Praperation Of Ionic Liquids And Their Applications On Extraction Of Hydroxytyrosol

The olive fruits,leaves and the olive oil contain hydroxytrosol as a natural antioxidant which has already been widely used for anti-oxidation,anti-bacteria and anti-cancer.The hydroxytrosol can be produced by chemical synthesis and extraction.The ionic liquids(ILs)which are composed of natural organic acid and natural alkaloids have been proved that ILs show positive effects on extraction as the solvents by many studies.The hydroxytrosol is hydrophilic and easy to be oxidized in air.This limits the application of hydroxytrosol as it is easy to deactivate.Liposome is made by phospholipid bilayer which has an outer layer with hydrophilic heads on both sides and two inner layers with hydrophobic tails.This“sandwich”structure can protect the hydroxytrosol in the inner layers as it is similar to cell membrane which has a hydrophilic cavity in the inner side,and a hydrophobic bilayer and a hydrophilic outer shell.The structure can isolate hydroxytrosol from the air and water to decrease the possibility of deactivation.In this work,5 ILs and 3 deep eutectic solvents(DESs)were prepared as the solvents to extract hydroxytrosol from olive fruits.The effects of pre-treatment methods and the amount of solvent used were studied with response surface method to optimize the processing conditions.The optimized result in this study is using the 40 w/v%DES:BeMa-1 aqueous solution to ultrasonic extract olive fruits for 34 min at 44~oC.(716.5±0.7)mg of hydroxytyrosol can be extracted from per kg dry olive fruit powder.The antioxidant properties of the raw hydroxytyrosol and extracted hydroxytyrosol with DES BeMa-1were examined by DPPH and ABTS comparing with ascorbic acid as a reference.The results showed that they all displayed a similar anti-oxidation ability.This indicated that the DES BeMa-1 did not affect the activity of hydroxytyrosol.The Gaussian 09 software was used to calculate the effects of bonds dissociation energy and molecule frontline orbit on hydroxytyrosol.This is in agreement with experimental results as it exhibited the strong anti-oxidation properties of hydroxytyrosol.Escherichia coli was used to test the anti-microbial activity of raw hydroxytyrosol and extracted hydroxytyrosol with DES BeMa-1.Based on our experimental results,the DES BeMa-1 increased the anti-microbial ability of hydroxytyrosol.The extracted hydroxytyrosol with DES BeMa-1 was encapsulated in the liposome to increase the stability.Liposome was produced by thin film evaporation method using lecithin,cholesterol and twain-80 as raw materials dissolved in ethanol.The optimized conditions were determined by single factor experiments with the ratio of lecithin and cholesterol,the volume of twain-80 added,processing temperature and the amount of hydroxytyrosol added.The maximum encapsulating rate of(50.60±0.31)%can be obtained with 4:1 ratio of lecithin and cholesterol,1.5 mL twain-80,4 mg hydroxytyrosol at 60~oC.The liposome coated hydroxytyrosol was studied on its stability,time-release and anti-oxidation properties.The liposome coated hydroxytyrosol solution displayed longer stable release time and better storage stability compared to normal hydroxytyrosol solution.At the same time it was confirmed that the liposome did not change the anti-oxidization properties of hydroxytyrosol.