Composition Analysis Of 24 Kinds Of Olive Oil From Liangshan And Its Effect On Lipid Oxidation During High Fat Beef Digestion

Olive oil has high edible value.Liangshan,Sichuan Province is the largest olive introduction and breeding base in China.Although it has been planted for many years,there are few reports on the composition and characteristics of olive oil.In this thesis,24 different varieties of olive oil cultivated in Liangshan were selected as the research object,and their components were systematically studied,and their polyphenol composition and content were identified and analyzed.Olive oil was used as edible oil to further assess its influence on lipid oxidation during co-digestion with high fat beef.Firstly,the physical and chemical indexes of 24 kinds of olive oil,such as fatty acid composition,trace elements,and oxidative stability were assessed.Our findings revealed that the different varieties had a significant difference in the composition(p<0.05).The content of oleic acid was 54%～80%,the content of polyphenols was 50.83～502.03 mg GAE/kg,the content of squalene was 3121.58～10709.32 mg/kg,the content of tocopherol was129.13～460.02 mg/kg,the oil content was 5.28%～21.06%,and the oxidation stability was observed to be between 2.40～20.50 h.Besides,the 24 kinds of olive oil were divided into five categories by principal component analysis and polymerization analysis.The first category(varieties 2,9,20,23,and 24)was characterized by rich oleic acid,polyphenols,and tocopherol;the second category(variety 16)was characterized by higher tocopherol and lower brightness;the third category(varieties 3,5,and 8)was characterized by higher water content and lower oxidation stability;the fourth group(varieties 6,11,13,14,15,17,18,19,and 21)was characterized by higher oil content and lower acid value;the fifth group(varieties1,4,7,10,12,and 22)was characterized by higher squalene content and lower oleic acid.Secondly,the phenolic extracts of 24 kinds of olive oil were qualitatively and quantitatively by UPLC-QTOF-MS.The outcomes displayed that 33 phenolic compounds were identified in 24 kinds of olive oil,and 16 polyphenol compounds were quantified.According to the chemical structure,the 16 phenolic compounds were divided into 5 groups:secoiridoid,phenolic acids,phenolic alcohols,flavonoids,and lignans.Among them,the contents of 3,4-DHPEA-EDA,3,4-DHPEA-EA,and p-HPEA-EDA were the highest.Meanwhile,the antioxidant activity of phenolic extracts was studied.The results showed that the content of secoiridoids was positively correlated with DPPH,FRAP,ABTS,and ORAC(p<0.01).Finally,the 24 kinds of olive oil were divided into four categories by thermogram analysis based on the trace accompanying substances such as polyphenols,tocopherols,sterols and squalene.Among them,there was a significant negative correlation between polyphenol rich olive oil and lipid oxidation during co-digestion with high fat beef(p<0.05).The effects of low(100 mg GAE/kg),medium(300 mg GAE/kg)and high(600 mg GAE/kg)concentrations of olive polyphenols on lipid oxidation during high fat beef digestion were further investigated.When the content of polyphenols reached 600 mg GAE/kg,the inhibition effect on lipid oxidation products(especially malondialdehyde)was the strongest.In addition,it was found that the contents of 3,4-DHPEA-EDA and 3,4-DHPEA-EA decreased significantly during the digestion process,and the total amount of lipid free radicals(especially alkyl free radicals)were also inhibited significantly(p<0.05),which further proved that olive polyphenols could inhibit the lipid oxidation of high fat beef during the digestion process.Therefore,extra virgin olive oil rich in polyphenols can be used as a healthy oil for high-fat diet.