Two-step enzymatic synthesis of α-linolenic acid-enriched diacylglycerols with high purities from silkworm pupae oil.

In this study, α-linolenic acid-enriched diacylglycerols (ALA-DAGs) were prepared via a two-step enzymatic way by combi-lipase using silkworm pupae oils as substrates. Firstly, several factors including temperature, mass ratio of water to oil, pH and enzyme loading were optimized for the hydrolysis of silkworm pupae oil. The maximum fatty acid content (96.51%) was obtained under the conditions: temperature 40 °C, water/oil 3:2 (w/w), pH 7, lipase TL100L loading 400 U/g, lipase PCL loading 30 U/g. Then, ALA was enriched by urea inclusion, with an increased ALA content of 82.50% being obtained. Secondly, the ALA-enriched silkworm pupae DAG oil (SPDO) was prepared by lipase PCL-catalyzed esterification reaction. After molecular distillation, the final SPDO product contained contents of DAGs (97.01%) and ALA (82.50%). This two-step enzymatic way for production of ALA-DAGs was successfully applied in a 100-fold scale-up reaction. Overall, our study provides a promising way for the preparation of ALA-DAGs.