earlierflowering and oil accumulation. Only in the case of flowering phenology was no significant genotype effect found. Furthermore, a strong genotype x environment effect was highly consistent in all characters considered. Regarding resistance to disease, such as Verticillium wilt, the variability of results from both natural and artificial inoculations also tends to indicate a considerable environmental effect and the need for careful testing of disease evolution. All this information strongly suggests the necessity of comparative trials of olive cultivars for both adequate choice of cultivar and final selection in breeding programs.

There is an increasing need for diversification of olive (Olea europaea L.) cultivars, mainly because of the new intensive industry and the current trend of establishing olive productions in new areas outside the Mediterranean basin. Olive breeding has traditionally been focused on the improvement of agronomic traits. However, the nutritional quality of virgin olive oil (VOO) is lately being considered as a breeding target because of the growing weight of scientific evidence supporting the positive impact of VOO on human health. Increasing VOO consumption, through improvement of its nutritional and sensory properties, will in turn have a positive effect on both consumer health and olive-producing areas. VOO metabolites responsible for its nutritional and sensory quality include components such as phenolics and volatile compounds, which are synthesized during the oil extraction process by endogenous enzymes. Here, we aimed to investigate olive diversity regarding the key VOO quality metabolites of olive accessions cultivated around the world. For this purpose, oils from 97 olive cultivars representative of the diversity found at the World Olive Germplasm Collection (CAP-UCO-IFAPA), located at IFAPA Centre “Alameda del Obispo” Cordoba, Spain, were obtained and the phenolic and volatile fractions were further analyzed. The component profiles were compared with those of a similar subset of seedlings arisen from the cross of two widely cultivated olive cultivars having contrasting oil compositions ('Arbequina' and 'Picual'). Results showed that a single cross provides enough variability to produce new olive cultivars with improved quality. The set of cultivars from the collection displayed, in general, higher levels of variability than the progeny cross for the main groups of volatile compounds. However, the latter displayed a wider variability than the set of cultivars under study for most of the main classes of phenolic compounds in the oil, except the lignans.

Olive growing is mainly based on traditional varieties selected by the growers across the centuries. The few attempts so far reported to obtain new varieties by systematic breeding have been mainly focused on improving the olive adaptation to different growing systems, the productivity and the oil content. However, the improvement of oil quality has rarely been considered as selection criterion and only in the latter stages of the breeding programs. Due to their health promoting and organoleptic properties, phenolic compounds are one of the most important quality markers for Virgin olive oil (VOO) although they are not commonly used as quality traits in olive breeding programs. This is mainly due to the difficulties for evaluating oil phenolic composition in large number of samples and the limited knowledge on the genetic and environmental factors that may influence phenolic composition. In the present work, we propose a high throughput methodology to include the phenolic composition as a selection criterion in olive breeding programs. For that purpose, the phenolic profile has been determined in fruits and oils of several breeding selections and two varieties (“Picual” and “Arbequina”) used as control. The effect of three different environments, typical for olive growing in Andalusia, Southern Spain, was also evaluated. A high genetic effect was observed on both fruit and oil phenolic profile. In particular, the breeding selection UCI2-68 showed an optimum phenolic profile, which sums up to a good agronomic performance previously reported. A high correlation was found between fruit and oil total phenolic content as well as some individual phenols from the two different matrices. The environmental effect on phenolic compounds was also significant in both fruit and oil, although the low genotype × environment interaction allowed similar ranking of genotypes on the different environments. In summary, the high genotypic variance and the simplified procedure of the prop

Ethanol is a substrate for the chemical synthesis of fatty acid ethyl esters (FAEE) during storage of virgin olive oil whose contents are officially regulated. Given the impact that the ethanol content might have on the olive oil commercialization, the level of this metabolite has been studied in an array of olive genotypes representing the diversity available in olive (Olea europaea L.). Substantial levels of ethanol have been found in the oils of all genotypes under study. Moreover, increasing levels of alcohol dehydrogenase activity have been found during olive fruit ripening in good correspondence with the accumulation of ethanol in advanced stages of fruit maturation. The results suggest that ethanol has a ubiquitous character in the fruits of Olea europaea and, therefore, in all the oils obtained from them. Besides, their concentration seems to depend on the cultivar, ripening stage and climatology, not discarding the influence of the growing conditions. Data suggest that the application of olive oil regulation for FAEE levels should consider the presence of basal levels of ethanol in the oils, which are quite high in many cultivars.

The suitability of the cold storage (2 °C) of fruit to maintain the quality of ‘Manzanilla de Sevilla’ and ‘Manzanilla Cacereña’ intended for virgin olive oil extraction was investigated. This temperature was effective in keeping the best commercial category of oil quality in both manually harvested olives and in mechanically harvested ‘Manzanilla Cacereña’ fruits for 11 days. Mechanical harvesting induced significant decreases in oxidative stability and in the main phenolic compounds contents in the oils during cold storage and, only initially, in the total volatiles, regardless of the cultivar considered. However, the contents of volatile esters, associated to fruity flavor, were always higher in the oils from mechanically harvested fruits. ‘Manzanilla de Sevilla’ oils exhibited higher total volatiles during fruit cold storage, regardless of the harvesting system used.

We have evaluated eight cultivars of strawberry, seven short-day and one day-neutral, for two years with two sampling dates and two repetitions by date to assess the relationship between sugar content and degree Brix. The fruits were collected and evaluated at the ripe stage. Contents of sucrose, glucose, fructose, °Brix, citric acid, ascorbic acid and malic acid in the fruit were measured. The data were analyzed using principal component analysis (PCA) and Pearson correlations. The PCA groups most of the variability in the first component (62.2%). This component shows a positive relationship between the Brix degrees, sugars and acids (higher values of this component indicate increased Brix degrees, and the contents of sugars and acids). The second component collects 20.74% of the variability, which is mainly related to differences in the sugars/acids ratio. The plotting of the factor barycenter over the two principal components of PCA analysis shows that second harvest date has a higher content of sugars, organic acids and °Brix. With regard to cultivars representation over PCA, the good quality cultivar 'Primoris' is characterized by a high sugar content and a balanced total sugars/acids ratio. Moreover, the day-neutral cultivar 'Nieva' shows the lowest values of sugars, acids, °Brix and total sugars/acids ratio. Featured correlations exist between ascorbic acid content and glucose and fructose content (R2=0.82 and 0.81, respectively). The °Brix shows a relative correlation with the total sugars content (R2=0.74). In conclusion, the genotype has large effect in the content of sugars and organic acids. Therefore, the high content of sugars and acids and a balanced relationship between them could be used as a quality trait for the selection of strawberry varieties. On the other hand, °Brix is a relative good measure of the total sugar content.

Phenolics are claimed to be one of the main responsible for the health benefits associated to the long term consumption of virgin olive oil (VOO). The variability of the phenolic composition was studied in an olive cultivar core collection which holds an extensive genetic diversity. The most abundant VOO phenolics were the secoiridoid derivatives resulting from the hydrolysis of oleuropein, ligstroside and demethyloleuropein present in the fruit, which showed to be on average their main phenolic glucosides. Total phenolic compounds in the fruits and the oils were, in general, significantly and positively strong correlated (r = 0.82) with p < 0.001. Thus, the fruit phenolic content seems to be the main factor determining the synthesis of VOO phenolics during oil extraction. Data on phenolic composition would be of interest for the selection of optimal parents in olive breeding programs with the aim of obtaining new cultivars with improved functional quality.

In the last few years organoleptic and nutritional traits have become the major breeding targets in most strawberry breeding programs all over the world. Furthermore, the joint improvement of the nutritional value and the sensory key parameters of strawberry might increase the consumption rate of this fruit, which in turn will have a positive effect on consumer's health and a positive economic impact on the producing areas. New cultivars and strawberry selections bred in Huelva (southwestern Spain) have been characterized in relation to their organoleptic and nutritional properties. Key metabolites associated to the strawberry flavor (sucrose, fructose, glucose, malic and citric acid and 20 main volatile compounds) as well as specific phytochemicals (nine phenolic compounds plus vitamin C) with relevant antioxidant capacities have been analyzed by high resolution gas chromatography coupled to mass spectrometry (HRGC-MS) and high performance liquid chromatography (HPLC). Data were analyzed using principal component analysis (PCA) and Pearson correlations to discriminate those strawberry selections that, besides good agronomic performances, produce fruits with high contents of key flavor components and health-promoting phytochemicals. PCA clearly distinguish selections A10-48-3 and A7-32-10 as having significantly different metabolic profiles and displaying the highest contents of sugars, organic acids, ethyl esters, mesifurane, terpineol, quercetin and vitamin C.

Virgin olive oil (VOO) is the only food product requiring official sensory analysis to be classified in commercial categories, in which the evaluation of the aroma plays a very important role. The selection of parents, with the aim of obtaining new cultivars with improved oil aroma, is of paramount importance in olive breeding programs. We have assessed the volatile fraction by headspace-solid-phase microextraction/gas chromatography-mass spectrometry-flame ionization detection (HS-SPME/GC-MS-FID) and the deduced aroma properties of VOO from a core set of olive cultivars (Core-36) which possesses most of the genetic diversity found in the World Olive Germplasm Collection (IFAPA Alameda del Obispo) located in Cordoba, Spain. The VOO volatile fractions of Core-36 cultivars display a high level of variability. It is mostly made of compounds produced from polyunsaturated fatty acids through the lipoxygenase pathway, which confirms to be a general characteristic of the olive species (Olea europaea L.). The main group of volatile compounds in the oils was six straight-chain carbon compounds derived from linolenic acid, some of them being the main contributors to the aroma of the olive oils according to their odor activity values (OAV). The high level of variability found for the volatile fraction of the oils from Core-36 and, therefore, for the aroma odor notes, suggest that this core set may be a very useful tool for the choice of optimal parents in olive breeding programs in order to raise new cultivars with improved VOO aroma.

BACKGROUND: Regulated deficit irrigation (RDI) is used in hedgerow olive orchards to achieve a sustainable balance between water savings, tree vigor and oil production. Its effects on the presence of compounds responsible for the taste of the oil and its nutritional value are controversial. The present 3-year study was conducted in an ‘Arbequina’ orchard (1667 trees ha−1) under a full irrigation (FI) treatment (470.1 mm year−1 of water) and two RDI treatments scaled to replace 60% and 30%, respectively, of FI. The quality parameters, antioxidant contents and volatiles of the extracted virgin olive oil (VOO) were analyzed. RESULTS: In general, oils from the 30% RDI treatment had higher contents of pigments and phenolic compounds, a higher oleic/linoleic ratio and the highest oxidative stability, despite theirlower tocopherol content. FI oils showed higher (E)-2-hexenal, 1-penten-3-one, ocimene, E-2-pentenal and pentene dimer contents than 30RDI oils, but lower contents of (E)-2-pentenol and volatile esters. CONCLUSION: The results of the present study suggest that a RDI strategy supplying 30% of the total irrigation needs induces an increase in natural antioxidants in VOO. Neither yield, nor the rest of the quality parameters were affected by the reduced irrigation. However, abundant autumn precipitation can over-ride these effects of 30% RDI treatment on oil quality. © 2016 Society of Chemical Industry

Volatile compounds are responsible for most of the sensory qualities of virgin olive oil and they are synthesized when enzymes and substrates come together as olive fruit is crushed during the industrial process to obtain the oil. Here we have studied the variability among the major volatile compounds in virgin olive oil prepared from the progeny of a cross of Picual and Arbequina olive cultivars (Olea europaea L.). The volatile compounds were isolated by SPME, and analyzed by HRGC–MS and HRGC–FID. Most of the volatile compounds found in the progeny's oil are produced by the enzymes in the so-called lipoxygenase pathway, and they may be clustered into different groups according to their chain length and polyunsaturated fatty acid origin (linoleic and linolenic acids). In addition, a group of compounds derived from amino acid metabolism and two terpenes also contributed significantly to the volatile fraction, some of which had significant odor values in most of the genotypes evaluated. The volatile compound content of the progeny was very varied, widely transgressing the progenitor levels, suggesting that in breeding programs it might be more effective to consider a larger number of individuals within the same cross than using different crosses with fewer individuals. Multivariate analysis allowed genotypes with particularly interesting volatile compositions to be identified and their flavor quality deduced.

© 2014 Published by Elsevier Ltd. The effect of modifying polyphenol oxidase (PPO) and peroxidase (POX) activity during the extraction of virgin olive oil has been assessed in terms of its influence on the phenolic profile of the oil produced. These enzymes were modified by adding exogenous enzyme or specific inhibitors during the milling and subsequent kneading step, studying the effect on specific phenolic compounds in the oils. PPO is the main enzyme involved in phenolic oxidation at the milling step whereas POX activity seems to be the main influence during the kneading step. The data obtained suggest it is possible to increase the nutritional and organoleptic quality of virgin olive oil by inhibiting these enzymes during olive fruit processing. Treatment with the PPO inhibitor tropolone produced a twofold increase in the phenolic fraction, which would therefore seem to be an interesting strategy to improve the nutritional and organoleptic properties of virgin olive oil.

La producción de aceites de oliva virgen (AOV) de mayor calidad, muy aromáticos y con notas amargas y picantes, de intensidad moderada, bien equilibrada es una prioridad tanto en la selección de variedades como en el desarrollo de procesos tecnológicos. Los compuestos secoiridoideos, entre los que se incluyen derivados de las agluconas de la oleuropeína, demetiloleuropeína y ligustrósido, son los derivados fenólicos más abundantes en el AOV (Servilli y Montedoro, 2002; Servili et al., 2004). La composición fenólica del AOV depende en buena medida de la variedad de olivo, aunque existen diversos factores como técnicas de cultivo, recolección, conservación y procesado de la aceituna que pueden modificarla (Artajo et al., 2006; Servilli et al., 2004). El efecto de estos factores sobre el perfil fenólico del aceite parece estar estrechamente relacionado con la modificación del nivel de actividad de diferentes enzimas endógenas presentes en el fruto (García et al., 2001; Servili et al., 2007). Durante el proceso de obtención del AOV, por acción de glucosidasas presentes en la aceituna, los principales glucósidos fenólicos son hidrolizados para dar lugar a derivados parcialmente solubles en el aceite, entre los que se encuentran las formas aldehídicas y dialdehídicas de la aglucona de la oleuropeína (AAO y DAOD) y del ligustrósido (AAL y DALD), que por posterior hidrólisis dan lugar a tirosol e hidroxitirosol. En proyectos anteriores se ha aislado y purificado a aparente homogeneidad, una proteína con actividad ß-glucosidasa en pulpa de aceituna que exhibe una potente actividad frente al principal glucósido fenólico de la aceituna, la oleuropeína. Sin embargo, los estudios preliminares sobre las cinéticas de formación y degradación de compuestos fenólicos durante el proceso de obtención del AOV señalan la importancia no sólo de las enzimas implicadas en la formación de compuestos secoiridoideos, como la ß-glucosidasa, sino también el importante papel que juegan las enzima

Virgin olive oil phenolic compounds are responsible for its nutritional and sensory quality. The synthesis of phenolic compounds occurs when enzymes and substrates meet as olive fruit is crushed during the industrial process to obtain the oil. The genetic variability of the major phenolic compounds of virgin olive oil was studied in a progeny of the cross of Picual x Arbequina olive cultivars (Olea europaea L.). They belong to four different groups: compounds that included tyrosol or hydroxytyrosol in their molecules, lignans, flavonoids, and phenolic acids. Data of phenolics in the oils showed that the progeny displayed a large degree of variability, widely transgressing the genitor levels. This high variability can be of interest on breeding programs. Thus, multivariate analysis allowed to identify genotypes within the progeny particularly interesting in terms of phenolic composition and deduced organoleptic and nutritional quality. The present study has demonstrated that it is possible to obtain enough degree of variability with a single cross of olive cultivars for compounds related to the nutritional and organoleptic properties of virgin olive oil. © 2014 Pérez et al.

Synthesis of the aroma compounds of virgin olive oil (VOO) occurs through the lipoxygenase (LOX) pathway comprising mainly the actuation of LOX and hydroperoxide lyase (HPL) enzymes. The aim of this work was to determine whether the cleavage of polyunsaturated fatty acid hydroperoxides catalyzed by HPL is a limiting factor for the biosynthesis of VOO volatile compounds during the oil extraction process. For this purpose, HPL activity and the availability of substrates for this activity were modified during the oil extraction process from olive fruits of cultivars Arbequina and Picual, which give rise to oils with quantitatively different volatile profiles. Experimental data suggest that the HPL enzyme activity is just slightly limited during the oil extraction process in both cultivars, being this limitation apparently more significant during the processing of Arbequina fruits than of Picual fruits. However, this difference in HPL limitation seems to be more related to the differences in the amount of hydroperoxides produced in each cultivar than to the level of HPL activity during the olive processing.

The aim of this work was to determine whether the lipoxygenase (LOX) activity is a limiting factor for the biosynthesis of virgin olive oil (VOO) volatile compounds during the oil extraction process. For this purpose, LOX activity load was modified during this process using exogenous LOX activity and specific LOX inhibitors on olive cultivars producing oils with different volatile profiles (Arbequina and Picual). Experimental data suggest that LOX activity is a limiting factor for the synthesis of the oil volatile fraction, this limitation being significantly higher in Picual cultivar than in Arbequina, in line with the lowest content of volatile compounds in the oils obtained from the former. Moreover, there is evidence that this limitation of LOX activity takes place mostly during the milling step in the process of olive oil extraction. © 2011 American Chemical Society.

The aim of the present work was to establish the limiting factors affecting the biosynthesis of volatile esters present in virgin olive oil (VOO). Oil volatile fractions of the main Spanish olive cultivars, Arbequina and Picual, were analyzed. It was observed that acetate esters were the most abundant class of volatile esters in the oils, in concordance with the high content of acetyl-CoA found in olive fruit, and that the content of C6 alcohols is limited for the synthesis of volatile esters during the production of VOO. Thus, the increase of C6 alcohol availability during VOO production produced a significant increase of the corresponding ester in the oils in both cultivars at two different maturity stages. However, the increase of acetyl-CoA availability had no effect on the VOO volatile fraction. The low synthesis of these C6 alcohols seems not to be due to a shortage of precursors or cofactors for alcohol dehydrogenase (ADH) activity because their increase during VOO production had no effect on the C6 alcohol levels. The experimental findings are compatible with a deactivation of ADH activity during olive oil production in the cultivars under study. In this sense, a strong inhibition of olive ADH activity by compounds present in the different tissues of olive fruit has been observed. © 2012 American Chemical Society.

The main objective of this study was to assess the ability of polyphenol oxidase (PPO) and peroxidase (POX) enzymatic activities present in olive fruit tissues to oxidize main phenolic compounds related to the process to obtain virgin olive oil (VOO) in order to ascertain their involvement in shaping the phenolic profile of this product. In the two olive cultivars under study, Arbequina and Picual, olive PPO activity was found to be largely present in the fruit mesocarp whereas most olive POX activity is in the seed. Moreover, both enzymatic activities display relatively constant values after the onset of fruit ripening when the fruit is harvested for VOO production. Results showed that both PPO and POX activities present in olive fruit at ripening stages are able to oxidize main phenolic glycosides present in the fruit as well as those phenolic compounds arising during the industrial process to obtain the oil, especially secoiridoid compounds derived from oleuropein that mainly determine VOO nutritional and sensorial properties. Experimental data suggest a key role for endogenous olive PPO and POX enzymatic activities in determining the phenolic profile of VOO. © 2010 Elsevier Ltd.

Benefits of virgin olive oil (VOO) consumption are related to protection against cancer and cardiovascular diseases due to its fatty acid profile and presence of minor constituents. However, the increase in the demand for high quality VOO can be attributed not only to its potential health benefits but to its unique sensory properties. The aim of increasing the quality standards for VOO is continuously stimulating the study of biochemical pathways related to sensory properties and the development of technological procedures to improve those sensory properties. In this sense, the limiting factors affecting the biosynthesis of VOO aroma through the lipoxygenase (LOX) pathway were studied. Results suggest that, besides the availability of non-esterified polyunsaturated fatty acids, the biosynthesis of VOO aroma depends mainly on the enzymatic activity load of the LOX/hidroperoxide lyase system during the process to obtain the oil. This enzymatic activity load seems to be cultivar dependent, thus shaping the content of volatile compounds present in the oils from the different olive cultivars.

A full-length cDNA clone (OepHPL) coding for hydroperoxide lyase was isolated from olive fruit (Olea europaea cv. Picual). The deduced amino acid sequence shows significant similarity to known plant hydroperoxide lyases and contains a N-terminal sequence that displays structural features of a chloroplast transit peptide. Genomic Southern blot analysis indicates that at least one copy of OepHPL is present in the olive genome. The recombinant hydroperoxide lyase was specific for 13-hydroperoxide derivatives of linolenic and linoleic acids but did not use 9-hydroperoxy isomers as substrates. Analyses of reaction products revealed that this enzyme produces primarily (Z)-hex-3-enal, which partially isomerizes to (E)-hex-2-enal, from 13-hydroperoxylinolenic acid and hexanal from 13-hydroperoxylinoleic acid. Expression levels were measured in different tissues of Picual and Arbequina varieties, including mesocarp and seed during development and ripening of olive fruits. The involvement of this olive hydroperoxide lyase gene in the biosynthesis of virgin olive oil aroma compounds is discussed.