Hydrolysis Of Astaxanthin Esters From Haematococcus Pluvialis By Lipase And Preparation Of Its Liposomes

In this study,astaxanthin esters extracted from Haematococcus pluvialis was hydrolyzed by lipase produced by Yarrowia lipolytica fermentation,and then converted into free astaxanthin.Astaxanthin liposomes were prepared by ethanol injection method,and subsequently their physical,chemical indexes and antioxidant capacity were determined.The main results are as follows:1.Haematococcus pluvialis as raw material,the main influencing factors in the test process were optimized by single factor and response surface experiments,and assisted with ultrasonic extraction.The optimal extraction process parameters were determined as follows:the mixed solvent of Haematococcus pluvialis powder and ethyl acetate and ethanol(volume ratio was 1:6)was extracted twice in ultrasonic water bath at 58 °C with solidliquid ratio of 1:50(g / m L),and each reaction lasted for 62 min.2.The enzyme activity was determined by p-nitrophenol method.The single factor and response surface experiments were used to optimize the effects of the main influencing factors on the lipase activity in the fermentation stage of the strain.Finally,the predicted response value of the enzyme activity under the optimal conditions was Y = 79.3624 U / L.3.The effects of four factors on the conversion of astaxanthin ester were optimized.The optimal conditions for lipase hydrolysis of astaxanthin esters were determined as follows: reaction time was 36 h,enzyme dosage was 1:10(v / v),reaction temperature was28 °C,and system p H was 7.0.Under these conditions,the hydrolysis rate was 76.89 %.4.TLC and HPLC were used to detect the samples before and after hydrolysis.The results showed that astaxanthin ester was the main component before hydrolysis,and free astaxanthin was the main part after hydrolysis.5.In order to improve the stability of astaxanthin,AST-LIP was prepared using lecithin and cholesterol as raw materials,and TWEEN-80 was added,and PEG was modified on its surface.The morphology,particle size potential,release in vitro,drug loading rate,encapsulation efficiency,and antioxidant activity and stability of AST-LIP were detected and analyzed.The results were as follows: The shape of AST-LIP was a regular spherical structure,and there was no aggregation of particles.The particle size was 105.8 ± 1.2 nm,and the Zeta potential was-38 m V.When the dosage of astaxanthin was 0.1 mg,the drug loading rate was 1.96 %,at this time,the encapsulation rate was the highest,which was88.83 %.The release study showed that the release time of AST-LIP became longer.The antioxidant activity of AST-LIP was lower than astaxanthin monomer.However,the storage stability of astaxanthin liposomes at 4 °C in dark was significantly improved.