Preparation of diacylglycerol-enriched palm olein by phospholipase A1-catalyzed partial hydrolysis

Partial hydrolysis of palm olein catalyzed by phospholipase A 1 (Lecitase Ultra) in a solvent-free system was carried out to produce diacylglycerol (DAG)-enriched palm olein (DEPO). Four reaction parameters, namely, reaction time (2-10 h), water content (20-60 wt-% of the oil mass), enzyme load (10-50 U/g of the oil mass), and reaction temperature (30-60 °C), were investigated. The optimal conditions for partial hydrolysis of palm olein catalyzed by Lecitase Ultra were obtained by an orthogonal experiment as follows: 45 °C reaction temperature, 44 wt-% water content, 8 h reaction time, and an enzyme load of 34 U/g. The upper oil layer of the reaction mixture with an acid value of 54.26 ± 0.86 mg KOH/g was first molecularly distilled at 150 °C to yield a DEPO with 35.51 wt-% of DAG. The DEPO was distilled again at 250 °C to obtain a DAG oil with 74.52 wt-% of DAG. The composition of the acylglycerols of palm olein and the DEPO were analyzed and identified by high-performance liquid chromatography (HPLC) and HPLC/electrospray ionization/mass spectrometry. The released fatty acids from the partial hydrolysis of palm olein catalyzed by phospholipase A 1 showed a higher saturated fatty acid content than that of the raw material.