Preparation Of Nanoflower-based Immobilized Enzymes And Their Functional Membranes And Their Hydrolysis Properties Of β-lactoglobulin

β-lactoglobulin,one type of whey protein,is the main sensitizing factor of infant attacked by milk allergy.Degradation by enzymes can effectively destroy the allergenic structure ofβ-lactoglobulin and thereby eliminating its allergenicity.Compared with free enzymes,immobilized enzymes can enhance the stability and reusability of enzymes,simultaneously promote the online separation of products.Biocatalytic membrane is a versatile and effective material that combining catalytic performance and membrane separation to achieve a higher efficiency of degradation and purification towards whey proteins.The synergistic role between opening membrane pores and transmembrane pressure can enhance solute-transfer efficiency and promote the separation of target product,but there still accompanied with a problem of instability which will reduce enzyme activity and induce other issues in preparation process.The use of organic-inorganic nanoflowers with larger specific surface area and more simple preparation process to immobilize enzymes has an advantage in preparing optimized biocatalytic membrane with high enzyme activity,good stability and reusability.This thesis adopted a blending and self-assembly method to fabricate the trypsin-copper phosphate nanoflowers,moreover,investigated the proteolytic properties of nanoflowers with various structure and morphology.On this basis,the nanofiber membrane with a higher specific surface area and porosity was selected as the carrier.Subsequently,nanoflowers were in-situ grown in membrane surface by the virtue of the prefabricated bio-adhesive dopamine functional platform.We finally construct the nanoflower immobilized catalytic film with a high through-pore structure and low mass transfer resistance,and its control of structure and catalytic performance were explored.The results showed that the enzyme loading capacity of the prepared nanoflower reached 109.1 mg/g,and the enzyme activity calculated by the catalytic simulation substrate BAEE was 40.4 U/mg,which was 416%of the free enzyme.Furthermore,the enzyme loading capacity of catalytic membrane prepared by combining nanoflowers and polydopamine-modified fiber membranes is 282μg/cm~2,the static catalytic activity and the dynamic catalytic activity for the simulated substrate BAEE is 38.6 U/mg and47.1 U/mg,respectively.For the repeatability and storage stability,the nanoflowers modified membrane can maintain more than 70%of its initial activity after repeated use for 10 cycles and/or after 90 days of storage.It demonstrated that the catalytic membranes have good repeatability and storage stability.Simultaneously,the all significantly increased ultraviolet absorption value of theβ-lactoglobulin contained hydrolysate after catalyzed by the catalytic membrane,under static and dynamic conditions,indicated that the catalytic functional membrane has a highly efficient hydrolysis effect onβ-lactoglobulin.