Evaluation of Authenticity of Iranian Olive Oil by Fatty Acid and Triacylglycerol Profiles

For evaluation of the authenticity of Iranian olive oil, samples from many Iranian olive oil producers especially north of Iran in the production year 2007 were collected. The fatty acid and triacylglycerol compositions were measured. The most recent calculation methods including ∆ECN the difference between the actual and theoretical ECN42 (equivalent carbon number), triglyceride content and R of olive oils according to IOOC methods were applied. On the basis of our results, we were able to classify the olive oils into the extra virgin, virgin olive and olive oil categories. The important fatty acids are oleic, palmitic and linoleic acids and their main triacylglycerols are OOO, POO, OOL, PLO, SOS plus POP, and OLL, respectively. On the basis of the triacylglycerol results, experimental ECN48, ECN46, ECN50, ECN44 and ECN42 were obtained. By using the fatty acids results and a computer program, the theoretical ECN42 and ECN44 were calculated. Then R values, being the ratio of r ECN42/r ECN44 for authenticity of all olive oils and ∆ECN for determining categories of olive oils, were defined. The results of olive oil samples were in the accepted limits of Codex and IOOC. Finally we suggest that the R and ∆ECN can be used in identification of adulteration of olive oils and also they are useful from the point of view of authenticity and classification.     

Evaluation of Potential and Real Quality of Virgin Olive Oil from “Campos de Hellín” (Albacete, Spain)

The regulated physicochemical and sensory parameters, stability parameters and fatty acid, sterol and triterpenic dialcohol composition of the olive oils from the varieties Arbequina, Benizal, Cornicabra, Cuquillo, Injerta, Manzanilla de Sevilla, Manzanilla Local, Picual and Negrilla, grown in the Campos de Hellin, were analyzed. Regarding potential quality, all the oil samples were classified in the “extra virgin” category according to the regulated parameters. The oils from the varieties Cornicabra and Picual showed remarkably high stability, due to their high total phenol content. The oils from the Benizal variety stood out due to their high campesterol and low total sterol content, exceeding and not reaching, respectively, the limits set by European regulations. This seems to be an intrinsic characteristic of this variety. When the real quality was analyzed, two clearly differentiated groups were observed: on one hand, oils from the Arbequina variety, and on the other hand, oils from the Picual variety and oils mixed from different varieties (Blend). The great number of olive varieties grown in the Campos de Hellin area enables the production of better balanced oils, producing high quality blended oils since the mixing of different varieties may compensate the deficiencies of monovarietal oils.     

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

The 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.     

On the importance of total polar phenols to monitor the stability of Greek virgin olive oil

A large number of virgin olive oil samples obtained from different areas in Greece were analyzed for various quality parameters. The work focuses on the colorimetric determination of total phenols with the Folin‐Ciocalteu reagent and its importance in predicting shelf life of virgin olive oil. The results indicate a good correlation of total polar phenol content with the stability of the oil. Colorimetric determination of ortho‐diphenol content does not seem to be a better means for predicting virgin olive oil stability. RP‐HPLC quantification of hydroxytyrosol and tyrosol in their free form gives poor results in the case of freshly extracted oils. It is concluded that until an easy‐to‐manage HPLC method will be available, which will quantify accurately both free and bound forms of hydroxytyrosol and other phenolics, the colorimetric method for the determination of total polar phenols remains a good practical means to evaluate the stability of virgin olive oil.     

Chemical Composition of Turkish Olive Oil––Ayvalik

Although large amounts of olive oil are produced in Turkey, not much information on its chemical composition is available in the literature to date. The aim of this study was to evaluate the chemical composition of commercial olive oils produced from the Ayvalik olive cultivar in Canakkale, Turkey. Five different samples corresponding to the olive oil categories of extra virgin (conventional, extra virgin olive oil (EVOO), and organic extra virgin olive oil (OGOO) production), virgin olive oil (OO-1), ordinary virgin olive oil (OO-2) and refined olive oil (RFOO) were evaluated. Olive oils were collected from two consecutive production years. According to the free fatty acids, the absorbance values (K₂₃₂ and K₂₇₀), and peroxide values of all the samples conformed to the European standards for olive oil. The level of oleic acid was in the range of 68–73%; while the linoleic acid content was significantly lower in the refined olive oils. The tocopherol and polyphenol content was in the lower range of some European olive oils. However, pinoresinol was a major phenolic compound (5–77 mg/kg depending on the oil category). Its content was markedly higher than in many other oils, which would be a useful finding for olive oil authentication purposes.     

Characterization of Turkish Virgin Olive Oils Produced from Early Harvest Olives

Olives were collected from various districts of Turkey (North and South Aegean sub-region, Bursa-Akhisar, South East Anatolia region) harvested over seven (2001–2007) seasons. The aim of this study was to characterize the chemical profiles of the oils derived from single variety Turkish olives including Ayvalik, Memecik, Gemlik, Erkence, Nizip Yaglik and Uslu. The olive oils were extracted by super press and three phase centrifugation from early harvest olives. Chosen quality indices included free fatty acid content (FFA), peroxide value (PV) and spectrophotometric characteristics in the ultraviolet (UV) region. According to the FFA results, 46% (11 out of 24 samples) were classified as extra virgin olive oils; whereas using the results of PV and UV, over 83% (over 19 of the 24 samples) had the extra virgin olive oil classification. Other measured parameters included oil stability (oxidative stability, chlorophyll pigment, pheophytin-α), cis–trans fatty acid composition and color index. Oxidative stability among oils differed whereas the cis–trans fatty acid values were within the national and international averages. Through the application of two multivariate statistical methods, Principal component and hierarchical analyses, early harvest virgin olive oil samples were classified according to the geographical locations categorized in terms of fatty acid profiles. Such statistical clustering gave rise to defined groups. These data provide evidence of the variation in virgin olive oil quality, especially early harvest and cis–trans isomers of fatty acid profiles from the diverse agronomic conditions in the olive growing regions of Turkey.     

Effect of the Addition of Chili Pepper Powder on Vegetable Oils Oxidative Stability

Red chili pepper represents an excellent source of functional bioactive compounds, and its use as food additive could be useful for protecting other products from spoilage. Olive oils show a limited shelf‐life due to a progressive quality deterioration linked mostly to oxidation reactions providing a loss of quality in terms of organoleptic and healthy properties. In this work, the addition of red chili pepper powder to virgin, extra‐virgin olive and sunflower oils was proved to be effective in improving their stability during 12 months of shelf‐life. Oil stability was monitored by employing the Oxitest system, based on accelerating the oxidation process. Three pepper powders of different pungency were added to the virgin olive oil samples with the aim of investigating whether capsaicinoids could be responsible for the observed effects. The strongest effect was recorded when employing the less pungent pepper showing that the protective effect could not be attributed to the capsaicinoids content. Besides, a screening on different oils demonstrated that the less stable samples received a stronger protective effect. The evaluation of a possible dose‐effect relation was also carried out pointing out that a threshold dose of about 1 % was required to record an effect. The results suggest potential perspectives in the field of food technology, as addition of a small amount of sweet pepper could be proposed to prolong food shelf‐life.     

Characterization and chemometric study of crude and refined oils from table olive by‐products

Table olive processing produces defective fruits and the conditioning operations give rise to solid by‐products which are processed to obtain oil. In this study, the most relevant characteristics of crude oils extracted from table olive by‐products were high average acidity values (4.5%, green olives; 8.1%, ripe olives), ECN42 values of 0.34 (green olives) and 0.10 (ripe olives), while 2‐mono‐palmitin averaged 0.92%. The overall content of sterols was 2257 mg/kg (green olives) and 1746 mg/kg (ripe olives), while the concentration of cholesterol was 36 mg/kg (green olives) and 19 mg/kg (ripe olives). The effect of refining was mainly reflected by a decrease in acidity and sterols. Although most characteristics were in agreement with the established regulation for olive oil, the overall trans fatty acid content, the low apparent β‐sitosterol content, and the relatively high cholesterol content prevented their inclusion into classes of crude or refined lampante or pomace olive oils, not even into the vegetable oil category. Therefore, the oils analyzed should be considered for non‐edible purposes. The physicochemical characteristics used for chemometric discrimination permitted discrimination among types of oils (crude, 100%; physically refined, 90%; chemically refined, 100%), elaboration styles (green and ripe olives, 100%) and cultivars (Gordal, Manzanilla, Hojiblanca and Cacereña, 100%), with the sterol composition being the most useful parameter for discrimination.     

A Survey of the Amounts of Oxidized Triglycerides and Triglyceride Dimers in Virgin and “Lampante” Olive Oils

The aim of this work was to ascertain the amount of oxidized triglycerides and triglyceride dimers in virgin and “lampante” olive oils: to this effect, 38 samples were collected from different oil-mills. No data on the above compound classes in ?lampante”? olive oils have ever appeared in literature up to now. However, fat autoxidation is known to imply polymerization reactions; so, low amounts of oligopolymers may be formed in oil at a given state of oxidation. This aspect also applies to virgin olive oils because the very few data reported in literature are mainly related to extra virgin olive oils which are classified as high quality oils. Column chromatography and high-performance size exclusion chromatography were used for oil analysis in this work. Triglyceride dimers were either absent or present in traces in virgin olive oils, but were found in ?lampante”? oils with a mean value of 0.07%. Oxidized triglyceride percentages in ?lampante”? oils were more than twice as high as those present in virgin oils. The data obtained suggest the following consideration: the presence of dimers in vegetable oils reveals a rather high oxidation level and is confirmed by the higher oxidized triglyceride values. This is a reliable index of oxidative degradation in oil.     

Characteristics and sensory assessment of extra virgin olive oils produced in two different zones of Brazil

The Brazilian olive oil production has been growing in recent decades and largest plantations are on two different zones, from Serra da Mantiqueira (states of Minas Gerais and São Paulo) and Campanha Gaúcha (state of Rio Grande do Sul). The total planted area, in 2022, reached approximately 6500 hectares. The aim of the present study was to characterize the sensory and analytical parameters of extra virgin olive oils (EVOO) from Southwestern (Serra da Mantiqueira) and Southern (Campanha Gaúcha) Brazil regions. Twenty-two EVOO samples were obtained from different cultivars of unlike regions. Quality parameters, oxidative stability, phenolic compounds ortho-diphenols and fatty acids were analyzed and relationships with olive variety or region. From the chemical perspective, the EVOO exhibited all parameters within the necessary to be qualified as extra virgin, according to international standard definitions. All samples showed a good quality of sensory perceptions and a high level of polyphenols, which are varied among samples but was more intense in Campanha Gaúcha olive oils.     

Chemical Composition and Sensory Quality of Tunisian ‘Sayali’ Virgin Olive Oils as Affected by Fruit Ripening: Toward an Appropriate Harvesting Time

Herein, the influence of the ripeness of Tunisian Sayali olives on the chemical composition and sensory quality of virgin olive oils have been investigated, with a particular focus on minor metabolites. Towards this end, five samples (S1–S5) were produced from fruits at increasing stages of maturity and then analyzed. Quality indices (free acidity, peroxide value, specific extinction in UV, sensory characteristics) and composition in major (fatty acids) and minor compounds (squalene, pigments, tocopherols, phenolic compounds, volatile compounds), as well as oxidative stability, were evaluated. Significant variations for the most analytical parameters of Sayali samples were demonstrated, highlighting the impact of stage of ripening. In particular, at later stages of ripening a decreased tendency was seen in minor compounds that are able to inhibit lipid oxidation (tocopherols, carotenoids, squalene and polar phenolic compounds) and, as a consequence, in the oxidative stability value. Moreover, a higher intensity of positive sensory notes (fruity, bitter and pungent) characteristic of extra virgin olive oil were found for samples produced with less ripe olives. Finally, a deeper knowledge of the influence of this factor would be helpful to correctly manage the optimal fruit harvesting time for producers for this variety and to improve the marketing of extra virgin olive oils by using a promising secondary variety (with a high oxidative stability and an interesting fatty acid composition).     

Machines for olive paste preparation producing quality virgin olive oil

Polyphenolic substances enhance the resistance to oxidation of virgin olive oils, but an excess of polyphenols determines a marked bitter, somewhat tannic taste of the oil, similar to the taste of unripe olives. Tests have been carried out on drupes of different cultivars in industrial productions to evaluate the effect of the machines used to prepare olive pastes on the contents of polyphenols in the oils. Notably greater amounts of polyphenols were found in the oils extracted from hammer-crushed pastes than in the oils extracted from milled pastes. The kneading process which follows, especially if it is long, often reduces the amounts of total polyphenols. Therefore, in order to obtain the best organoleptic and chemical quality in extra virgin olive oils, two systems are suggested for the processing procedures. For olives of certain cultivars (Coratina) and for not-blackened or slightly blackened drupes yielding oils with a very high content of total polyphenols, it is most expedient to use the stone-mill together with a kneader system. But it is more suitable to utilize the hammercrusher together with a kneader system in processing olives (such as the Ogiiarola Salentina or Leccino cultivars) yielding normally “sweet” oils with a low content of total polyphenols.     

Classification of Turkish Monocultivar (Ayvalık and Memecik cv.) Virgin Olive Oils from North and South Zones of Aegean Region Based on Their Triacyglycerol Profiles

In this study, a total of 22 domestic monocultivar (Ayval?k and Memecik cv.) virgin olive oil samples taken from various locations of the Aegean region, the main olive growing zone of Turkey, during two (2001–2002) crop years were classified and characterized by well‐known chemometric methods (principal component analysis [PCA] and hierarchical cluster analysis [HCA]) on the basis of their triacylglycerol (TAG) components. The analyses of TAG components (LLL and major fractions LOO, OOO, POO, PLO, SOO, and ECN 42–ECN 50) in the oil samples were carried out according to the HPLC method described in a European Union Commission (EUC) regulation. In all analyzed samples the value of trilinolein (LLL), the least abundant TAG, did not exceed the maximum limit of 0.5 % given by the EUC regulation for different olive oil grades. The ranges of abundant TAG, namely LOO, OOO, POO, PLO, and SOO, were 13.30–16.08, 37.27–46.36, 21.39–23.24, 4.93–7.03, and 4.72–6.00 %. The TAG data of Aegean virgin olive oils were similar to those of products from important olive‐oil‐producing Mediterranean countries was determined. Also, the estimation of major fatty acids (FA) was carried out by using a formula based on TAG data. The PCA results showed that some TAG components have an important role in the characterization and geographical classification of 22 monocultivar virgin olive oil. The Aegean virgin olive oil samples were successfully classified and discriminated into two main groups as the North and South (growing) subzones or Ayval?k and Memecik olives (cultivars) according to the HCA results based on experimental TAG data and calculated major FA profile.     

Effect of filtration on virgin olive oil stability during storage

The effect of filtration and dehydration on the stability and quality of virgin olive oil during storage at room temperature (25 °C) and under accelerated conditions (40 °C) was studied. Different types of monovarietal olive oil, namely unfiltered (UF), filtered (F) and filtered‐dehydrated (FD), were obtained from Arbequina, Colombaia, Cornicabra, Picual and Taggiasca cultivars. Results showed that filtration and dehydration decreased the rate of hydrolysis of the triacylglycerol matrix, especially at the higher temperature and in oils with a higher initial free acidity (e.g. free acidity of 0.82% and 0.63% in UF and FD Colombaia samples, respectively, after 8 months of storage), and delayed the appearance of rancid defects (e.g. UF and FD Arbequina samples lost extra‐virgin grade after 10 and 12 months of storage, respectively). The formation of simple phenols due to the hydrolysis rate of their secoiridoid derivatives was also greater in unfiltered olive oils (e.g. 174 μmol/kg and 137 μmol/kg in UF and FD Picual samples, respectively, after 8 months of storage). Thus, filtration and especially dehydration could help to prolong the shelf life of high‐quality and less stable olive oils like those obtained from the Arbequina and Colombaia varieties.     

Characterization of grape seed oil from different grape varieties (Vitis vinifera)

In this work, oil obtained from seeds of different red grape varieties, grown in the Autonomous Regions of Castilla‐La Mancha and Murcia (Spain), was characterized by determining physicochemical and sensory quality parameters, stability, and the composition in fatty acids and sterols. The physicochemical quality parameters (free acidity, peroxide index, K₂₇₀ and wax) scored high (meaning low quality) compared with virgin olive oils, while the negative sensory attributes stood out over the positive ones. Therefore, the oil was not considered suitable for table use without undergoing a refining process. The samples showed high linoleic and low linolenic acid contents, while β‐sitosterol was the main sterol found. Drying grape seeds with hot air before extraction gave higher physicochemical quality, total phenolic content and stability, and lower wax content in comparison to air‐drying of seeds. The drying process affected the sterol composition but not the fatty acid composition.     

The olive oil oxygen radical absorbance capacity (DPPH assay) as a quality indicator

The antioxidant properties of some single components and the total antioxidant activity of extra‐virgin olive oil have been evaluated by the oxygen radical absorbance capacity (ORAC) method. The total ORAC of the extra‐virgin olive oil was found to be positively correlated with the concentration of total polyphenols, which are important to the shelf life of the product. Among the single phenolic compounds studied, gallic acid showed a higher ORAC than caffeic acid and oleuropein, while among the derivates of oleuropein, hydroxytyrosol was found to be the most active compound among all the phenols studied. The total ORAC of commercial olive oils differed according to the concentration of total polyphenols. The total ORAC of extra‐virgin olive oil was constant during 1 year of storage in rational conditions, whereas it worsened dramatically in olive oil damaged by the lipase‐producing yeast Williopsis californica or by lipase from Pseudomonas spp. The study accomplished on the oily fraction of the fruits before harvesting demonstrated that the total ORAC of the oil of under‐ripe green olives is higher compared to that shown by mature fruits; therefore, through the choice of the harvesting time, it is possible to define also the future content of polyphenols of the oil. The total ORAC test, together with other analyses, can be considered as a qualitative parameter that can contribute to the expression of technological and health virtues of extra‐virgin olive oil.     

Effect of Agronomical Practices on the Nutritional Quality of Virgin Olive Oil at Different Ripening Stages

There is a need to verify the quality of organically produced olive oils and to compare them to conventional ones. The objective of this study was to assess possible differences in nutritional quality between agronomic practices in Picual and Hojiblanca olive oil varieties at different stages of olive ripeness. The results showed that organic versus conventional cultivation did not consistently affect acidity, peroxide index or spectrophotometric constants of the virgin olive oils considered in this study. On the contrary, phenol content, oxidative stability, tocopherol content and fatty acid composition were affected by the agronomical practices. Principal component analysis indicated that linolenic acid and β‐tocopherol were mainly responsible for discriminating Hojiblanca organic oils, whereas total phenols, palmitoleic acid and α‐tocopherol were the major contributors to differentiating Picual conventional oils. Lignoceric and stearic acids were related to oils from unripe and ripe olive fruits, respectively. Long‐term experiments are required to confirm these results.     

Characterization and Classification of Extra Virgin Olive Oil from Five Less Well-Known Greek Olive Cultivars

The present study comprises the second part of an ongoing study focusing on olive oil from five less well‐known Greek cultivars for three of which there are no data available in the literature regarding their chemical composition. A total of 74 olive oil samples were collected during the harvesting periods 2012–2013 and 2013–2014. Headspace‐solid phase microextraction was applied to determine the olive oil volatile profile. Fifty‐six compounds were identified and semi‐quantified by CG–MS. Furthermore, fatty acid composition, conventional quality parameters and color parameters were determined in an effort to characterize and differentiate olive oils according to cultivar. All samples were characterized as extra virgin olive oils. Data obtained showed significant differences between the cultivars. Multi‐element analysis in combination with chemometrics resulted in a high classification rate of 86.5 % for the combination of volatiles plus color, 89.2 % for the combination of VC plus FA, and 91.9 % for the combination of FA composition plus color plus CQP.     

Influence of the type of olive‐crusher used on the quality of extra virgin olive oils

An experimental investigation was carried out to evaluate the quality of virgin olive oils obtained when either a hammer‐crusher or a disk‐crusher were used for the olive paste preparation; the effect of the temperature rise caused by rapid olive crushing was also assessed. Oxidative degradation in the oils obtained from hammer‐crushed olives was significantly higher than in those obtained from disk‐crushed olives as shown by the levels of oxidised triacylglycerols and the results of the oven test. A significant inverse correlation (p <0.001) was found between the Rancimat induction time values and the amounts of oxidised triacylglycerols as determined by the high‐performance size exclusion chromatography analysis of polar compounds. These findings suggested that polar compound analyses, just as routine analyses, may be used as a suitable analytical tool to effectively evaluate the quality of virgin olive oils.     

Evaluation of the polyphenolic content of extra virgin olive oils using an array of voltammetric sensors

A novel system to evaluate the phenolic content of extra virgin olive oils is reported. The method uses an array of voltammetric electrodes. Such electrodes are chemically modified with electroactive materials (five phthalocyanines and six conducting polymers). The voltammetric responses towards the phenolic fractions extracted from extra virgin olive oils consist in complex voltammograms. Curves show redox processes related to the electrochemical activity of the phenolic fraction under study, and redox peaks associated to the electroactive material. In addition the antioxidant activity of polyphenols influences drastically the electrochemical behaviour of the electrodic material. The pattern of responses provided by the array represents the fingerprint of each sample and can be used to discriminate and evaluate the degree of phenolic content of extra virgin olive oils. Principal component analysis (PCA) conducted using kernel functions has demonstrated the capability of the array of electrodes to discriminate olive oils according to their phenolic content and bitterness index. Using partial least square discriminant analysis (PLS-DA) good correlations between the results obtained using the array of sensors and the polyphenol content, the bitterness index (analysed by chemical methods) and the bitterness degree determined by the panel of experts has been obtained.