Volatile Compounds Of Virgin Olive Oil Research Articles

Virgin Olive Oil Volatile Compounds: Composition, Sensory Characteristics, Analytical Approaches, Quality Control, and Authentication.

Volatile organic compounds strongly contribute to both the positive and negative sensory attributes of virgin olive oil, and more and more studies have been published in recent years focusing on several aspects regarding these molecules. This Review is aimed at giving an overview on the state of the art about the virgin olive oil volatile compounds. Particular emphasis was given to the composition of the volatile fraction, the analytical issues and approaches for analysis, the sensory characteristics and interaction with phenolic compounds, and the approaches for supporting the Panel Test in virgin olive oil classification and in authentication of the botanical and geographic origin based on volatile compounds. A pair of detailed tables with a total of approximately 700 volatiles identified or tentatively identified to date and tables dealing with analytical procedures, sensory characteristics of volatiles, and specific chemometric approaches for quality assessment are also provided.

Changes in Virgin Olive Oil Volatiles Caused by in Vitro Digestion.

Volatile compounds are responsible for some sensory characteristics of virgin olive oil (VOO); however, they have not been studied from a nutritional point view. In this work, the effect of the simulated digestion on VOO volatile compounds responsible for green flavor was studied, analyzing their changes through the three steps of an in vitro digestion model (mouth, stomach, and small intestine). Index of recovery and bioaccessibility were determined for the main volatiles of "Picual" VOO. At end of the duodenal step, higher recoveries of ethanol, pent-1-en-3-ol, β-ocimene, and nonanal were observed. From the 10 volatile compounds analyzed, only six compounds were bioaccessible. The compounds with the highest bioaccessibility were pent-1-en-3-ol, nonanal, β-ocimene, and ethanol. The results showed for the first time the recovery and bioaccessibility of several volatile compounds present in VOO.

Temporal changes of virgin olive oil volatile compounds in a model system simulating domestic consumption: The role of biophenols

Virgin olive oil (VOO) aroma is one of the main quality attributes, to be maintained and preserved from the production to the use. We investigated the changes in VOO volatile compounds in a model system, made by refined olive oil spiked with selected VOO volatile molecules representative of its aroma, and the effect of VOO phenolic compounds addition upon storage to simulate the home consumption. Storage up to 7days was carried out under conditions simulating the home-use/storage of the oil, at 10°C in darkness, by sampling periodically an aliquot of oil by opening the bottle. SPME–GC/MS was used to quantify headspace concentration of 12 target volatile compounds. Storage resulted in a general lowering of most of the key aroma compounds. The presence of phenolic compounds resulted in a lower loss (17–44%) of aroma compounds with respect to the system without phenolics, whereas the strength of the effect depended upon the chemical classes and specific volatile compounds considered. Our results showed how the volatiles changes in 1week of use and that biophenols reduce the loss of positive odor notes of VOO also during home/restaurant consumption and storage once the bottle is opened.

EFFECT OF DIFFERENT IRRIGATION REGIMES ON QUALITY OF VIRGIN OLIVE OIL

An experiment was carried out in a high-density olive (Olea europaea L. 'Frantoio') orchard in Tuscany over two growing seasons to compare the effect of three different irrigation regimes on virgin olive oil (VOO) quality. Subsurface drip irrigation was used to supply 100% (FI), 46-48% (DI) or 2-6% (CI) of water needs for about 14 weeks during the summer. The irrigation regime had no effect on fatty acids composition of VOO and the unsaturated/saturated and mono-unsaturated/poly-unsaturated ratios. On the contrary, FI trees yielded oils with lower concentrations of total phenols and ortho-diphenols than those obtained from severely stressed trees (55 and 40% of CI oils, respectively). Over the two-year period regulated deficit irrigation allowed to recover 85 and 84% of total phenols and ortho-diphenols, respectively, of the maximum concentrations yielded by CI trees. Tree water status had a marked effect on the concentrations of volatile compounds. In particular, oils from CI trees had lower concentration of alcohols and esters than FI oils (28 and 38%, respectively), whereas no significant differences were observed between FI and DI oils. These results show that deficit irrigation can be used to optimize the concentration of phenolic and volatile compounds in VOO.

Synthesis of aroma compounds of virgin olive oil: Significance of the cleavage of polyunsaturated fatty acid hydroperoxides during the oil extraction process

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.

Volatile Compounds, Profiles of Virgin Olive Oils Produced In the Eastern Morocco: Oxidative Stability and Sensory Defects

<p>Studies on flavor profiles of virgin olive oil (VOO) are becoming more and more numerous. The VOO aromas are determined by a mixture of chemicals in olive oil, which influence its quality. Various studies around the world have shown that the volatile compounds in VOO depend on the climate, cultivation and process.</p> <p>The present work is a first approach to compare volatile profiles of VOO largely produced in eastern of Morocco after 6 months of storage at ambient temperature in darkness. Oxidative stability measured by Rancimat method at 101C was also determined. VOO volatile profiles were examined using the solid-phase micro extraction fibre method (SPME) in conjunction with gas chromatography/mass spectrometer (GC/ MS). 84 volatile compounds were identified; they belong to various chemical classes, such as aldehydes, alcohols, esters, ketones, carboxylic acids and hydrocarbons. The main volatile compounds present in olive oil samples were compounds with 6 carbon atoms (C6) such as Hexanal, (E)-hex-2-enal, Z-3-Hexen-1-ol and 1-Hexanol. Ethanol and Z-3, 7-dimethyl-1, 3, 6-octatriene, methyl acetate and ethyl acetate were also found. In general, these compounds have been identified in all VOO analyzed samples. The chemical compositions of the analyzed virgin olive oil headspaces evidenced that the most representative compounds In Isly and Kenine were carboxylic acids accounted for 59.24%-49.7% respectively, whereas the volatile fraction of the oil from Achajara almoubaraka showed significantly higher amounts of the alcohols (46%). Concerning oxidative stability, Isly and Kenine OO, have lower stability values compared to Achajara almoubaraka. Their potential oxidative susceptibility is therefore much higher than Achajara almoubaraka.</p>

Thermal Inactivation Kinetics of Recombinant Proteins of the Lipoxygenase Pathway Related to the Synthesis of Virgin Olive Oil Volatile Compounds

The aim of this work was to characterize the thermal inactivation parameters of recombinant proteins related to the biosynthesis of virgin olive oil (VOO) volatile compounds through the lipoxygenase (LOX) pathway. Three purified LOX isoforms (Oep2LOX1, Oep1LOX2, and Oep2LOX2) and a hydroperoxide lyase (HPL) protein (OepHPL) were studied. According to their thermal inactivation parameters, recombinant Oep1LOX2 and Oep2LOX2 could be identified as the two LOX isoforms active in olive fruit crude preparations responsible for the synthesis of 13-hydroperoxides, the main substrates for the synthesis of VOO volatile compounds. Recombinant Oep2LOX1 displayed a low thermal stability, which suggests a weak actuation during the oil extraction process considering the current thermal conditions of this industrial process. In addition, recombinant OepHPL could be identified as the HPL activity in crude preparations. The thermal stability was the highest among the recombinant proteins studied, which suggests that HPL activity is not a limiting factor for the synthesis of VOO volatile compounds.

Monitoring of virgin olive oil volatile compounds evolution during olive malaxation by an array of metal oxide sensors

In addition to the sanitary aspects of production and the genetic and/or geographic origin of the drupes olive malaxation is a critical control point of virgin olive oil (VOO) production from a qualitative point of view. In particular the sensory peculiarities of malaxation are determined by the presence of C 6 and C 5 aldehydes and alcohols in the VOO head space due to lipoxygenase activity. On-line monitoring of the evolution of these substances during VOO processing could be very useful for defining the operative conditions of malaxation (i.e. time and temperature) in order to improve the VOO sensory quality according to product type. In this study, a MOS sensor array (electronic nose) was connected to the malaxer chamber during malaxation of olive pastes for the on-line monitoring of the accumulation of volatile compounds in the head space. To verify the validity of the electronic nose data, the same olive pastes were analyzed by HS-SPME-GC/MS for comparing sensor response and volatile compound production. For all the varieties considered (Ogliarola, Coratina and Frantoio Cvs.), the results illustrated a high potential for gas sensor technology since a high correlation was observed between the conductivity determined by the electronic nose and the level of the most important VOO volatile compounds, such as E-2-Hexenal, Hexanal, Z-3-Hexen-1-ol, E-2-Hexenol.

Comparative study on volatile analysis of extra virgin olive oil by dynamic headspace and solid phase micro-extraction

The dynamic headspace thermal desorption (DHS-TD) apparatus using Tenax-TA and Carbotrap-300 traps, connected to a gas chromatography (GC)-ion trap-mass spectrometry (MS) equipment, as well as the solid phase micro-extraction (SPME) tool, with polydimethylsiloxane (PDMS) and polydimethylsiloxane-divinylbenzene (PDMS-DVB) fibers and connected to a GC-time of flight-MS equipment were implemented for the isolation and identification of virgin olive oil volatile compounds under various sampling conditions. Applying the DHS-TD Tenax-TA procedure separated a higher number of compounds compared to the SPME-PDMS-DVB, which on the other hand required shorter total times for the analysis. High ratio of gas flow rate/amount of oil gave better results for DHS-TD, while a high ratio of headspace/amount of oil worked better for SPME. PDMS exhibited a low sensitivity to olive oil polar volatile compounds while PDMS-DVB showed the overall best sensitivity for all classes of volatile compounds. Results indicate that SPME may find a wide application as an analytical technique for quick analysis of quality related volatile compounds of olive oil. The analyses performed on the GC-TOF-MS-system demonstrated high sensitivity and also high selectivity due to the high quality of mass spectra obtained. The SPME-GC/TOFMS technique appears to be faster and simpler than DHS-TD/GC/MS but the latter provides higher efficiency.

Analysis of virgin olive oil volatile compounds by headspace solid-phase microextraction coupled to gas chromatography with mass spectrometric and flame ionization detection

The efficiency of headspace solid-phase microextraction (SPME) was evaluated for the qualitative and semi-quantitative analysis of virgin olive oil volatile compounds. The behaviour of four fibre coatings was compared for sensitivity, repeatability and linearity of response. A divinylbenzene–Carboxen–polydimethylsiloxane fibre coating was found to be the most suitable for the analysis of virgin olive oil volatiles. Sampling and chromatographic conditions were examined and the SPME method, coupled to GC with MS and flame ionization detection, was applied to virgin olive oil samples. More than 100 compounds were isolated and characterised. The presence of some of these compounds in virgin olive oil has not previously been reported. The main volatile compounds present in the oil samples were determined quantitatively.

Effect of fruit stone removal on the production of virgin olive oil volatile compounds

To verify if the quantitative composition of volatiles arising from lipoxygenase pathway was affected by the olive fruit stones, oils from whole olives and from the pulp-only tissues, respectively, were submitted to gas chromatographic determination of volatile compounds extracted by dynamic head-space. Results showed different quantitative compositions for the two oil kinds because of the greater accumulation of C 6 compounds from the lipoxygenase pathway in oils obtained from de-stoned olives, which is related to serious cellular disruption observed in the crushed pulp tissues. C 5 compounds were affected by the stone removal from fruits. Furthermore, the enzymatic oxidation of linoleic acid was promoted in oils obtained after removing fruit stones because of the more significant increase of the concentrations of corresponding C 6 metabolites.

Virgin olive oil volatile compounds from lipoxygenase pathway and characterization of some italian cultivars.

Fruits from seven different varieties of Olea europaea L., grown in the same environmental conditions, were harvested in two succeeding years at the same ripening degree and immediately processed. The oils obtained were submitted to gas chromatographic determination of the volatile compounds extracted by dynamic headspace technique. The results demonstrated that the accumulation of the different metabolites in the oils obtained from the various cultivars were strictly connected with the varietal parameter because of the enzyme differences genetically determined. This feature made possible the differentiation of the examined cultivars on the basis of the percent of each metabolite from the enzymatic transformation of 13-hydroperoxides of linolenic acid. Oils from Picual and Koroneiki varieties cultivated in Spain and Greece, respectively, showed contents of volatiles very similar to those detected in the oils of the same varieties cultivated in Italy, proving that they were not significantly influenced by the environmental conditions.