Immobilization Of Candida Antarctica Lipase B Onto Organically-modified SBA-15 For Efficient Production Of Diacylglycerols

Since the preferable effiency and low cost advantages of glycerol reaction makes glycerol triglyceride(TAG)glycerol reaction as the mean pathway for producing monoglyceride(MAG),diglyceride(DAG).DAG is micro component of natural vegetable oils and fats in which its own metabolic and physiological effects,makes DAG become the focus of oil industry in recent years.Quantity methods for enzymatic production of DAG have been extensively studied,however it is still a hot point to produce immobilized lipase for catalyst DAG in high efficiency.The characters of enzyme could be changed by immobilized on the carriers modified.Ordered mesporous material(OMM)can diminish leaching of lipase when used as the supports.OMM are potential carrier because of its great advantages such as high surface area,good connectivity,tortuosity as well as its adjustable pore size.Due to those advantage features make OMM widely used in functional materials,medical,food and many other fields.SBA-15 the most representative example of porous material which has been often used in recent years,its average pore size is around 8nm,the narrow distribution of pore size makes it good thermal and mechanical stability,on the other hand,the internal surface of these pores posses affinities suitable for surface modification by silane,alcohols,metal ions groups.In this study,different organic groups would be used to modify SBA-15 with immobilizing CALB afterwards,the enzymatic parameters were illuminated in details including lipase activity,thermal stability,reusability of the obtained immobilized CALB.The immobilized CALB was then used to catalyze glycerolysis of soybean oil for producing DAG which its catalytic performance was also evaluated,the main results represented as follow,(1)The surface chemistry and chemical state of the parent SBA-15,R-SBA-15 and R-SBA-15-CALB were analyzed by X-ray photoelectron spectroscopy,Small-angle powder XRD and ourier transform in-frared(FT-IR),comparing to the characterization of SBA-15 before organic modification.Results demonstrates that silanols function groups were trapped inside the mesoporous materials SBA-15 with retains its ordered structure,and CALB had been successfully introduced into the channels of modified SBA-15(2)The variants' enzymatic properties,including activity,thermostability and reusability of the immobilized CALB,were studied,which indicated that High activity up to 6100.00 ± 246.41 was obtained from propyl methacrylate modifications.The different incubation media significantly affects the stability of lipase,the thermostability of immobilized CALB in hexane was not desirable;When incubated in air,no loss of activity was observed from the propyl methacrylate group modified SBA-15 supported CALB;a higher than the initial activity was found from 3-aminopropyl group modified SBA-15 supported CALB and n-octyl group modified SBA-15 supported CALB;Expected stability and higher than their initial activity was observed from N-phenylaminomethyl and n-dodecyl group modified SBA-15 supported CALB samples after five cycles of use;In addition,80%of the initial activity was retained from 2-(propoxymethyl)oxirane group modified SBA-15 SBA-15 supported CALB.High hydrolysis activity does not mean good glycerolysis activity,proper hydrophobicity of carrier surface would favor contact with substrates in turn promote the glycerolysis reaction as well the enzymatic activity(3)Results suggested that 1-isocyanatopropane group modified SBA-15 supported CALB was selective for DAG production from the glycerolysis re-action.high DAG content up to 61.90±2.38 wt%and a DAG/MAG ratio at 3.11±0.08 was obtained from 1-isocyanatopropane group modified SBA-15 supported CALB mediated glycerolysis reaction.The effects of different reaction temperature,catalyst amount,reaction time were studied,it showed that the best condition for glycerolysis reaction were 60?,5%wt(immobilized CALB),24h,with the highest DAG yield.The organically modified SBA-15 immobilized CALB was used to catalyze glycerolysis in a continuous batch,after 2 continuous batches,over 60%yield of DAG retains compared to the first reaction cycle.