Preparation of ethyl esters highly enriched in DHA via enzymatic ethylation and molecular distillation

In the present study, the total lipids from Schizochytrium sp. were ethylated by immobilized lipase and ethyl esters highly enriched in C22∶6 n-3 (DHA) was obtained through molecular distillation. The effect of temperature, reaction time, substrate ratio, and enzyme dosage on enzymatic ethylation was investigated. Under optimum reaction conditions (reaction temperature 40℃, reaction time 24 h, substrate ratio 10∶2, Lipozyme 435 dosage 6%) , immobilized lipase had good operational stability. Ethyl esters with no less than 80% DHA was obtained via molecular distillation, and the yield of DHA ethyl esters could be significantly improved by multistage molecular distillation and recycle of light fractions.