Compounds In Olive Oil Research Articles

Polyphenolic extract attenuates fatty acid-induced steatosis and oxidative stress in hepatic and endothelial cells.

Phenolic compounds (PC) of virgin olive oil exert several biochemical and pharmacological beneficial effects. Some dietary PC seem to prevent/improve obesity and metabolic-related disorders such as non-alcoholic fatty liver disease (NAFLD). We investigated the possible effects of PC extracted from olive pomace (PEOP) and of the main single molecules present in the extract (tyrosol, apigenin, oleuropein, p-coumaric and caffeic acid) in protecting hepatocytes and endothelial cells against triglyceride accumulation and oxidative stress. Rat hepatoma and human endothelial cells were exposed to a mixture of oleate/palmitate to mimic the condition of NAFLD and atherosclerosis, respectively. Then, cells were incubated for 24h in the absence or in the presence of PC or PEOP. Different parameters were evaluated, such as lipid accumulation and oxidative stress-related markers. In hepatic cells, expression of peroxisome proliferator-activated receptors (PPARs) and of stearoyl-CoA desaturase 1 (SCD-1) were assessed as index of lipid metabolism. In endothelial cells, expression of intercellular adhesion molecule-1 (ICAM-1), activation of nuclear factor kappa-B (NF-kB), release of nitric oxide (NO), and wound-healing rate were assessed as index of inflammation. PEOP extract ameliorated hepatic lipid accumulation and lipid-dependent oxidative imbalance thus showing potential applications as therapeutic agent tuning down hepatosteatosis and atherosclerosis.

Study of Volatile Compounds of Virgin Olive Oils with 'Frostbitten Olives' Sensory Defect.

Freeze injuries in olives are responsible for the 'frostbitten olives' sensory defect that is sometimes detected in virgin olive oil. This defect is becoming one of the most common negative attributes today because climate change has modified weather patterns. The temperature changes can take place abruptly, with rapid freeze-thaw cycles, or gradually. These changes produce significant alterations in the quality of the oils. This study analyzed the volatile composition of virgin olive oils characterized with 'frostbitten olives' defect. The volatile information allowed grouping these oils into two types characterized with two different profiles. One of them is characterized by 'soapy' and 'strawberry-like' perceptions and the presence of two volatile compounds (ethyl 2-methyl butanoate and ethyl propanoate). The second profile is characterized by 'wood' and 'humidity' descriptors and a high concentration of two volatiles (pentanal and octanal). These results on volatiles explain the existence of two sensory profiles associated with the 'frostbitten olives' defect.

The Role of Polyphenoloxidase, Peroxidase, and β-Glucosidase in Phenolics Accumulation in Olea europaea L. Fruits under Different Water Regimes.

Olive fruits and oils contain an array of compounds that contribute to their sensory and nutritional properties. Phenolic compounds in virgin oil and olive-derived products have been proven to be highly beneficial for human health, eliciting increasing attention from the food industry and consumers. Although phenolic compounds in olive fruit and oil have been extensively investigated, allowing the identification of the main classes of metabolites and their accumulation patterns, knowledge of the molecular and biochemical mechanisms regulating phenolic metabolism remains scarce. We focused on the role of polyphenoloxidase (PPO), peroxidase (PRX) and β-glucosidase (β-GLU) gene families and their enzyme activities in the accumulation of phenolic compounds during olive fruit development (35–146 days after full bloom), under either full irrigation (FI) or rain-fed (RF) conditions. The irrigation regime affected yield, maturation index, mesocarp oil content, fruit size, and pulp-to-pit ratio. Accumulation of fruit phenolics was higher in RF drupes than in FI ones. Members of each gene family were developmentally regulated, affected by water regime, and their transcript levels were correlated with the respective enzyme activities. During the early phase of drupe growth (35–43 days after full bloom), phenolic composition appeared to be linked to β-GLU and PRX activities, probably through their effects on oleuropein catabolism. Interestingly, a higher β-GLU activity was measured in immature RF drupes, as well as a higher content of the oleuropein derivate 3,4-DHPEA-EDA and verbascoside. Activity of PPO enzymes was slightly affected by the water status of trees during ripening (from 120 days after full bloom), but was not correlated with phenolics content. Overall, the main changes in phenolics content appeared soon after the supply of irrigation water and remained thereafter almost unchanged until maturity, despite fruit growth and the progressive decrease in pre-dawn leaf water potential. We suggest that enzymes involved in phenolic catabolism in the olive fruit have a differential sensitivity to soil water availability depending on fruit developmental stage.

Biofortification (Se): Does it increase the content of phenolic compounds in virgin olive oil (VOO)?

Extra-Virgin Olive Oil (EVOO) is a fundamental component of the Mediterranean diet and it may contain several anti-oxidant substances, such as phenols. Previous research has shown that this food may be enriched in phenols by spraying a sodium-selenate solution (100 mg L-1 Se) onto the crop canopy before flowering. The aim of this research was to evaluate the effect of this Se-fertilization before flowering (cv. Leccino) on the phenolic profile of EVOOs, and test to what extent such effects depend on the weather pattern, as observed in two contrasting experimental seasons (2013 and 2014). Results showed that Se-fertilisation enriched EVOOs both in selenium (up to 120 μg kg-1) and in phenols (up to 401 mg kg-1). This latter enrichment was related to an increase in PAL (L-Phenylalanine Ammonia-Lyase) activities and it was largely independent on the climatic pattern. Considering the phenolic profile, oleacein, ligustroside, aglycone and oleocanthal were the most affected compounds and were increased by 57, 50 and 32%, respectively. All these compounds, especially oleacein, have been shown to exert a relevant anti-oxidant activity, contributing both to the shelf-life of EVOOs and to positive effects on human health. It is suggested that Se-fertilisation of olive trees before flowering may be an interesting practice, particularly with poor cultivars and cold and rainy weather patterns, which would normally lead to the production of EVOOs with unfavourable phenolic profile.

Comparison of the effects of major fatty acids present in the Mediterranean diet (oleic acid, docosahexaenoic acid) and in hydrogenated oils (elaidic acid) on 7-ketocholesterol-induced oxiapoptophagy in microglial BV-2 cells

Increased levels of 7-ketocholesterol (7KC), which results mainly from cholesterol auto-oxidation, are often found in the plasma and/or cerebrospinal fluid of patients with neurodegenerative diseases and might contribute to activation of microglial cells involved in neurodegeneration. As major cellular dysfunctions are induced by 7KC, it is important to identify molecules able to impair its side effects. Since consumption of olive and argan oils, and fish is important in the Mediterranean diet, the aim of the study was to determine the ability of oleic acid (OA), a major compound of olive and argan oil, and docosahexaenoic acid (DHA) present in fatty fishes, such as sardines, to attenuate 7KC-induced cytotoxic effects. Since elaidic acid (EA), the trans isomer of OA, can be found in hydrogenated cooking oils and fried foods, its effects on 7KC-induced cytotoxicity were also determined. In murine microglial BV-2 cells, 7KC induces cell growth inhibition, mitochondrial dysfunctions, reactive oxygen species overproduction and lipid peroxidation, increased plasma membrane permeability and fluidity, nuclei condensation and/or fragmentation and caspase-3 activation, which are apoptotic characteristics, and an increased LC3-II/LC3-I ratio, which is a criterion of autophagy. 7KC is therefore a potent inducer of oxiapoptophagy (OXIdation+APOPTOsis+autoPHAGY) on BV-2 cells. OA and EA, but not DHA, also favor the accumulation of lipid droplets revealed with Masson’s trichrome, Oil Red O, and Nile Red staining. The cytotoxicity of 7KC was strongly attenuated by OA and DHA. Protective effects were also observed with EA. However, 7KC-induced caspase-3 activation was less attenuated with EA. Different effects of OA and EA on autophagy were also observed. In addition, EA (but not OA) increased plasma membrane fluidity, and only OA (but not EA) was able to prevent the 7KC-induced increase in plasma membrane fluidity. Thus, in BV-2 microglial cells, the principal fatty acids of the Mediterranean diet (OA, DHA) were able to attenuate the major toxic effects of 7KC, thus reinforcing the interest of natural compounds present in the Mediterranean diet to prevent the development of neurodegenerative diseases.

Influence of refining processes on content of bioactive compounds, rheology, and texture of olive pomace oil for use in topical formulations

Retaining the bioactive ingredients of olive pomace oil is a crucial step in ensuring their functional or pharmaceutical value. To help select the best method for retaining bioactive compounds in olive pomace oil, three refining processes, namely, chemical, classical physical, or molecular distillation, were compared at different temperatures. For each method, the contents of triacylglycerols, fatty acids (oleic acid, linoleic, and linolenic acids), triterpenic acids (oleanolic and maslinic acids), and unsaponifiable matter (squalene, aliphatic, sterols, and terpenic) were studied. We observed that physical refining by molecular distillation provided oils with interesting amounts of bioactive compounds, especially triterpenic acids. Of these oils, the samples submitted to a temperature of 190°C exhibited a greater albeit low acidity compared with the other oils obtained by chemical and classical physical refining but exhibited higher amounts of all bioactive compounds. Conversely, the molecular distillation refining process had only a slight effect on the values of the consistency index. The firmness, cohesiveness, and adhesiveness parameters from texture profile analysis indicated that in general, all deodorized oils had high smoothness and spreadability but low adhesiveness. Molecular distillation was concluded to be the best refining process. Nevertheless, it is necessary to improve the working conditions of this process.Practical applications: Olive pomace oil has all functional compounds of extra virgin olive oil, but with a higher concentration of some minor components. It is, therefore, very interesting to use it in skin care formulations. However, for use in the pharmaceutical field must be refined. This study aimed to provide determine the influence of different refining processes (chemical refining, classical physical refining, or physical refining by molecular distillation at different temperatures) in determining the composition of bioactive compounds. The best refining process was selected based on the analytical determination of bioactive compounds by gas chromatography. Results indicated that molecular distillation is the best refining process. Nevertheless, it is necessary to improve the working conditions.Scheme of the extraction and refining processes to which olive pomace oil is subjected, to achieve the lowest losses of bioactive compounds for use in topical formulations.

Metabolic profiling approach to determine phenolic compounds of virgin olive oil by direct injection and liquid chromatography coupled to mass spectrometry

A LC–MS method involving direct injection of extra-virgin olive oil (EVOO) – after a simple dilution – for determining its phenolic compounds has been developed. Optimization of the most appropriate solvent for sample dilution, selection of the optimum oil/solvent ratio, and establishment of column cleaning strategy and maximum number of injections were some of the most relevant steps. Then, the analytical parameters of the method were evaluated, establishing LOD (from 3.3 to 31.6µg/L) and LOQ, precision (RSD values for inter-day repeatability were found between 3.49 and 6.12%), and trueness (within the range 89.9–102.3% for 1.0mg/L) and checking possible matrix effect (which was no significant). Three kinds of calibration were used: external standard, standard addition and calibration in a phenols-free matrix, which was subsequently applied to quantify the phenolic compounds in 16 EVOOs (from 6 cultivars). A total of 21 compounds were determined without the need of using any extraction protocol.

Antioxidant potential of extra virgin olive oils extracted from three different varieties cultivated in the Italian province of Reggio Calabria

In this study, the physicochemical properties and bioactive compounds of olive oils from cultivars “Roggianella”, “Sinopolese” and “Ottobratica”, grown in the province of Reggio Calabria (Italy) have been evaluated.Polyphenols are a large family of compounds found in fruits and vegetables, which exhibit strong antioxidant activity by scavenging different families of Reactive Oxygen Species (ROS).Dialdehydic form decarboxymethyl oleuropein aglycon, hydroxytyrosol acetate, dialdehydic form oleuropein aglycon, pinoresinol, 1-acetoxypinoresinol, tyrosol and vanillic acid were the main phenolic compounds in all samples analyzed. Pinoresinol was the most abundant compound in the lignin fraction. In all oil samples analyzed the highest antioxidant capacity was attributed to Roggianella oil (36.85% I of DPPH and 4.07% I of ABTS) compared to Ottobratica (27.37% I of DPPH and 2.52% I of ABTS) and Sinopolese (18.33% I of DPPH and 1.72% I of ABTS). The main characteristics of the Roggianella cultivar were a very high concentration of total phenols (530 mg/kg of gallic acid) and α-tocopherol (211 mg/kg).

Oleuropein improves insulin resistance in skeletal muscle by promoting the translocation of GLUT4.

As the beneficial effects of the Mediterranean diet on human health are well established, the phenolic compounds in olive oil have been gaining interest. Oleuropein, a major phenolic compound in olives, is known to reduce the blood glucose levels in alloxan-induced diabetic rats and rabbits, however, its effect on type 2 diabetes caused by obesity is not clear. The purpose of this study is clarifying the effect of oleuropein on the glucose tolerance in skeletal muscle under the condition of lipotoxicity caused by type 2 diabetes. Oleuropein enhanced glucose uptake in C2C12 cells without insulin. Translocation of glucose transporter 4 (GLUT4) into the cell membrane was promoted by activation of adenosine monophosphate-activated protein kinase (AMPK) but not protein kinase B (Akt). Physiological concentration of oleuropein (10 µM) was sufficient to express beneficial effects on C2C12 cells. Oleuropein prevented palmitic acid-induced myocellular insulin resistance. Furthermore, in gastrocnemius muscles of mice fed a high fat diet, oleuropein also induced the GLUT4 localization into cell membrane. These results suggest the possibility of oleuropein to be effective for type 2 diabetes by reducing insulin resistance in skeletal muscles.

Oleic Acid and Hydroxytyrosol Inhibit Cholesterol and Fatty Acid Synthesis in C6 Glioma Cells

Recently, the discovery of natural compounds capable of modulating nervous system function has revealed new perspectives for a healthier brain. Here, we investigated the effects of oleic acid (OA) and hydroxytyrosol (HTyr), two important extra virgin olive oil compounds, on lipid synthesis in C6 glioma cells. OA and HTyr inhibited both de novo fatty acid and cholesterol syntheses without affecting cell viability. The inhibitory effect of the individual compounds was more pronounced if OA and HTyr were administered in combination. A reduction of polar lipid biosynthesis was also detected, while triglyceride synthesis was marginally affected. To clarify the lipid-lowering mechanism of these compounds, their effects on the activity of key enzymes of fatty acid biosynthesis (acetyl-CoA carboxylase-ACC and fatty acid synthase-FAS) and cholesterologenesis (3-hydroxy-3-methylglutaryl-CoA reductase-HMGCR) were investigated in situ by using digitonin-permeabilized C6 cells. ACC and HMGCR activities were especially reduced after 4 h of 25 μM OA and HTyr treatment. No change in FAS activity was observed. Inhibition of ACC and HMGCR activities is corroborated by the decrease of their mRNA abundance and protein level. Our results indicate a direct and rapid downregulatory effect of the two olive oil compounds on lipid synthesis in C6 cells.

Special issue on olive oil

Lanfranco Conte Maria Tsimidou Virgin olive oil (VOO) is probably one of the most ancient foods of the Mediterranean area and it has been extensively studied for decades mainly with the aim to guarantee its purity and quality (sometimes just for taxation needs). The olive industry in the 21rst century has some unique characteristics. Production and consumption are in balance the last decades mainly because of the increasing evidence for the health benefits to the humans. Climatic changes affected the sector in recent years. This year's production is expected to drop by 7% (IOC provision), which is critical for the sustainability of exports from the major European producing countries. Research on the particular health properties of polar phenolic compounds of virgin olive oil has recently led the European Food Safety Authority to approve a health claim for their antioxidant activity. The interest in retaining organoleptic characteristics and a high content of these polar bioactive compounds became the driver for changes in the harvest and processing practices in the producing countries. The increasing demand for “high quality extra virgin olive oil” among certain groups of consumers from all over the world had a positive impact on the marketing of premium products that command high values/liter. Virgin olive oil is now appraised not only because of its high content in monounsaturated fatty acids and a balanced ratio of unsaturated fatty acids to alpha-tocopherol content but also for the fruity aroma and bitter/pungent taste related to the presence of valuable bioactive polar phenols. Freshness of the product and its maintenance is becoming important for producers, distributors and consumers. Recent innovations in the extraction system of olive oils are promising towards further improvement of quality. Legislation for olive oil characteristics is tight in the European Union since 1991. It involves the examination of different quality and authenticity characteristics, and also includes sensory scores. Similar regulations cannot be found for any other agricultural product, or for another edible oil and fat. Nevertheless, all interested parties work continuously on reducing the possibilities for fraudulent practices. This is reflected in a dedicated EU call on “Olive Oil Authenticity”. Analytics of olive oil cover a wide range of approaches and techniques. From the era of establishing indices of quality and authenticity, to the extensive application of separation techniques a century has elapsed. Thanks to GC-MS, sterols structure was adequately elucidated since the end of ‘60th, even if the presence of some sterols (e.g. delta 5 avenasterol) had been highlighted later, when more polar stationary phases became available. Sterols profile and concentrations of individual members has become a pertinent tool in olive oil authentication studies. Triacylglycerol analysis using HPLC together with the GC analysis of FAMEs were used for the calculation of a new index (Delta ECN 42) to detect adulteration with seed oils. The issue of “polyphenols” attracted the interest of the analysts since the end of ‘70s. Currently, new high throughput spectroscopic and molecular techniques have found application for different objectives. Ongoing research indicates that as far as analytical instruments performances improve, more and more knowledge is acquired on VOO composition that leads on one hand to a more perceptive control on its purity and quality and on the other hand to discover new compounds and to understand the biochemical mechanisms of their function in the human body. Still, the challenges in the olive sector never stop. Fair trade has many enemies within every country and region. One of the next goals is to protect the many different European Products of Denomination of Origin (PDOs) in a reliable objective way that guarantees the origin whereas some difficult frauds like the addition of deodorised oil must be combated through administrative and analytical approaches. We invited a number of researchers, who have been active for many years in this field to contribute to this Special Issue. The issue contains review articles and original research papers diverse in context. Authors from different countries and research groups contributed eagerly and we are indebted to them. We are also thankful to the reviewers, who supported this venture. Virgin olive oil, the olive juice, has a history that dates back to the very beginning of human presence on the earth as it has been used for multiple purposes, not only as a food item. Working on olive oil seems to be a life time endeavour for those researchers devoted to its chemistry, analysis and biological properties. We hope that you will enjoy reading the papers in this Special Issue. Lanfranco Conte University of Udine Maria Tsimidou Aristotle University of Thessaloniki

Effect of cultivar and harvest time on C6 and C5 volatile compounds of Turkish olive oils

Aroma is an important quality criterion for extra virgin olive oil. The goal of this study was to determine C6 and C5 volatile compounds in different Turkish olive oils. Two factors namely (1) olive cultivar including Ayvalik, Memecik, and Topakasi, and (2) harvest time (ripening degree) were studied. Both factors significantly affected the volatile profiles of the studied oils. Headspace solid phase micro-extraction with GC/MS was used to detect volatiles in different olive oils. The detected volatile compounds included up to 11 compounds (4 from C5, and 7 from C6). Hexanal and (E)-2-hexanal were predominated as the major volatiles in Ayvalik, and Memecik oils, while pentanal, and hexanal were predominated in Topakasi oil. Topakasi oil was also characterized by its low content of (E)-2-hexenal. The only clear trend observed during ripening of olives was the increase in the total content of esters. Therefore, the information obtained in this study is useful in selecting the proper harvest time for each cultivar according to the desired volatile compounds found in the oil.

α-Tocopherol, β-carotene, lutein, squalene and secoiridoids in seven monocultivar Italian extra-virgin olive oils

Fatty acids and bioactive lipophilic and hydrophilic compounds (tocopherols, β-carotene, lutein, squalene, total polyphenols and secoiridoids) in monocultivar Italian extra-virgin olive oil (EVOO) samples produced from the Leccino cultivar and six other yet uncharacterised cultivars (Rustica, Carpinetana, Dritta, Gentile di Chieti and Intosso) were analysed, also taking into account the effect of the type of decanter used for the oil extraction. Significant differences among cultivars were found for α-tocopherol and squalene, but not for carotenoids. Among phenols, cultivars significantly influenced oleuropein and ligstroside aglycones contents, but not those of the dialdehydic form of decarboxymethyl elenolic acid linked neither to tyrosol nor hydroxytyrosol. As previously reported, phenol is quantitatively affected by the type of decanter used for oil extraction. Accordingly, we found that the two-phases decanter preserved in the oil 1.5 times more phenolic compounds as compared with three-phases, whereas it did not influence the amount of lipophilic compounds. Moreover, our data statistically support the finding that type of decanter affects phenols also qualitatively. In fact, the two-phases decanter preferably preserved more the hydroxytyrosol secoiridoid derivatives than the tyrosol ones. Our results from one hand characterise for the first time oils previously unreported, from the other give some new indications on the relative role of factors relevant for the achievement of biologically active extra-virgin oil, i.e. the cultivar and technological ones.

Optimization of Malaxation Process using Major Aroma Compounds in Virgin Olive Oil

Optimization of major aroma compounds in olive oils produced from fruits at three maturity stages wasstudied. A central composite design was used for the optimization of malaxation conditions of temperature and times, each at five levels with 13 runs including five central points. The responses of interest were trans-2-hexenal and hexanal, which were investigated and their contents were optimized. A full quadratic second order regression model including the linear, quadratic, and two factor interaction effects was proposed to explain the variation in the contents of target compounds depending on the malaxation conditions. Adequacies of models were evaluated by checking regression coefficients for each model. Models were found to work with high success for trans-2-hexenal prediction for oils from fruits at both purple and black stages, whereas the model for hexanalwas only in black stage oil. Their regression coefficients were higher than 0.86. Influences of time and temperature for the malaxation process were found to be significant for the transition of major aroma compounds from the fruit matrix to olive oil. The optimum conditions of temperature and time pairs to maximize trans-2-hexenal and hexanal was found to be 23°C/31 minutes for black olive and to maximize only trans-2-hexenal was also 29°C/41 minutes for purple olive.

Protective Effects of α-Tocopherol, γ-Tocopherol and Oleic Acid, Three Compounds of Olive Oils, and No Effect of Trolox, on 7-Ketocholesterol-Induced Mitochondrial and Peroxisomal Dysfunction in Microglial BV-2 Cells.

Lipid peroxidation products, such as 7-ketocholesterol (7KC), may be increased in the body fluids and tissues of patients with neurodegenerative diseases and trigger microglial dysfunction involved in neurodegeneration. It is therefore important to identify synthetic and natural molecules able to impair the toxic effects of 7KC. We determined the impact of 7KC on murine microglial BV-2 cells, especially its ability to trigger mitochondrial and peroxisomal dysfunction, and evaluated the protective effects of α- and γ-tocopherol, Trolox, and oleic acid (OA). Multiple complementary chemical assays, flow cytometric and biochemical methods were used to evaluate the antioxidant and cytoprotective properties of these molecules. According to various complementary assays to estimate antioxidant activity, only α-, and γ-tocopherol, and Trolox had antioxidant properties. However, only α-tocopherol, γ-tocopherol and OA were able to impair 7KC-induced loss of mitochondrial transmembrane potential, which is associated with increased permeability to propidium iodide, an indicator of cell death. In addition, α-and γ-tocopherol, and OA were able to prevent the decrease in Abcd3 protein levels, which allows the measurement of peroxisomal mass, and in mRNA levels of Abcd1 and Abcd2, which encode for two transporters involved in peroxisomal β-oxidation. Thus, 7KC-induced side effects are associated with mitochondrial and peroxisomal dysfunction which can be inversed by natural compounds, thus supporting the hypothesis that the composition of the diet can act on the function of organelles involved in neurodegenerative diseases.

Oleuropein aglycone enhances UCP1 expression in brown adipose tissue in high-fat-diet-induced obese rats by activating β-adrenergic signaling

Oleuropein is the pungent principle of raw olives. Oleuropein aglycone (OA) is a major phenolic compound in extra virgin olive oil and the absorbed form of oleuropein. We aimed to determine the mechanism underlying the nutritional effects of oleuropein and OA on interscapular brown adipose tissue (IBAT) in rats with high-fat (HF) diet-induced obesity by examining the agonistic activity of oleuropein and OA toward the transient receptor potential ankyrin 1 (TRPA1) and vanilloid 1 (TRPV1). Four-week-old male Sprague–Dawley rats were fed an HF (palm oil 30% wt:wt) diet alone or with oleuropein (HF-O, 1 g/kg diet) for 28 days. In rats fed HF-O compared to HF, urinary noradrenaline, adrenaline and UCP1 levels in IBAT were significantly higher, whereas plasma leptin levels and the total weight of the abdominal cavity adipose tissue were significantly lower. In anaesthetized 7-week-old male Sprague–Dawley rats, the OA (3.8 mg of intravenous injection)-induced increase in plasma noradrenaline secretion was suppressed by TRPA1 or TRPV1 antagonist and by a β2- or β3-adrenoceptor antagonist. Furthermore, OA-activated rat and human TRPV1s expressed on HEK293 cells at the same level as zingerone (pungent component in ginger). OA also activated humanTRPA1, and its potency was approximately 10-fold stronger than that for TRPV1. These findings suggest that OA is the agonist of both TRPA1 and TRPV1 and that OA enhances UCP1 expression in IBAT with a concomitant decrease in the visceral fat mass of HF-diet-induced obese rats through enhanced noradrenaline secretion via β-adrenergic action following TRPA1 and TRPV1 activation.

Assessment of polar phenolic compounds of virgin olive oil by NIR and mid‐IR spectroscopy and their impact on quality

Chemometric analyses of near‐ (NIR) and middle‐infrared (mid‐IR) spectroscopy spectral data (12 500–4000 cm−1 and 4000–400 cm−1) by Partial Least Square (PLS) regression combined with analytical determination of polar phenolic compounds measured by HPLC in different varieties, geographical origin and marketplace categories olive oils—Protected Denomination of Origin (PDO) “Montes de Toledo”; Galician; high quality extra virgin (“Gourmet”/“Premium”); and commercial extra virgin and olive oils—were used to generate calibration and validation models in order to be able to predict the content and profile of these minor compounds, and thereby the quality of the product. Satisfactory multivariate test set validation algorithms were obtained for virgin olive oil (VOO)'s total polar phenolic (TPP) compounds (r = 0.91), hydroxytyrosol and tyrosol secoiridoid derivatives (HtyrSec, TyrSec; r = 0.91 and 0.92, respectively). Contrary to NIRS, the chemometric analysis of the mid‐IR spectra gave no satisfactory validation models (r = 0.43, 0.54, and 0.66 for HtyrSec, TyrSec, and TPP), despite that the calibration algorithms gave even higher correlation than NIRS (r > 0.96 for all the polar phenolics studied).Practical applications:The results establish that NIRS is a very useful technique that allows rapid screening of VOO samples to estimate polar phenolic profile, and thereby their quality and commercial grade. Furthermore, it may give real time information about olive oil composition during processing in order to automatically control technological parameters.NIRS is a very useful technique that allows rapid screening of VOO samples to estimate polar phenolic profile, and thereby their quality and commercial grade.

Anti-inflammatory effects of tyrosol in streptozotocin-induced diabetic Wistar rats

The anti-inflammatory effect of tyrosol (4-(2-hydroxyethyl)), a phenolic compound in olive oil (20 mg/kg body weight), in streptozotocin (STZ)-induced diabetic rat was evaluated. Diabetic rats showed significant (P < 0.05) increase in plasma glucose and lipid peroxidation products and significant (P < 0.05) decrease in plasma insulin and enzymatic and non-enzymatic antioxidants in the liver and pancreas. The levels of inflammatory marker, C-reactive protein in plasma and protein expressions of nuclear factor-kappa B p65, tumour necrosis factor-alpha and interleukin-6 in the liver and pancreas were significantly (P < 0.05) increased in STZ-induced diabetic rats. Conversely, daily oral treatment with tyrosol for 45 days significantly (P < 0.05) restored all the above mentioned parameters to near normal levels. The immunohistochemical studies confirm the anti-inflammatory effects of tyrosol. Tyrosol exerts anti-inflammatory effects on the liver and pancreas of STZ-induced diabetic rats via its antioxidant activity, hence it may play an important role in the management of diabetes mellitus.

The Chemical Properties and Volatile Compounds of Virgin Olive Oil from Oueslati Variety: Influence of Maturity Stages in Olives

AbstractThe aim of the present work was to investigate the influence of fruit ripening on oil quality and volatile compounds in an attempt to establish an optimum harvesting time for Oueslati olives, the minor olive variety cultivated in Tunisia. Our results showed that many analytical parameters, i.e., peroxide value, UV absorbance at 232–270 nm, chlorophyll pigments, carotenoids and oleic acid contents decreased during ripening, whilst linolenic acid increased. Free acidity remained practically stable with a very slight rise at the highest maturity index. The volatile compounds emitted by the Oueslati olive oil were characterized and quantified by HS‐SPME‐GC‐EIMS. Twenty‐three volatile compounds were identified, mainly aldehydes, sesquiterpenes and esters. The results show variations in the volatile fractions and quality parameters of Oueslati extra virgin olive oil obtained at different olive‐ripening stages. Fifteen sesquiterpenes were identified for the first time in this cultivar, mainly hydrocarbon derivatives, but also oxygenated ones. On the basis of the quality parameters and volatile fractions studied, the best stage of Oueslati olive fruits for oil processing seems to be at ripeness index about 3.0. Indeed, these results suggested the possibility of using sesquiterpenes for olive authenticity and traceability and demonstrated that the volatile fractions can be used as indicators of the degree of ripening of the olives used to obtain the corresponding virgin olive oils.

Antioxidant compounds of Iranian olive oils influenced by growing area, ripening stage, and cultivar

Phenolic and tocopherol compounds of virgin olive oils, obtained from three imported cultivars (cvs) of Mission, Beleydi, and Koroneiki collected in two different ripening stages from two completely different regions (subdesertic zone (Qom) and Caspian zone (Gorgan)), were determined. Regardless of the growing area conditions, Beleydi cultivars showed the lowest oil content, total phenolic content, secoiridoids, and oleuropein aglycone along with the highest content of decarboxy methyl ligstroside aglycon, ligstroside aglycone, and consequently the lower oxidative stability. Moreover, in spite of lower oil contents, the cvs growing in Qom had higher total phenolic compounds, secoiridoids, oleuropein aglycone and higher oxidative stability. Furthermore, the amount of most of the studied components decreased during the ripening stages.Practical applications: For selection of well‐characterized cvs, assessing cv‐cultivation zone‐maturity seems unavoidable before commercialization. This trend supports the differentiation of various olive oils and have motivated new and unique branding that assist their sales as well as the need for evaluating the adaptability of imported olive cvs into different growing areas and the most appropriate time of harvest before developing plantations, as a key point for mills due to the increased competitiveness and quality protection.Physicochemical properties of selected olive cultivars grown in Iran were determined and a correlation between their phenolic compounds and oxidative stability was achieved. Finally, geographic origin of olive cvs was determined by using principal component analysis.