Chemistry Reference
In-Depth Information
Influence of pH and incubation time on yield
85
pH = 5.0
80
pH = 5.5
75
70
65
60
55
50
45
40
1
2
3
4
5
6
7
Incubation time (h)
Fig. 15.15
Oil recovery from gums with phospholipase.
Lyso-phospholipases have also been developed in an attempt to further degrade lyso-
phospholipids to glycero-phospholipids which would be even more hydrophilic than the lyso
form. These enzymes may play a role in oil recovery from gums as they would increase the
separation of gum and oil by further reducing the ability of the gum to bind oil.
In enzymatic degumming using the A
1
or A
2
phospholipase there is also a release of fatty
acid coming from the hydrolysis of the phospholipid. Stochiometric calculations suggest that
a reduction in phosphorus of 100 ppm should be accompanied by the release of 0.1% free
fatty acids (FFAs). On that basis degumming of crude oil with
750 ppm of phosphorus
would result in an increase level of FFAs of 0.75%. This would need to be removed in
a deodorizer and would increase the load on this equipment. Laboratory and plant-scale
tests reveal that the amount of generated FFAs is lower than the amount mentioned because
not all the phospholipid needs to be hydrolyzed in order to obtain the desired reduction in
phosphorus (Table 15.4).
Phospholipase C has been suggested as an alternative, as this enzyme would produce
a diglyceride which would remain in the oil fraction. The first phospholipase C that was
introduced could, however, not hydrolyze PA which resulted in the need for a subsequent
chemical degumming stage. This reduced markedly the value of this approach. Another
solution was to combine the existing phospholipase A
1
, which is capable of hydrolyzing all
the phosphatides, with phospholipase C. This compromise avoids the need for the chemical
∼
Table 15.4
FFA generation during degumming.
Enzymatic degumming of Canola oil
Reduction in P (ppm)
175
Calculated increase in FFA
0.175%
Observed increase
0.08%
