Olive Oil Production in Albania, Chemical Characterization, and Authenticity

Olive tree is present to the Western and Southern regions of Albania, alongside Adriatic and Ionian Sea, two body waters of the Mediterranean basin. Genetic studies have revealed the existence of 22 native olive cultivars, while several introduced foreign olive cultivars are present. Two most important olive cultivars respectively, exploited in the olive oil production, and table olive, are Kalinjot and Kokërrmadh Berati . Olive fruit production ranks the country 20th in the world. Olive tree comprises an important permanent crop with considerable potential for the Albanian economy. Principal component analyses (PCA) of fatty acids in OO displays their differentiation according to the cultivar and their region. Chemometric analysis gives support to the differentiation of OO according to the olive cv. in terms of phenolic compounds. Secoiridoids are found in abundance, 3,4-DHPEA-EDA and p-HPEA-EDA as dominant compounds, especially in Kalinjot olive oils. Albanian OO shows high levels of aroma compounds with ( E )-2-hexenal as the principal aroma compound. Its concentrations reach up to 40411 μ g/kg in Kalinjot cv., much higher compared to Bardhi Tirana cv (27542.7 μ g/kg). The authenticity of OOs constitutes an opportunity for domestic production and certification according to the geography or origin and present an important resource to the development of a sustainable economy.


Introduction
In the last decades, the interest in olive tree (Olea europaea L.), an important crop for Mediterranean countries, has been extended to other regions of the world, such as Australia, North and South America, due to its valuable products; olive oil and table olive [1]. Olea europea L. is an evergreen plant-derived from tropical and subtropical species. It is native to the Mediterranean region, tropical and central Asia, and other parts of North Africa. Fossil remains of olive species have been found in Italy, France, and many other countries. Olive tree includes many clusters and more than 2600 cultivars, many of which may be ecotypes. Native olive O. oleaster and cultivated olive O. sativa are the main species in the Mediterranean [2].
The geography of Albania has shaped the climate characteristics, with South and Western regions typical of the Mediterranean climate while the Eastern and Northern regions with typical continental climate (Figure 1). Olive tree is cultivated mainly in the regions with Mediterranean climate, by penetrating the

Olive tree cultivation and production
The olive tree dominates the country's permanent crops with 10.28 million in a total of 13.82 million fruit trees, or 74.4%. The main regions where the olive tree is cultivated are Vlora, Fieri, Berat, and Elbasan (Table 1) [6,7].
The entire agriculture sector and especially permanent crops suffered in the last in the alternation of the 20th century with the 21st the consequences of economic transition (Figure 2). The arable land reform distributed the entire area to the small farms. This was a big reverse step toward the permanent crop's cultivation, which suffered the most, with negative consequences such decrease in tree Source: [6]. Table 1. Permanent crops data in 2019 (Â 1000).
numbers, and productivity. Only around 2010 because of the central government policy, focusing the priority on agriculture, and especially to crops that countries already have high productivity, the interest in olive culture highly increased. A steady increase was observed in the number of trees and the area planted. Currently, over 47000 ha are planted with olive tree, or 7.6% of the arable land [6,8]. FAO statistics on olive fruit production ranks Albania the 20th in the world, with 98313 tons. The world production during 2019 harvesting year reached 19.46 million tons, with Albania's contribution of 0.51% [8]. A total of 8.23 out of 10.28 million olive trees are under production [6]. The olive oil production was calculated to as 20,038 tons, contribution up to 95% of domestic demands. Data on olive oil consumption increased to five liters per capita, being the highest level among the non-European Union member countries [9]. With an average production varying to 40,000 tons olive fruit, a sharp increase was evident in 2008 as well as in the following years (Figure 3) [10]. A key role to this positive trend was the application of support schemes subsidizing local farmers. Currently the annual production fluctuates in 100000 tons of olives. Intensive production belongs to three regions: Berat (38,000 tons), Fier (33,000 tons) and Vlora (17,000 tons), with figures belonging to 2019 [6].

Table olive production
The olive fruits are exploited in 79 percent for olive oil production, while the remaining goes to table olives production. Country holds the global record for table olive consumption per capita. According to International Olive Council, table olive consumption was 10.8 kilograms per capita [9]. Kokërrmadh Berati cv is the most distinguished native cultivar used as table olive. It is mainly present in the Berati region. Other olive cultivars used as table olive are not industrially processed but used only locally by families. Another important olive cultivar, Kalinjot is used both to extract olive oil, as well as table olive. Their nutritional profiles show small differences regarding to the main fatty acids ( Table 2). Their n/6/n-3 ratio is around 10, showing very good profiles of unsaturated FA, compared to other distinguished olive cultivars worldwide [11]. Both are classified as High-Content Oleic Acid cultivars.

Olive oil extraction industry in Albania
OO extraction is organized in small extraction mills, with only 1/3 of their extraction capacity exploited. OO production is reached mainly in Southern and Central parts of the country, comprising Vlora, Fieri, Berati, Elbasani and Tirana regions. These regions, in total they comprise more than 80% of the olive trees in production [12,13]. The extraction process produces high amounts of Olive Husk (OH) and Olive Mill Wastewaters (OMWW). Their disposal in the environment is a critical issue to the Mediterranean countries. It has been shown that the OMWW disposal into surface waters influence negatively in their biodiversity due to high organic load and toxic substances. The OMWW composition varies qualitatively and quantitatively according to the olive variety, climate condition, cultivation practices, the olive storage time and olive extraction process. Composed of 83-92% water, 4-16% organic matter, and 1-2% minerals, constitute a potential for exploitation as irrigation source and fertilizer in arable lands [13,14]. Solid residues show high interest if they are used in soil enrichment with potassium (K) and other minerals. Up to 254.85 mg/kg of K, 20 mg/kg magnesium on dry weight basis is found [14,15].
Regions where the extraction lines are stationed face the deteriorating situation in the environmental conditions. OMWW discharge to surface waters, solid waste disposal produces bad odors on a large perimeter, disturbing the community. The OMWW amounts produced is 125-137 Â 10 6 kg, while the OH approximately to 60 Â 10 6 kg with a fluctuation in a yearly basis [15]. Traditionally, olive husk is used as feedstuff to animals or burned to farmers' houses. Recently, showing the high interest for exploitation of OH by-products, an investment in processing plant is operating at capacity 2.5 ton/hour for production of pellets.

Kalinjot cv. Olive oils
Unique in its nutritional and sensory characteristics [16], VOO plays a vital role as the primary source of fats in the traditional Mediterranean diet [1,17].
Kalinjot, the most important olive cultivar, gives the main contribution to the national level on the OO production. It covers 70% of the plantations' structure, to Vlora and Mallakastra regions, and relatively resilient to drought and cold weather (Figure 4). Fruit and stone weight, respectively to approximate values of 3.6 g and 0.5 g, with the extractability rate that varies up to 28% w/w. Fatty acid composition for olive oils obtained from different locations from Vlora and Mallakastra regions, in different harvesting years the last decade ( Table 3) [18][19][20][21][22].
The main fatty acid, Oleic acid, interval is 68.03-76.83%; with linoleic acid interval 7.85-14.22% and palmitic acid interval 8.54-13.62%. The Linolenic acid content range is 0.63-0.89% lying under the value established by EU legislation to olive oil ( Table 3).
As expected, no statistically significant differences were observed between fatty acids of Kalinjot olive oils, and therefore the data presented refer to all samples analyzed. The distribution of fatty acid composition of the oil samples studied is shown in Table 1 and covers the normal range expected for olive oil. The Kalinjot OO has a high percentage of oleic acid, with an average value of 74.25 and an interquartile range of 1.899 (the difference between samples percentiles), and a low percentage of linoleic acid, with an average value of 9.788 and an interquartile range of 1.471. Principal component analysis given in Figure 5 displayed the distribution of Kalinjot OO samples from different location within regions of Vlora and Mallakastra. As it can be seen in the chart, according to the PCA biplot, the samples were well categorized. The samples coded with numbers 1, 2, 6, 7, 12, 13, 16, 19, 21, 22, 23 and 24 were positioned on the positive F1 axis while the remaining were on the negative F1 axis. In addition to those, samples coded as 29 and 30 were positioned on the negative F1 axis and clearly separated from other OO samples. OO sample (29) belong to Nisjot olive cv., another olive cv of the Vlora and Mallakastra region, while the OO sample (30) belonged to the same olive cultivar, Kalinjot, but from a different geographical region, Central Albania.
Foreign olive cultivars were introduced last century during sixties, with two Italian cv. Frantoio and Leccino. Nowadays this olive cultivars are well adopted. Palmitic acid concentrations are higher 13,09% (Leccino) and 14.16% (Frantoio) compared to OO from native olive cv. There is a similarity in respect to OA among two foreign cv and others, while their LA concentrations were very low 4.68% (Leccino) and 6.64% (Frantoio), compared to OO from Albanian olive cultivars. The content of alfa-LA acid was 0.52% from both foreign cultivars [19].
A similarity was found in FA profiles among Albanian OO from native cultivars and OO from Italy and Greece [24]. In our study, the comparison of olive cultivars with cultivars' data from the Southern coast of the Mediterranean Sea showed a profile with a high content of polyunsaturated fatty acids [26,27]. Statistical analyses reveal differences among the cultivars for individual fatty acids (p < 0.05) ( Table 6): only the primary fatty acids, C16:0, C18:1 (n-9), and C18:2 (n-6), presented differences among them statistically.
Principal component analysis (PCA) was applied in order to determine the relations between fatty acid compositions in the OO samples. Based on the results of the PCA, two different principal components were determined, and these two components described 95% of the total variability of the experimental data. The PCA biplot of the fatty acids detected in the OO samples is shown in Figure 6. According to the PCA biplot, OO samples were well categorized. As seen in   Table 6, the OO samples coded as 1,4,5,6,7,8,11,17,18,19,20,21,26,28 and 31 were positioned on the positive F1 axis while the other OO samples were on the negative F1 axis.
Regarding the cultivar Kalinjot, OO samples have been taken from some regions of the country, because this cultivar is more widespread and more productive for olive oil. OO Kalinjot cv from Vlora region, no 2, and Kalinjot cv from Mallakastra region, no 33, fall very close, indicating the opportunity to produce OO with designated origin. OO samples no 24, 27 and 30, belonging to Kalinjot cv, fall together, telling the possibility yo produce OO from this cultivar and to authenticate them ( Table 7 (19) and Frantoio (28).

Phenolic compounds in Albanian OO
Phenolic compounds in Olive oils usually range between 50 and 1000 ppm (mg/ kg) depending on the cultivars, pedoclimatic conditions, maturity stage of the fruit, and extraction conditions [28]. OO is celebrated not only for its nutritional value but also for the content of minor compounds of pharmacologically active principles, belonging to the nutraceutical family, otherwise known as functional foods, such as polyhydroxylated phenolic and catecholic species [17] (Figure 7). A variety of over 230 chemical compounds, approx. 2% of the weight found in the VOO's unsaponifiable fraction, such as polyphenols, tocopherols, sterols, flavors [29][30][31]. Polyphenols present in VOO, are classified into two groups: lipophilic phenols (tocopherols) and hydrophilic or polar phenols [32,33]. The hydrophilic phenols (HP) present in the VOO belong to different classes: phenolic acids, phenyl ethyl alcohols, secoiridoids, hydroxy-isochromans, flavonoids, and lignans [31]. Phenolic compounds show many health benefits, including reducing the risk factors of coronary heart disease, the prevention of several chronic diseases (for example, atherosclerosis), cancer, chronic inflammation, strokes, and other degenerative disorders [29,34]. EFSA has concluded that polyphenols in olive are the health claims' subject. The claimed effects are "reduces oxidative stress," "antioxidant properties," "lipid metabolism," "antioxidant activity, they protect body cells and LDL from oxidative damages." An amount of 5 mg hydroxytyrosol and its derivatives (e.g., oleuropein complex and tyrosol) in olive oil should consume daily to bear the claim [35].
Results on Total Polyphenol Content (TPC) indicate that Bardhi Tirana variety presented the highest values, 445.03 AE 16.83 mg/kg Gallic Acid in olive oil. In contrast, Frëng cultivar shows the lowest levels, 42.78 AE 7.04 mg GAE/kg olive oil ( Table 4). Results also show significant differences among cultivars, which may correlate to the cultivar, rather than agriculture practices or other factors. The comparison of TPC content in the ten studied cultivars with different cultivars, already published from Albania [18], and neighboring countries reveal that these cultivars are like cultivars from the Toscana Region (Italy) and Dalmatian Coast (Croatia) [26]. Montedoro et al. [36] have grouped the monovarietal olive oils according to the three groups' total phenol content. A classification for studied VOO is: "low" (50-200 mg/kg) Ulli i Zi, Frëng, Krips, Mixan, and Peperri cultivars; "medium" (200-500 mg/kg) Bardhi Tirana, Bardhi Kruja, Managjel, Kalinjot, and Ulli deti cultivars. The results obtained for the studied cultivars relate mainly to the cultivar differences. The results show that the studied olive oils' polyphenol content had significant differences (p < 0.05) among the cultivars. The actual stage of agriculture in Albania does not have a premise for irrigation of the olive plantations. Furthermore, concerning the maximum and minimum temperature values in the different regions, respectively, gives evidence that differences are not significant; hence, differences reported on the TPC content do not come due to climatic conditions. The TPC values of Bardhi Tirana are comparable with Koreiniki (Greece), Picual (Spain), and Frantoio (Italy) cultivars [25,26] [18,19]. Total phenolic content in OO compared with OO from neighboring countries reveals that these cultivars are similar to cultivars from the Toscana Region (Italy) and Dalmatian Coast (Croatia) [26]. TPC values among studied cultivars resulted in statistically different. Montedoro et al. (1992) have grouped the monovarietal olive oils according to the three groups' total phenol content. The studied cultivars are classified as: "low" (50-200 mg/kg) Frëng and Mixan cultivars; "medium" (200-500 mg/kg) Bardhi Tirana, Bardhi Kruja, and Kalinjot olive cultivars. The results obtained can be related mainly to the cultivar differences. The results show that the studied olive oils' polyphenol content had significant differences (p < 0.05) among the cultivars. Bardhi Tirana samples are comparable with Koreiniki (Greece), Picual (Spain), Frantoio (Italy) and Memecik, Ayvalik and Gemlik (Turkey) cultivars [25,26,36].
Additionally, PCA was applied to generate models for the classification of OO samples in terms of total phenolic contents. It can be observed that three groups were mainly formed on the plot, of these, Krips Kruja and Bardhi Kruja cv. as a group were positioned on the positive F1 axis, while the remaining samples were located on the negative axis. The formation of this group is expected as these two cvs. Had the lowest values of total phenolic content. On the other hand, Ulli-i-Zi cv. is seen to be clearly separated from the others, expectedly as it had the highest content of phenolics.
Total alcohols in Kalinjot OO vary between 6903 and 9375 μg/kg, and in Bardhi Tirana OO 6874 μg/kg. The main C-5 alcohol resulted is 3-penten-2-ol in the range 2504-3442 μg/kg. This alcohol was found in higher levels compared to olive oils from Greek, Italian and Spanish olive cultivarssuch as Croatian cv. Coratina [43], Italian cv. Leccino, Spanish cv. Cornicabra and Arbequina, Greek cv. Koroneiki and Adramytini [39], and Turkish cv. Halhali, [44]. Total content of terpenes in Kalinjot OO varies 1895-2941 μg/kg, while the presence of β-ocimene may serve to distinguish OO both in olive cv and region. Terpene compounds give olive oils characteristic floral odors. (E)-3-Hexenyl acetate and methyl salicylate are two esters found in OO from both Kalinjot and Bardh Tiranai cultivars. Another ester found only in OO from Kalinjot is 2-butoxyethyl acetate. (E)-3-hexenyl acetate concentrations vary between 2705 and 3555 μg/kg in Kalinjot OO, while are found in lower levels to Bardhi Tirana OO (1107.7 μg/kg). The esters concentration compared with Greek cultivars is lower, however, higher when compared with Italian and Spanish cv. [42]. This ester compound gives olive oils pleasant and fruity odor notes. In conclusion, 2-butoxyethyl acetate may use as molecular marker to distinguish OO from these two cultivars.

Conclusions
Despite the modest contribution in global OO production, world ranking 20th, olive tree comprises an important permanent crop with considerable potential for the Albanian economy. OO with certified origin will increase the value of the final product. With a contribution of 0.51% to total world production, OO production reached 20,038 tons contributing almost to 95% of domestic demands. Interestingly, table olive consumption ranks the country the 1st in world. Principal component analyses (PCA) for OO samples from Kalinjot cv. displayed the differentiation with OO samples. The authenticity of OOs originating from Vlora region constitutes an opportunity for domestic production. In parallel, PCA of OO from different native and foreign olive cv. displayed differentiation regarding fatty acids.
Phenolic compounds found to be significantly different among the olive oil samples of different cultivars. 3,4-DHPEA-AC was determined as the main phenolic compound. Secoiridoids are found in abundance, 3,4-DHPEA-EDA and p-HPEA-EDA as dominant compounds, especially in Kalinjot OO. It was found that Albanian VOOs had lower levels of flavonoids consisting of luteolin and apigenin. Studies in OO aroma compounds from main cv indicate that Albanian OO is considered with high content OO with aroma compounds. (E)-2-hexenal is found as the principal aroma compound. Kalinjot OO concentrations vary between 36700 and 40411 μg/kg, much higher compared to Bardhi Tirana OO (27542.7 μg/kg).