Estimation of Docosahexaenoic Acid Glycerides in Schizochytrium sp. Oil by Open Column Chromatography and Reversed-phase HPLC

Column chromatography and reversed-phase HPLC using a Sepax BR-C18 column were applied for the analysis of glycerides in the docosahexaenoic acid (DHA) oil by Schizochytrium sp. The oil was detected under UV light after isocratic elution with 20 % 2-propanol/hexane (5:4, v/v) + 80 % acetonitrile. The correlation coefficients for the calibration of HPLC for DHA glycerides were in the range of 0.9958–0.9998. The accuracy was confirmed with recoveries of 93.47–102.25 %. DHA oil samples under different aeration rates were successfully analyzed and the content of the binding of DHA on the acylglycerol backbone was very low (1.81–4.21 %). However, the content of glycerides (tri-, di-, mono-) separated by column chromatography was more than 87.22 %. The glycerides were largely composed of triacylglycerides (TAG) (82.29–89.54 %), where higher content of TAG correlated to higher contents of DHA and TAG of DHA (TriDHA). In addition, the optimal aeration rate of 250 m³/h was obtained for TAG, DHA, and TriDHA production by Schizochytrium sp. with the temperature 30 ± 0.5 °C, impeller speed 85 ± 5 rpm and pressure 0.04 Mpa.