Occurrence of C15-C45 mineral paraffins in olives and olive oils.

Different classes of olive oils and other olive samples (olives, olive paste and olive pomace) collected during their production were analysed for mineral paraffins in the range of C(15)-C(45). None of the 22 extra virgin olive oils contained mineral paraffins above the detection limit of 1 mg kg(-1). Also, lampante virgin olive oil from the olive mill showed no detectable amounts, but olive oil from the market contained 6-30 mg kg(-1). This contamination cannot be attributed to the refining step, which, on the contrary, partially removes the more volatile hydrocarbons, but could result from transport. Olive-pomace oils obtained by second centrifugation contained 16-145 mg kg(-1) mineral paraffins, presumably because of contamination during storage of the pomace. All olive-pomace oils from solvent extraction contained more than 100 mg kg(-1) mineral paraffins, also mainly from storage. Deposition of particulate matter from the air, vehicle exhaust emissions and direct contamination from the bulldozers used to move the pomace were identified as potential sources.     

Optimised off-line SPE–GC–FID method for the determination of mineral oil saturated hydrocarbons (MOSH) in vegetable oils

An optimised off-line SPE–GC–FID method based on the use of silver-silica gel was developed for the determination of mineral oil saturated hydrocarbons (MOSH) in vegetable oils, including olive pomace oil. The method is specific in not including the aromatic hydrocarbons. The performance of different silica gels (untreated, activated and treated with silver nitrate) was compared in terms of capacity to retain fat and retention of interfering olefins present in particularly large amounts in refined olive oils. A coefficient of variation of 9% was obtained performing six replicate analyses of an extra virgin olive oil fortified with an amount of MOSH near the estimated LOQ (15 mg/kg). Recoveries were close to 100%. The use of activated aluminium oxide as an additional tool to eliminate interference by endogenous long-chain n-alkanes, is discussed.     

Characterisation of phenolic extracts from olive pulp and olive pomace by electrospray mass spectrometry

Methanol extracts of olive pomace (two‐phase olive oil extraction) and olive pulp were analysed by reverse phase HPLC and the eluted fractions were characterised by electrospray ionisation mass spectrometry. This technique allowed the identification of some common phenolic compounds, namely, verbascoside, rutin, caffeoyl‐quinic acid, luteolin‐4‐glucoside and 11‐methyl‐oleoside. Hydroxytyrosol‐1′‐β‐glucoside, luteolin‐7‐rutinoside and oleoside were also detected. Moreover, this technique enabled the identification, for the first time in Olea europaea tissues, of two oleoside derivatives, 6′‐β‐glucopyranosyl‐oleoside and 6′‐β‐rhamnopyranosyl‐oleoside, and of 10‐hydroxy‐oleuropein. Also, an oleuropein glucoside that had previously been identified in olive leaves was now detected in olive fruit, both in olive pulp and olive pomace. With the exception of oleoside and oleuropein, the majority of phenolic compounds were found to occur in equivalent amounts in olive pulp and olive pomace. Oleoside was the main phenolic compound in olive pulp (31.6 mg g^?1) but was reduced to 3.6 mg g^?1 in olive pomace, and oleuropein (2.7 mg g^?1 in the pulp) almost disappeared (<0.1 mg g^?1 in the pomace). Both these phenolic compounds were degraded during the olive oil extraction process. Copyright © 2004 Society of Chemical Industry     

Solvent and enzyme-aided aqueous extraction of goldenberry (<Emphasis Type="Italic">Physalis peruviana</Emphasis> L<Emphasis Type="Italic">.</Emphasis>) pomace oil: impact of processing on composition and quality of oil and meal

Goldenberry pomace (seeds and skins) represent the waste obtained during juice processing (ca. 27.4% of fruit weight). In the present contribution, the potential of goldenberry pomace for use as a substrate for the production of edible oil was evaluated. Toward developing goldenberry as a commercial crop, the results provide important data for the industrial application of goldenberry. Three extraction methods were checked for the best oil yield. The n-hexane-extractable oil (expressed as SE) content of the raw by-products was estimated to be 19.3%. Enzymatic treatment with pectinases and cellulases followed by centrifugation in aqueous system (expressed as EAE) or followed by solvent extraction (expressed as ESE) was also investigated for recovery of oil from pomace fruit. Enzymatic hydrolysis of pomace followed by extraction with n-hexane reduced the extraction time and enhanced oil extractability up to a maximum of ca. 7.60%. Moreover, enzymation followed by solvent extraction increased the levels of protein, carbohydrates, fiber and ash in the remaining meal. The study covers also the chemical composition and some fractional properties of different pomace extracts (EAE, SE and ESE). Concerning the oil composition, there were relatively no changes noted in the fatty acid pattern of the oils extracted with different techniques. Slight alterations in the amounts of other fat-soluble bioactives (i.e., sterols, tocopherols and phenolics) were recorded. The different pomace oils obtained were tested for their radical scavenging activity toward the stable 1,1-diphenyl-2-picrylhydrazyl radical and their oxidative stability. Generally, the quality of solvent extracted oils (ESE and SE) manifested higher radical scavenging activity and oxidative stability than the enzyme-extracted oil (EAE). The levels of polar lipids, unsaponifiables, peroxides and phenolics in different extracts were associated with oxidative stability and radical scavenging activity.     

Determination of 3-monochloropropane-1,2-diol fatty acid esters in Brazilian vegetable oils and fats by an in-house validated method

An in-house validated GC-MS method preceded by acid-catalysed methanolysis was applied to 97 samples of vegetable oils and fats marketed in Brazil. The levels of the compounds ranged from not detected (limit of detection = 0.05 mg kg^?1) to 5.09 mg kg^?1, and the highest concentrations were observed in samples containing olive pomace oil and in products used for industrial applications, such as palm oil and its fractions (olein and stearin). The content of diesters and monoesters was also investigated by employing solid-phase extraction on silica cartridges, indicating that the majority of the compounds were present as diesters. This study provides the first occurrence data on these contaminants in Brazil and the results are comparable with those reported in other countries.     

Contribution of olive seed to the phenolic profile and related quality parameters of virgin olive oil

BACKGROUND: Conflicting results have been reported about the effect of fruit de‐stoning on the virgin olive oil (VOO) phenolic profile. The aim of the present study was to determine whether olive seed plays any role in the synthesis of this oil phenolic fraction. RESULTS: Increases of around 25% of total phenolic compounds were observed in oils obtained from de‐stoned olive fruits in three main Spanish cultivars. To investigate the involvement of olive seed in determining the phenolic profile of VOO, whole intact olive fruits were added with up to 400% olive stones. Excellent regression coefficients were found in general for the decrease of total phenolic compounds and, particularly, of o‐diphenolics in the resulting oils. On the other hand, it was found that olive seed contains a high level of peroxidase (POX) activity (72.4 U g^?1 FW), accounting for more than 98% of total POX activity in the whole fruit. This activity is able to modify VOO phenolics in vitro, similar to the effect of adding stones during VOO extraction. CONCLUSION: Olive seed plays an important role in determining VOO phenolic profile during the process to obtain an oil that seems to be associated with a high level of POX activity. Copyright © 2007 Society of Chemical Industry     

Estimation of the intake of phenol compounds from virgin olive oil of a population from southern Spain

The objective of the study was to determine the mean polyphenol composition of different varieties of virgin olive oil (VOO) habitually consumed in the region of southern Spain and to estimate the dietary exposure to olive oil polyphenols in that population. There were statistically significant differences in total polyphenols among varieties, with the Picual variety containing the largest amount with a mean value of 591.8 mg kg^–1. The main phenolic compounds found in the VOOs under study were tyrosol and hydroxytyrosol. The highest amounts of both substances were found in Picual olive oils with concentrations of 2.3–6.6 mg kg^?1. The total intake of polyphenols from VOO ranged between 8.2 mg day^–1 (SD = 4.14) for the under 19 year olds and 21.3 mg day^–1 (SD = 3) for the over 50 year olds. Some polyphenols, including tyrosol and hydroxytyrosol, were consumed principally as olive oil. The intake of these compounds in the studied population was in the range of 88.5–237.4 μg day^–1. This has particular importance as recent studies have demonstrated that hydroxytyrosol helps to improve plasma lipids levels and repair oxidative damage related to cardiovascular disease. There was a greater dietary consumption of polyphenols in olive oil among the participants who more closely followed the Mediterranean diet pattern. A higher consumption of olive oil and therefore a greater exposure to polyphenols was observed in females versus males and in participants of normal weight versus those who were overweight. The total intake of polyphenols from VOO significantly increased with higher age, reflecting the greater intake of this oil by older people, who also show a closer adherence to the Mediterranean diet. The over 50-year-old age group showed the greatest consumption of this olive oil and therefore of phenolic compounds, which are healthy protectors in the human diet that contribute to the acknowledged benefits of the Mediterranean diet.     

Waxy fraction containing long-chain aliphatic aldehydes in virgin olive oils

Long-chain aliphatic aldehydes are natural minor components occurring in the cuticle of numerous plant species and also evidenced in virgin olive oils. The fraction containing these compounds can be isolated from the oil samples by using a solid-phase extraction silica-gel cartridge and then directly analysed by GC on a 5% diphenyl-95% dimethylsiloxane capillary column, using an on column-injection system. The proposed methodology showed that extra virgin olive oils contain long-chain aliphatic aldehydes, with even carbon-atom numbers from C₂₂ to C₃₀. Quantitative results, using the synthesised aldehyde C₂₁ as internal standard, give concentrations of total long-chain aliphatic aldehydes in a variable range below 116 mg kg⁻¹, being hexacosanal (C₂₆-al) the most abundant aldehyde. The different experimental conditions utilised during olive oil extraction processes influence the total aldehydes concentration. Besides contribution to the knowledge of the minor-component composition present in olive oil, their interest and relationship with wax esters, aliphatic alcohols and n-alkanes are discussed.     

Estimation of olive oil acidity using FT-IR and partial least squares regression

Olive oil characteristics are directly related to olive quality. Information about olive quality is of paramount importance to olive and olive oil producers, in order to establish its price. Real-time characterization of the olives avoids mixtures of high quality with low quality fruits, and allows improvement of olive oil quality. This work describes an indirect determination of olive acidity and that allows a rapid evaluation of olive oil quality. The applied method combines chemical analysis (30 min Soxhlet olive pomace extraction) in tandem with a spectroscopic technique (FT-IR) and multivariate regression (PLS1). The most suitable calibration model found used SNV pre-processing and was built with 4 Latent Variables giving a RMSECV of 8.7% and a Q² of 0.97. This accurate calibration model allows the estimation of olive acidity using a FT-IR spectrum of the corresponding Soxhlet oil dry extract and therefore is a suitable method for indirect determination of FFA in olives.     

Migrated phthalate levels into edible oils

The determination of phthalates in edible oils (virgin olive oil, olive oil, canola oil, hazelnut oil, sunflower oil, corn oil) sold in Turkish markets was carried out using gas chromatography–mass spectrometry. Mean phthalate concentrations were between 0.102 and 3.863 mg L^?1 in virgin olive oil; 0.172 and 6.486 mg L^?1 in olive oil; 0.501 and 3.651 mg L^?1 in hazelnut oil; 0.457 and 3.415 mg L^?1 in canola oil; 2.227 and 6.673 mg L^?1 in sunflower oil; and 1.585 and 6.248 mg L^?1 in corn oil. Furthermore, the influence of the types of oil and container to the phthalate migration was investigated. The highest phthalate levels were measured in sunflower oil. The lowest phthalate levels were determined in virgin olive oil and hazelnut oil. The highest phthalate levels were determined in oil samples contained in polyethylene terephthalate.     

Addition of enzymes complex during olive oil extraction improves oil recovery and bioactivity of Western Australian Frantoio olive oil

Olive oil consumption has increased as many studies revealed the health benefits of regular consumption of olive oil. There is a need to find effective oil extraction techniques capable of increasing oil recovery without compromising its quality. This study investigated the impact of adding enzymes complex Viscozymes during olive oil extraction on oil recovery, total phenolic compounds, antiradical activity and the standard quality parameters. It was found that at a concentration of 0.30 g mL^?1, Viscozymes could significantly improve the oil recovery from 49 to 69% (P < 0.001) when compared to the Control sample. The concentration of total phenolic compounds was also significantly improved from 110 to 266 mg kg^?1 oil (P < 0.01) and the antiradical activity increased from 31 to 48% inhibition of 2,2‐diphenyl‐1‐picrylhydrazil radical (P < 0.001). Addition of Viscozymes therefore represents an effective extraction technique that increases oil recovery without compromising the concentration of total phenolic compounds and antiradical activity.     

Determination of high molecular mass polycyclic aromatic hydrocarbons in refined olive pomace and other vegetable oils

A new and simple method has been developed for determining high molecular mass polycyclic aromatic hydrocarbons (PAHs) in refined olive pomace, and other vegetable oils from an initial sample of 0.25 g. The hydrocarbon fraction is isolated by solid‐phase extraction (SPE) on silica gel using hexane as eluent. The fraction is evaporated to reduced volume and cleaned‐up by SPE on an amino phase eluting with toluene. The evaporated residue, dissolved in acetonitrile, is analyzed by reverse‐phase high‐performance liquid chromatography with fluorescence detector using programmed excitation and emission wavelengths. The benzo(e)pyrene is determined together with other usual heavy PAHs. Interferences due to squalene and other hydrocarbons are minimized. Recoveries were greater than 80% and detection limits ranged from 0.01 to 0.2 µg kg^?1. The method was validated using certified oil samples and was applied to various vegetable oils. Copyright © 2004 Society of Chemical Industry     

Gas chromatography screening of bioactive phytosterols from mono-cultivar olive oils

Phytosterols (PS) from nine samples of olive oil from Olea europaea L., the Carolea, Cassanese and Coratina mono-cultivars, have been analyzed by gas chromatography. Coratina virgin olive oil (VOO) from the month of November showed highest contents of β-sitosterol (5491 mg kg⁻¹) and Δ⁵ avenasterol (1767 mg kg⁻¹). Olive pomace oil had the lowest total content of all PS, when compared to VOO. These results suggests that, PS can be an important regulatory factor for the functional quality of olive oil along the agro-industry chain from the orchard to nutraceutical.     

Transfer of phenolic compounds during olive oil extraction in relation to ripening stage of the fruit

The transfer of phenolic compounds of Olea europaea L. cv. Arbequina variety during olive oil extraction in relation to ripening stage was investigated. The parameters of oil extraction by the Abencor system are shown together with mass balances of the products and by products from the olive oil extraction in relation to olive paste. The phenolic compounds in olive paste, pomace, oil and wastewater were identified and measured by HPLC. Throughout the study, the concentrations of simple phenols, secoiridoids and flavonoids were higher in the olive paste and pomace phases than in oil and wastewater phases. High concentrations of 4‐(acetoxyethyl)‐1,2‐dihydroxybenzene (3,4‐DHPEA‐AC) and secoiridoid derivatives such as the dialdehydic form of elenolic acid linked to 3,4‐DHPEA (hydroxytyrosol) or p‐HPEA (tyrosol) (3,4‐DHPEA–EDA, p‐HPEA–EDA, where EDA is elenolic acid dialdehyde) and an isomer of oleuropein aglycone (3,4‐DHPEA–EA, where EA is elenolic acid aldehyde) were found in olive oil, together with lignan compounds. It was observed that 3,4‐DHPEA–EDA was the most abundant polyphenol present in the wastewater phase. This indicates that biotransformation occurred during olive extraction, especially in the crushing and malaxation operations, and reflects the possible chemical changes that lead to the formation of new compounds. Moreover, the distribution of compounds showed their affinities toward different phases. Copyright © 2005 Society of Chemical Industry     

Functional compounds from olive pomace to obtain high‐added value foods – a review

Olive pomace, the solid by‐product from virgin olive oil extraction, constitutes a remarkable source of functional compounds and has been exploited by several authors to formulate high value‐added foods and, consequently, to foster the sustainability of the olive‐oil chain. In this framework, the aim of the present review was to summarize the results on the application of functional compounds from olive pomace in food products. Phenolic‐rich extracts from olive pomace were added to vegetable oils, fish burgers, fermented milk, and in the edible coating of fruit, to take advantage of their antioxidant and antimicrobial effects. Olive pomace was also used directly in the formulation of pasta and baked goods, by exploiting polyunsaturated fatty acids, phenolic compounds, and dietary fiber to obtain high value‐added healthy foods and / or to extend their shelf‐life. With the same scope, olive pomace was also added to animal feeds, providing healthy, improved animal products. Different authors used olive pomace to produce biodegradable materials and / or active packaging able to increase the content of bioactive compounds and the oxidative stability of foods. Overall, the results highlighted, in most cases, the effectiveness of the addition of olive pomace‐derived functional compounds in improving nutritional value, quality, and / or the shelf‐life of foods. However, the direct addition of olive pomace was found to be more challenging, especially due to alterations in the sensory and textural features of food. © 2020 Society of Chemical Industry     

Optimisation of extra virgin olive oil quality

This study investigated the correlation between total polyphenol content and the stability (ie induction time by Rancimat) of oil samples according to different regions, cultivars, extraction technologies and ripening times of raw material. Results indicate a correlation of oil stability with total polyphenols, (r=0·88), a chemical variable easy to determine. We have set up an oil quality index as a measure of desirability including legal parameters, especially the Council Olive Oil International score (COI Score), stability (phenol content) and process yield into account. The study of the effects of olive ripening and storage prior to processing and olive paste mixing times and temperatures on the quality index using an experimental factorial design (2⁴) were investigated. The process variables selected in the experimental factorial design were studied and the main effects on desirability were identified. Based on this information, the extraction process was optimised for quality index in relation to fruit ripening and olive paste mixing time using a response contour to identify optimal experimental conditions. This innovative procedure shows that process conditions can be optimised as a function of D_tot, evaluated according to scientific determinations. © 1998 SCI.     

Chemical composition of Arbequina virgin olive oil in relation to extraction and storage conditions

The chemical composition of virgin olive oils from Arbequina olives cultivated in Córdoba (Argentina) was studied in relation to the oil extraction system and production year. Significant variations were found between oils obtained by pressure (PEOs) and centrifugation (CEOs) systems. PEOs were characterised by higher values of acidity, pigments and oleic acid, while CEOs showed greater phenol content. Moreover, a significant effect of crop year was observed. Arbequina oils produced in Córdoba contained lower amounts of oleic acid but higher amounts of phenolic compounds than Arbequina oils produced in Spain. A storage stability test was carried out in order to study the combined effects of oil extraction system and storage conditions (packaging material and illumination) on quality indices related to oxidative stability. Multivariate analysis applied to the chemical data emphasised the differences between PEOs and CEOs, indicating that variations due to extraction system were greater than those due to illumination condition and package type. Cluster analysis of oils from each extraction system stressed the influence of illumination condition on the oxidative stability of olive oils, showing increased amounts of secondary oxidation products in oils exposed to light. Glass and tin packages appear to be the most appropriate containers for maintaining the quality of olive oils, but this supposition is strongly dependent on the type of oil (PEO or CEO) and its initial chemical properties. Copyright © 2006 Society of Chemical Industry     

Simple phenolic content in olive oil residues as a function of extraction systems

Olive oil residues were tested for their composition in simple phenolic compounds as a function of the extraction system, i.e. the three- and two-phase centrifugation systems. Phenolic compound extraction with ethyl acetate was efficient and allowed recovery of 28.8 and 42.2% of total phenols present in dry olive oil residues originating from three-phase and two-phase systems, respectively. The qualitative and quantitative HPLC analyses of the extracts showed that hydroxytyrosol and p-tyrosol were the most abundant phenolic compounds. p-coumaric, caffeic, ferulic and vanillic acids were also present. The phenolic extract from the two-phase system had the highest concentration in hydroxytyrosol (1.16% (w/w) dry residue) and the strongest antioxidant activity. Olive oil residues were confirmed as a cheap source of large amounts of natural phenolic antioxidants.     

Nutraceutical potential of olive pomace: insights from cell-based and clinical studies

Olive oil production yields a substantial volume of by-products, constituting up to 80% of the processed fruits. The olive pomace by-product represents a residue of significant interest due to the diverse bioactive compounds identified in it. However, a thorough characterization and elucidation of the biological activities of olive pomace are imperative to redirect its application for functional food, nutraceutical, and pharmaceutical purposes both for animals and humans. In this review, we examine data from experimental models, including immortalized human vascular endothelial cells, human corneal and conjunctival epithelial cells, human colorectal adenocarcinoma cells, non-tumorigenic human hepatoma cells, and murine macrophages alongside clinical trials. These studies aim to validate the safety, nutritional value, and pharmacological effects of olive pomace. In vitro studies suggest that biophenols extracted from olive pomace possess antioxidant, anti-inflammatory, and antiproliferative properties that could be beneficial in mitigating cardiovascular disorders, particularly atherosclerosis, hepatosteatosis, and dry-eye disease. Protective effects against dry-eye disease were confirmed in a mouse model assay. Olive pomace used in the feed for fish and poultry has demonstrated the ability to enhance animals' immunity and improve nutritional quality of meat and eggs. Human clinical trials are scarce and have revealed minimal biological changes following the consumption of olive pomace-enriched foods. However, alterations in certain biomarkers tentatively suggest cardioprotective properties. The review underscores the value of olive pomace while addressing potential drawbacks and future perspectives, with a specific focus on the need for further investigation into the animal feed and human nutritional properties of olive pomace. © 2024 Society of Chemical Industry.     

Temperature dependence of the autoxidation and antioxidants of soybean, sunflower, and olive oil

Effects of temperature on the autoxidation and antioxidants changes of soybean, sunflower, and olive oils were studied. The oils were oxidized in the dark at 25, 40, 60, and 80 °C. The oil oxidation was determined by peroxide (POV) and p-anisidine values (PAV). Polyphenols and tocopherols in the oils were also monitored. The oxidation of oils increased with the oxidation time and temperature. Induction period decreased with the oxidation temperature; 87 and 3.6 days at 25 and 60 °C, respectively, for sunflower oil. The activation energies for the autoxidation of soybean, sunflower, and olive oils were 17.6, 19.0, and 12.5 kcal/mol, respectively. Olive oil contained polyphenols at 180.8 ppm, and tocopherols were present at 687, 290, and 104 ppm in soybean, sunflower, and olive oils, respectively. Antioxidants were degraded during the oil autoxidation and the degradation rates increased with the oxidation temperature of oils; for tocopherols, 2.1 × 10⁻³ and 8.9 × 10⁻²%/day at 25 and 60 °C, respectively, in soybean oil.