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Characterization of the Olive Oil from Three Potentially Interesting Varieties from Aragon (Spain) M. Benito, R. Oria and A.C. Sánchez-Gimeno Food Science and Technology International 2010 16: 523 DOI: 10.1177/1082013210367542 The online version of this article can be found at: http://fst.sagepub.com/content/16/6/523
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Characterization of the Olive Oil from Three Potentially Interesting Varieties from Aragon (Spain) M. Benito, R. Oria and A.C. Sa´nchez-Gimeno* Tecnologı´a de los Alimentos. Facultad de Veterinaria. Universidad de Zaragoza Miguel Servet, 177, 50013 Zaragoza, Spain The commercial potential of olive oils from three autochthonous olive varieties Bodocal, Racimilla and Negral from Arago´n (Spain) has been examined. Physicochemical characteristics, sensory analysis, nutritional composition, color and pigments were considered. The three varieties are generally used for producing table olives or olive oil in coupages but not for the production of monovarietal virgin olive oil. The values of the physicochemical and sensory analysis for the three olive oils corresponded to extra virgin category, however important differences among the three oils were observed in relation to pigment content, color measurements and fatty acid and phenol and tocopherol composition. Several characteristics such as oil yield, fatty acid and phenol and tocopherol content and sensory profiles suggested that some of these oils are of a promising composition. The olive yield of the Bodocal variety was the lowest (17%) and its corresponding oil had the smallest oleic acid (69%), phenols (272 mg gallic acid/kg) and tocopherol (96 mg/kg) contents and not equilibrated sensory parameters. The main characteristics of the Racimilla variety were a very high oil yield (28%) with very high contents in oleic acid (79 %) and phenols (831 mg gallic acid/kg). The oil of the Negral variety had very equilibrated sensory properties and its oleic acid content (76%) was similar to that of Racimilla. Its phenol content (456 mg gallic acid/kg) was between that of the other two varieties and its tocopherol content (190 mg/kg) was the highest. Therefore, the two last varieties could be of great interest for producing monovarietal olive oils. Key Words: olive oil, olive varieties, Racimilla, Bodocal, Negral
INTRODUCTION Olive oil is a genuine fruit juice with excellent nutritional, sensory and functional quality obtained from the fruit of olive trees (Olea europaea L.). It represents a typical lipid source of the Mediterranean diet and is frequently associated with a low incidence of cardiovascular diseases as well as with antioxidant properties. These benefits have been associated to its well-balanced fatty acids composition, of which oleic acid is the main component and to the presence of minor biomolecules, such as vitamins and natural antioxidants (Medeiros, 2001). These characteristics make olive oil a product of major economical importance in the Mediterranean area, especially in Spain, the main producer of olive oil in the world with an average production of
*To whom correspondence should be sent (e-mail:
[email protected]). Received 23 September 2009; revised 3 December 2009. Food Sci Tech Int 2010;16(6):0523–8 ß SAGE Publications 2010 Los Angeles, London, New Delhi and Singapore ISSN: 1082-0132 DOI: 10.1177/1082013210367542
1,200,000 tons per year (Ministerio Medio Ambiente y Medio Rural y Marino, 2008). The European Community establishes the commercial classification of olive oils using physicochemical and sensory parameters in three categories: extra virgin, virgin and lampant (CE, 2003). Extra virgin olive oil is the highest quality product obtained from olives using only mechanical processing steps or other physical means and its acidity is lower than 0.8%. In Spain there are different cultivars of Olea europaea, each one with specific physical and biochemical characteristics, providing olive oil with typical compositions and performances. The Aragon region (the sixth producer of olive oil in Spain with an average of 10 000 tons per year) (Ministerio Medio Ambiente y Medio Rural y Marino, 2008) possesses a substantial genetic diversity among its olive tree varieties. However, its oleoculture principally depends on only one: Empeltre (Anonymous, 2007), the characteristic variety of the designation of origin ‘Aceite del Bajo Arago´n’. Few studies concerning to Aragon olive oils have focused on the characterization of this variety (Gracia Go´mez, 2001; Pe´rez-Arquillue´ et al., 2003) and there is a lack of information on the sensory and physicochemical characteristics of several minor varieties that are sustained in restricted areas of different parts of this 523
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region, for example in the province of Zaragoza. Here, the olive trees are a historically and important orchard and includes traditional varieties such as Racimilla, Negral and Bodocal (Priego, 1930). The olive oil of these varieties remains commercially unexplored and has not been characterized because generally the fruit of these varieties is used as table olives and not for the production of monovarietal olive oil. There are many studies that characterize different monovarietal olive oils from Spain (Gracia Go´mez, 2001; Osorio- Bueno et al., 2003; Sa´nchez-Casas et al., 2003, 2006; Pardo et al., 2007; Go´mez- Rico et al., 2008; Criado et al., 2008, etc.) and other countries such as Italy (Boggia et al., 2005), Tunisia (Oueslati et al., 2009) or Portugal (Matos et al., 2007). Usually these investigations are focused on the analysis of the parameters established by the regulatory agencies but only a few studies include other useful analysis for the characterization of olive oil such as measurements of color and pigments (Criado et al., 2008; Pe´rez et al., 2003; Moyano et al., 2008a, b). Color and pigment measurements could also be very interesting parameters for characterizing the different varieties of olive oils. Nevertheless the color of virgin olive oils is not considered a quality parameter according to the International Olive Council (COI). Therefore this parameter is not valued in sensory analysis by accredited taste panels. In addition nutritional parameters such as phenol content, tocopherol content or fatty acid profiles could also be very important for characterization studies. The present study was motivated by the view that the genetic heritage of olive tree diversity must be protected from disappearance and by a desire to explore the potential of traditional minor varieties to obtain quality olive oil. Furthermore the valuation of these olive trees could help to maintain population levels in their homelands given that oleoculture is traditionally an important agricultural activity in these areas. Characterizing both the olives and their oils could be seen as a first step towards making producers aware of their commercial potential and to bringing official attention to this issue. The aim of this work was to evaluate and characterize the olives and monovarietal olive oils obtained from Cvs. Racimilla, Bodocal and Negral. Olive oil was characterized using officially recognized methods as well as other less frequently used methods such as the measurements of pigments and of color and nutritional determinations (phenol and tocopherol content).
(Olea europea racemosa), Negral (Olea europea atrorubens) and Bodocal (Bodrocal). The trees were identified and carefully marked, and five trees of each cultivar were sampled. Only healthy fruits from each tree were handpicked on November 2008 and immediately transported to the laboratory. Methods Maturity Index and Morphologic Parameters of the Olive Fruits The olives were carefully blended and a hundred of each cultivar randomly taken for determining the maturity index (MI) as a function of fruit color of both skin and pulp (Hermoso et al., 1991). In this system a group of 100 olives was separated in different categories in function of the color of the skin and pulp: 0-Deep green; 1-Yellow green; 2-Turning color with reddish spots; 3-Turning color with red or light purple color in all the fruit; 4-Black, without color under the skin; 5-Black, with color in less than the half of the pulp; 6-Black, with color in more than the half, but not in the stone; 7-Black, with color in all the pulp. After that the MI is calculated as follows: MI ¼ ða 0 þ b 1 þ c 2 þ d 3 þ e 4 þ f 5 þ g 6 þ h 7Þ=100 Where a, b, c, d, e, f, g and h are fruit number of each category Five olives were also randomly selected in order to calculate the average weight and diameter. The skin, stone and pulp of five olives of each variety were separated using a scalpel in order to determine the percentages represented by these parts of the fruit as a whole. Oil Extraction An Abencorß analyzer (MC2 System, Sevilla, Spain) was used for oil extraction (Martı´ nez et al., 1975). The unit consists of three essential elements: the mill, the thermo-beater and the pulp centrifuge. Racimilla, Negral and Bodocal oils were obtained from 10 kg of olives. After processing, the oil was decanted, filtered by using a cellulose filter and then transferred into dark glass bottles, and stored in the dark at 15 C. Industrial Oil Yield
MATERIALS AND METHODS Sampling The studied cultivars grown in traditional orchards in Zaragoza (Northeast of Spain) were Cvs. Racimilla
The industrial oil yield was expressed as a percentage of fresh olive paste weight using the equation: Oil yield ¼ ðV d=WÞ 100 Where V is the volume of olive oil obtained (mL), d is the density of the olive oil (0.915 g/mL) and W is the weight of olive paste used.
Olive Oil of Three Varieties Potentially Interesting from Aragon
Analytical Determinations Determinations of the regulated physicochemical quality parameters (free acidity, peroxide value and UV absorption characteristics, K270 and K232), were carried out following the analytical methods described in Regulation EEC/2568/91 of the Commission of the European Union (CE, 1991). Free acidity, given as % of oleic acid, was determined by titration of a solution of oil dissolved in ethanol/ether with 0.1 M potassium hydroxide ethanolic solution. Peroxide value, expressed in milliequivalents of active oxygen per kilogram of oil (meq/kg) was determined as follows: a mixture of oil and chloroform-acetic acid was left to react with a solution of potassium iodide in darkness; the free iodine was then titrated with a sodium thiosulfate solution. K270 and K232 extinction coefficients were calculated from absorption at 270 and 232 nm respectively, with a UV spectrophotometer Unicam 6405 using a 1% solution of oil in cyclohexane and a path length of 1 cm. Determination of Fatty Acids The fatty acid composition of the olive oil samples was determined by gas chromatography using a modified fatty acid methyl ester (FAME) method as described by Frega and Bocci (2001). The FAME was prepared by vigorous shaking of a solution of each olive oil sample in n-hexane and 2 N methanolic potassium hydroxide. Chromatographic analyses were performed using a Hewlett Packard 5890 gas chromatograph equipped with a flame ionization detector and a splitsplitless injector. The experimental conditions used were: DB- 225 column (30 m 0.25 mm i.d. 0.15 mm film thickness) (J & W Scientific, Agilent). The injector and detector temperatures were maintained at 250 C. The oven temperature was programmed from 190 C (1 min) to 210 at 4 C/min and maintained for 5 min, then heated to 215 at 3 C/min and finally an isotherm during 18 min; the carrier gas was nitrogen. Commercial mixtures of fatty acid methyl esters were used as reference data for the relative retention times. Tocopherol Determination A solution of oil in hexane was analyzed by HPLC (HP series 1100) with a Zorbax SB-C18 phase reverse column (Agilent), which was eluted with acetonitrile/ water (98 : 2 v/v) at a flow rate of 1 mL/min. A photodiode matrix detector (G1315B, serie 1100) was used. Chromatograms were registered at 295 nm. Total Phenols Determination Total phenols were extracted by a Solid Phase Extraction System using C18 Isolute columns.
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A modification of the method of Favati et al., (1994) was used. Colorimetric total phenols determination was done using the Folin and Ciocalteau method. Gallic acid was used as a standard. Sensory Analysis The sensory analyses of the samples were carried out by 10 selected and trained panelists from Aragon’s accredited panel and the Zaragoza Faculty of Veterinary Science, according to the method described in Regulation EEC/796/2002 (CE, 2002). The intensities of the positive (fruity, bitter and pungent) and negative (fusty, winey, musty, muddy, rancid, metallic and other) attributes were evaluated for each oil sample, on a nonstructured, 10 cm scale anchored by its origin. The presence of other bouquets (sweet, ripened fruits, green) was also studied to define the sensory profile of the olive oils. A spider graph was employed to obtain profiles for each oil. Color and Pigments Measurement The entire visible spectra (380780 nm) at 2 nm intervals was measured and recorded using a spectrophotometer Avantes Ava Spec 1024 after zeroing the apparatus with n- hexane. Chlorophyll and carotenoid compounds (mg/kg) were determined using the method described by Mı´ nguezMosquera et al., (1991). This method consists of a quantitative estimation of chlorophyll and carotenoid content by measuring the olive oil absorbance at 670 nm 470 nm. The CIELAB color coordinates (CIE, 1986) of the olive oils were determined from the spectra. Illuminant 65 was chosen as well as observer CIE64. The following color coordinates were determined: lightness (L*), redness (a*, red-green) and yellowness (b*, yellowblue). In addition, the hue angle, which describes the hue or color (h ) (h ¼ tan1(b*/a*)) and the saturation index or chroma (C*) (C* ¼ (a*2 þ b*2) 1/2) that describes the brightness or vividness of a color were determined. Statistical Analysis Statistical analysis was performed using the Graph Pad Prisma 5.0 program. Significant differences between the varieties were determined using the ANOVA and Bonferroni test (p < 0.05) to discriminate among the mean values.
RESULTS AND DISCUSSION The results of the maturity index, morphologic parameters and oil yield of the three olive varieties investigated in this study are shown in Table 1. In all three
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Table 1. Maturity index, morphologic index of the Racimilla, Bodocal and Negral olives and their oil yields.
Maturity index Weight of fruit (g) Polar diameter (mm) Equatorial diameter (mm) Weight of skin (g) Weight of pulp (g) Weight of stone (g) Oil yield (%)
Racimilla
Bodocal
Negral
5.9±0.15 2.34±0.05 a 18.1±0.83 14.9±0.61 a
6.2±0.10 3.38±0.06 b 18.5±0.08 17.5±0.66 b
6.0±0.15 1.9±0.20 c 18±1.40 13.3±0.99 c
0.55±0.03 a 1.27±0.04 a 0.52±0.01 a 28.4±0.36 a
0.41±0.04 b 1.42±0.05 b 1.55±0.03 b 17.0±0.67 b
0.34±0.02 c 0.82±0.01 c 0.74±0.01 c 27.0±0.40 a
All data are means±SD, n ¼ 5. Data followed by different letters in the same line are significantly different.
cases the skin color was black and the color of the pulp was mainly purple although the pulp area near the stone was white. Therefore, no significant differences in the maturity index for the three olive varieties were found. Concerning the morphological indexes for Racimilla and Negral the polar diameter was higher than the equatorial however both diameters were similar in the Bodocal variety indicating that its shape was spherical. The fruit of this variety was the heaviest and the stone corresponded to 46% of the fruit weight. The large stone of the Bodocal variety could explain why the oil yield obtained for this variety was the lowest (17%). The Racimilla fruit was heavier than the Negral, but the relationship between the weight of the stone and the weight of the fruit was lower for Racimilla (22%) than for Negral (39%). Although the pulp content of Racimilla (78%) was higher than Negral (61%), the oil yield for both varieties was similar indicating higher oil content in the pulp of the Negral variety. The ripeness of the three olive varieties was similar and the oil was obtained in our laboratory within 6 h after sampling under the same extraction conditions. Consequently, the differences between the olive oil samples studied in this investigation are due to the intrinsic characteristics of the olive varieties and not to the conditions used to process the olives or to obtain the oil. The regulated physicochemical quality parameters (free acidity, peroxide value and UV absorption characteristics, K270 and K232) for the three samples types are shown in Table 2. The oil from the Bodocal variety had the highest values for all the parameters evaluated however the parameters of the oils produced from the three varieties falling within the ‘extra virgin’ category according to EC Regulation (CE, 1991). These low values for the regulated physicochemical parameters confirm that the oil was obtained from healthy olives carefully handpicked and processed as soon as possible after harvesting.
Table 2. Free acidity, peroxide value, K232 and K270 values of the olive oils from Racimilla, Bodocal and Negral varieties.
Variety Racimilla Bodocal Negral
Peroxide Acidity value (% oleic acid) (meq O2/kg) 0.18±0.02 a 0.38±0.02 b 0.11±0.00 a
K232
K270
3.77±0.19 a 1.99±0.05 a 0.16±0.003 7.68±0.20 b 2.21±0.04 b 0.16±0.005 5.30±0.02 c 1.96±0.05 a 0.16±0.003
All data are means±SD, n ¼ 5. Data followed by different letters in the same column are significantly different.
Fatty acids composition of the olive oil from the three varieties is shown in Table 3. Although, in all cases the values meet the requirements of the European Regulation (CE, 1991) for extra virgin olive oil (linolenic acid 1%, araquidic acid 0.6% and gadoleic acid 0.4%), significant differences in the fatty acid content of the three olive varieties were observed. The fatty acid patterns found corresponded to the normal type and content expected for olive oil. Concerning the composition of saturated fatty acids, it is well known that palmitic acid is the main saturated acid present in olive oil. The content of this fatty acid in the Bodocal oil was significantly higher than in the Racimilla and Negral oils that contained a similar amount of palmitic acid. Total content of SFA for the Racimilla and Negral oils was similar and significantly lower than for the Bodocal oil. Significant differences were observed in the oleic and linoleic acid content for the different varieties. The monounsaturated acids of olive oil, especially oleic acid, are very important because of their nutritional benefits and their role in the oxidative stability of the oil. The oleic acid content of the Racimilla and Negral oil was similar and higher than that of Bodocal oil. However, Bodocal oil showed the highest linoleic acid and PUFA content. The oleic/linoleic ratio is frequently used as a stability parameter with higher ratios corresponding to higher oxidative stability. Sa´nchez-Casas et al., (2003) classified the Spanish monovarietal olive oils in two groups according to their oleic/linoleic ratio. Those with high oleic and low linoleic content such as Picual oil and those with low oleic and high linoleic acid content such as Verdial oil. The highest oleic/linoleic ratio was found in Racimilla oil followed by Negral and Bodocal. According to this ratio the oxidative stability of Racimilla oil would be expected to be high and similar to other Spanish oils from Andalucia such as Cornicabra or Picual (Alba et al., 1996; Salvador et al., 2001). On the other hand, the expected oxidative stability for Negral would be lower and similar to olive oil of the Arbequina variety as a consequence of its lower oleic/linoleic acid ratio (Pardo et al., 2007). The Bodocal olive oil showed the lowest oleic/linoleic acid ratio and a PUFA value higher
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Olive Oil of Three Varieties Potentially Interesting from Aragon
Table 3. Fatty acid, total phenol and a-tocopherol contents in olive oil from Racimilla, Bodocal and Negral varieties.
Palmitic acid (C16:0, %) Palmitoleic acid (C16:1, %) Margaric acid (C17:0, %) Margaroleic acid (C17:1, %) Stearic acid (C18:0, %) Oleic acid (C18:1, %) Linoleic acid (C18:2, %) Linolenic acid (C18:3, %) Arachidic acid (C20:0, %) Gadoleic acid (C20:1, %) Saturated fatty acids (SFA, %) Monounsaturated fatty acids (MUFA, %) Polyunsaturated fatty acids (PUFA, %) Oleic acid/linoleic acid (C18:1/C18:2) MUFA/PUFA Total phenols (mg gallic acid/kg) a-tocopherol (mg/kg)
Racimilla
Bodocal
Negral
9.26±0.00 a 0.67±0.00 a 0.09±0.02 0.20±0.01 a 2.24±0.00 a 79.26±0.01 a 7.26±0.00 a 0.48±0.01 a 0.27±0.01 a 0.28±0.02 a 11.86±0.01 80.41±0.01 7.73±0.00 10.92±0.01 10.40±0.00 831.33±16.2 a 159.28±1.13 a
11.69±0.05 b 0.77±0.00 b 0.06±0.01 0.08±0.00 b 3.56±0.00 b 69.03±0.04 b 13.63±0.02 b 0.61±0.03 b 0.35±0.01 b 0.21±0.01 b 15.66±0.06 70.10±0.05 14.24±0.00 5.07±0.01 4.92±0.00 272.5±1.15 b 96.17±1.72 b
9.26±0.01 a 0.43±0.00 c 0.10±0.00 0.18±0.00 a 2.62±0.01 c 76.75±0.03 c 9.55±0.01 c 0.49±0.00 a 0.33±0.00 b 0.29±0.00 a 12.31±0.02 77.65±0.03 10.04±0.01 8.04±0.01 7.74±0.01 456.33±1.44 c 190.42±0.34 c
All data are means±SD, n ¼ 5. Data followed by different letters in the same line are significantly different.
than that described for other olive oil varieties (Matos et al., 2007). This oil is thus expected to be the least stable variety to oxidation. The fatty acid profile of Bodocal characterized by a high content of palmitic, stearic, and linoleic acids and a low content of oleic acid is similar to those of other varieties of olive oil from Extremadura such as Cornezuelo and Morisca (Sa´nchez- Casas et al., 2003). Negative sensory attributes were not detected by the panellists for any of the oils analyzed, confirming the category of extra virgin olive oils as stated by Regulation EEC/796/2002 (CE, 2002). The sensory profiles for the oils of the three varieties were completely different (Figure 1). Negral oil had the higher fruity score in comparison with Racimilla and Bodocal oils and an equilibrated score in bitter and pungent attributes. On the other hand Racimilla oil gave the highest score for pungent and bitter attributes and Bodocal oil the lowest for these two attributes. Therefore, the sensory profile of the later was the less equilibrated. The Negral was the oil most highly appreciated by the members of the panel. Besides the regulated quality parameters, other physicochemical analyses can be very useful in order to characterize and discriminate the oils from different olive varieties such as total phenols analysis and tocopherol content. The total phenol contents of the three olive oils are given in Table 3. Racimilla had a very high content in comparison with the other two but similar to that of other varieties such as Chetoui, Frantoio and Leccino (Rallo et al., 2004; Aguilera et al., 2005). For this reason this oil must be very stable to oxidation in accordance with the high oleic acid content. This high content would also be related with the sensory profile for this variety
Fruity 6 4 Ripened fruits
Bitter 2 0
Sweet
Pungent
Green
Figure 1. Sensory profile of the Racimilla, Bodocal and Negral olive oils. (. . .) Negral, ( ) Racimilla, (—) Bodocal.
especially as regards the high pungent and bitter attributes as described above. On the other hand the Bodocal olive oil should be much more sensitive to oxidation because of its lower content of total phenols and also for its fatty acid composition. This content is similar to other Spanish varieties such as Empeltre (GraciaGo´mez, 2001). The Negral olive oil had an average phenol content similar to those of the Cornicabra and Hojiblanca varieties (Beltra´n et al., 2005). The tocopherol fraction in virgin olive oils consists mainly of a-tocopherol (95%). These substances exert both vitaminic potency and antioxidant action. The a-tocopherol content of the three olive oils (Table 3) showed significant differences between cultivars. The Negral olive oil had the highest content, Bodocal the
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M. BENITO ET AL. 1.5
Absorbance
1.25 1 0.75 0.5 0.25 0 380
430
480
530
580
630
680
730
780
Wavelength (nm)
Figure 2. Spectra (380780 nm) of the olive oils from Racimilla, Bodocal and Negral varieties. (. . .) Negral, ( ) Racimilla, (—) Bodocal.
Table 4. Chlorophyll and carotenoid contents in olive oil from Racimilla, Bodocal and Negral varieties.
Chloropylls (mg/kg) Carotenoids (mg/kg)
Racimilla
Negral
Bodocal
0.40±0.11 a 6.23±0.11 a
2.69±0.23 b 5.56±0.17 b
1.101±0.28 c 3.35±0.13 c
All data are means±SD, n ¼ 5. Data followed by different letters in the same line are significantly different.
Table 5. Color parameters (L*, a*, b*, h, C*) in olive oil from Racimilla, Bodocal and Negral varieties.
Racimilla Bodocal Negral
L*
a*
b*
a/b
h
C*
92.08±0.43 93.63±1.37 90.59±1.45
1.80±0.43 a 3.57±0.01 b 2.10±0.47 a
99.54±0.65 a 64.71±0.25 b 90.13±0.70 c
0.018±0.00 a 0.055±0.00 b 0.019±0.01 a
91.05±0.11 a 93.21±0.06 b 91.34±0.29 a
99.56±0.64 a 64.82±0.26 b 90.16±0.70 c
All data are means±SD, n ¼ 5. Data followed by different letters in the same column are significantly different.
lowest and Racimilla variety an intermediate value. The tocopherol content is highly variety dependent, with concentrations ranging from 5 to 300 ppm (Deiana et al., 2002). Usual values reported for good quality oils vary between 100 and 300 ppm (Baldioli et al., 1996). The pigment content of olive oil is influenced by a great number of factors among which the olive variety and the ripening stage are two of the most important. The presence of pigments not only determines the color but also plays a role in the oxidative stability due to their antioxidant nature in the dark and pro-oxidant activity in the light (Mı´ nguez- Mosquera et al., 1990; Salvador et al., 2001; Criado et al., 2008). As would be expected for olive oil, the spectra of the three varieties contained three peaks for carotenoids (Figure 2). The carotenoid content for Racimilla oil was significantly higher than for the Negral and Bodocal oils (Table 4). However, Racimilla showed the lowest content in chlorophyll. The chloropyll/carotenoid ratios were 0.064, 0.483 and 0.328 for the Racimilla, Negral and Bodocal oils
respectively. In general, as olive ripening progresses the chlorophyll content decreases and the carotenoid content increases (Kozukue and Friedman, 2003). Similar to oils of other olive varieties such as Picudo and Arbequina (Moyano et al., 2008a,b), the oils studied showed high values of L*. On the other hand the a* values were negative for the three oils studied (Table 5). The yellow color of the three oils is corroborated by the positive values of b* the Bodocal oil having the lowest value of this parameter.
CONCLUSIONS The results of this investigation have demonstrated that the Racimilla and Negral olive varieties grown in the Aragon region have the highest potential for producing high quality virgin olive oil. The high oil yield and oxidation stability of the Racimilla variety and the sensory properties of Negral olive oil could be of
Olive Oil of Three Varieties Potentially Interesting from Aragon
considerable interest for their commercialization as monovarietal olive oils.
ACKNOWLEDGMENTS This work was supported by the Government of Arago´n which awarded a predoctoral fellowship to M. Benito and by the University of Zaragoza and the Government of Arago´n with financial assistance for buying the Abencor system to A C Sa´nchez- Gimeno (INF2007- CIE-20).
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