The Antioxidant Interaction And Migration Characteristics Into Oil Phase Of Phenolic Compounds In Different Forms From Camellia Seed Oil

Phenolic compounds were the important secondary metabolites in camellia seeds,and closely related to the oxidation stability and healthful properties of camellia seed oil.Previous studies had found that the forms of phenolic compounds affected their antioxidant activity,but the researches in this area was mostly focused on fruits,vegetables and grains.In the oil system,these researches were mainly focused on free phenolics(FP),ignoring the existence of bound phenolics(BP).Therefore,in order to clarify the antioxidant interaction of phenolic compounds with different forms in camellia seed oil,this thesis divided them into FP,esterified phenolics(EP)with the alkaline hydrolysis,EP without the alkaline hydrolysis and insoluble-bound phenolics(ISP)according to the extraction method of phenolic compounds,and optimized the extraction technology of them.Secondly,Schaal oven method and chemical antioxidation evaluation methods were used to study the antioxidant interactions of phenolic compounds in different forms.Finally,the qualitative and quantitative analysis of phenolic compounds with different forms in camellia seeds and camellia seed oil was performed with UPLC-MS/MS technology.This research revealed the distribution and the migration characteristics of phenolic compounds from camellia seeds to the oil,and provided a basis for regulating the camellia seed oil extraction process.Obtain the following results:(1)The single factor experiments and orthogonal experiments were used to optimize the extraction methods of phenolic compounds in different forms from camellia seed oil.The optimal extraction process for FP was to repeat extraction 3 times at 45?,each time for 1.5 h,and the material-liquid ratio was 1:15 g/mL;For EP with the alkaline hydrolysis,the volume ratio of ethyl acetate and alkaline hydrolysis solution was 1:1 and extracted for 3 times;ISP was alkaline hydrolysis for 6 h at 45? with 0.25 mol/L NaOH,and the material-liquid ratio was 1:3 g/mL.Under these optimal conditions,the contents of FP,EP with alkaline hydrolysis,EP without alkaline hydrolysis and ISP were 43.43 ± 2.05 mg/kg,28.67±1.51 mg/kg,27.33±1.74 mg/kg and 65.87±1.34 mg/kg,respectively.(2)Research on the antioxidant interactions of phenolic compounds with different forms in camelia seed oil.The Schaal oven method and chemical antioxidant evaluation methods(DPPH radical scavenging capacity,ABTS radical scavenging capacity,ferric ion reducing antioxidant power and ?-carotene bleaching ability)were used to reveal the antioxidant interactions of phenolic compounds in the non-polar oil system and the polar system.The results showed that single or composite of phenolic compounds in different forms produced an effective inhibition of oxidation products,and enhanced the oxidation stability in the non-polar oil system.Among them,the oxidation stability of the EP with alkaline hydrolysis+ISP was the strongest.In the polar system,the three forms of phenolic compounds showed different degrees of antioxidant capacity under different mechanisms,and there was a positive correlation with their concentrations.In addition,due to the difference in the evaluation systems,the compound ratio and the addition amounts of phenolic compounds,different compound components exhibited different interaction relationships under the two evaluation methods.In the non-polar oil system,the FP+ISP and the EP without alkaline hydrolysis+ISP showed additive interaction,other interacting components showed antagonistic interaction,and the antagonistic interaction of the three forms composite samples were the strongest.In the polar system,the two forms of phenolic compounds complex samples containing ISP showed synergistic and additive interaction,and the antioxidant activity of the EP with alkaline hydrolysis+ISP was stronger.And other samples showed antagonistic or additive effect under different mechanisms.(3)Explore the distribution and migration characteristics of phenolic compounds with different forms in camellia seeds and the oil.Under the premise of preparing camellia seed oil by cold pressing method,qualitative and quantitative analysis of phenolic compounds in different forms from camellia seeds and camellia seed oil were performed with UPLC-MS/MS technology.Analyze the composition differences of phenolic compounds with different forms in the seeds and oil to explore the distribution and migration characteristics of phenolic compounds with different forms.The results showed that the phenolic compounds in camellia seeds and the oil were mainly distributed in ISP,and the distribution of total phenols in ISP accounted for 60.43%and 53.40%,respectively.A total of 93 phenolic compounds were identified in camellia seeds and camellia seed oil.Among them,there were 33 and 18 phenolic compounds were only identified in the camellia seeds and camellia seed oil,respectively.And only 41 compounds were found both in the camellia seed and the oil.The chemical transformation in the oil production process made some phenolic compounds only detected in camellia seed oil,and factors such as physical loss,stability or fat solubility caused a large number of phenolic compounds only founded in camellia seeds.On the whole,only 0.46%of phenolic compounds migrated from camellia seeds to its oil,and benzaldehyde derivatives and phenols had the highest migration rate.Among them,benzaldehyde derivatives mainly migrated to FP,and phenolic substances mainly migrated to ISP.