Study On Enrichment To PUFAs Of Sargassum Thunbergii

Polyunsaturated fatty acids has been widely used food,health care and other fields.Currently,polyunsaturated fatty acids is from plants,fish, microorganisms,microalgae.The present production level can not meet the demand of polyunsaturated fatty acids.As a dominant plant of sea group in the world,large-scale algea be considered as abundant polyunsaturated fatty acids sources.Thus,it is worth developing polyunsaturated fatty acids sources and it may bring a promising prospect to human being.Sargassum thunbergii is a common big algae.But little study on Sargassum thunbergii was carried over. This research attempts to make a systematic research on the polyunsaturated fatty acids separated from it,which would pay a way to exploration and production of polyunsaturated fatty acids of algae.The study was carried out of four aspects.The first aspect is to identify the best conditions of cell Sargassum thumbergii -break through the single-factor experiment and orthogonal experiment.The results showed:the optimum conditions on cell-break of Sargassum thumbergii with the ultrasonic method were power 700 W,total work time 15min,work/interval time10s/10s and the extracting rate can reach 1.07%.Compared with other cell-break methods,the experimental results showed that the ultramicro smashing and ultrasonic cell-break methods were best.The second aspect mainly studied the extraction process of lipid from Sargassum thumbergii.On the basis of one factor tests and the central composite rotatable design principle,the method of response surface analysis with 3 factors and 5 levels was adopted.A second order quadratic equation for extraction of lipid was built.Response surface and contour were graphed with the extraction rate of lipid as the response value.Based on the analysis of the response surface plots and their corresponding contour plots,effects of extraction time impregnant capacity and petroleum ether to diethyl ether ratio were explored.By using this new method the optimum extraction condition was obtained as follows extraction time 19.39 hours impregnant capacity 18.90mL and percent of petroleum ether 46.26%.Under the optimized condition the average extraction rate of lipid was the most value.The third aspect determined the contents of polyunsaturated fatty acids in Sargassum thumbergii by capillary gas chromatography.DB-WAX(60 m×0.32 mm×0.25μm)was used.The injection temperature was 250℃.The temperature of column was kept at 230℃for 20 min.FID detector was used and detection temperature was 300℃,flow rate was 1.7ml/min.The experimental results showed that the relative standard deviation was 0.524%～1.297%.The average rate ranged from 97.6%to 99.8%;r²ï¼ž0.99.The method is simple,accurate reproducible and suitable for the determination of Sargassum thumbergii.The fourth aspect,response surface methodology was used to optimized conditions for production of polyunsaturated fatty acids(PUFAs)concentrates from Sargassum thumbergii.A three-factor central composite rotatable design (CCRD)was used to study the effect of urea-to-fatty acid ratio(X₁), crystallization temperature(X₂)and crystallization time(X₃).Second order polynomial regression models for resonse value were employed to generate response surfaces.Under optimum conditions the maximum amount of the total PUFAs(85.02%)from Sargassum thumbergii were obtained at a urea-to-fatty acid ratio of 3.5,a crystallization temperature of -5℃,and a crystallization time of 20.4h.The experimental results showed that Sargassum thumbergii is worth developing polyunsaturated fatty acids sources and it may bring a promising prospect to human being.