Biomedical Engineering Reference
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Phospholipase A 1
O
CH 2 -O-C-R 1
Phospholipase A 2
R 2 -C-O-CH
O
O
CH 2 -O-P-O-X
O -
Phospholipase C
Phospholipase D
Figure 4.1 Indication of bonds on a phospholipid molecule that are hydrolyzed by various phospholipase
enzymes. X = H, choline, ethanolamine, inositol.
processes could be a good alternative to conventional oil degumming processes. However,
acceptance of this technology by oil refiners requires improvements in flux rates, membrane
life and membrane availability at lower costs.
4.4.1.3 Enzymatic degumming
Although the idea of using enzymes to remove PLs from crude oil has been around since the
1980s, it is attracting a lot of attention just recently. Oil degumming can be accomplished by
using certain phospholipases, which can hydrolyze the ester bonds of phospholipids.
Lysophospholipids that are hydrophilic and insoluble in oil are released from the glyceride
backbone of PLs by the action of enzymes, then these insoluble compounds (gums) are
separated by centrifugation. The main phospholipase types include A1, A2, C and D
(Figure 4.1). The first enzymatic degumming process, EnzyMax ® , used Lecitase ® 10 L
(porcine phospholipase A2) (Dahlke and Eichelsbacher, 1998). The process was not very
successful for the following reasons: (1) the production capacity of Lecitase ® 10 L was very
limited as the enzyme was extracted from porcine pancreas, (2) the optimal pH for Lecitase ®
10 L activity was too high for some processors, (3) the enzyme did not meet the requirements
for a kosher grade product because of its source (Clausen, 2001). Later, microbial enzymes,
the phospholipases A1 (Lecitase Novo and Ultra) and, more recently, a phospholipase C
(Purifine) and a lipid acyl transferase (LysoMax a phospholipase A2), became commercially
available. Purifine only acts on PC and PE but does not catalyze the hydrolysis of PI or PA
and its non-hydratable salts (Dijkstra, 2009). Diacylglycerols (DAG) formed during the
degumming process using Purifine remain in the oil, consequently minimizing oil losses.
Unlike Purifine, Lecitase Ultra produces free fatty acids and contributes to the oil loss during
the degumming process (Dijkstra, 2009). LysoMax catalyzes the transfer of a fatty acid
moiety from a phosphatide to free sterols or stanols present in the oil being degummed.
During LysoMax treatment lysophosphatides are formed and removed with the water phase.
Hence, this process does not form any FFA unless there is insufficient sterol or stanol
substrate present to receive the FFA (Dijkstra, 2009).
Response surface methodology was used to optimize enzymatic rapeseed oil degumming
process parameters (Yang et al ., 2006). Lecitase Ultra was used to degum rapeseed oil. The
optimal conditions were determined as follows: enzyme dosage 39.6 mg/kg, temperature
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