Study On Decolorization Pretreatment And Extraction And Isolation Of Polar Lipids From Nannochloropsis Sp.

Algae in Nannochloropsis sp.has much eicosapentaenoic acid(EPA)in the form of polar lipids(phospholipids and glycolipids).These polar lipids have good emulsification and bioavailability,and have great application potential in the fields of food,medicine and cosmetics.Due to the small size of the Nannochloropsis sp.and the cell wall is tough and difficult to break.However it is rich in chlorophyll a,which seriously restricts the use of intracellular polar lipids.Therefore,there is an urgent need to choose a method suitable for the removal of chlorophyll of the algae,the extraction of polar lipids and the separation of polar lipids,to effectively improve the utilization rate of polar lipids.In view of the above problems,this article firstly carried out saponification and decolorization pretreatment of Nannochloropsis sp.algae powder,and then used enzyme-assisted wall breaking three-phase distribution extraction method to extract total fat.Finally,ethanol was used to separate and purify high-purity polar fat,and the following results were obtained:(1)Nannochloropsis sp.saponification for removal ChlorophyllCompared with the physical adsorption,oxidative decolorization and column chromatography treatment of chlorophyll in the microalgal lipid extract,it was found that the chlorophyll removal rate of the algae powder was better after direct saponification pretreatment.In order to ensure the chlorophyll removal rate and lipid retention rate,the two conditions were used to optimize the decolorization process.Based on the single-factor experiment,the Plackett-Burman experiment and the Box-Behnken experiment were used to optimize the saponification pretreatment process.The optimized process is: the saponification agent is absolute ethanol + 1% Na OH(1:4,v/v),the material-liquid ratio of algae powder and saponification agent is 1:4,the treatment time is 78 min,and the treatment temperature is 70℃.After saponification pretreatment,the chlorophyll removal rate and lipid retention rate of algal powder were 95.05% and 89.12%,respectively,and the lipid extract was bright orange,and the decolorization effect was good.(2)Enzyme wall breaking and total lipid extraction of Nannochloropsis sp.Simple,efficient and mild enzyme-assisted three-phase extraction is used to extract microalgal lipids.First,the cell wall composition of N.oceanica.detected and analyzed.,which showed that it contained 68.32% cellulose,12.64% hemicellulose,8.68% pectin,and 10.33% other components,the cellulase and hemicellulase complex enzyme system was used to break the wall;through single factor experiment With the central orthogonal design experiment,the best enzymatic hydrolysis process conditions were: cellulase dosage 8.7 mg/g,hemicellulase dosage 5.0 mg/g,enzymatic hydrolysis temperature 50.5℃,enzymatic hydrolysis p H 5.0,and enzymatic hydrolysis time 208min;and then use three-phase extraction to obtain the total lipid of Nannochloropsis sp.,the extraction rate is 36.7 g/100 g dried algae powder.(3)Study on separation and purification of polar lipids by ethanolIt is necessary to separate and purify the polar lipids in the extracted lipids.The best process conditions for the separation and purification of polar lipids by ethanol obtained through single factor and orthogonal experiments are: ethanol concentration 80%,materialliquid ratio 1:8,extraction temperature 55℃ and extraction time 3h.Under this condition,the polar lipid was separated and purified,and the purity of the polar lipid was 73.6%.The factors that affect the purity of polar lipids are analyzed in the order of: ethanol concentration> material-liquid ratio> extraction time> extraction temperature.Finally,101 lipid components of different lipid classes were identified from the polar lipid extract of Nannochloropsis sp.microbes isolated and purified,including 15 triglycerides,21 glycero-glycolipids,34 glycero-phospholipids,and total EPA content It accounts for 10.2% of polar lipids.In this paper,Nannochloropsis sp.was used as the raw material to study the methods of chlorophyll removal,lipid extraction and polar lipid separation.Lay the foundation for commercial applications such as food.