Enrichment of DHA and EPA glycerides by selective hydrolysis of waste fish oil with immobilized Geotrichum sp.lipase

Selective hydrolysis of waste fish oil in attempt to enrichment of EPA and DHA glycerides by immobilized Geotrichum sp.lipase was investigated.Through single factor design and response surface analysis,the optimal condition was determined as follows: 2 g crude fish oil,2.5 g water,221.3 U lipase,and hydrolysis time 11.7 h at 30 ℃.Under the optimal condition,42.1% of hydrolysis degree with 7.8% of EPA and 41.1% of DHA was achieved.Moreover,the hydrolysis degree further increased to 45.9%,and the EPA and DHA contents in the resulted glycerides increased to 8.5% and 42% by the second enzymatic hydrolysis reaction,respectively.Compared with original fish oil with 4.2% of EPA and 18.9% of DHA,the contents of EPA and DHA in the resulted glycerides increased to 2-fold and 2.2-fold,respectively.