Quality Assessment of Five Mono-cultivar Virgin Olive Oils Produced in Longnan (China) from 2013 to 2017.

The aim of this work was to evaluate the quality of the five mono-cultivar (Frantoio, Leccino, Picholine, Coratina and Ezhi-8) virgin olive oils (Mc-VOOs) produced in Longnan (China) from 2013 to 2017 through analysing the organoleptic quality, physicochemical properties, phenolic contents, antioxidant activity and fatty acid composition. The leading principal components for assessing the quality of Mc-VOOs were extracted by principal component analysis (PCA). The results indicated that the five Mc-VOOs showed obvious differences (p < 0.05) in flavour and substance composition with the variation of cultivar and production year; however, the same cultivar of VOO displayed certain homogeneity in five consecutive years of assessment. The five Mc-VOOs were rich in phenolic compounds and unsaturated fatty acids such as oleic acid. The quality of VOO was mainly determined by the genetic characteristics of olive cultivar, meanwhile, fruit maturity, soil and climate factors also affected its quality. The content of phenolic compound, DPPH· scavenging rate, proportion of unsaturated fatty acids and iodine value of Coratina were the highest, on the contrary, Ezhi-8 was the lowest in general. The results of PCA showed that the five leading principal components to evaluate the quality of Mc-VOOs were oleic acid, linoleic acid, acid value, total phenol and trace components (such as C20:1 and squalene) successively. In conclusion, the five McVOOs from Longnan show excellent quality and have certain uniformity in different production years.


Introduction
As an important woody oil crop, olive is widely planted in the Mediterranean. Olive oil is a high quality edible vegetable oil rich in unsaturated fatty acids, antioxidant polyphenols, tocopherol and other bioactive substances, such as hydroxytyrosol and oleuropein 1 . With the enlarging consumption of olive oil globally, many countries far away from the Mediterranean begun to introduce and cultivate olive 2 .
The history of olive introduction and cultivation in China is more than 60 years. After long-term trials, agronomists generally agreed that the hot and dry valley in southwest China is more suitable for olive cultivation, especially in Sichuan Guangyuan , Yunnan Lijiang , Chongqing Fengjie , and Gansu Longnan provinces 3 . Due to superior geographical location, suitable climate and environmen-backward. More urgently, there is a lack of in-depth investigation on the quality of olive oil produced in Longnan as it is the world s emerging olive oil production area.
Because of the difference from the cultivation environment of original place, the research on the quality of virgin olive oil VOO produced in the area beyond origin has been widely concerned and studied. The genotype of olive cultivar as well as the growing environment and climate have very important impacts on the quality of VOO 4 . Kosma et al. 5 evaluated the quality of VOO extracted from five less well-known Greek olive cultivars and found that the VOO quality differed significantly in cultivars. The quality of seven monovarietal VOO from five different regions of Chile was appraised by the determination of phenolic compounds and volatiles, and the results suggested that the amount of some of characteristic compounds in VOO was related to the location of olive orchards 6 . The characterisation of VOO from the main Italian varieties Frantoio and Leccino showed that there were significant differences between the oils extracted from both cultivars when planted in the environments at different altitudes 7 . Kharazi et al. 8 described the physicochemical properties of Iranian VOO Zard, Mari and Phishomi cultivated in Roodbar, Gilan, and they found that most of the parameters showed statistically significant differences. Mailer et al. 9 reported that the growing region, cultivar and harvest time influence on the quality of olive oil, especially the growing region of some varieties could affect the fatty acid composition. Xiang et al. 10 detected the quality, chemical composition and antioxidant activity of VOO extracted from cultivars of Barnea, Coratina, Koreniki, and Manzanilla in Liangshan Sichuan province in China . They found that the tested parameters were different from the variety of VOO and the quality of Coratina and Manzanilla was relatively excellent in terms of fatty acid composition and peroxide value.
Considering the changes of climate and environmental factors after the introduction and planting of olive in China, we are very concerned about the quality of VOO produced in Longnan where far from the origin of olives. Therefore, in this work, the quality of five mono-cultivar extra virgin olive oils Mc-VOOs, Frantoio, Leccino, Picholine, Coratina, and Ezhi-8 produced in Longnan from 2013 to 2017 was detected and evaluated. We hope that this effort will contribute to understanding the quality of VOO produced in Longnan.
The five Mc-VOOs Frantoio, Leccino, Picholine, Coratina and Ezhi-8 samples were provided by Longnan Garden City Olive Technology Development Co., LTD. Among the five Mc-VOOs, Frantoio, Leccino and Coratina were originated and introduced from Italy; Picholine was introduced from France; Ezhi-8 was bred by the Hubei Institute of Botany China . The olive fruits used for VOO extraction were collected from Zazipo orchard Altitude: 1200-1300 m, Northern latitude: 33 26 47 , East longitude: 104 46 38 , sunny side sloping field in Liangshui Town Wudu district, Longnan city, Gansu province, China , and the average age of the olive trees was 14 to 15 years. The olive orchard was irrigated by drip irrigation. The maturity index MI at harvest time ranged from 5 to 6. The VOO extraction process was performed in an industrial scale within 24 h after fruit samples were harvested. About 750 kg of olive fruits were sorted, cleaned, milled and mixed 45 min at 25-27 . After that, the obtained paste was centrifuged at 5400 rpm using a three-phase separator Alfa Laval, Sweden . VOO samples were prepared after the crude oil was precipitated and vacuum filtered with double filter paper and stored at 4 . The analyses of VOO samples collected from three production batches annually were carried out within 2 months.

Evaluation of organoleptic quality of Mc-VOOs
The absorbance of Mc-VOOs was measured at the wavelength of 410 nm and 600 nm with a UV-spectrophotometer UV 1800, Shanghai . Three parallel tests were performed to compare and analyse the colour and turbidity of Mc-VOOs. According to the method recommended by the China National Standard GB 23347-2009, Olive oil and olive-pomace oil , the trained volunteers were invited to evaluate the organoleptic quality of Mc-VOOs.

Extraction and determination of total polyphenols
content from Mc-VOOs and antioxidant activity assay in vitro The total polyphenols content TPC in Mc-VOOs was extracted through the modified method from Tasioula-margari and Okogeri 11 . About 5.0 g of Mc-VOOs was added in a centrifuge tube; 5.0 mL n-hexane and 5.0 mL 80 v/v methanol water solution were added to extract TPC. After 2 min of violent oscillation, centrifugation was conducted at 3000 r/min for 5 min, and the methanol phase was collected. Then, the extraction was repeated twice. The obtained methanol extract sample MES was incorporated and for further assay.
In the determination of TPC, 2.5 mL of Folin-Ciocalteu s phenol and 2 mL of sodium carbonate 7. 5 were added into 0.5 mL of MES, then 5 mL of distilled water was added and shake well. The absorbance at 760 nm was detected after 2 h. The TPC was expressed as the absolute concentration of gallic acid 12 . The equation of gallic acid calibration curve was C 202.59A 760 1.8223.
The radical scavenging activity RSA was evaluated according to the method reported by Brand-Williams 13 . The scavenging rate of DPPH was monitored in the presence of MES. A 2.9 mL of 6 10 5 mol/L DPPH in methanol was used and the reaction was started by adding 100 μL of MES. The UV absorbance of DPPH was monitored at 517 nm and room temperature for 30 min in darkness.
The RSA toward DPPH was expressed as DPPH scavenging rate 1 As Ab /Ac 100 , where As is the absorbance of 2.9 mL DPPH 100 μL MES, Ab is the absorbance of 2.9 mL methanol 100 μL MES, and Ac is the absorbance of 2.9 mL DPPH 100 μL 80 v/v methanol. The equivalent concentration of MES was expressed as the concentration of Vc; and the regression equation is Y 0.1552X 1.0775 R 2 0.9965 , where Y is Vc μg and X is DPPH scavenging rate .

Analysis of fatty acid compositions FACs
The FACs and their relative percentages of Mc-VOOs samples were analysed by GC-MS Agilent 7890B-5977A after methyl esterification by the methods of KOH-methanol according to GB/T 17376-2008. The detailed analysis method and conditions of GC-MS was the same as our previous work 14 .
The calculation of different fatty acid ratios and theoreti-cal iodine values IV was referred to Maestri 15 . Iodine value IV, g/100 g palmitoleic acid 1.001 oleic acid 0.899 linoleic acid 1.814 linolenic acid 2.737.

Data statistics and analysis
All tests were performed in triplicate. SPSS Statistics 17.0 was applied for significant difference, correlation analysis, and principal component analysis PCA . PCA was performed by the dimensionality reduction technology. Values are expressed as Mean SD n 3 . Different lowercase letters in the same line are significantly different at p 0.05 Tukey HSD among the five cultivars in the same year; capital letters in the same column are significantly different at p 0.05 among the five years in the same cultivar.

Organoleptic quality of the ve Mc-VOOs
The colour and transparence of the five Mc-VOOs from 2013 to 2017 are shown in Table 1. The colour of the five Mc-VOOs samples was evaluated by measuring the absorbance at the wavelength of 410 nm A 410 , and the turbidity and transparence of the samples were expressed as the absorbance at 600 nm A 600 . The colour values of A 410 ranged from 0.69 to 2.08, while the values of A 600 ranged from 0.02 to 0.46, and all values varied with olive cultivar and production year p 0.05 . The actual appearance of the five Mc-VOOs reflected that the filtered VOO were all clear, but the colour had remarkable difference due to variety; specifically, the colour of Coratina was the darkest and greenest, followed by Picholine, and the other three varieties Frantoio, Leccino and Ezhi-8 were yellow-green in colour. As olive cultivar, origin, maturity stage of fruit, storage Note: Different lowercase letters in the same line are significantly different at p < 0.05 (Tukey HSD) among the five cultivars in the same year; capital letters in the same column are significantly different at p < 0.05 among the five years in the same cultivar.
conditions of fruit, and olive fruit processing all influence the exterior and flavour of olive oil, thus its organoleptic quality includes colour, taste and aroma 16 . Our results also suggested that the olive cultivar has a significant influence on the sensory quality of VOO. The special flavour of olive oil is due to the evolution and development of volatile compounds in oil extracted from olive fruit 1 . A specific vocabulary also has been developed for virgin oil sensory descriptors. The positive attributes of virgin olive oil are explained as fruity, bitter and pungent IOOC 2007 . The results of organoleptic evaluation showed that all the VOO had the unique aroma and flavour characteristics of virgin oil; however, the taste varies significantly according to different varieties. Coratina had a pungent and bitter aftertaste, followed by Picholine and Frantoio; Leccino and Ezhi-8 had a relatively light taste. The results of comparative analysis on the five VOO samples in five consecutive years showed that there were differences in data level, yet such differences were relatively small in visual sensory and flavour evaluation, which indicates that the VOO of the same variety shows certain homogeneity in organoleptic properties in different production years. Those quality differences in vision, aroma and taste are largely determined by the olive variety, as well as geographical and climatic conditions, the harvesting time, fruit storage condition and processing techniques in the production year of VOO 16,17 .
Wudu district of Longnan city, where the olive orchard is located, is in the middle reaches of Bailongjiang river basin. Wudu district is a transition zone from the semi-humid climate of the north subtropics to the semi-arid climate of the warm temperate zone. The annual average temperature in Wudu district is about 14.7 , the annual sunshine hours are 1782 h, and the annual precipitation is around 467 mm 3 . It mainly belongs to the semi-humid climate of the north subtropics, which is different from the Mediterranean basin, where summers are hot and dry and winters are mild and rainy. The cultivation of the same variety of olive in different geographical and climatic conditions will affect the quality of VOO. Our results indicated that olive cultivar played a decisive role in the sensory quality of VOO in the same orchard, while the climate, agronomic management, fruit maturity and processing in different production years also may affect the quality of VOO.

Physicochemical properties of the Mc-VOOs
The International Olive Oil Council IOOC has defined the quality of olive oil based on parameters like free fatty acid FFA content, peroxide value PV and sensory score taste and aroma . In particular, the quantity of FFA is an important factor for classifying olive oil into commercial grades 18 . As shown in Table 2, the PV and acid value AV of the five Mc-VOOs varied with varieties and production years p 0.05 . During the continuous five years of testing, the PV of the five Mc-VOOs ranged from 2.39 mmol/kg to 9.65 mmol/kg, and the AV ranged from 0.07 mg/ g to 0.82 mmol/kg. All the PV and AV meet the requirements of IOOC 2013 and China National Standards GB 23347-2009 on the quality standards of extra VOO in general. Moreover, there were significant differences in PV and AV among different VOO varieties produced in the same year, as well as the same VOO produced in different years. For instance, during the five-year period, the PV and AV of Frantoio were 4.64-9.05 mmol/kg and 0.26-0.78 mg/g, respectively; the PV and AV of Ezhi-8 ranged within 2.39-8.17 mmol/kg and 0.09-0.34 mg/g, respectively. The results also indicated that the cultivar, production year, maturity degree and other factors of olive fruit would lead to the differences in VOO physicochemical parameters PV and AV . Although the differences were significant at the sta- Note: Different lowercase letters in the same line are significantly different at p < 0.05 (Tukey HSD) among the five cultivars in the same year; capital letters in the same column are significantly different at p < 0.05 among the five years in the same cultivar.
tistical level, the absolute values of the data showed that they were relatively small, especially, the PV and AV of the same VOO variety in different years. The PV and AV of Coratina ranged within 4.11-5.60 mmol/kg and 0.19-0.52 mg/g respectively, which also implied that the quality of Mc-VOOs from the same producing area and variety showed certain uniformity in different years. AV and PV are the most commonly used parameters to evaluate the quality of edible oil. Xiang et al. 10 reported that the free acidities of four olive oils introduced to and cultivated at Liangshan in Sichuan ranged from 0.14 to 0.28 and the PV ranged from 0.98 to 2.46 meq O 2 /kg. Both the free acidity and PV did not exceed the upper limit prescribed in the EVOO. The relatively low AV and PV showed the excellent quality of the Mc-VOOs produced in Longnan and were related to the ripeness of olive fruit, storage time and oxidation degree of VOO 19, 20 .  Table 3. The data indicated that the equivalent Vc concentration per gram of olive oil ranged from 35.3 μg/g to 121.4 μg/g, the antioxidant activity of olive oil extracted from Coratina was the highest for the five consecutive years from 2013 to 2017 ; however, the antioxidant activity of other monocultures of VOO showed little difference. Researches have confirmed that Coratina was noteworthy for its high content of phenolic compounds 287.8 μg/g 22 . The results of correlation analysis showed that there was a significant positive correlation between TPC and Vc equivalent concentration p 0.01, r 0.531 , which indicated that the content of polyphenols was directly correlated with the antioxidant activity of VOO. Previous studies have shown that the TPC determined by the Folin reagent was better correlated with antioxidant activity than each tested polyphenol or polyphenols groups such as o-diphenols 23 , which is similar to our results.
The main antioxidant phenolic compounds in VOO  Note: Different lowercase letters in the same line are significantly different at p < 0.05 (Tukey HSD) among the five cultivars in the same year; capital letters in the same column are significantly different at p < 0.05 among the five years in the same cultivar.
mainly include phenolic acids, hydroxytyrosol and oleuropein 24 . Xiang et al. 10 found that the total polyphenol contents of the four olive oils produced in Liangshan ranged from 55.4 mg/kg to 180.2 mg/kg, and the main compounds were hydroxy tyrosol, p-hydroxybenzoic acid, rutin, and quercetin, which exhibited excellent anti-oxidation properties. The concentration of healthy phenols in VOO is directly related to the cultivar of olive fruit 25 . Miho 26 reported that secoiridoid derivatives oleuropein, ligstroside aglycon isomers, oleocanthal, oleacein, apigenin and luteolin were the most concentrated phenols in VOO, showing high variability that was significantly related to the cultivar. In addition, the harvesting system and extraction process such as harvesting machines, storage time and malaxation conditions of olive oil also affects the phenolic profile of VOO, which in turn determines the quality of VOO. The latest report revealed that fruit damage explains most of the worsening of oil quality across harvesting systems and storage duration 27 . Malaxation under vacuum led to an increase in phenolic contents compared to standard conditions carried out at atmospheric pressure 28 . The five Mc-VOOs produced in Longnan are rich in phenolic compounds, which also show their good nutritional and health potential. The phenolic profiles and functions of these VOO are being further studied.

Fatty acids compositions and squalene of the Mc-VOOs
The main fatty acids composing olive oil are triacylglycerols triglycerides or fats and small quantities of free fatty acids FFA . Oleic acid C18:1 , a monounsaturated omega-9 fatty acid, accounts for 55 to 83 of olive oil. Palmitic acid C16:0 , a saturated fatty acid makes up 7.5 to 20 of olive oil. Linoleic acid C18:2 , a polyunsaturated omega-6 fatty acid, accounts for about 3.5 to 21 in olive oil 29 . The fatty acid compositions of the Mc-VOOs from 2013 to 2017 are presented in Table 4. The main fatty acids in the five Mc-VOOs were oleic acid C18:1, 72.5 -83.8 , palmitic acid C16:0, 9.3 -16.3 , linoleic acid C18:2, 2.73 -6.55 , stearic acid C18:0, 1.28 -3.56 , palmitoleic acid C16:1, 0.25 -2.30 , eicosanoic acid C20:0, 0.21 -0. 37 and eicosenoic acid C20:1, 0.16 -0.35 in order of content. During the five-year test, the contents of palmitoleic acid C16:1 and palmitic acid C16:0 in Coratina were the lowest, while their contents in Ezhi-8 were the highest. Moreover, the fatty acids with higher contents such as C18:1 and C16:0 showed some differences p 0.05 , but the fatty acids with lower contents such as C20:0 and C20:1 did not display significant differences, which reflected the difference and determinacy resulting from olive cultivar. The fatty acid composition varies significantly in olive cultivars; the oleic acid contents of six olive cultivars from Tunisian arid zones ranged from 57.9 to 75.9 , while the linoleic and palmitic acid ranged within 5.7 -17.5 and 11.1 -18.2 , respectively 22 . In comparison, the composition and proportion of the primary fatty acids in VOO from Longnan were similar to those in other regions 30 and generally meet the standards of IOOC 2013 , but they may vary due to olive cultivar, growing region, fruit maturity, and processing technique of VOO. The fatty acid compositions of the five Mc-VOOs were similar to those of four olive cultivars Barnea, Coratina, Koreniki, Manzanilla from Liangshan Sichuan province in China in general 10 , however, linolenic acid C18:3 and docosanoic acid C22:0 were not detected or trace, possibly due to analytical techniques, testing methods and olive variety differences. Recent work reported that the quality parameters, antioxidant activity, total phenol content, saturated fatty acids and monounsaturated fatty acids of VOO were directly related to ripening state and olive variety Manzanilla and Picual . They concluded that the type of olive cultivar is more important than collection date regarding fatty acid composition and antioxidant capacity 31 . Meanwhile, irrigation conditions in olive orchard also affect the fatty acids compositions, phenols and vitamins contents and oxidative stability of VOO 32 .
Analysis results of fatty acids proportions of the five Mc-VOOs from 2013 to 2017 are presented in Table 5. The analysis parameters mainly include the sum of saturated fatty acids SSFA , the sum of unsaturated fatty acids SUFA , the sum of monounsaturated fatty acids SMUFA , the sum of polyunsaturated fatty acids SPUFA , the sum of saturated fatty acids SSFA , C18:1/C18:2 O/L and iodine value IV . The SSFA, SUFA, SMUFA, and SPUFA of the five Mc-VOOs during the five continuous years were 12.2 -18.3 , 81.4 -87.6 , 75.0 -84.4 , and 2.7 -6.6 , respectively; and the IV ranged from 77.0 to 83.1 . The SSFA of Ezhi-8 was the highest while that of Coratina was the lowest, the SUFA of Ezhi-8 was the lowest and that of Coratina was the highest in view of cultivar. Correspondingly, the cultivars with higher SUFA had higher IV Coratina , while the cultivars with lower SSFA were lower in iodine values Ezhi-8 . The above parameters related to the proportion of fatty acids had some significant differences in different cultivars, but the same cultivar did not have significant differences among different years p 0.05 . The results showed that the main fatty acid types and concentrations of different Mc-VOOs had high similarities. Moreover, the major fatty acid compositions and contents of different Mc-VOOs were not significantly different in continuous production years, which suggested that the five Mc-VOOs produced in Longnan China showed certain homogeneity in the five consecutive years of evaluation.
The ratios of SMUFA/SPUFA and O/L can reflect the oxidation and storage stability of oil products; the higher the ratios, the better the stability of oils 33 . The results showed that the SMUFA/SPUFA and C18:1/C18:2 varied from 11.7 to 32.1 and from 11.3 to 31.3 , respectively. The O/L Note: Different lowercase letters in the same line are significantly different at p < 0.05 (Tukey HSD) among the five cultivars in the same year; capital letters in the same column are significantly different at p < 0.05 among the five years in the same cultivar. The results showed that the higher oleic acid content and the lower linoleic acid content in VOO, the larger the O/L ratio higher than 11 , which also indicated that the five Mc-VOOs had better storage and oxidation stability. The differences of the five Mc-VOOs in fatty acid profiles were attributed to their genetic differences, production year and area, irrigation and water stress, as well as the extraction system 34,35 . Squalene, the major olive oil hydrocarbon, is an intermediate compound in the biosynthesis of sterols in plant, microorganism and animal world. It makes up more than 90 of the hydrocarbon fraction ranging from 200 to 12000 mg/ kg oil 36 . As shown in Fig. 2, the relative content of squalene in Mc-VOOs from 2013 to 2017 ranged from 0.12 to 0.32 , and the differences among varieties and production years were not significant. The squalene content of 28 olive cultivars from World Olive Germplasm Collection of Cordoba ranged from 1100 to 8390 mg/kg oil, and the high variability observed could be explained by the genetic component 37 . Our results also confirm that the squalene content depends on olive cultivar and oil extraction technology 38 .

Principal component analysis of characteristic com-
ponents of the Mc-VOOs Principal component analysis PCA is often used to evaluate food quality, including olive oil 28,31 . To further explore the main factors that affect the quality of VOO, PCA was conducted on the all measured parameters, and the results are shown in Table 6 and Table 7. The contribution rates of the first five extracted principal components are 30.9 , 22.8 , 10.8 , 8.6 , and 7.2 , respectively, and the cumulative contribution rate is 80.3 . These components contain most of the information of olive oil and can fully reflect the overall quality of Mc-VOO, so the first five principal components can be selected for analysis.
As shown in Table 7, the principal eigenvector can reflect the contribution rate of each index to the principal component PC 39 . The first PC mainly includes the information of C18:1 0.96 and MUFA 0.93 , which indicates that the first PC can be divided into the proportion of oleic acid in VOO from the eigenvectors. It also indicates that oleic acid and MUFA are the main factors which determine the quality of VOO. The second PC mainly expresses the information of C18:2 0.86 , PUFA 0.86 and IV 0.76 , which suggested that the second PC can be divided into the PUFA of VOO. The third PC mainly covers the information of AV 0.88 and turbidity 0.72 , which implied that the third PC can be divided into the appearance and physicochemical properties of VOO. The fourth PC mainly reflects the information of TPC 0.58 , which showed that the fourth PC can be divided into the phenolic bioactive ingredients of VOO. The fifth PC mainly represents the information of C20:1 0.66 and squalene 0.50 , which indicated   Fig. 3. The results of PCA can reflect the main factors for evaluating the comprehensive quality of VOO, and have good agree-ment with related norms IOOC, 2013; GB 23347-2009 . The results of PCA show that the comprehensive quality of VOO can be evaluated by determining its fatty acid composition and proportion, sensory characteristics, physicochemical properties and phenolic compound content.

Conclusion
In conclusion, the quality of the five leading mono-cultivar Frantoio, Leccino, Picholine, Coratina and Ezhi-8 virgin olive oils produced in Longnan from 2013 to 2017 was evaluated; the main factors that determine the quality of virgin olive oil were identified by principal component analysis. The AV and PV of the five Mc-VOOs from Longnan were less than 1.0 mg/g and 10 mmol/kg respectively, while the relative percentage of C18:1 ranged from 72.5 to 83.8 . There were significant differences p 0.05 in the flavours, physicochemical parameters and active ingredients fatty acid compositions and phenolic compounds of the five Mc-VOOs; however, the quality of the same cultivar varied slightly in different years. The five Mc-VOOs produced in Longnan were rich in polyphenols and monoun-  Evaluation of the Quality of Five Mc-VOOs from Longnan saturated fatty acids with antioxidant activity, and varied with varieties. The quality of VOO was determined by its variety, but planting and climatic conditions also affected its quality. The results of PCA showed that the five PCs to evaluate the quality of VOO included oleic acid proportion, PUFA, transparence and acidity, phenolic compounds content, squalene and other trace components. The five Mc-VOOs from Longnan China showed certain quality uniformity and homogeneity in the five consecutive years from 2013 to 2017. This work provides important data for the quality evaluation of VOO introduced, cultivated and processed in Longnan, an emerging olive oil production region far from the Mediterranean where olive originates.