| The oil was extracted from Schizochytrium sp. dry algae powder by two-step enzymatic method with clear oil extraction rate as evaluation indicator. On the basis of single factor experiment, using response surface methodology to optimize the conditions of alkaline protease that had a great influence on the clear oil extraction rate, the optimal alkaline protease conditions were determined by regression analysis. The results showed that the optimal extraction conditions were obtained as follows: solid-liquid ratio 1∶?7, neutral protease dosage 7%, enzymolysis temperature 45?℃, enzymolysis time 3 h, enzymolysis pH 6.5; alkaline protease dosage 10%, enzymolysis temperature 68?℃, enzymolysis time 6 h, enzymolysis pH 9.4. Under these conditions, the clear oil extraction rate of Schizochytrium sp. reached (91.37±0.14)%. GC-MS analysis results showed that the content of unsaturated fatty acids in Schizochytrium sp. oil was 47.43%, in which the DHA content was 35.09%. |
