Pigments profile in monovarietal virgin olive oils from various Italian olive varieties

This paper presents the investigation of the chlorophyll and carotenoid pigments composition in monovarietal virgin olive oils produced from the five main olive varieties (Minuta, Ottobratica, Calabrese, Ogliarola, Baddarica) cultivated in Sicily (southern Italy), from four main olive varieties (DolceAgogia, Moraiolo, Leccino, Frantoio) cultivated in Umbria (central Italy), and from three main olive varieties (Leccino, Oliva Nera di Collecorto, Noccioluta) cultivated in Molise (central Italy). Reversed-phase high performance liquid chromatography using a C-30 column with photodiode array detection was used for pigments analyses. In all, 19 compounds were identified and quantified in 60 olive oils samples. The qualitative pigments pattern was similar among the varieties investigated, whereas quantitative differences were found among the different cultivars; among the varieties investigated in this work, the oils from Umbria showed the highest pigment content (34.19 ppm in average), followed by the oils from Molise (18.61 ppm in average) and the oils from Sicily which showed the lowest pigment contents (13.38 ppm in average). In general, pheophytin a was the major component (range 0.49–19.42 ppm), followed by β-carotene (range 1.27–9.30 ppm) and lutein (range 0.44–5.12 ppm). Those differences may be due to genetic factors and/or geographical differences. Moreover, auroxanthin was detected for the first time in olive oils and was detected only in olive oils from Umbria and Molise regions. The ratio between the two isochromic pigment fractions, namely the ratio between the chlorophyll and carotenoid fractions showed an average value close to unity. The lutein/β-carotene ratio was less than one in the majority of the cases. These parameters, along with other analytical parameters, could be used as indicators of typicality in olive oils. The presence of a specific pigment profile in olive oils could infact be used to guarantee the genuineness of the product, since the quality control of food requires a precise knowledge of the pigments composition of the original products.     

Pigment profile and chromatic parameters of monovarietal virgin olive oils from different Italian cultivars

The aim of this study was to characterise the pigment profile (chlorophylls and carotenoids) of monovarietal virgin olive oils from six Italian olive cultivars (Ghiacciolo, Giarraffa, Sant’Agatese, Biancolilla, Nocellara del Belice and Gentile di Larino), from three Italian olive-growing regions (Emilia-Romagna, Sicily and Molise). The results show that the qualitative study of the pigment chlorophyll and carotenoid fractions of virgin olive oils demonstrated a common pattern that did not depend on the olive cultivar or growing region. Besides these, mutatoxanthin was only detected in oils from the Nocellara del Belice and Gentile di Larino cultivars, and pheophorbide a was only detected in oils from the Ghiacciolo and Sant’Agatese cultivars. However, significant quantitative differences were observed in the composition of the pigment fractions. The principal component discriminate analysis showed that the first two discriminate functions of the statistical analysis explained 78.9% of the total variance. The plot of discriminate functions showed an effect of the olive cultivar and growing area on the chlorophyll and carotenoid contents of the virgin olive oils. The results of this study are a contribution to the pigment characterization of the Italian monovarietal olive oils, which should be completed with more samples obtained from different crop seasons and different growing areas.     

Comparative study of the effect of the maturation process of the olive fruit on the chlorophyll and carotenoid fractions of drupes and virgin oils from Arbequina and Farga cultivars

Two varieties of olive fruit (Arbequina and Farga) have been characterized by their contents and types of chlorophyll and carotenoid pigments during the olive ripening. Independently of the initial content, the pigment concentrations decreased with fruit maturity. Chlorophyllides a and b, esterified xanthophylls and α-carotene were only detected in Arbequina fruits. Moreover, the synthesis of esterified xanthophylls, when the skin fruit colour changed from green to turning-colour only, was observed in this variety. The pigments transferred from fruit to the oil were also studied. All the pigments that were found in the fruit were transferred to the oils, in addition to derivative pigments associated with acidic medium in the oil extraction process. The destruction of the chlorophyll fraction was greater than of the yellow pigments during the olive oil extraction process.     

Preliminary characterisation of virgin olive oils obtained from different cultivars in Sardinia

Chemical characterisation was carried out on 12 virgin olive oil samples obtained from seven olive cultivars (Bosana, Carolea, Nocellara del Belice, Pizz'e Carroga, Semidana, Tonda and Zinzala cvs.). The olives came from different groves in Sardinia (Italy) and Corsica (France) that were processed by different types of continuous mills. Several qualitative parameters were evaluated (free acidity, peroxide value, and UV spectrophotometric indices) and analyses of major (fatty acids and triacylglycerol compositions) and minor components (chlorophylls, carotenoids, tocopherols and phenolic compounds) was also carried out. The oxidative stability index (OSI) and ABTS^•− test values were determined to evaluate the oxidative stability and antioxidant activity of the phenolic fraction, respectively. The results were subjected to a discriminative study by principal component analysis (PCA) to characterise the different oils. A first PCA using only the triglyceride compounds and a second using the minor polar compounds and their antioxidant activity was performed. The triglyceride composition was found to be particularly useful in discriminating the oil samples.     

Effect of cultivar and ripening on minor components in Spanish olive fruits and their corresponding virgin olive oils

Phenolics and volatiles are the compounds mainly responsible for the desirable flavour of extra virgin olive oils and therefore to a large extent determine the degree of consumer preference for this highly regarded product. The effect of both (i) the nature of the cultivar and (ii) the degree of ripening of the olive fruit on the biophenolic and volatile profiles of six different Spanish varieties (Arbequina, Cornicabra, Morisca, Picolimón, Picudo and Picual) and their corresponding virgin olive oils was determined in this study. A clear and statistically significant difference was observed for the oleuropein content, the main phenolic component found in the olive varieties studied. Demethyloleuropein was only found in the Arbequina variety and its content doubled during the ripening process. Verbascoside steadily increased throughout fruit maturation and cyanidin 3-O-rutinoside was the most abundant anthocyanin in all the varieties studied. Within the same cultivar a relationship between the oleosides content in the fruit and the presence of secoiridoids in the virgin olive oils was observed; however, the ratio between biophenols content in the olive fruit and in the virgin olive oil varied significantly for each of the cultivars studied (ranging from 2.3 for Picudo and 28 for Picolimon). The major volatile component was the C6 aldehyde fraction whose content varied greatly between the different varieties studied: E-2-hexenal content ranged from 20.5 mg of internal standard (4-methyl-2-pentanol) per kg of oil in the Arbequina variety to 3.1 mg/kg for Cornicabra; the amount of hexanal ranged from 1.75 mg/kg in Morisca to 0.70 mg/kg for Picual samples.     

Comparative study on volatile compounds from Tunisian and Sicilian monovarietal virgin olive oils

The effects of ripening degree of olives on volatile profile of monovarietal virgin olive oils (VOO) from Tunisian and Sicilian cultivars were investigated. Fruits obtained from Tunisia (Chétoui and Chemlali) and Italy (Nocellara del Belice, Biancolilla and Cerasuola) were picked at three different stages of ripeness and then immediately processed. Moreover, the changes in volatile composition were evaluated in Chétoui variety as a function of the irrigation regime versus the rain-fed control. Using headspace–solid-phase microextraction (HS–SPME) technique coupled to GC–MS and GC–FID, the volatile compounds of the monovarietal virgin olive oils were identified and quantitatively analyzed. The proportions of different classes of volatiles of oils showed significant differences throughout the maturity process. The results suggest that adding to the genetic factor; agronomic conditions affect the volatile formation and therefore the organoleptic properties of VOO.     

陇南两种单品种初榨橄榄油的化学性质和脂肪酸组成随成熟度的变化

分析了陇南2个品种初榨橄榄油的化学性质和脂肪酸组成随成熟度增加的变化规律。结果表明：随着成熟度的增加2个品种的鲜果出油率增加且存在显著性差异。初榨橄榄油风味成分中氮氧化合物、含硫以及烷烃类化合物变化幅度较大,通过电子鼻可以区分不同品种不同成熟度的橄榄油。恩帕特雷和科拉蒂的k232、270值最高分别为1.85和1.91、0.18和0.14,多酚、黄酮含量变化范围分别为2.39～4.53和7.47～10.39、0.07～0.40和0.75～2.84 mg/g。氧化稳定时间在第6（6.28 h）和第5(16.71 h)成熟度为最高。酸价的变化范围分别为0.37～1.02和0.19～0.38 mg/g,过氧化值的变化范围分别为2.92～8.32和2.38～5.19 mmol /kg,油酸含量分别为72.36%～77.76%和59.23%～65.73%,亚油酸含量分别为7.70%～11.81%和9.74%～15.86%,SFA含量分别为11.81%～13.15%和14.25%～20.99%,PUFA含量分别为8.34%～12.36%和10.92%～16.84%,MUFA含量为72.69%～78.50%和62.36%～68.20 %。同一品种的MUFA/PUFA、C18:1/C18:2和MUFA含量变化趋势一致,与PUFA呈相反的变化趋势,2个品种之间各种脂肪酸含量差异明显,上述测定指标完全符合GB 23347—2009中特级初榨橄榄油的标准。科拉蒂的出油率、多酚、黄酮、油酸含量和氧化稳定时间明显大于恩帕特雷,而酸价、过氧化值低于后者。综合考虑认为科拉蒂的初榨橄榄油品质优于恩帕特雷,恩帕特雷和科拉蒂分别在第6和第5成熟度的初榨橄榄油品质最好。     

Pigments composition in monovarietal virgin olive oils from various sicilian olive varieties

This paper presents the first investigation of the chlorophyll and carotenoid pigments composition in sicilian monovarietal virgin olive oils from the three (Cerasuola, Nocellara, Biancolilla) main olive varieties cultivated in Sicily (Italy). In all, 19 compounds were identified and quantified in 24 olive oil samples. The application of reversed-phase liquid chromatography with photodiode array detection using a C-30 column in the simultaneous qualitative–quantitative analysis of virgin olive oils pigments, has been shown. The qualitative pigment pattern was similar among the varieties investigated, whereas quantitative differences were found among the different cultivars, which can all be considered as having an high pigment content. Pheophytin a, was the major component (19.36–25.04 ppm), followed by β-carotene (8.06–16.27 ppm). Pheophytin a′ (2.92–4.17 ppm), lutein (2.28–4.49 ppm) and neoxanthin (1.54–2.11 ppm) were also well represented. The presence of carotenoid esters was also detected. The neoxanthin and β-carotene contents were higher compared to reports present in the literature for other olive oil varieties. This may be due to genetic factors and/or geographical differences. The ratio between the two isochromic pigment fractions, namely the chlorophyll and the carotenoid fractions, was around one in all varieties, showing that they were in balance. The lutein/β-carotene ratio was less than one in all cases. These parameters, along with other analytical parameters, could be used as indicators of typicality in olive oils. The presence of a specific pigment profile in olive oils could in fact be used to guarantee the genuineness of the product, since the quality control of food requires a precise knowledge of the pigments composition of the original products.     

Profiles of volatile compounds from some monovarietal Tunisian virgin olive oils. Comparison with French PDO

The volatile profiles of seven Tunisian and four French virgin olive oils were established by solid phase micro-extraction (SPME) and gas chromatography (GC), using flame ionisation and mass spectrometer detectors. Eighty-six compounds were identified and characterized, representing 97.4–99.9% of the total GC area. (E)-2-hexenal, the main compound extracted by SPME, characterized the olive oil headspace for approximately 90% of the oils examined. Significant differences in the proportions of volatile constituents from oils of different varieties were detected. The results demonstrated that the accumulation of the different metabolites in the oils obtained from the various cultivars was strictly connected with the varietal parameters on the basis of the enzyme differences genetically determined. This feature made possible the differentiation of the examined cultivars on the basis of the percent of each metabolite.     

Influence of filtration on volatile compounds and sensory profile of virgin olive oils

The influence of filtration through a hydrophilic cotton layer on volatile compounds, sensory characteristics and colour of two monovarietal oils was investigated in this study. Volatiles were evaluated using headspace solid-phase microextraction-gas chromatography. After the filtration of Bu?a oils only a slight increase in total alcohols was noticed. In filtered ?rna oils a significant decrease of total alcohols and slight changes in total aldehydes, total ketones and total C5 volatile compounds concentration were detected. No significant influence on the sensory scores of oils, but some slight changes in sensorial profiles were noted (slightly higher intensities of sensory characteristics apple and grass, and higher values of the lightness L^∗ in filtered samples). The results point to unequal filtration impact on different monovarietal oils and could be useful in developing targeted technologies for specific monovarietal oils quality improvement.     

Chemical composition and oxidative stability of Tunisian monovarietal virgin olive oils with regard to fruit ripening

The chemical composition of virgin olive oil may be influenced by genotype and different agronomic (i.e. fruit ripeness degree, water supply) and technological factors. This article reports the evaluation of the influence of the olive ripening stage on the quality indices, the major and the minor components and the oxidative stability of the two main monovarietal Tunisian cultivars (cvv. Chétoui and Chemlali) virgin olive oils. Moreover, the olives cv. Chétoui were tested in a rain-fed control and an irrigation regime. The oils sampled at five different ripeness stages were submitted to liquid chromatographic determination (HPLC-DAD/MSD) of their quali-quantitative phenolic and tocopherolic profiles. Moreover, the triacylglycerol and fatty acid compositions, and minor components such as squalene, pigments and their relation with the oil oxidative stability were evaluated. The tested oils showed very good correlation between the oxidative stability and the concentrations of total phenols, practically secoiridoids and α-tocopherol.     

Microsatellite markers to identify specific alleles in DNA extracted from monovarietal virgin olive oils

The suitability of DNA present in olive oil for PCR analysis has been reported by several authors. However, low concentration, degradation, and the possible presence of additional alleles due to paternal contribution in oils extracted from entire drupes, should be taken into consideration when comparing the amplification profiles of leaves with the corresponding oils for varietal traceability purposes. The aim of this work was to assess, by capillary electrophoresis of microsatellite markers, the phenetic relationships among seven certified Olea europaea L. cultivars, and to verify the genomic equality between leaf DNA and the corresponding monovarietal oil DNA. Moreover, the aim was to establish an identification key to distinguish all the types of oil among them with the minimum number of markers. The results referred to oil DNA, obtained in 70 PCR experiments, confirmed the possibility, in 85.7% of cases, of extracting DNA suitable for the analysis of microsatellites. Ninety percent of the successful amplifications led to identical patterns for leaves and oil DNA. Cima di Melfi shared only 20% of the alleles with the other cultivars. Toscanina and Leccino, showed the highest similarity (about 60%). A single microsatellite was able to distinguish the seven types of oil.     

Variety differentiation of virgin olive oil based on n-alkane profile

An on-line LC–GC method was used to assess the n-alkane composition of 40 olive oil samples obtained from three different cultivars from a restricted grove zone in Croatia. Olive samples were handpicked at three different ripening stages during four consecutive years. No significant differences were found in relation to the variable “period of harvesting”, while the effects “variety” and “year” as well as their interaction caused significant differences for most of the n-alkane components (p0.05). Despite the influence of the production year, linear discriminant analysis based on the n-alkane components was able to correctly identify the variety of 97.5% of the samples.     

Comparative study of extra virgin olive oil flavor profile of Koroneiki variety (Olea europaea var. Microcarpa alba) cultivated in Greece and Tunisia during one period of harvesting

The effects of geographical region, irrigation and ripening degree of olives on the profile of volatile compounds isolated by monovarietal virgin olive oils from Crete and Tunisia of Koroneiki variety (Olea europaea var. Microcarpa alba) using the SPME GC/MS technique were investigated. Fruits obtained from Greece (island of Crete) and Tunisia (Sfax region) were picked at three and two different growth stages respectively and then immediately processed. The most important compounds identified were esters, alcohols, carbonyl compounds and hydrocarbons. The main volatile compounds present in the oil samples were C6 derivatives, such as [E]-2-hexenal, [E]-2-hex-1-enol, [Z]-3-hexen-1-ol and 1-hexanol. In addition to C6 compounds, the aroma of the studied samples contained reasonable amounts of various classes of C5 components. The tested oil samples showed different volatile profiles. Specifically, the concentration of total esters, carbonyl, C6 and C5 compounds increased significantly with the ripening degree in Cretan, but not in Tunisian olive oils. Principal component analysis of the results indicated that primary maturity and geographical region rather than irrigation affected significantly the volatile’s profile of olive oil.     

Sensory and chemical evaluation of winey-vinegary defect in virgin olive oils

Winey-vinegary sensory defect was evaluated in virgin olive oil samples from a sensory and chemical point of view. Qualitative and quantitative differences were found in the profile of volatiles of extra-virgin olive oil samples without sensory defects and samples with high intensities of winey-vinegary sensory attribute. Several volatile compounds were found to be correlated to winey-vinegary sensory defect in virgin olive oils, acetic acid and ethyl acetate having correlation coefficients of 0.98 and 0.94 respectively. A synthetic sample was obtained with the sensory characteristics of the winey defect. Samples with low values of winey sensory defect were also studied and the evaluation of the presence of the defect using the content of four volatile compounds only was demonstrated. Received: 5 August 1999 / Revised version: 22 October 1999     

Changes during storage of quality parameters and in vitro antioxidant activity of extra virgin monovarietal oils obtained with two extraction technologies

Extraction technology has a great effect on quality of olive oils. This paper studied 18 months of storage of two Sardinian extra virgin monovarietal oils obtained with a traditional and with a low oxidative stress technology. Oil samples were subjected to the following chemical analyses: acidity, peroxide value, ultraviolet light absorption K₂₃₂ and K₂₇₀, carotenoids, chlorophylls, tocopherols and total polyphenols. The antioxidant capacity of oils, polyphenol extract and oil extract (remaining after polyphenol extraction) was also determined as radical scavenging activity. The results show that both extraction technologies resulted in minor changes in legal and quality indices during storage, due surely to the high quality of the oils as well as to the very good storage conditions used. Oils obtained with the low oxidative stress technology showed lower peroxide value and acidity and resulted in up to 103% higher total polyphenol content as well as increased radical-scavenging activity, with respect to oils obtained with the traditional technology.     

AFLP molecular markers to identify virgin olive oils from single Italian cultivars

Olive oil traceability becomes instrumental to ensure the consumer’s protection, particularly for extra virgin olive oil, the quality of which is highly related to the cultivars employed. The aim of this investigation was to evaluate the possibility of identifying the cultivar used to obtain the derived olive oil by the analysis of amplified fragment length polymorphism (AFLP) markers. To this purpose, ten virgin olive oils were prepared in the laboratory from ten different very common Italian cultivars and were then analysed using six AFLP primer combinations. The technique was optimised for fragmented DNA of oil in order to enhance the intensity of the bands in the AFLP patterns. The obtained results indicated a percentage of polymorphism ranging from 16% for Pst-AGC/Mse-AGT to 43% for Pst-AGC/Mse-ACA. The diversity index was comprised between 90.2% for Pst-AGC/Mse-AGT and 95.2% for Pst-AGG/Mse-AGG. One of the six primer combination analysed, namely Pst-AGG/Mse-AGG, was able to distinguish all the olive oil examined, and a similarity tree of the samples was elaborated.     

A spectroscopic and chemometric study of virgin olive oils subjected to thermal stress

The paper describes a study of thermal stress of three different samples of virgin olive oil in terms of oxidative stability. Fatty acid composition, evaluation of oxidative stability under forced conditions (OSI), determination of UV-spectrophotometric oxidation indexes (k₂₃₂ and k₂₇₀) and spectral properties were explored along the thermal treatment. The samples were subjected to heating treatment at 180 °C and evaluated after 0, 30, 60, 90, 120, 150 and 180 min. Middle infrared (MIR) and visible–near infrared (Vis–NIR) spectra were elaborated by partial least squares modelling to individualise regions and bands where critical variations were present. Two bands were found as principal influential ones (1245–1180 cm⁻¹ and 1150–1030 cm⁻¹) on MIR while one primary region was identified on Vis–NIR (2200–1325 cm⁻¹).     

Effect of phospholipids on extraction of hydrophilic phenols from virgin olive oils

Three methods, most frequently used in hydrophilic phenols extraction from virgin olive oils (liquid–liquid, solid-phase with C18 and solid phase with diol-bound sorbents), were applied on virgin olive oils enriched with 2.0–10.0 mg/kg of phospholipids (granular de-oiled soy lecithin). Phospholipids addition significantly decreased the total phenols concentration determined colorimetrically. Liquid–liquid extraction showed the best repeatability and recovery, and the lowest decrease of total phenols extracted in the presence of phospholipids. Extraction rate declined with the increase of phospholipids concentration, but showed a kind of saturation behaviour. Addition of phospholipids (5 g/kg) to various commercial extra virgin olive oils resulted in a different degree of total phenols decrease (from 1% to 45%), probably because of different affinity of phospholipids toward different classes of phenolic compounds. During prolonged contact time between phenols and phospholipids (60-days storage), oxidation monitored by K270 and a decrease of total phenols concentration proceeded more rapidly in the presence of phospholipids.     

Influence of genetic matrix and crop year on chemical and sensory profiles of Italian monovarietal extra‐virgin olive oils

BACKGROUND: Commercial virgin olive oils belonging to the cultivars (Bosana, Carolea, Coratina, Frantoio, Itrana, Leccino, Moraiolo, Peranzana, Piantone di Mogliano and Ravece) most represented at the Italian National Review of Monovarietal olive oils (Rassegna Nazionale Italiana degli oli Monovarietali) were considered. The evaluation of the influence of the cultivar and of the crop year as well as their interaction on oil composition were statistically analysed by a complete factorial design by principal components analysis and by linear discriminant analysis. RESULTS: In fatty acids composition, the effect of the cultivar and crop year and their interaction were highly significant. The statistical analysis showed that the sensory attributes (olive fruity, grassy, fresh almond, artichoke, tomato, aromatic herbs, bitter and pungent) were strongly influenced by the cultivar. The prevalent effect of the cultivar on the sensory profile was also demonstrated by the low or absent level of significance observed in the crop year. CONCLUSION: The construction of a databank based on a large number of samples, which is available at URL http://www.olimonovarietali.it , has contributed to the reduction of the variable effects involved in the oil production process. Knowledge of the chemical and sensory profiles of the Italian monovarietal olive oils could start a certification process of these oils, thus giving greater guarantees about their origin. Copyright © 2010 Society of Chemical Industry