Compounds In Olive Oil Research Articles

Towards new analyses of aroma and volatiles to understand sensory perception of olive oil

AbstractThe rich flavor of virgin olive oil (VOO) is one of the reasons why it stands out as a gourmet product. The classification of olive oils into quality categories basically relies on the sensory assessment, together with some chemical indices that do not provide information about aroma or taste. Some analytical techniques attempt to analyze the volatile compounds of olive oil, which are actually responsible for the aroma, and give objective chemical information that can explain the sensory perception. They are based on gas chromatography (GC) and gas sensor, such as metal oxide semiconductor (MOS) sensors. In both cases, the chemical data should be interpreted from a sensory perspective, considering the impact of each compound on aroma and trying to get as much information as possible with new data processing. In the case of MOS sensors, the coupling of a GC column allows gaining more information on aroma. Despite the extensive knowledge on the volatile compounds of olive oil, these techniques still fail in reproducing some results of the panellists. The physiological processes implied in the olfaction needs to be explored with new approaches to understand the sensory perception. These new approaches will support the alternatives to sensory assessment.

Effect of growing location, malaxation duration and citric acid treatment on the quality of olive oil

The total phenolic compounds of olive oil exert antiradical activity at cellular level and can prevent cardiovascular disease, metabolic syndrome and cancer. Increased awareness of its health benefits has increased the consumption of olive oil around the world. An alternative processing technique effective in increasing the amount of oil extracted while maintaining the oil quality is needed to meet the rising global demand for olive oil. Addition of 0.3 g mL(-1) citric acid at 1:1000 (v/w) to olive paste followed by a 30 min malaxation period significantly increased the oil recovery, concentration of total phenolic compounds and antiradical activity by 46.23, 120.27 and 31.48% respectively. While there was no significant effect on the acidity, the peroxide value was significantly reduced by 63.85%. The organoleptic characteristics of the olive oil extracted with citric acid were also comparable to those of the control. Addition of 0.3 g mL(-1) citric acid (i.e. 30% w/v) at 1:1000 (v/w) to olive paste followed by a 30 min malaxation period in a Blixer(®) 4.0 blender is the most promising extraction technique to improve the oil recovery, concentration of total phenolic compounds and antiradical activity of the extracted olive oil without compromising other quality parameters.

The influence of the malaxation temperature on the activity of polyphenoloxidase and peroxidase and on the phenolic composition of virgin olive oil

The effect of the malaxation temperature under sealed conditions on the qualitative and quantitative composition of the phenolic compounds in virgin olive oils produced from four Italian cultivars was assessed for two atmospheric conditions. In both cases, the results show a positive relationship between temperature and the concentration of the derivatives of the secoiridoid aglycones; the effect of the temperature on the oxidoreductases that promote oxidation (polyphenoloxidase and peroxidase) was investigated to determine their optimal temperatures and thermal stability. While olive peroxidase (POD) showed the highest activity at 37°C and high stability in the temperature range tested, polyphenoloxidase (PPO) exhibited the optimum activity at approximately 50°C, but showed low stability at 40°C, with a large variation in stability according to the olive cultivar. These results may contribute to an understanding of the increase in the phenol concentration found in virgin olive oils obtained following higher temperatures of malaxation.

Jubilee conference on fats and oils held in the Czech Republic

Scatter plot for scores of olive oil compounds based on the first two canonical discriminant functions separating ripeness stages (a), using all data except sterol data (1, MI1; 2, MI2; 3, MI3; 4, MI4); (b), using all data including sterol data (1, MI2; 2, MI3; 3, MI4), and cultivar (c) (1, Cordovil MVOOs; 2, Carraquinha MVOOs; 3, Verdeal MVOOs; 4, Negrinha do Freixo MVOOs).

Analysis of Total Contents of Hydroxytyrosol and Tyrosol in Olive Oils

The most abundant phenolic compounds in olive oils are the phenethyl alcohols hydroxytyrosol and tyrosol. An optimized method to quantify the total concentration of these substances in olive oils has been described. It consists of the acid hydrolysis of the aglycons and the extraction of phenethyl alcohols with a 2 M HCl solution. Recovery of the phenethyl alcohols from oils was very high (<1% remained in the extracted oils), and the limits of quantification (LOQ) were 0.8 and 1.4 mg/kg for hydroxytyrosol and tyrosol, respectively. Precision values, both intraday and interday, remained below 3% for both compounds. The final optimized method allowed for the analysis of several types of commercial olive oils to evaluate their hydroxytyrosol and tyrosol contents. The results show that this method is simple, robust, and reliable for a routine analysis of the total concentration of these substances in olive oils.

Changes in volatile compounds and oil quality with malaxation time of Tunisian cultivars of Olea europea

SummaryWhile there has been considerable work examining the effect of malaxation time on different characteristics of olive oils, there have been few that deal with all the major aspects. Here, the influence of malaxation time was evaluated using major local Tunisian (cv. Chemlali and Chetoui) cultivars. Standard characteristics were measured as well as detailed analyses of volatile compounds were conducted. Headspace solid‐phase microextraction (HS‐SPME) was applied to the analysis of volatile compounds of virgin olive oils from Chemlali and Chetoui varieties with differing malaxation time. Twenty‐seven compounds were characterised by GC‐FID and GC–MS. Compounds belonging mainly to alcohols, esters, aldehydes, ketones and hydrocarbons chemical classes characterized the volatile profile. Significant differences in the proportion of volatiles from oils of different malaxation time were detected. The results suggest that besides genetic factors, malaxation time influences volatile formation. The main variables that were affected by malaxation time were the total amount of phenols and composition of the volatile compounds. At malaxation time of 30 min, Chemlali and Chetoui olive oils presented the highest total phenol content (244.19 and 877.63 mg kg−1, respectively), while the lowest content was observed at 60 min from regardless of cultivars. In turn, this influenced the oxidative stability and peroxide value. It was also clear that the cultivars behaved differently and this prevented general conclusions being made for all of the quality characteristics.

Oleuropein supplementation increases urinary noradrenaline and testicular testosterone levels and decreases plasma corticosterone level in rats fed high-protein diet

The effects of oleuropein, a phenolic compound in extra virgin olive oil, on protein metabolism were investigated by measuring testicular testosterone and plasma corticosterone levels in rats fed diets with different protein levels. In Experiment 1, rats were fed experimental diets with different protein levels (40, 25 and 10 g/100 g casein) with or without 0.1 g/100 g oleuropein. After 28 days of feeding, the testosterone level in the testis was significantly higher and the plasma corticosterone level was significantly lower in rats fed the 40% casein diet with oleuropein than in those fed the same diet without oleuropein. The urinary noradrenaline level, nitrogen balance and hepatic arginase activity were significantly higher in rats fed the 40% casein diet with oleuropein supplementation than in those fed the 40% casein diet without oleuropein supplementation. In Experiment 2, the effects of oleuropein aglycone (a major phenolic compound in extra virgin olive oil and the absorbed form of oleuropein ingested in the gastrointestinal tracts) on the secretion of luteinizing hormone (LH) from the pituitary gland, which regulates testosterone production in the testis, were investigated in anesthetized rats. Plasma LH level increased dose dependently after the administration of oleuropein aglycone (P<.001, r=0.691). These findings suggest that dietary supplementation with 0.1 g/100 g oleuropein alters the levels of hormones associated with protein anabolism by increasing urinary noradrenaline and testicular testosterone levels and decreasing plasma corticosterone level in rats fed a high-protein diet.

Phenolics profiles of olive fruits (Olea europaea L.) and oils from Ayvalık, Domat and Gemlik varieties at different ripening stages

Phenolic compounds in olive fruit and oils obtained from Ayvalık, Domat and Gemlik olive varieties collected at different ripening periods were evaluated by High Performance Liquid Chromatography (HPLC). Gallic acid and p-cumaric acid were identified for Ayvalık and Domat at each period of ripening, respectively. In addition, gallic acid, p-cumaric acid, sinapinic and apigenin acids were detected in Gemlik olive fruit. Hydroxytyrosol, rutin, oleoropein, luteolin, tyrosol, vanilic acid and gallic acid in Ayvalık olive fruit in all ripening periods were determined. The tyrasol contents varied between 0.18 to 1.57mg/kg. Luteolin contents of olive oils ranged at the levels between 0.12 to 2.28mg/kg. In contrast, oils had the lowest syringic, p-cumaric, chlorogenic and ferulic acids. Vanillic acid contents of oils ranged between 0.08 to 2.38mg/kg.

Influence of harvest year, cultivar and geographical origin on Greek extra virgin olive oils composition: A study by NMR spectroscopy and biometric analysis

Two hundred twenty-one extra virgin olive oils (EVOO) were extracted from four olive mono-cultivars (Koroneiki, Tsounati, Adramitini, and Throubolia) originated from four divisions of Greece (Peloponnesus, Crete, Zakynthos, and Lesvos) and collected in five harvesting periods (2002–2006 and 2007–2008). All samples were chemically analysed by means of 1H and 31P NMR spectroscopy and characterised according to their content in fatty acids, phenolic compounds, diacylglycerols, total free sterols, free acidity, and iodine number. The influence of cultivars on the compositional data of the EVOO samples according to harvest year and geographical origin was examined by means of the forward stepwise canonical discriminant analysis (CDA) and classification binary trees (CBT). The CDA, when the a priori grouping was in accordance with harvest, was high (94%), whereas the classification in terms of groups formed by inclusions of geographical origin was reduced to 85%. Inclusion of both the harvesting year and geographical origin in the CDA analysis resulted in a high classification (90%) for the EVOO samples grouped into the four cultivars. The variables that most satisfactorily classified the Greek olive oils were the phenolics p-coumaric acid, pinoresinol, 1-acetoxypinoresinol, syringaresinol, luteolin, apigenin, and the hydrolysis products of oleuropein expressed collectively by the concentration of total hydroxytyrosol. Amongst the fatty acids, linoleic acid was the predictor with the highest discriminatory power. Finally, the phylogenetic significance of the olive oil compounds as determined by NMR was investigated by estimating their support to monophyly of cultivars.

Potential of selected Portuguese cultivars for the production of high quality monovarietal virgin olive oil

AbstractThe effect of cultivar and ripeness stage on the potential nutritional value of monovarietal extra virgin olive oils (MEVOOs) obtained from Cordovil, Carrasquinha, Verdeal, and Negrinha do Freixo cultivars was investigated. MEVOOs produced were characterized by high oleic acid (72–83%), tocopherol (182–530 mg/kg), and phenolic compounds (326–1110 mg/kg) content and by a similar polyphenolic profile. 1‐Penten‐3‐one was found to be the compound with the highest contribution for the aroma of the four MEVOO, related to bitter, pungent, and leaf attributes. MEVOO from Verdeal cultivar showed the best performance in terms of the composition: the highest yield of oil, the highest content of oleic acid, high tocopherol, polyphenol and sterol content, and the lowest content of linoleic acid. These characteristics give to these MEVOO not only a great oxidative stability but also interesting properties from the health point of view. MEVOO obtained with fruits at the maturity index of around 4 were in general richer in beneficial minor compounds. MEVOO produced were discriminated by variety and ripeness stage, using a stepwise linear discriminant analysis. This discrimination will in the future enable the prevention of adulteration of these monovarietal olive oils with specific nutritional composition with other olive oils.Practical implications: High‐quality MEVOOs have recently been introduced in the market, which for growers is a practical way to differentiate and increase the commercial value of extra virgin olive oil. The quantification of major and minor olive oil compounds in monovarietal olive oils represents an objective way of predicting the sensory characteristics, stability, and potential health benefits of the oils, as well as preventing their adulteration with other olive oils. This study will help in the selection of olive varieties during the maintenance or development of new olive orchards and also to select optimum harvest period for these varieties, in order to obtain MEVOOs with the maximum quality and health benefits for consumers.

Phenolic profiles of Turkish olives and olive oils

AbstractPhenolic compound distribution of Turkish olive cultivars and their matching olive oils together with the influence of growing region were investigated. One hundred and one samples of olives from 18 cultivars were collected during two crop years from west, south and south‐east regions of Turkey. The olives were processed to oils and both olive and olive oil samples were evaluated for their phenolic compound distribution. The results have shown that main phenolics of Turkish olives were tyrosol, oleuropein, p‐coumaric acid, verbascoside, luteolin 7‐O‐glucoside, rutin, trans cinnamic acid, luteolin, apigenin, cyanidin 3‐O‐glucoside and cyanidin 3‐O‐rutinoside. Oleuropein and trans cinnamic acid were present in higher amounts among all phenolics. Principal component analyses showed that the growing region did not have drastic effect on phenolic profile of olives. The major phenolic compounds of olive oils were tyrosol, syringic acid, p‐coumaric acid, luteolin‐7‐O‐glucoside, trans cinnamic acid, luteolin and apigenin. Luteolin is a predominant phenolic compound in almost all oil samples. Total phenol concentrations of Southeast Anatolian oils were found to be lower than those of the other regions.

Hydroxytyrosol Attenuates Peripheral Neuropathy in Streptozotocin-Induced Diabetes in Rats

Peripheral neuropathy is one of the most frequent and severe complications of diabetes. Hydroxytyrosol (HT), the major antioxidant polyphenolic compound of olive oil, has been investigated as a new potential treatment to counteract the progression of peripheral diabetic neuropathy in rats. An established model of streptozotocin-induced diabetes has been used. After confirmation of hyperglycemia, diabetic and nondiabetic animals were randomized to receive either a low dose or a high dose of HT, or the corresponding vehicle, for 6 weeks. At the end of the 6-week period of treatment, HT blunted plasma thiobarbituric acid-reactive substances increase (p < 0.05) and significantly reduced nerve conduction velocity (p < 0.05) and thermal nociception impairment in diabetic rats (p < 0.05). Sciatic nerve Na(+), K(+)-ATPase activity reduction was also abolished by HT (p < 0.05). The present study provides evidence of the therapeutic potential of the natural substance hydroxytyrosol in the early stage of diabetic neuropathy.

Mechanisms of Action of Phenolic Compounds in Olive

ABSTRACTOlive oil, an oil rich in monounsaturated fatty acids (MUFCs) and minor constituents including phenolic compounds, is a major component of the Mediterranean diet. The potential health benefits of the Mediterranean diet were highlighted by the seminal Seven Countries Study, and more contemporary research has identified olive oil as a major element responsible for these effects. It is emerging that the phenolic compounds are the most likely candidates accounting for the cardioprotective and cancer preventative effects of extra virgin olive oil (EVOO). In particular, the phenolic compound, hydroxytyrosol has been identified as one of the most potent antioxidants found in olive oil. This review will briefly consider historical aspects of olive oil research and the biological properties of phenolic compounds in olive oil will be discussed. The focus of the discussion will be related to the mechanisms of action of hydroxytyrosol. Studies have demonstrated that hydroxytyrosol induces apoptosis and cell cycle arrest in cancer cells. Further, research has shown that hydroxytyrosol can prevent cardiovascular disease by reducing the expression of adhesion molecules on endothelial cells and preventing the oxidation of low-density lipoprotein (LDL). The molecular mechanisms accounting for these effects are reviewed.

Analysis of phenolic compounds in olive oil by solid-phase extraction and ultra high performance liquid chromatography–tandem mass spectrometry

In this study a simultaneous determination of several classes of polyphenolic compounds (benzoic acid derivates, cinnamic acid derivates, phenyl ethyl alcohols, flavones and other phenolic acids) in feed oils has been carried out by ultra-high performance liquid chromatography coupled to tandem mass spectrometry (UHPLC-MS/MS). Solid-phase extraction (SPE) with Diol and C(18) cartridges were compared in terms of recovery and number of extracted compounds, obtaining better results when Diol cartridges were used. The analytical procedure was validated, obtaining recoveries ranging from 70% (vanillic acid) to 111% (gallic acid) with repeatability values (expressed as relative standard deviations, RSDs) lower than 20% at two concentration levels (500 and 1000 μg/kg). Limits of quantification (LOQs) were always equal or lower than 50 μg/kg except for gentisic acid (100 μg/kg). Finally the method was applied to different types of feed oils, and it can be observed that higher concentrations of polyphenols were found in olive oil, whereas pomace olive oil and sunflower oil had the lowest level of these compounds.

Virgin olive oil in preventive medicine: From legend to epigenetics

AbstractAmong vegetable oils, extra virgin olive oil (EVOO) has nutritional and sensory characteristics that make it unique and a basic component of the Mediterranean diet. EVOO has always been used over the centuries for its preventive and therapeutic properties, as well as precious and valuable dietary lipidic condiment. Benefic effects of a diet rich in EVOO on the human health, especially in prevention and/or reduction of hypercholesterolaemia, serum lipoprotein levels and atherosclerosis, hypertension, cardiovascular diseases and thrombotic risk, oxidation and oxidative stress, obesity and type 2 diabetes, inflammatory processes and cancer are discussed in these review. Recent studies suggest also its role in regulating the sense of satiety. The chemical compounds of EVOO that may contribute to its overall therapeutic characteristics, the epigenetic and physiological mechanisms involved are focused, taking into account the most important studies in the literature of the last years.Practical applications: Many studies on various aspects of nutrition indicated that many human diseases are influenced by lifestyle, in which the diet has an important aspect. The use of extra virgin olive oil is especially important from early childhood and throughout adult life to contribute to hinder the aging process. The importance of preventive and sometimes curative action, carried out by its various components in several pathological conditions has emerged from clinical, experimental, and epidemiological studies which, in many cases, are accompanied by indisputable scientific evidences. Taking into account the most important studies in the literature of the last years, the chemical compounds of extra virgin olive oil and the physiological mechanisms involved in their curative/health effects are the focus of this article.

Evaluation of the anti-angiogenic potential of hydroxytyrosol and tyrosol, two bio-active phenolic compounds of extra virgin olive oil, in endothelial cell cultures

Abstract Hydroxytyrosol and tyrosol are phenolic compounds found in virgin olive oil. A number of health-related properties have been previously demonstrated for both. The aim of this study was to investigate the potential anti-angiogenic effects of these compounds. Three different types of endothelial cells were used in several in vitro assays designed to test the specific effects of tested compounds on different key steps of the angiogenic process. Only hydroxytyrosol (but not tyrosol) had significant inhibitory effects on endothelial cell proliferation, migration and “tubule-like” structure formation on Matrigel. Furthermore, hydroxytyrosol changed endothelial cell cycle distribution, with a remarkable increase of subG1 subpopulation, indicative of apoptotic cells. Finally, hydroxytyrosol also behaved as a potent inhibitor of the invasive potential of endothelial cells, as revealed by decreased matrix metalloproteinase 2 in conditioned media. For the first time, this study shows that only hydroxytyrosol (but not tyrosol) is a new multi-targeted anti-angiogenic compound.

Development of a non-aqueous capillary electrophoresis method with UV–visible and fluorescence detection for phenolics compounds in olive oil

Response surface methodology has been applied to the optimization of a simple and rapid non-aqueous capillary electrophoresis method for the separation and determination of several phenolic compounds belonging to the different families present in olive oil. A Box-Behnken design was employed and a total of 27 experiments were performed using olive oil samples spiked with the phenols and injected directly in the capillary after dilution 1:1 with 1-propanol. Finally, the background electrolyte (BGE) was constituted of 25 mM boric acid and 18 mM KOH in a mixture of 74:26 (v/v) 1-propanol/methanol. The hydrophobicity of the BGE allows its miscibility with the olive oil and, as a consequence, the possibility of characterizing and determining these kinds of compounds in this sample without any pretreatment. A hydrodynamic injection (6 s, -30 mbar) was applied and the separation was carried out using 35 °C and +20 kV of separation temperature and voltage, respectively. A capillary with two detection windows for serial online UV and fluorescence detection was satisfactorily employed. The validation of the method was carried out by setting the calibration curves, and the figures of merit were finally obtained. A lineal relationship between the corrected peak area and concentration and limits of detection in the order of micrograms per milliliter were found.

Phenolic composition of virgin olive oils from cross breeding segregating populations

AbstractThe evaluation and characterization of segregating populations is a critical step in olive breeding programs. In this work, phenolic profiles of virgin olive oils (VOOs) from segregating populations obtained by cross breeding in Cordoba (Spain) have been evaluated. Genotypes obtained from open pollination of the cultivar Manzanilla de Sevilla, and from crosses between the cultivars Arbequina × Arbosana, Picual × Koroneiki and Sikitita × Arbosana were tested. The phenolic composition was determined after liquid–liquid extraction with 60:40 v/v methanol–water and subsequent chromatographic analysis with ultraviolet (UV) detection of both absorption and fluorescence in a sequential configuration. Results for all studied compounds showed high degree of variability between genotypes, with a higher range of variation than the observed for the genitors. Most of the observed variability was attributable to differences in genotypes within crosses rather than among crosses. Some issues related to breeding strategies are discussed.Practical applications: Phenolic compounds are considered to be of paramount importance for the assessment of virgin olive oil quality due to their contribution to the nutraceutical and sensory profile of this natural food. This study focuses on the evaluation of the content of phenolic compounds in olive oils originated from cross breeding in an olive breeding program (Cordoba, Spain). This step is crucial to determine the range of variation of phenolic compounds and the selection of interesting genotypes with higher composition in total phenols or in an individual phenol targeted at a breeding program.

Synthesis of Volatile Compounds of Virgin Olive Oil Is Limited by the Lipoxygenase Activity Load during the Oil Extraction Process

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.

Evolution of phenols and pigments in extra virgin olive oil from irrigated super‐intensive orchard

AbstractPhenolic compounds have a high importance in olive oil because of their effect on shelf life and sensory properties. This study reports on the HPLC profiles of the phenolic compounds of virgin olive oils obtained from Arbequina olives from the harvesting in a super‐intensive orchard under a linear irrigation system. In addition, phenolic content, carotenoid and chlorophyllic pigments, and oxidative stability were analyzed. Total phenol content and 3,4‐DHPEA‐EDA increased up to a maximum throughout the ripening process. The simple phenols tyrosol and hydroxytyrosol acetate increased throughout the ripening process, however, there was not found a clear trend in hydroxytyrosol content. Minor constituents such as vanillic acid and p‐coumaric acid increased up to a maximum and then decreased, since vanillin decreased progressively throughout the time of harvest. 3,4‐DHPEA‐EDA and lignans were present in considerable amounts in the studied samples, while oleuropein aglycone was present in a low amount. Total phenol content and oil stability followed the same trend throughout the study, so a very good correlation was established between them. Total secoiridoids and, specifically, 3,4‐DHPEA‐EDA seemed to be responsible for oil stability. The pigment content decreased during ripening, and not a positive correlation was found between pigments and oil stability.Practical applications: The results can be used to determine the best time for harvesting in order to obtain olive oils with different phenols and pigment contents. This is important for sensory characteristics of the olive oils and also for olive oil stability.