Saccharification in Membrane Reactor for Immobilizing Glucoamylase

Abstract

Glucoamylase was immobilized on a capillary membrane of UF by the glutaraldehyde cross- linkage method. The membrane has an asymmetric structure and contains a great number of amino groups in porous areas. Liquefied starch of DE 13 was used as substrate and forced by applying pressure to permeate through the membrane. The obtained permeate once again permeated through the immobilized membrane. However, polymers in the liquefied starch were rejected by the membrane, and the glucose content in permeate was not more than 94%.
Permeability of the polymers through the membrane was improved by making the skin layer of membrane porous and using liquefied starch of DE 20. Glucose content in permeate increased by using glucoamylase co-immobilized with pullulanase. The glucose formation rate increased and the glucose content reached 97%. The hydrolysis ratio of polymers in the substrate was higher when using glucoamylase with pullulanase than that when using only glucoamylase. Even if pullulanase was added to substrate of nearly 90% glucose content, glucose formation proceeded smoothly.
It was found that continuous saccharification of liquified starch was possible by use of glucoamylase immobilized on a porous membrane in the first stage of reaction and that co-immobilized with pullulanase in the final stage.