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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.

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.

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.

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.

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.

Localized irrigation, which wets a part of the root zone only, is widely used in olive orchards. The effect of partial wetting of the root zone on plant performance is unknown. The aim of this work was to compare fruit and oil yields in olive trees under localized irrigation (LI treatment) to those from trees with the whole root zone under non-limiting soil water conditions (Pond treatment). The LI trees received enough water to replace the crop water needs. The study was made for three consecutive years in mature 'Manzanilla de Sevilla' olive trees growing under field conditions. Main variables were also measured in young trees of the same cultivar growing in 50. L pots. Samples from rain-fed trees were also analysed. The LI trees showed similar water status than the Pond trees, but reduced stomatal conductance. As expected, the effect of the irrigation treatments on net photosynthesis was less evident. We observed a decrease in fruit yield in the LI trees, as compared to the Pond trees, likely because of the reduced gas exchange. No differences between the LI and Pond treatments were found for fruit weight, pulp:stone ratio, volume and the longitudinal and equatorial diameters. The LI treatment did not cause detrimental effect either on total oil content or virgin olive oil yield. The phenols content was greater in the LI treatment, but the (E)-hex-2-enal, one of the major volatile compounds and most related to the positive attributes of olive oil, was lower. No significant differences with the Pond treatment were found, however, in the sensory description of the oil flavours.

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.