In this study, Lecitase® Ultra (LU) was immobilized onto the parent and the amino-functionalized SBA-15. The immobilization conditions were studied and the activity of the parent SBA-15 supported LU (SBA-15-LU) was found to be at 2177.78 ± 101.84 U/g. After 3-aminopropyl and n-(2-aminoethyl)-3-aminopropyl groups functionalization, enzymatic activity was increased to 3555.56 ± 200.21 and 3444.44 ± 346.41 U/g respectively. The immobilized LU samples were then used to catalyze glycerolysis. The possibility for diacylglycerols (DAG) and monoacylglycerols (MAG) production was evaluated and it was found only suitable for DAG production. In addition, the glycerolysis activity of the immobilized LU was impaired by the tert-pentanol and solvent-free was found suitable. Similar DAG content over 50 wt% could be obtained from glycerolysis by the three immobilized LU samples. The reusability in glycerolysis was evaluated, and 9.79 % of the initial glycerolysis activity was remained from the SBA-15-LU after 5 cycles of reuse. Encouragingly, after 3-aminopropyl and n-(2-aminoethyl)-3-aminopropyl groups functionalization, 62.93 and 83.91% of their initial activity was respectively remained after 5 cycles of reuse.
In this study, SBA-15 was functionalized by organic groups (-CH3, -C4H9, -C8H17, -CH2CH2NH2, -C6H5, et al.), and then Lecitase® Ultra (LU) was immobilized onto the modified SBA-15 for soybean oil degumming. The hydrolysis activity, degumming performance, reusability in degumming, and the composition of phospholipids in the gum, of the immobilized LU samples, were carefully studied. Hydrolysis activities over 1800 U/g were obtained from all the immobilized LU samples. The highest activity of up to 4554.17 U/g was observed from the 3-ureidopropyl group-modified SBA-15-supported LU. Most of the immobilized LU samples removed the phospholipids effectively from crude soybean oil (initial phosphorous content 314.23 mg/kg), with a residual phosphorus content of less than 10 mg/kg. The reusability of the immobilized LU samples in the degumming process was evaluated. No loss of activity was observed from the methyl and N-(2-aminoethyl)-3-aminopropyl group-modified SBA-15-supported LU samples after five cycles of reuse. In addition, 3-aminopropyl and 3-glycidyloxypropyl group-modified SBA-15-supported LU samples retained over 90% of their initial activity; N-phenylaminomethyl and 1-isocyanatopropane group-functionalized SBA-15-supported LU samples retained approximately 80% of their initial activity. The phospholipids in the gum were analyzed. The n-octadecyl and N-(2-aminoethyl)-3-aminopropyl group-functionalized SBA-15-supported LU samples were selective for lysophosphatidylethanolamine (LPE) preparation, and LPE percentages up to 37.14 and 38.80% were obtained, respectively. The N-phenylaminomethyl group-modified SBA-15-supported LU showed selectivity toward lysophosphatidylcholine (LPC) production, with an LPC percentage of up to 38.5%.
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