Characterization Of Virgin Olive Oils Research Articles

Description of virgin olive oil: Descriptive evaluation by trained assessors vs flash profile using panels with diverse degrees of training

Although a very robust and thorough sensory description of virgin olive oil can be obtained with highly specialized assessors, grouping well-trained panelists can be very expensive as it requires a long period of time. The fast descriptive methodologies developed in recent years could potentially be used to obtain the profiles of diverse products to be used, for example, in gastronomy.This study aimed to compare the conventional descriptive sensory characterization of virgin olive oil by trained judges and a faster descriptive methodology (Flash Profile) conducted by panelists with diverse degrees of training (experienced panelists, wine sommeliers, and consumers).Panels with diverse degrees of training were able to differentiate between virgin olive oil samples; however, the description given by the panelists depended on both the degree of knowledge of the technique used in testing and their product knowledge. Wine sommeliers and consumer groups could not describe the differences between products linked to quality.Experienced panelists seem to be a viable option for describing virgin olive oil samples using the Flash Profile methodology. Said use should not be considered as a replacement for trained judges, but rather as an approach to obtain fast descriptions of the products.

A multivariate approach to qualify “Moroccan Picholine” virgin olive oil according to extraction and environmental factors

AbstractThis paper describes the composition and quality characteristics of the “Moroccan Picholine” virgin olive oil (VOO) produced in Taza province (northern Morocco). Legal quality indices, pigments, total phenols, oxidative stability, and fatty acid composition were analyzed under the impact of three extraction systems (two phase [C2] and three phase [C3] centrifugation decanters and super‐pressure [SP]) in three production sites (Bni Frassen, Bouchfaa, and Taza) during three consecutive crop seasons (2014, 2015, and 2016). All the assessed parameters were largely affected by the extraction system. Indeed, the two phase centrifugation system provided the better quality of VOO with the lowest values of free fatty acids and oxidation indices and the highest amounts of oleic acid, carotenoids, and total phenols therefore the greatest oxidative stability. Crop season and production site had only significant impacts on some parameters. VOO produced in 2015 from Bni Frassen was richer on total phenols hence presented lower values of peroxide value. Principal component analysis (PCA) showed a clear separation along PC1 (58%) between C2 with better VOO characteristics from both C3 and SP, while PC2 (11%) allowed a net distinction of VOO produced in 2014 from those in 2015 and 2016. Moreover, the oxidative stability of the assessed VOO was found strongly related to total phenol and carotenoid contents as well as oleic/linoleic ratio.

A comprehensive comparison of Chinese olive oils from different cultivars and geographical origins.

China has become increasingly interested in producing olive oil in recent years. In this study, we determined the characteristics of virgin olive oil in five typical cultivars (cv. 'Arbequina,' 'Coratina,' 'Ezhi 8,' 'Frantoio,' and 'Koroneiki') from two of the most suitable production areas for olive cultivation in China. In addition, linear discriminant analysis (LDA) was used to differentiate oils originating from various cultivars and geographical origins. Heatmap was also constructed to describe the differences straightly. Compared to Xichang oils, Longnan oils generally contained higher levels of C18:0, lignans, total esters and total furans, and lower levels of phenolic acids and phenolic alcohols. A variety of cultivars differed in total sterols, hydroxytyrosol derivatives, and volatile compounds. Coratina oils showed excellent properties in two regions. Our findings are closely related to select the optimum olive cultivars in different regions to promote the development of Chinese olive industry scientifically.

Effect of Combined Sulfur and Nitrogen Foliar Supply on Olive Oil Volatile Compounds and Sensory Attributes

Up to date, there are no reports on the effects of combined sulfur (S) and nitrogen (N) foliar application in olive orchards on volatile compounds and sensory characteristics of virgin olive oil (VOO). In this work, the effects of increasing the fertilizer S and N concentration on volatile compound composition and odor and taste attributes of monovarietal VOOs of Istarska bjelica and Leccino cultivars were investigated. The volatile compounds were analyzed by gas chromatography with flame ionization and mass spectrometric detection after isolation by solid-phase microextraction, while sensory attributes were assessed by a professional panel. In all the investigated VOO samples, aldehydes were the most represented group of compounds, with (E)-2-hexenal as the most abundant, followed by (Z)-3-hexenal and 1-penten-3-one. Significant differences in the volatile profiles and sensory attributes were observed between VOOs from different treatments, mainly attributable to the interactions between all the factors that were investigated: treatment, cultivar, and year. Although significant interactions were noted for sensory attributes as well, the score for overall quality was generally lower for Leccino VOOs and for VOOs from both cultivars that were obtained after the highest SN dose treatment. All the samples were graded by overall sensory scores that were higher than eight and were characterized by well-pronounced fruitiness and the absence of sensory defects. The results of this study showed that foliar application of S and N significantly affects the quality of VOO, confirming that such a practice can modulate the characteristic olive oil odor and taste attributes and thus possibly influence its acceptability and preference among consumers.

Is the volatile compounds profile a suitable tool for authentication of virgin olive oils (Olea europaea L.) according to cultivars? A study by using HS-SPME-GC-MS and chemometrics

Sensory characteristics of Virgin Olive Oil (VOO) strongly influence consumer preferences. These characteristics are also affected by the varietal origin of the olives used for producing the oils, and consequently a reliable approach is strongly required to authenticate the varietal origin of VOO. However, an approach is still missing to differentiate VOOs of the most worldwide spread cultivars, thus protecting consumers and producers from frauds. The aim of this research was to propose chemometric models for discriminating monocultivar virgin olive oils of nine widespread cultivars. 72 volatile compounds of 320 monocultivar samples from 4 crop seasons and several geographic areas were quantitated by a validated HS-SPME-GC-MS method. The VOCs able to discriminate among cultivars were selected through ANOVA: most of them belonged to the lipoxygenase pathway. A PLS-DA model was successfully validated, with percentages of correct classification up to 95.9% after external validation. Three clusters of cultivars were then defined using Agglomerative Hierarchical Clustering and Correlation Analysis. LDA and PLS-DA models correctly classified 94% of samples in the three clusters. The results indicated that the volatile profile of samples of diverse cultivars are not completely independent from each other, and that specific groups of cultivars showed strong similarities not given by the geographic origin. Overall, this study will contribute to protect from frauds and to valorize monocultivar extra virgin olive oils.

The Impact of Mild Frost Occurring at Different Harvesting Times on the Volatile and Phenolic Composition of Virgin Olive Oil.

The organoleptic characteristics of virgin olive oil (VOO), together with its nutritional and health properties, have led the olive tree to be cultivated beyond the Mediterranean basin, reaching latitudes with colder climates, with minimum temperatures below 0 °C and with a higher probability of early frosts. The freezing of olives generates destruction within the tissues and promotes degradation reactions. In this study, the impact of mild frost occurring at different harvesting times on the composition of volatiles and phenolic compounds in VOO were investigated. Arbequina variety olives were harvested at different stages of ripening. Half of the olives were subjected to oil extraction and the other half were frozen at −3 ± 1 °C for 12 h prior to oil extraction. A significant decrease of phenolic compounds with harvesting time was observed in both types of oils (fresh and frozen olives). Oils from frozen olives presented a slightly higher content of total phenols, except in the advanced ripening stage (September), and a slightly lower content of volatile compounds at all harvesting times. In addition, a higher content of 3,4-DHPEA-EDA was observed in oils from frozen olives, which is attributed to an early action of the endogenous β-glucosidase enzyme on oleuropein in freeze-damaged olive fruits. Principal component analysis and Discriminant Partial Least Square Regression allowed the oils to be classified according to the type of fruit (fresh and frozen) and the month of harvest. This study would indicate that mild frost would have a low impact on the chemical composition of virgin olive oil, although, this depends on the ripening stage.

Effect of processing technology on chemical, sensory, and consumers' hedonic rating of seven olive oil varieties.

This study established physicochemical and sensory characteristics of virgin olive oils (VOOs) and linked them to consumers’ liking using external preference mapping. We used five Tunisian and two foreign VOO varieties produced by two processing systems: discontinuous (sp) and continuous three‐phase decanter (3p). The samples were analyzed and evaluated by a panel of 274 consumers. The external preference mapping revealed five VOO clusters with a consumer preference scores rating from 40% to 65%. Consumers highly appreciated the foreign Coratina cultivar's olive oil; the main drivers being richness in polyphenols (markers of bitterness and pungency), mainly the oleuropein aglycone, and volatile compounds (markers of green fruity, green leaves, green apple, cut grassy almond, and bitterness), particularly the trans‐2‐hexenol. The Tunisian Chemlali (3p) oil was second highly preferred (scoring 55%). The positive drivers for olive oil preference (a profile of almond fruity green and low bitterness and pungency) are the richness in hexanal compounds. Arbequina (sp and 3p) and Chemlali (sp) were the least appreciated due to the fact that Arbequina VOO is not in the tradition of Tunisian consumers, whereas Chemchali VOO is a minor variety representing only 2% of olive oil production in Tunisia and consumed mostly in blends. The differentiation between the two processing systems depends on the variety of cultivar; consumers are able to identify the two processing system in the case of Chetoui, Leguim, and Chemchali.

Characterization of virgin olive oils obtained from minor Tunisian varieties for their valorization

Several compositional parameters (fatty acids, tocopherols, polar phenols and volatiles) in virgin olive oils from varieties located at the center of Tunisia, namely Baldi, Chemchali, Neb Jmel, Tounsi and Besbessi from Gafsa and Chemchali and Sehli cultivated in Sidi Bouzid, were studied. To the best of our knowledge, this is the first study focusing on the chemical composition of virgin olive oils (VOO) from Sidi Bouzid. Significant differences were found between varieties from Sidi Bouzid and Gafsa in monounsaturated saturated fatty acid levels, some volatile compounds and γ-tocopherol amounts. Notably, Tounsi and Baldi VOOs showed the highest six carbon atoms alcohol contents, whereas Neb Jmel VOO revealed the highest aldehyde six carbon atoms content. Fatty acid composition, as well as tocopherol content, showed differences among different VOO. Principal component analysis and hierarchical component analysis on polar phenols, fatty acids, tocopherols and volatiles data evidenced a good discrimination among oils from the different investigated varieties.

Impact of variety and extraction process on physico-chemical and sensory characteristics of virgin olive oil

Abstract The aim of this study was to evaluate the effects of variety and extraction system on the physico-chemical and sensorial characteristics of olive oils produced from three dominant varieties of Algeria (Azeradj, Chemlal and Sigoise). The olive oils were extracted by three different processes (pressure system, two-phase centrifugation and traditional process). Physicochemical parameters including free acidity, peroxide value, absorbance in ultra violet (K232, K270, ΔK) and sensory evaluation were studied. The results show that free acidity, peroxyde value and K270 were influenced by the extraction system and variety. Olive oils obtained from the two phases centrifugation and Chemlal cultivar were characterized by higher oxidative stability. Sensory characteristics of olive oils were mainly influenced by the variety and extraction system. Olive oils obtained from the two phases centrifugation, traditional cold process and Sigoise variety were characterized by the lower mean values of negative attributes.

Virgin Olive Oil Quality Is Affected by the Microbiota that Comprise the Biotic Fraction of the Oil.

This review summarizes the current knowledge on the effects of oil-borne yeasts on the physicochemical, sensorial, and health-related characteristics of virgin olive oil (VOO) during storage. Bacteria, yeasts, and molds constitute the biotic fraction of freshly produced VOO. During storage, the bacteria and molds often die after a short period, while the yeasts survive and condition the quality of VOO. To date, approximately twenty-four yeast species have been isolated from different types of olive oil and its by-products, and seven of these species have been identified as new species. The activity of some yeasts of the biotic fraction of olive oil improves the sensorial characteristics of VOO. Some yeasts can also worsen the quality of the product by allowing the appearance of defects, oxidation of polar phenols, and triacylglycerol hydrolysis. Some yeast species of VOO show in vitro beneficial health effects, such as probiotic and antioxidant activities.

Tracking Sensory Characteristics of Virgin Olive Oils During Storage: Interpretation of Their Changes from a Multiparametric Perspective

Virgin olive oil is inevitably subject to an oxidation process during storage that can affect its stability and quality due to off-flavors that develop before the oil surpasses its ‘best before’ date. Many parameters are involved in the oxidation process at moderate conditions. Therefore, a multiparametric study is necessary to establish a link between physico-chemical changes and sensory quality degradation in a real storage experiment. In this context, a storage experiment of 27 months was performed for four monovarietal virgin olive oils, bottled in transparent 500-mL PET bottles and subjected to conditions close to a supermarket scenario. Volatile composition, quality parameters and phenolic compounds were determined monthly. Simultaneously, an accredited sensory panel assessed their sensory characteristics. The stability of the fresh samples was also studied with the oxidative stability index (OSI) and mesh cell-FTIR. (E)-2-hexenal, (Z)-3-hexen-1-ol and (E)-2-hexen-1-ol were identified as markers of the fruity attribute. Hexanal and nonanal were also identified as compounds that were associated with the rise of median of defect during storage. Some disagreements were observed between the sensory assessment and the OSI analyzed by Rancimat. However, the increase of concentration of rancid markers agreed with the increase of aldehyde band measured with mesh cell-FTIR.

Quality of olive oils from southeastern Brazil

ABSTRACT This study aimed to characterize the volatile composition and sensory characteristics of virgin olive oils (VOOs) from eight olive cultivars grown in the southeast region of Brazil. The volatiles were extracted by Solid Phase Micro Extraction (SPME) and analyzed by Gas Chromatography coupled to MassSpectrometry (GC-MS). The dominant sensory attributes were determined by Temporal Dominance of Sensations (TDS). C5 and C6 alcohols and C6 aldehydes were the most abundant volatiles in the investigated VOOs. E-2-hexenal was among the majorityof volatiles in all investigated olive oils, mainly in VOOs fromcultivars Arbequina, Arbosana and Grappolo 541, in which it had the most of their chromatographic area (about 60-80%). VOOs from cultivars Maria da Fe, Mission, Arbosana and Arbequina were characterized by the dominance of pungency sensation, as well as Frantoio regarding to bitter. Grappolo yielded an olive oil withpredominance of bitter, and a blended VOO (Grappolo 541 and Arbequina) had predominance of green leaf. VOO from Ascolano cultivar had dominance of fruity and pungency. Overall, pungent was the main dominant sensation in most of the investigated VOOs, which can be related to C5 and C6 volatiles.

Physicochemical characterization of virgin olive oil obtained using an ultrasound-assisted extraction at an industrial scale: Influence of olive maturity index and malaxation time

Ultrasound-assisted extraction is an innovative technique applied to the extraction process for virgin olive oil (VOO), which is generally employed to increase plant efficiency and improve product quality. A high-power ultrasound (US) device was introduced at an industrial plant that can process at 2 tons/h to evaluate the technique’s physicochemical impact on quality parameters of VOO that was caused by an intensive mass transfer induced by acoustic cavitation process and shockwaves. The impact on oil yield was also evaluated with respect to the ripening stage and malaxation time. No significant effects on the legal and commercial parameters of VOO (including quality indices, sterols, triterpene dialcohols, waxes and diacylglycerols) were found for olives at medium-early ripening stage. Significant physical changes, increased extraction yield (22.7%), enhanced phenol content (10.1%) were observed in US-VOO compared to control (C) oil extracted with a traditional process at an early maturity index.

Chemometric characterization of virgin olive oils of the two major Cypriot cultivars based on their fatty acid composition

The effects of the geographical region and the botanical origin of olive oils on the profile of fatty acids isolated from monovarietal virgin olive oils from Cyprus were investigated, in order to establish, for the first time, promising models for authentication and classification of monovarietal virgin olive oils produced on the island. The two dominant Cypriot olive cultivars, Cypriot (ladoelia), and Koroneiki (lianolia), were analyzed for fatty acid composition by GC/FID after preparation of Fatty Acid Methyl Esters from olive oil, using a cold esterification method. The data obtained were analyzed statistically using multivariate and univariate ANOVA, principal components analysis (PCA) and hierarchical cluster analysis. Results showed that the olive oils can be separated into two distinct groups using the FAME data bank obtained from 225 samples. Significant differences in the proportion of some variables such as polyunsaturated linoleic acid, and the ratio C18:1/C18:2 from oils of different varieties and geographical regions were detected. The ratios C18:1/C18:2 and MUFA/PUFA, as well SFA, ω-9 and PUFA showed the higher discriminant power based on the cultivar.

Changes in Virgin Olive Oil Volatiles Caused by in Vitro Digestion.

Volatile compounds are responsible for some sensory characteristics of virgin olive oil (VOO); however, they have not been studied from a nutritional point view. In this work, the effect of the simulated digestion on VOO volatile compounds responsible for green flavor was studied, analyzing their changes through the three steps of an in vitro digestion model (mouth, stomach, and small intestine). Index of recovery and bioaccessibility were determined for the main volatiles of "Picual" VOO. At end of the duodenal step, higher recoveries of ethanol, pent-1-en-3-ol, β-ocimene, and nonanal were observed. From the 10 volatile compounds analyzed, only six compounds were bioaccessible. The compounds with the highest bioaccessibility were pent-1-en-3-ol, nonanal, β-ocimene, and ethanol. The results showed for the first time the recovery and bioaccessibility of several volatile compounds present in VOO.

Chemosensory characterization of virgin olive oils obtained from organic and conventional practices during fruit ripening

AbstractThe current increase in demand for organic products by consumers, including virgin olive oils (VOO), makes it necessary to study the characteristics of these types of foods. Moreover, the higher quality of organic products versus that of conventional products is controversial. In this regard, the chemosensory qualities of several virgin olive oils produced from fruit grown in an experimental orchard at four different stages of maturation under organic and conventional management systems were analysed. The resulting oils were subjected to sensory and chemical analyses. According to the data organic virgin olive oils showed higher concentrations of volatile compounds synthesized throughout lipoxygenase (LOX) pathway, responsible for green grass and olive fruity sensory attributes and showed lower concentrations of phenols, related to bitter and pungent attributes. Sensorily, conventional oils were more bitter and richer in green‐leaf character, while organic oils were sweeter. Multivariate analysis showed that 10 sensory descriptors and 6 compositional parameters clearly discriminate between Picual and Hojiblanca cultivars and between organic and conventional samples. These results could be useful to clarify the different sensory characteristic between virgin olive oils obtained by conventional and organic olive crops.

Evolution of endogenous enzyme activities and virgin olive oil characteristics during Chétoui and Chemlali olive ripening

The composition and biochemical characteristics of olive fruits, mainly olive enzymes system, are crucial in determining the final quality of virgin olive oil (VOO). Thus, olives endogenous olive enzyme activities were studied during Chétoui and Chemlali olive ripening. The compositional quality of the corresponding VOO was also studied. Peroxidase (POX) and β‐glucosidase activities increased during olives ripening. However, polyphenoloxidase activity decreased slowly. Moreover, the POX enzyme appears to play an essential role in determining VOO total phenol amounts, as the decrease in phenol content registered during olive ripening coincided with the increase in POX activity. A positive correlation between oil antioxidant activity and the total phenol content was established for both the olive cultivars studied. With regard to pigments, chlorophyll content was much higher than that of carotenoids in both Chétoui and Chemlali oils. Moreover, different trends in chlorophyll and carotenoid contents were observed, depending on the olive cultivar. Concerning volatile compounds, our results showed that the highest content of total C6, C5 LOX compounds, and pentene dimers was observed at a RI of approximately 3 for both cultivars. However, C6 alcohols and total C5 compounds decreased in Chétoui and Chemlali oils, respectively, during olive ripening.Practical applications: Volatile and phenolic compounds play an important role in determining VOO quality. However, these compounds were affected by numerous factors, such as, endogenous olive enzyme activities. Monitoring these enzymes activities (peroxidase, polyphenoloxidase, and β‐glucosidase) during olive fruits ripening by a simple spectrophotometric assay could be useful to establish an optimum harvesting date for each olive cultivar and their possible correlation with VOO total phenol amount.Evolution of endogenous olive enzyme activities (POX, peroxidase; PPO, polyphenoloxidase; and β‐glucosidase) during Chétoui (●) and Chemlali (○) olive ripening.

Characterization of Virgin Olive Oils with Two Kinds of 'Frostbitten Olives' Sensory Defect.

The frost of olives on the tree due to drops of temperature can produce sensory defects in virgin olive oil (VOO). Temperature changes can be abrupt with freeze-thaw cycles or gradual, and they produce sensory and chemical variations in the oil. This study has analyzed the quality parameters (free fatty acids, peroxide value, UV absorption, and fatty acid ethyl esters) and phenols of VOOs described with the 'frostbitten olives' sensory defect. The phenol profiles allowed grouping these VOOs into two types. One of them, characterized with "soapy" and "strawberry-like" aroma descriptors, had higher values of 1-acetoxypinoresinol, pinoresinol, and aldehydic form of the ligstroside aglycon. The other one, characterized with "wood" and "humidity" descriptors, had higher concentrations of luteolin and apigenin. Most VOOs (75%) from the first group, associated with abrupt drops of temperature, have concentration of phenols higher than the value established by the health claim on olive oil polyphenols approved by the European Commission.

The influence of crusher speed on extra virgin olive oil characteristics

Milling is an aspect of olive oil production that has received very little attention, and there have been very few studies of the relationship between crusher speed and oil quality. This work compares the effect of three blade cutter crusher speeds used in an industrial plant on the main olive oil chemical and sensory parameters, at two points in time: immediately post‐production, and after eight month of storage. The ANOVA results showed that faster crushing significantly increases chlorophyll and total biophenol content. Secoiridoids are particularly affected and concentrations of 3,4‐DHPEA‐EDA and p‐DHPEA‐EDA significantly varied in oils milled at different speeds. From the lowest to the highest speed a difference of roughly 50 mg/kg (on about 400 mg/kg) for total biophenols, and about 40 mg/kg of 3,4‐DHPEA‐EDA is found. Panel testing found higher bitterness and astringency scores in oils produced at the higher speed. These findings suggest that crushing speed can be used to characterize olive oils.Practical applications: Crushing speed is easy to change in olive mills, and could be used to control the sensory and nutraceutical profile of extra virgin olive oil through its effect on bitterness, astringency, and phenolic content parameters. Hence, it is very useful to have a better understanding of the relationship between crushing speed and olive oil characteristics.Crushing speed can be used to characterize olive oils. Faster crushing significantly increases chlorophyll, total biophenol, 3,4‐DHPEA‐EDA, and p‐DHPEA‐EDA. Panel testing found higher bitterness and astringency scores in oils produced at the higher speed.

How the Addition of Spices and Herbs to Virgin Olive Oil to Produce Flavored Oils Affects Consumer Acceptance

With the aim to expand the olive oil market to a larger number of consumers who are not familiar with the sensory characteristics of virgin olive oil, the use of novel products known as "flavored olive oils", obtained by adding different kind of spices and aromatic herbs, is spreading in many countries. In order to test consumer acceptability of this type of product, in a country (Tunisia) in which virgin olive oil is regularly consumed, flavored olive oils were prepared by adding aromatic extracts of thyme, oregano, a mix of herbs (used as pizza seasoning), rosemary, and basil to a monovarietal Chemlali virgin olive oil and a consumer test on 206 subjects was performed. Selected quality parameters (free acidity, peroxide number, oxidative stability, specific absorption at K232 nm and K270 nm) were also measured and no significant variations were detected. Slight differences were found concerning the content of minor compounds (chlorophylls, carotenoids and total phenols). On the other hand, notable differences were seen in the profiles of volatile compounds, which appeared to be responsible for the observed variability in consumer acceptance. Although the unflavored oil was more appreciated than the flavored ones, among the latter, thyme flavored olive oil was the most appreciated.