Preparation of n-3 Polyunsaturated Phosphatidylglycerol from Salmon Roe Lipids by Phospholipase D and In Vitro Digestion

Phosphatidylglycerol (PG) is a highly functional phospholipid (PL), which has many physiological functions. However, naturally occurring PG binding n-3 polyunsaturated fatty acid (n-3 PUFA) is low in content, resulting in a scarcity of industrial bio-resources of n-3 PUFA enriched PG. The current study investigates the preparation of salmon roe PG (SRPG) from three types of salmon roe lipids and glycerol via phospholipase D (PLD)-mediated transphosphatidylation. The yields of SRPG obtained from salmon roe total lipid (SRTL) and salmon roe PL (SRPL) are higher than those obtained from purified salmon roe phosphatidylcholine (SRPC) in aqueous system. Following a 24 h reaction with 0.75 U PLD, SRTL, and SRPL yield up to 96.4 mol% and 96.7 mol% SRPG, respectively. In addition, more fatty acids are released from synthesized SRPG via hydrolysis by pancreatic enzymes than from SRPC and soybean PC in in vitro digestion model. Fatty acids at the sn-2 position of SRPG are completely liberated by 0.04 U of phospholipase A(2) (PLA(2)) during a 6 h reaction, whereas fatty acids of SRPC are partially unhydrolyzed even after a 24 h reaction. Our results suggest that SRPG converted from salmon lipids by PLD is a functional PL with high bioavailability of n-3 PUFAs. Practical Applications: Phosphatidylglycerol rich in n-3 PUFAs is prepared from salmon roe lipids (SRPG) catalyzed by PLD. The SRPG yields reach 96.4 mol% and 96.7 mol% of phosphatidylcholine contained in SRTL and SRPL, respectively, in aqueous reaction system. Fatty acids rich in n-3 PUFAs at sn-2 position of prepared SRPG are rapidly liberated by PLA(2) in an in vitro digestion model.