| Olive(Olea europaea L.)is one of the four major woody oil plants in the world.Olive oil is a kind of vegetable oil extracted from fresh fruit via physical cold pressing,which is the best method to reduce the loss of its active compounds,and is popular throughout the world because of its rich nutritional ingredients,such as unsaturated fatty acids(UFA),a-tocopherol,polyphenol,sterol,and a variety of inorganic elements.So olive oil has highly edible value and healthcare function.Olive has been researched for many years,but the studies on quality of oil in different olive varieties were litte.In this paper,oil yield,free fatty acid,peroxide value,a-tocopherol content,stigmasterol content,?-sitosterol content,polyphenol content,fatty acid composition and inorganic element were analyzed using soxhlet extraction,acid-base titration,oxidation-reduction titration,high performance liquid chromatography(HPLC),gas chromatography-mass spectrometry(GC-MS)and atomic absorption spectrometry(AAS).At the same time,in order to provide theoretical basis for breeding high quality and yield varieties,the oil quality of 8 olive varieties was comprehensive evaluated by principal component analysis(PCA).The main results were as follows:1.The oil yield of 8 introduced olive varieties were from 10.30 to 19.35%,which the Koreniki had the highest oil yield,while the Chenggu 32 had the lowest oil yield,and the sequence from high to low were Koreniki,Ottibratica,Frantoio,Barnea,Arbequina,Coratina,Manzanilla and Chenggu 32,respectively.2.The free acidity of 8 varieties were from 0.29 to 1.11 mg/g and the sequence from high to low were Frantoio,Chenggu 32,Ottibratica,Arbequina,Koreniki,Manzanilla,Barnea and Coratina,respectively.The peroxide value of 8 varieties were from 0.09 to 1.92 mmol/kg and the sequence from high to low were Chenggu 32,Frantoio,Koreniki,Barnea,Coratina,Arbequina,Manzanilla and Ottibratica,respectively.The two indexes of all varieties did not exceed the upper limit of extra virgin olive oil that national standard formulated.3.The a-tocopherol,stigmasterol and ?-sitosterol contents of 8 olive oils were determined.The a-tocopherol contents were from 73.62 to 164.48 mg/kg and the sequence from high to low were Chenggu 32,Koreniki,Coratina,Ottibratica,Barnea,Arbequina,Manzanilla and Frantoio,respectively.The stigmasterol contents were from 19.08 to 71.62 mg/kg and the sequence from high to low were Arbequina,Barnea,Frantoio,Chenggu 32,Koreniki,Manzanilla,Ottibratica and Coratina,respectively.The ?p-sitosterol contents were from 279.14 to 1149.59 mg/kg and the sequence from high to low was Chenggu 32,Manzanilla,Frantoio,Barnea,Arbequina,Ottibratica,Coratina and Koreniki,respectively.4.The total polyphenol contents of all oils were from 21.26 to 180.21 mg/kg,and Koreniki had the highest content while Chenggu 32 had the lowest content.The main polyphenol compounds included hydroxytyrosol,p-hydroxy benzoic acid,caffeic acid,epicatechin,p-coumaric acid,ferulic acid,rutin,oleuropein and quercetin.The mian polyphenol compounds' contents of 8 kinds of oils were little.The contents of rutin were from 11.21 to 21.74 mg/kg and more than others.The contents of p-coumaric acid were less than others and from 0.07 to 0.13 mg/kg.The oleuropein content of Ottibratica was 3.71 mg/kg and exceeded the limit of quantitation.The contents of hydroxytyrosol were not different obviously.Synthetical scores of 8 varieties from high to low were Manzanilla,Koreniki,Ottibratica,Coratina,Barnea,Frantoio,Arbequina and Chenggu 32,respectively.5.The antioxidant of total polyphenol of 8 olive oils indicated that the EC50 of DPPH radical were from 20.00 to 120.66 ?g/mL,and Koreniki had the lowest value while the Arbequina had the highest value.However,the EC50 of hydroxyl radical were from 5.33 to 63.00 ?g/mL,and Coratina was the best for the lowest EC50 while Barnea was the worst.The EC50 of Fe2+ chelating were from 5.66 to 83.00 ?g/mL,and Arbequina had the lowest value while Koreniki had the highest value.The results of correlation analysis showed that there were correlation among DPPH radical scavenging efficiency,hydroxyl radical scavenging efficiency and Fe2+ chelating activity.Meanwhile,the hydroxytyrosol,p-hydroxy benzoic acid,rutin and quercetin had high correlation with DPPH radical scavenging efficiency,hydroxyl radical scavenging efficiency and Fe2+ chelating activity,while the total polyphenol,caffeic acid,epicatechin,p-coumaric acid,ferulic acid and oleuropein had low correlation with antioxidant.6.The main fatty acids in olive oils were oleic acid,palmitic acid,linoleic acid,stearic acid,lignolenic acid,palmitoleic acid,arachidic acid,heptadecanoic acid,heptadecenoic acid and so on.The unsaturated fatty acids contents of 8 olive oils were from 73.23 to 81.30%,while the saturated fatty acids contents were merely from 15.52 to 18.87%.Oleic acid contents were the highest among 6 kinds of unsaturated fatty acids and from 54.17 to 74.03%,while the contents of heptadecenoic acid were low and from 0.06 to 0.24%.The oleic acid content of Koreniki was the highest while the oleic acid content of Chenggu 32 was the lowest.The palmitic acid contents were the highest among 5 kinds of saturated fatty acids and from 12.69 to 16.40%,while the contents of heptadecanoic acid were from 0.08 to 0.11%and lower than others.All the samples conformed to extra virgin olive oil reference established by national council except the oleic acid and lignolenic acid of Chenggu 32,behenic acid content of Koreniki and Frantoio,arachidonic acid contents of Frantoio and Coratina.Synthetical scores of 8 varieties from high to low were Arbequina,Ottibratica,Manzanilla,Frantoio,Barnea,Chenggu 32,Koreniki and Coratina,respectively.7.The results of inorganic element content showed that the contents of calcium were from 364.67 to 637.69 mg/kg and higher than other elements that determined.The calcium content of Chenggu 32 was the highest and Manzanilla was the lowest.The potassium contents,magnesium contents and zinc contents of 8 olive oils were 17.45?49.93 mg/kg,18.56?23.87 mg/kg and 18.19?25.07 mg/kg,respectively.There were minor difference among these three elements contents.The contents of manganese,iron and copper were little and were 2.41?4.14 mg/kg,1.58?7.17 mg/kg and 0.26?0.43 mg/kg,respectively.The iron element and copper element contents of 8 olive oils exceeded the extra virgin olive oil reference established by national council except the iron contents of Barnea and Coratina.Synthetical evaluation indicated that Chenggu 32,Koreniki and Arbequina were better varieties.Synthetical scores of 8 varieties from high to low were Chenggu 32,Koreniki,Arbequina,Manzanilla,Frantoio,Ottibratica,Coratina and Barnea,respectively.8.Principal component analysis(PCA)was applied to evaluate olive oil quality synthetically and the synthetical scores from high to low were Koreniki,Chenggu 32,Frantoio,Manzanilla,Coratina,Barnea,Ottibratica and Arbequina,and the oil of Chenggu 32,Koreniki and Frantoio had better quality.Synthetical evaluation indicated Koreniki was the best variety that had the highest oil yield and the best oil quality among 8 introduced varieties. |
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