Commercial Olive Oil Research Articles

Preparation and characterization of nanostructured materials for an artificial olfactory sensing system

Pure and Ni-, Pt-, Pd-, Os-doped tin oxide and pure and Fe-doped indium oxide thin films have been prepared by the sol–gel process. The microstructural properties of the as-prepared films have been investigated by means of X-ray diffraction (XRD). All the samples showed a polycrystalline structure that resulted to be dependent on the presence of the particular doping element. Integrated gas microsensor devices based on both pure and doped sol–gel thin films of these two different metal oxides (SnO 2 and In 2O 3) were realized. They were linked in an array configuration and exposed to the volatile compounds of different commercial olive oils samples in order to test the application of the array in an electronic nose for the discrimination among different commercial olive oils. The differently modified sensitive materials showed different sensing characteristics to the headspace of the olive oil, hence modulating the selectivity of the array. PCA analysis was performed on the array responses and the results showed the capability to discriminate olive oils of different quality.

Polyphenolic content in olive oil waste waters and related olive samples.

The production of olive oil yields a considerable amount of waste water, which is a powerful pollutant and is currently discarded. Polyphenols and other natural antioxidants, extracted from olives during oil extraction process, partially end up in the waste waters. Experimental and commercial olive oil waste waters from four Mediterranean countries were analyzed for a possible recovering of these biologically interesting constituents. Identification and quantitation of the main polyphenols were carried out by applying HPLC-DAD and HPLC-MS methods. Representative samples of ripe olives were also analyzed at the same time to correlate, if possible, their polyphenolic profiles with those of the corresponding olive oil waste waters. The results demonstrate that Italian commercial olive oil waste waters were the richest in total polyphenolic compounds with amounts between 150 and 400 mg/100 mL of waste waters. These raw, as yet unused, matrices could represent an interesting and alternative source of biologically active polyphenols.

Alpha-tocopherol content of Greek virgin olive oils.

alpha-Tocopherol, the main tocopherol homologue found in olive oil, was determined using normal phase HPLC. Ninety Greek virgin olive oils, selected according to a designed sampling protocol from different cultivars and regions all over Greece for three successive crop years, were analyzed. For a specific olive cultivar, which is widely used for the production of olive oil in Greece, additional measurements were made to study the effect of milling conditions on alpha-tocopherol concentration. Finally, a significant number of commercial olive oil samples (25) obtained from the retail market were analyzed. High concentrations of alpha-tocopherol were observed in most of the samples selected from various regions. Values ranging between 98 and 370 mg/kg were found (>200 mg/kg in 60% of samples). Extraction conditions were not found to influence alpha-tocopherol level. alpha-Tocopherol content of retail market samples was high, ranging from 120 to 250 mg/kg of oil (>180 mg/kg in 60% of samples). Storage of samples under domestic conditions for two years showed that good handling is quite important for retaining high alpha-tocopherol levels and for increasing, thus, the storage life and nutritional value of this exquisite oil.

Characterisation of olive oil by an electronic nose based on conducting polymer sensors

The selection and test of an array of conducting polymer sensors with extra-virgin olive oil samples is presented in this paper as a first step towards the development of an electronic nose dedicated to the detection of olive oil aroma. Different sensors produced by both electrochemical and chemical techniques were initially exposed to a set of pure substances present in the headspace of extra-virgin olive oil and meaningful for the evaluation of its overall organoleptic characteristics. Four sensors showing the best sensitivity to these standard substances were chosen to carry out further experiments on samples of commercial olive oil. Two different experimental set-ups and protocols for olive oil sampling were tested and compared, providing evidence on the best procedure needed to handle this foodstuff and on the possibility of using a dedicated sensing system for practical purposes in the olive oil industry. Three different extra-virgin Italian types of olive oil can be easily distinguished with an array of four sensors and it is also possible to detect changes in the aromatic content of the headspace after handling of the samples. Different samples of the same oil show reproducible responses.

Automated flow injection spectrophotometric non-aqueous titrimetric determination of the free fatty acid content of olive oil

An automated flow injection titrimetric method for the determination of olive oil acidity is proposed. A 175 μl olive oil aliquot is injected in a carrier stream (the titrant) of n-propanol containing 7.5 × 10 −4 M KOH and 4.0 × 10 −5 M phenolphthalein indicator. The sample zone is dispersed in the titrant while flowing at 4.4 ml min −1 through a 1.1 ml Plexiglas mixing chamber and the absorbance of the resulting mixture is continuously monitored at 562 nm, λ max , for the basic form of the indicator. The resulting negative absorbance peaks indicate the transition base (red)-acid (colorless)-base (red) of the indicator. Quantitation is based on peak width measurements. Peak widths of 31.7–97 s were measured with a relative standard deviation (RSD) of < 2.1% ( n = 10), and the analytical range was 0.15 – 8.0% (w/w) free fatty acid content calculated as oleic acid. The sampling rate is 30 – 100 h −1 while n-propanol consumption is only 3 – 7 ml per run. Recoveries of oleic acid from commercial olive oils ranged from 97.9 to 101.6% (mean 99.5%). The method was applied for the determination of free fatty acid content of thirty two samples of olive oils. Results obtained by the proposed method compare well (0.3 – 3.6% relative difference, mean 1.5%) with those obtained by the official European Community method that is time consuming and uses gross amounts of organic solvents. Moreover comparison with a Fourier transform infrared (FT-IR) method reveals that by using the proposed method the useful range can be extended to lower concentrations.

Catalytic Behaviour of Lipase Free and Immobilized in Biphasic Membrane Reactor with Different Low Water-Soluble Substrates

The catalytic activity and reaction rate of lipase have been studied using the biocatalyst free in an organic/aqueous emulsion and immobilized in a biphasic organic/aqueous membrane reactor. The first reaction system was realized in a stirred tank reactor. The other was obtained by immobilizing the enzyme in the sponge layer of an asymmetric capillary membrane and recirculating the two phases along the two separate circuits of the membrane module. The performance of the reactors has been studied using two different low water-soluble substrates: triglycerides present in commercial olive oil and (R,S)-cyanomethyl-[2-(4-isobutylphenyl)propionate] (CNE). The effects of substrate viscosity and flow dynamics conditions, such as organic phase flow rate, on the biphasic membrane reactor performance have been evaluated on the basis of observed reaction rate and catalytic activity of free and immobilized lipase for both substrates. It has been observed that free lipase showed higher catalytic activity with olive oil, while immobilized lipase showed higher catalytic activity with CNE which has a lower viscosity than olive oil. The increase of organic phase flow rate negatively affected the reactor performance, with a minor effect when using CNE rather than olive oil. The influence of temperature on the biocatalyst performance with the two substrates has also been investigated. The optimal temperature value of lipase was different for the two substrates: 28°C with CNE and 40°C with olive oil.

Multicomponent phase equilibria of an extra-virgin olive oil in supercritical carbon dioxide

The possibility of using supercritical carbon dioxide to deacidify olive oils without modifying their triglycerides composition has been previously studied. For the design of this extraction process, multicomponent equilibrium data are needed. We have therefore measured the vapor-liquid equilibria of a commercial olive oil in supercritical carbon dioxide at temperatures between 313–353 K and pressures up to 30 MPa. The initial free fatty acid content (expressed in oleic acid) was changed from 3 to 15 wt %. This data was later used to simulate a countercurrent packed column for the deacidification of olive oil, by using a staged-equilibrium model program. Some of the calculated results were compared with previously obtained experimental mass transfer data.

Effect of natural antioxidants in virgin olive oil on oxidative stability of refined, bleached, and deodorized olive oil

AbstractThe factors influencing the oxidative stability of different commercial olive oils were evaluated. Comparisons were made of (i) the oxidative stability of commercial olive oils with that of a refined, bleached, and deodorized (RBD) olive oil, and (ii) the antioxidant activity of a mixture of phenolic compounds extracted from virgin olive oil with that of pure compounds andα‐tocopherol added to RBD olive oil. The progress of oxidation at 60°C was followed by measuring both the formation (peroxide value, PV) and the decomposition (hexanal and volatiles) of hydroperoxides. The trends in antioxidant activity were different according to whether PV or hexanal were measured. Although the virgin olive oils contained higher levels of phenolic compounds than did the refined and RBD oils, their oxidative stability was significantly decreased by their high initial PV. Phenolic compounds extracted from virgin olive oils increased the oxidative stability of RBD olive oil. On the basis of PV, the phenol extract had the best antioxidant activity at 50 ppm, as gallic acid equivalents, but on the basis of hexanal formation, better antioxidant activity was observed at 100 and 200 ppm.α‐Tocopherol behaved as a prooxidant at high concentrations (&gt;250 ppm) on the basis of PV, but was more effective than the other antioxidants in inhibiting hexanal formation in RBD olive oil.o‐Diphenols (caffeic acid) and, to a lesser extent, substitutedo‐diphenols (ferulic and vanillic acids), showed better antioxidant activity than monophenols (p‐ ando‐coumaric), based on both PV and hexanal formation. This study emphasizes the need to measure at least two oxidation parameters to better evaluate antioxidants and the oxidative stability of olive oils. The antioxidant effectiveness of phenolic compounds in virgin olive oils can be significantly diminished in oils if their initial PV are too high.

Analysis of Volatile Organics in Cooking Oils by Thermal Desorption Gas Chromatography-Mass Spectrometry

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTAnalysis of Volatile Organics in Cooking Oils by Thermal Desorption Gas Chromatography-Mass SpectrometrySantford V. Overton and John J. ManuraCite this: J. Agric. Food Chem. 1995, 43, 5, 1314–1320Publication Date (Print):May 1, 1995Publication History Published online1 May 2002Published inissue 1 May 1995https://doi.org/10.1021/jf00053a036RIGHTS & PERMISSIONSArticle Views405Altmetric-Citations29LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (2 MB) Get e-Alerts Get e-Alerts

Development of high‐performance liquid chromatography criteria for determination of grades of commercial olive oils. Part I. The normal ranges for the triacylglycerols

Criteria for authentic olive oils were developed from isocratic high‐performance liquid chromatography analyses of 99 olive oils from the major Mediterranean producers in the 1983–1986 crop years. Authentic olive oils include extra virgin, virgin and pure or refined oils, but exclude all reesterified and adulterated oils. The extra virgin through pure grades will have a combined area for the LOO (C18:2C18:1C18:1), LOP (C18:2C18:1C16:0), OOO (C18:1C18:1C18:1), POO (C16:0C18:1C18:1), POP (C16:0C18:1C18:1), and SOO (C18:0C18:1C18:1) peaks between 82.0 and 92.6% of the total area (L, linoleic; O, oleic; P, palmitic; S, stearic). Authentic oils will have ratios of LOO/LOP and OOO/POO that coincide with a line defined by OOO/POO=0.7844(LOO/LOP)+0.0968; correlation coefficient is 0.885. Authentic oils will not have a trilinolein (LLL) peak over 0.5% in area. Neither triolein (OOO) nor any other single peak suffices to characterize an olive oil sample as one of the authentic grades.

Effect of method of extraction on the total polyphenol, 1,2‐diphenol content and stability of virgin olive oil

AbstractThe effect of the method of olive oil extraction on the total polyphenol, 1,2‐diphenol content and stability of the oil was studied. The total polyphenol and 12,‐diphenol content of oils extracted in commercial olive oil mills was 60% and 45% lower, respectively, than oil extracted on the laboratory scale. A significant difference was found in total polyphenol content between oils obtained by traditional press systems and new continuous systems. The stability of the industrially extracted oil was considerably lower on account of its reduced phenol content.

Migration of dioctylphthalate and dioctyladipate plasticizers from polyvinylchloride films into olive oil

The migration of dioctylphthalate (DOP) and dioctyladipate (DOA) plasticizers from food grade polyvinylchloride (PVC) films into commercial olive oil has been studied. Olive oil was chosen as a fat simulant. Experiments were carried out at 6, 22 and 30°C with and without agitation as a function of time (0–100 h). Two different PVC films were used containing 31·5% DOA and 29·5% DOP, respectively. Results showed a significantly higher amount of plasticizer migration into oil with agitation than without (30% versus 22·2% for DOP after 100 h). The equilibrium amount of DOA migrated was found to be higher than the respective amount of DOP whereas diffusion coefficients determined were slightly higher for DOP than DOA. These findings were related to solubility, compatibility and molecular weight of plasticizer. Data were fitted to the Arrhenius equation and activation energies for diffusion of plasticizers in PVC were calculated.

Chemometrics in food research: Relationships between triglyceride groups and fatty acid composition in olive oil

AbstractThe values (mol %) of the triglyceride Gnu groups, each containing all the molecular species with the same carbon numer and unsaturation, are different for various oils; in this paper, their use for analytical purposes is therefore hypothesized. To this end, the values (mol %) of Gnu groups—with respective means, standard deviations and coefficients of variation‐were first of all established using the l, 3‐random‐2‐random distribution hypothesis on 50 olive oil samples; with these values, along with the relative data of the fatty acid composition, a computer study was carried out to obtain some regression models of use for estimating the Gnu values (mol %) of other olive oil samples. The evaluation of the regression models procedure (RMP) was carried out comparing the values obtained by such a method for 6 other commercial olive oils with those experimentally determined by Ag+‐TLC coupled with direct triglyceride GLC analysis. Moreover, these models were tested with the data of fatty acid composition of 4 different seed oils, providing often negative Gnu values, always different, however, from those of olive oil.

Detection of B‐residue oil in commercial olive oils

Detection of B‐residue oil in commercial olive oils