Monovarietal Extra Virgin Olive Oils from the Marche Region, Italy: Analytical and Sensory Characterization

Abstract

This study aims to contribute to the knowledge of the commercial, sensory, and analytical characteristics of extra virgin olive oil (EVOO) from the Marche region (Italy), renowned since ancient times. The chemical composition of all the most typical monovarietal oils collected in four crop seasons, was studied in relation to the year of harvesting (from 2004–2007) and the genotype. In order to obtain a complete description of oil samples, free acidity, peroxide value, fatty acid composition, ultraviolet indices, carotenoids, chlorophylls, and phenols were determined. The main characteristics of these oils are large total phenol content, low acidity and peroxide values, low oxidative susceptibilities. All the chemical parameters fell within the limits established for the maximum olive oil category. Sensory evaluation showed that the total score of all the monovarietal extra virgin olive oils was always much higher than the 6.5 limit established for the ‘extra-virgin’ category. The overall quality indices support claims of excellence for monovarietal EVOOs from this geographical area. Results from the present study are of key importance for the specific Production Standards a document that contains regulations for supervising the entire olive oil production cycle and a prerequisite for both the European Protected Denomination of Origin (PDO) and Quality granted by the Marche region (QM) labels.

Keywords:

• Monovarietal extra virgin olive oil
• Marche-Italy
• Analytical measurements
• Sensory characterization
• Olive oil business

INTRODUCTION

Olive oil has been cultivated for over 2000 years around the Mediterranean. It is the most widely used oil in the countries bordering the Mediterranean Sea and it is actually the principal ingredient of the Mediterranean diet. EVOO, compared to other olive oil categories, is superior in economic, nutritional, and gastronomic importance, because of its taste, and aroma. The value of olive oil from the Marche region was already appreciated in the medieval period. Due to its sensory superiority, it was sold to merchants from Florence and Venice at a much higher price compared to olive oils from other Italian regions.

The quality of EVOO from Marche region is continuously improving because of a strong attention paid by the producers, addressed and supervised by the know-how of local boards and associations, to all the steps of the production process. Expectations from the international EVOO business and final consumers, as regards the attributes of high quality traditional local products, are reflected in important acts of legislation (EEC 2081/1992, EEC 1187/2000) that allow the PDO labeling of some European EVOOs with the names of the area where they are produced. PDO labeling certifies the origin, authenticity, and high quality of EVOO produced in a delimited geographical area. The first PDO labeling for an EVOO from the Marche region (‘Cartoceto’) was obtained in 2004. However, the local network of small mills lacks adequate laboratory facilities, and as a result, detailed chemical and sensorial properties data are required because they must be indicated in the Production Standards of the Marche PDO.

During the last years autochthonous monovarietal EVOOs were the focus of interest of producers and consumers because they allow to distinguish the Marche products and to emphasize the peculiarities of each genotype via different gastronomic combining. The study of the chemical composition of EVOO of a pure variety in a specific production area is of great interest from both a scientific and commercial points of view, since consumers are more and more oriented towards purchasing certified EVOOs typical of a certain geographical area. According to the Italian Regional Law 23/2003, the analytical and sensory definition of monovarietal olive oils are also required in the Production Standards for the label QM. It follows that it is extremely important to increase the international awareness of these EVOOs. Despite the large annual production of EVOO in the Marche region, no significant data on chemical composition and properties is available in the scientific literature. The aim of this paper is to characterize the ten most representative monovarietal EVOOs from Marche region and to assess their chemical composition and sensory evaluation during four successive crop seasons. Several analytical parameters were chosen: quality indices, as defined by the EU Regulations (free fatty acid content, peroxide value, and spectrophotometric characterization in the UV region), chlorophyll and carotenoid pigments, fatty acid composition, and total phenols.

MATERIALS AND METHODS

Chemicals

Folin–Ciocalteu reagent, solvents, acetic acid, potassium hydroxide, sodium thiosulfate, β-carotene, and Gallic acid (GA), were of analytical grade.

Samples and Experimental Design

Olives of ten different cultivars were processed within 24 h from the harvest. The oil mill temperature was controlled (25–28°C) and the kneading time was 30 min. The oils were extracted via a three-phase decanter. Monovarietal EVOOs from the Marche region were obtained in dark-green glass bottles from ASSAM (Ancona, Italy) in December 2004, 2005, 2006, 2007, respectively. They were stored in dark-green glass bottles, without headspace, at room temperature in the dark, and they were analyzed within one week. The experiment was run in duplicate and the analyses were carried out in triplicate. Consequently, each analytical parameter (e.g., chlorophylls) was analyzed 24 times (2 bottles × 3 times × 4 years) for each cultivar. Each result of the present experimental design, for each cultivar, is expressed as the mean value (2004, 2005, 2006, 2007) ± its standard deviation (SD, n = 24). The statistical analysis of variance (ANOVA) and Post Hoc Student-Newman-Keuls (SNK) test of ANOVA were performed to identify, respectively, statistically significant differences (p < 0.001) among the cultivars and homogeneous subsets of the means that do not differ from each other: the actual differences between the means were considered to be statistically significant when probability was greater than 95% (p < 0.05).[1]

Instruments

The GC-MS was a Hewlett Packard G1800C GCD Series II (Palo Alto, CA) equipped with a Carbowax fused silica capillary column (30 m × 0.25 mm I. D. × 0.20 μm film thickness). A Perkin Elmer EZ 301 UV-VIS spectrophotometer equipped with quartz cuvettes was used for the spectrophotometric assays.

Analytical Measurements

Peroxide value (PV) analysis (meq O₂/kg), free fatty acids (FA) value analysis (determined as g of oleic acid per 100 g oil), ultraviolet indices, and fatty acid methyl esters (FAME) quantitation were performed according to the European Community regulations EEC 2568/91 and EEC/2472/97. Carotenes and chlorophylls were determined spectrophotometrically, according to Caponio et al.[2] and AOCS Method Cc 13i-96, 1993, respectively. Iodine values (IV) were calculated from Fatty acid percentages[3] using the formula:

(1)

where PO, O, LO, and LON are the palmitoleic, oleic, linoleic, linolenic acid percentages (g/100 fatty acids), respectively. Oxidative susceptibility (OS) was calculated according to the equation[4]:

(2)

where MUFAs are the monounsaturated fatty acids percentage (g/100 fatty acids). The total polyphenol content (PP) was determined by means of the Folin–Ciocalteu method.[5] The PP was expressed in mg GA/kg EVOO.

Sensory Analysis

Quantitative sensory evaluation (SE) was carried out by twenty selected and trained panelists leaded by Dr. B. Alfei (Panel Regionale ASSAM—Marche, acknowledged by International Olive Oil Council in 2000 and by the Italian Government in 2004), according to the methods described in EEC 796/02.

Maturity Index and Pulp Consistency Measurement

For the maturity index (MI) a modified Jaen Index was used. The scale ranges from 0 to 5, according to the percentage of ripened olives. The pulp consistency (PC) was estimated by the penetrometer method with a push rod of 1 mm in diameter; it is expressed as g/mm².

Overall Quality Index

The Overall quality index (OQI) introduced by the International Olive Oil Council in 1990 was used to express EVOO quality numerically.[6] The scale ranges from 0 to 10 and considers 4 quality parameters: the score for SE, FA, K₂₇₀, and PV according to the following equation: OQI = 2.55 + 0.91SE-0.78FA-7.35K₂₇₀-0.066PV.

RESULTS AND DISCUSSION

The geographical diffusion area, the botanic and agronomic characteristics of autochthonous olive cultivars typical of the Marche region are presented in Table 1. Different olive varieties are characterized by a strong variability in productive potentiality, their attributes, and traits. The oil is predominantly contained in the pulp of the olive berry (16–24%), but also in the kernel (1–2%): the final quantity of the oil depends on the genetic characteristics of the cultivar that modulate its physiologic accumulation, but it is also dependent on the pedological conditions and harvest year. The mean PC, the ripening process, the resistance to detachment (during the harvest) and to infestations, are additional features that strongly depend on the cultivar as detailed in Table 1.

Table 1 Geographical diffusion area, botanic and agronomic characteristics of autochthonous olive cultivars typical of Marche region, Italy

Cultivar	Geographical area	Vigor	Productivity	Drupe
Ascolana tenera	Ascoli Piceno	hight	medium and constant	very big, ellipsoidal
Carboncella	Ascoli Piceno	low	hight and constant	small, round
Coroncina	Macerata	medium	medium and constant	medium, ovoidal
Mignola	Macerata, Ancona	hight	hight and slightly constant	small, ovoidal
Nostrale Rigali	Pesaro	low	hight and constant	big, ovoidal
Orbetana	Macerata	hight	medium and not constant	medium, ovoidal
Piantone Falerone	Ascoli Piceno, Macerata	medium	medium and not constant	medium, cylindrical
Piantone Mogliano	Macerata	low	hight and constant	medium, ovoidal
Raggia	Ancona	hight	hight and constant	medium, ovoidal, asymmetric
Sargano Fermo	Ascoli Piceno	hight	hight and not constant	small
Cultivar	Resistence to detachment	PC [g/mm^2]	Color change	Best harvest period
Ascolana tenera	decreasing with ripening	417	later and gradual	November
Carboncella	high	437	later and simultaneous	late November
Coroncina	high	549	later and gradual	late November-early December
Mignola	decreasing with ripening	317	precocious and simultaneous	early November
Nostrale Rigali	decreasing with ripening	360	later and simultaneous	late October
Orbetana	high	544	later and simultaneous	late November-early December
Piantone Falerone	low	384	later and simultaneous	late Octobetr-early November
Piantone Mogliano	high	558	later and gradual	middle November
Raggia	decreasing with ripening	402	later and gradual	middle November
Sargano Fermo	decreasing with ripening	394	later and gradual	November
Cultivar	Oil yield		Agronomic Characteristics
Ascolana tenera	medium		Bactrocera Oleae sensitive
Carboncella	medium-high		cold and Spilocaea Oleaginasensitive
Coroncina	medium-low		not Bactrocera Oleae sensitive
Mignola	high		not Bactrocera Oleae sensitive
Nostrale Rigali	very high		not cold sensitive
Orbetana	medium-low		not cold sensitive
Piantone Falerone	medium-high		Bactrocera Oleae sensitive
Piantone Mogliano	high		not cold sensitive
Raggia	medium-high		Pseudomonas syringae subsp. Savastanoi and Spilocaea Oleagina sensitive
Sargano Fermo	low		slightly cold sensitive

Fatty Acid Composition

Triglycerides represent 98–99% of the EVOO. The fatty acid composition of the oil differs depending on the cultivar but displays a wide range also due to environmental factors. It has been used for oil classification.[7] Table 2 shows the fatty acid composition of monovarietal EVOOs. The high unsaturated/saturated fatty acid ratio and the predominance of monounsaturated oleic acid compared to polyunsaturated linoleic and linolenic acids confer and grant nutritional value and stability, respectively, to these monovarietal EVOOs that are essential for a balanced diet. Oleic acid is the main fatty acid and it is present in higher concentrations (71.2–78.8%). The level of palmitic acid, ranged from 11.1–14.5%: the lowest percentage of oleic acid and the highest percentage of palmitic acid were found in the Mignola variety, while the lowest percentage of palmitic acid and the highest percentage of oleic acid were found in the Piantone di Mogliano cultivar. With regard to linoleic acid, which is much more susceptible to oxidation than MUFAs, the highest percentage was observed in Orbetana oils (10.4%) whereas the lowest was found in Ascolana Tenera (5.2%) samples.

Table 2 Fatty acid composition, IV, OS, MUFAs/PUFAs ratios and O/LN ratio for monovarietal EVOOs (n = 24)

	Arachidic Acid C20:0			Gadoleic Acid C20:1			Margaric Acid C17:0			Margaroleic Acid C17:1			Linoleic Acid C18:2			Linolenic Acid C18:3			Oleic Acid C18:1			Palmitic Acid C16:0			Palmitoleic Acid C16:1			Stearic Acid C18:0			Iodine Value			Oxidative Susceptibility			MUFAs/PUFAs			Oleic Acid/Linoleic Acid
Cultivar	Mean	SD	Homogeneous subset	Mean	SD	Homogeneous subset	Mean	SD	Homogeneous subset	Mean	SD	Homogeneous subset	Mean	SD	Homogeneous subset	Mean	SD	Homogeneous subset	Mean	SD	Homogeneous subset	Mean	SD	Homogeneous subset	Mean	SD	Homogeneous subset	Mean	SD	Homogeneous subset	Mean	SD	Homogeneous subset	Mean	SD	Homogeneous subset	Mean	SD	Homogeneous subset	Mean	SD	Homogeneous subset
Ascolana tenera	0.4	0.0	c	0.4	0.0	e	0.3	0.2	c	0.3	0.0	d	5.2	1.4	a	0.7	0.1	b,c	77.9	1.9	e	12.5	0.6	c	0.9	0.1	e	1.8	0.3	a	82.3	1.0	a	383.7	61.6	a	13.9	3.0	d	15.6	3.7	d
Carboncella	0.3	0.0	b	0.3	0.1	a,b	0.1	0.1	a,b	0.1	0.0	a	7.5	1.7	b	0.7	0.1	c	74.7	1.5	b	14.1	0.6	d,e	0.9	0.1	d,e	1.5	0.4	a	83.5	1.6	b,c	485.2	67.4	b	9.5	1.9	b	10.3	2.3	b
Coroncina	0.4	0.0	c,d	0.4	0.1	d	0.1	0.0	a,b	0.1	0.0	b	8.3	1.3	b,c	0.7	0.1	a,b	76.0	1.6	d	11.8	0.7	b	0.8	0.1	c	1.8	0.2	a	86.0	0.8	e	517.8	49.4	b,c	8.7	1.4	b	9.3	1.7	b
Mignola	0.3	0.1	b	0.3	0.0	a,b	0.1	0.2	a,b	0.1	0.0	a,b	9.9	1.2	d	0.6	0.1	a	71.2	1.6	a	14.5	0.6	e	1.5	0.1	g	1.6	0.4	a	85.2	1.1	d	579.8	60.8	d	7.0	0.9	a	7.3	0.9	a
Nostrale di Rigali	0.5	0.1	f	0.3	0.1	c,d	0.1	0.1	a,b	0.1	0.0	a,b	7.8	1.2	b	0.6	0.1	a	73.9	2.4	b	12.9	0.8	c	0.8	0.1	c,d	3.4	0.4	b	83.0	1.4	a,b	486.9	58.9	b	9.1	1.6	b	9.6	1.8	b
Orbetana	0.3	0.0	a	0.3	0.0	b,c	0.4	0.2	d	0.4	0.0	f	10.4	1.1	d	0.8	0.2	d	71.5	1.5	a	13.8	0.3	d	1.1	0.2	f	1.5	0.1	a	86.4	1.3	f	619.3	63.2	d	6.6	0.8	a	6.9	0.9	a
Piantone di Falerone	0.4	0.0	c	0.4	0.1	e	0.2	0.1	b	0.2	0.1	c	8.9	2.8	c	0.6	0.1	a	73.6	3.5	b	13.7	0.9	d	0.7	0.1	b	1.6	0.2	a	84.6	1.8	d	535.6	118.2	c	8.3	2.1	b	8.8	2.4	b
Piantone di Mogliano	0.5	0.1	e	0.4	0.0	e	0.3	0.2	c	0.3	0.0	e	5.9	1.2	a	0.6	0.1	a,b	78.8	1.5	e	11.1	0.6	a	0.7	0.0	a	1.8	0.7	a	84.0	1.5	c	409.5	59.7	a	12.6	2.3	c	13.8	2.7	c
Raggia	0.4	0.0	c	0.3	0.0	a	0.0	0.0	a	0.1	0.0	a	7.6	1.3	b	0.6	0.0	a	75.8	1.3	c,d	12.9	0.5	c	0.8	0.1	c,d,e	1.8	0.2	a	84.4	1.1	c,d	478.4	56.7	b	9.6	1.8	b	10.2	2.1	b
Sargano di Fermo	0.4	0.0	d,e	0.4	0.0	d	0.1	0.1	a,b	0.1	0.0	a,b	9.8	0.4	d	0.6	0.1	a,b	71.5	0.7	a	14.4	1.1	e	1.2	0.1	f	1.7	0.3	a	85.0	0.6	d	578.9	21.8	d	7.0	0.3	a	7.3	0.3	a
ANOVA F ratio	32.7			35.0			15.4			311.3			32.2			12.7			47.3			64.0			152.3			55.6			23.8			31.1			42.6			43.3
Homogeneous subsets are indicated by the same letter.

The mean oleic acid/linoleic acid ratio is always higher than the minimum recommended value of 7,[8] except for Orbetana oils (6.9), thereby indicating good and excellent stabilities of monovarietal oils from the Marche region. Interestingly Orbetana oil is also characterized by the highest iodine value, the highest oxidative susceptibility, and the lowest MUFAs/PUFAs ratio. From Table 2 it is clear that there were high statistically significant differences (p < 0.001) among the cultivars in terms of concentrations of all

the fatty acids and derived values, on the basis of their ANOVA F ratios. The cultivars are divided into homogeneous subsets, on the basis of the SNK test, where the difference in the means of any two groups in the subset is not significant at the chosen level of significance (p < 0.05).

As for a given olive variety, the oleic acid/linoleic acid ratio decreases with increasing maturity[9] this hypothesis was tested for different varieties. The strongest correlation was found in year 2005 as detailed in Table 3. Table 3 also illustrates the correlation and the regression equation between the Iodine Value and the oxidative susceptibility: the stability of Ascolana Tenera is the best, while that one of Orbetana is the worst as can also be inferred from data in Table 2. From standard deviations shown in Table 2, it is clear that the most conservative parameter in different production years is the Iodine Value. Oleic acid content varies with the crop season, but a very good correlation can be found between the oleic acid content of different monovarietal oils in different years. For example, when considering the crop seasons 2004 and 2006, in Table 3 it can be observed that the oleic acid contents are well correlated, and a t-student test indicated that there are no significant differences in different years. The same can be said for palmitoleic acid (Table 3). This confirms that the harvest year has no significant effect on the fatty acid composition, unless extremely poor climatic conditions occur.[10] Levels of fatty acids in the monovarietal oils are always compliant with the established limits (Commission Regulation (EU) No. 61/2011) for EVOOs. The values of the MUFAs/PUFAs ratio and of the oleic acid/linoleic acid ratio detailed in Table 2 shows that the consumption of these oils has a favorable impact in the dietetic regimes.

Table 3 Relationship between the values of the indicated parameters for different cultivars, with the equation and correlation coefficient of the fitted line

Parameters for which correlation is tested	Equation	R
MI vs. O/LO, 2005	y = −0.1939x + 3.7342	0.7972
Mean OS vs. mean IV	y = 47.151x − 3474	0.8118
Oleic acid % : 2006 vs. 2004	y = 0.9261x + 5.7164	0.8843
Palmitic acid % : 2006 vs. 2004	y = 0.7934x + 1.9873	0.9009
OS vs. PV, 2005	y = 38.245x + 317.78	0.7122
K232 vs. PV, 2007	y= 0.0407x + 1.9829	0.7491
MI vs. PV, 2007	y= 0.2334x + 0.0724	0.6071
PC vs. MI, 2005	y= −92.13x + 520.23	0.8632
PP2007 vs. PP2006	y = 0.5396x + 418.26	0.8059
Chlorophylls (mg/kg) vs. carotenoids (mg/kg), 2006	y = 0.4516x − 2.3578	0.8805
Pungency vs. bitterness	y= 0.6957x + 1.269	0.7160
Bitterness vs. fruity, 2005	y= 1.0584x − 0.8921	0.7217
Pungency vs. PP (mg/kg), 2006	y = 0.0052x + 2.1528	0.8379

Acidity, Peroxide Value, UV Spectrophotometric Indices

Quality and authenticity criteria for various olive oil types are described in EU Regulations EEC 2568/91 and the later modification EEC 656/95 and EEC 2472/97, Commission Regulation (EU) No. 61/2011. The PV does not highlight the secondary oxidative products but it can be used as an indicator of oil quality as autoxidation is the most important factor resulting in decreased quality of a food product. FA can be used to track hydrolytic rancidity. The spectrophotometric assay provides information about the presence of conjugated dienes (K₂₃₂) and trienes (K₂₇₀) that are formed during autoxidation of the oil due to the position shift of double bonds. The values of the analytical parameters always fell within the ranges established for the highest quality category EVOO (Commission Regulation (EU) No. 61/2011) as presented in Table 4. No samples exceeded the upper threshold limit for free fatty acid content (0.8% as oleic acid), peroxide value (20 meq/kg), and for the spectrophotometric parameters K₂₃₂ (2.5), K₂₇₀ (0.22), and ΔK (0.01), and actually, the mean values are far below the upper limit for the EVOO category.

Table 4 Quality and authenticity criteria for monovarietal EVOOs (n = 24)

	Free Fatty Acids [% oleic acid]			Peroxyde value [meq/kg]			K232			K270			ΔK270
Cultivar	Mean	SD	Homogeneous subset	Mean	SD	Homogeneous subset	Mean	SD	Homogeneous subset	Mean	SD	Homogeneous subset	Mean	SD	Homogeneous subset
Ascolana tenera	0.2	0.0	b,c,d	6.9	1.1	b	1.8	0.3	a,b	0.14	0.00	a,b	0.00	0.00	a,b
Carboncella	0.2	0.2	e	6.6	3.2	b	1.8	0.2	a,b,c	0.13	0.03	a	0.00	0.00	a,b
Coroncina	0.1	0.1	a,b,c	6.8	2.9	b	2.1	0.1	b,c	0.13	0.02	a	0.00	0.01	c
Mignola	0.2	0.0	c,d	7.0	1.0	b	2.4	0.4	d	0.16	0.03	b,c	0.00	0.00	a,b
Nostrale Rigali	0.1	0.0	a,b,c	7.4	1.0	b	1.7	0.1	a	0.18	0.03	d	0.00	0.00	a
Orbetana	0.1	0.0	a	6.2	1.8	b	2.1	0.6	c	0.12	0.01	a	0.00	0.01	d
Piantone Falerone	0.1	0.0	a,b	7.9	1.6	b	2.0	0.2	b,c	0.13	0.02	a	0.00	0.00	b,c
Piantone Mogliano	0.1	0.0	a,b	4.2	1.9	a	1.9	0.4	a,b,c	0.12	0.03	a	0.00	0.00	a,b
Raggia	0.2	0.0	d	9.2	3.3	c	1.9	0.1	a,b,c	0.17	0.04	c,d	0.00	0.00	a
Sargano di Fermo	0.1	0.0	a,b,c	7.6	2.8	b	2.4	0.5	d	0.14	0.03	a,b	0.00	0.00	a,b
ANOVA F ratio	11.4			8.0			11.2			12.06			8.08
Homogeneous subsets are indicated by the same letter.

Free fatty acid content, as a percentage of oleic acid, ranged from 0.1 to 0.2. Peroxide value, expressed as meq/kg presented a range between 6.2 and 7.9. For each year, no significant correlation was found between the peroxide value and the linoleic acid content (R² < 0.200). The peroxide values, for a given year are weakly correlated with the oxidative susceptibility, thus indicating that the higher is the OS, the higher the autoxidation. The highest correlation was found in crop season 2005 as seen in Table 3. For a given year, PVs that are primary oxidation products are quite correlated with K₂₃₂, as expected[2] and the relationship for year 2007 can be seen in Table 3. We point out that since conjugated dienes are only formed in free radical auto-oxidation, whereas nonconjugated dienes can be found in photo-oxidation, K₂₃₂ values should represent only part of the dienes (the conjugated ones).

From Table 4, it is clear that there were high statistically significant differences (p < 0.001) among the cultivars in terms of all quality and authenticity criteria, on the basis of their ANOVA F ratios. The cultivars are divided into homogeneous subsets, on the basis of the SNK test (p < 0.05) and the statistical significance of the actual differences between the means supports compositional differences among different varieties, as detailed in Table 4. It must be emphasized that the PVs are more closely related to the processing than to the genetic characteristics of a given cultivar: to be precise we found no clear correlation between the PVs measured in different years for the same monovarietal EVOOs. The same can be said for the UV indices. Only in the 2007 crop season, higher PVs were observed when the MI was high and the PC was low (Table 3): the low value of the determination coefficient indicates that olive harvest, storage, and processing are the main causes of the peroxide number value.

Polyphenols, Carotenoids, and Chlorophylls

Monocultivar EVOOs, from the Marche region, contained large amounts of polyphenols, compared to other mono-varietal EVOOs,[11 –12] which affects its stability and taste. Table 5 shows the PP of the studied mono-varietal EVOOs. No clear correlation can be found between PP and MI and PC, most likely due to genetic variability. The correlation among PPs in two different crop seasons is not always present most likely a result of the influence of pedological characteristics. The strongest correlation was found between years 2006 and 2007 as shown in Table 3. The median content of polyphenol compounds in the samples analyzed was 532.8 ranging from 389.7 and 761.7 mg/kg as GA. Polyphenols are very strongly correlated with the antioxidant activity of the EVOOs estimated via the Briggs-Rauscher oscillating reaction.[13]

Table 5 Polyphenols, carotenoids and chlorophylls contents for monovarietal EVOOs (n = 24)

	Polyphenols [mg/kg]			Carotenoids [mg/kg]			Chlorophylls [mg/kg]
Cultivar	Mean	SD	Homogeneous subset	Mean	SD	Homogeneous subset	Mean	SD	Homogeneous subset
Ascolana Tenera	500.5	169.0	b	34.3	1.9	a	14.8	2.2	b
Carboncella	532.8	74.1	b	42.8	2.9	b	20.2	2.1	c, d
Coroncina	563.3	160.9	b	40.3	4.0	b	17.8	5.9	b, c
Mignola	714.3	100.4	c	30.4	9.7	a	14.9	8.5	b
Nostrale Rigali	598.3	195.5	b	28.6	4.3	a	10.0	5.0	a
Orbetana	389.7	36.3	a	55.7	3.8	c	19.6	2.6	c
Piantone di Falerone	528.3	99.8	b	26.4	10.4	a	14.0	4.6	b
Piantone di Mogliano	492.5	125.0	b	34.6	10.8	a	14.5	5.7	b
Raggia	761.7	244.0	c	43.1	15.5	b	15.3	4.9	b
Sargano di Fermo	500.3	104.3	b	45.5	13.8	b, c	22.9	8.6	d
ANOVA F ratio	14.1			24.0			11.2
Homogeneous subsets are indicated by the same letter.

Table 5 also illustrates the variability of carotenoids and chlorophylls among different cultivars. The natural pigment contents of the oils are important quality parameters as they are involved in autoxidation and photo-oxidation mechanisms.[14] The chlorophyll and pheophytins are responsible for the green color of the oil, while carotenoids, such as β-carotene and lutein, give the yellow color. Table 3 shows the correlation between chlorophylls and carotenoids in crop season 2006; interestingly chlorophylls and carotenoids content to not depend on the genetic characteristics of the cultivar, as they are not correlated in different years, probably because of the influence of harvest conditions and pedological conditions. From Table 5 it is clear that there were high statistically significant differences (p < 0.001) among the cultivars in terms of polyphenols, carotenoids, and chlorophylls, on the basis of their ANOVA F ratios. The cultivars are divided into homogeneous subsets, on the basis of the SNK test (p < 0.05) and the statistical significance of the actual differences between the means supports polyphenols, carotenoids, and chlorophylls differences among different cultivars.

Sensory Evaluation

As seen in Table 6, from a sensory point of view all the examined samples actually belonged to the extra virgin olive oil class, (Regulation EEC/796/2002), without defects and with a score of at least 6.5. The direct observation of the intensities of attributes detected by panelists indicated that the oils studied were mainly characterized by medium intensities of bitterness, pungency and fruitiness, with equilibrated tastes. Bitterness and pungency—two positive attributes—ranged similarly from 4.0 to 5.6, and they are quite correlated: the relationship in crop season 2005 is described in Table 3. Bitterness is also correlated with the fruity taste (Table 3). Table 3 also illustrates the strong correlation between the pungency attribute of the oil and its PP, for crop season 2006. A much weaker correlation was found between the bitterness and PP.

Table 6 Sensory evaluation and OQI for monovarietal EVOOs (n = 24)

	Fruity			Bitter			Pungency			Fluidity			SE score			OQI
Cultivar	Mean	SD	Homogeneous subset	Mean	SD	Homogeneous subset	Mean	SD	Homogeneous subset	Mean	SD	Homogeneous subset	Mean	SD	Homogeneous subset	Mean	SD	Homogeneous subset
Ascolana Tenera	5.2	0.4	d	4.0	0.7	a	4.0	0.1	a	5.1	0.5	b,c,d	8.0	0.2	c,d	8.2	0.1	c
Carboncella	4.5	0.8	b,c	4.4	0.4	a,b	4.4	0.7	a	4.7	0.8	b	7.6	0.4	b	7.9	0.2	b
Coroncina	5.7	0.1	f	5.6	0.8	c	5.5	0.3	b	5.9	0.2	e	8.4	0.2	e	8.7	0.1	e
Mignola	5.0	0.3	d	6.2	0.1	d	5.2	0.5	b	5.0	0.1	b,c	8.2	0.3	c,d	8.2	0.1	c
Nostrale Rigali	5.0	1.1	d	4.2	1.4	a,b	4.5	1.6	a	5.4	0.1	c,d,e	7.8	0.6	c,d	7.8	0.3	b
Orbetana	5.6	0.2	e	4.2	0.6	a,b	4.3	0.9	a	5.6	0.8	d,e	7.8	0.2	d	8.2	0.1	c
Piantone di Falerone	4.2	0.6	a,b	4.1	1.1	a	4.3	1.7	a	4.9	1.4	b,c	7.6	0.2	b	7.9	0.1	b
Piantone di Mogliano	4.8	0.5	c,d	4.5	0.3	a,b	5.1	0.1	b	5.8	0.7	e	8.0	0.3	b,c	8.5	0.2	d
Raggia	4.9	0.7	d	4.8	1.2	b	5.3	0.4	b	5.8	0.5	e	8.0	0.5	b,c	7.8	0.4	b
Sargano di Fermo	4.0	0.2	a	4.1	0.1	a	4.5	0.6	a	4.1	0.7	a	7.2	0.5	a	7.4	0.3	a
ANOVA F ratio	23.0			20.3			8.7			16.4			20.0			79.4
Homogeneous subsets are indicated by the same letter.

Table 6 also outlines the OQIs of the studied monovarietal EVOOs. The median value, 7.9, is very high, considering the large number of samples from successive crop seasons that were analyzed.

From Table 6 it is clear that there were high statistically significant differences (p < 0.001) among the cultivars in terms of the sensory evaluation, on the basis of their ANOVA F ratios. The cultivars are divided into homogeneous subset, on the basis of the SNK test (p < 0.05) and the statistical significance of the actual differences between the means supports sensory differences among the cultivars.

CONCLUSIONS

The study of the quality and the sensory evaluation of monovarietal EVOOs are of great interest not only to the local industrial sector, but also to the international EVOOs business and consumers as there was a dearth of reliable data on its chemical composition and properties in the international scientific literature. Results from the present study enable producers of EVOOs in the Marche region to demonstrate the excellent quality of their oils.

ACKNOWLEDGMENTS

Dr. Alessandro Valbonesi, Professor L. Cifani, P. Donati, C. Matricardi, J. M. Monterubbianesi, and N. Tesei, are gratefully acknowledged for their helpful support.