Continuous production of high-glucose syrup by chitin-immobilized amylase.
A simple method of preparing a chitin-immobilized alpha-amylase and glucoamylase from the protease- and glycosidase-less Mutant HF-15 of Aspergillus awamori var. kawachi was developed and used for the production of high-glucose syrup. The glucoamylase was tightly bound onto chitin without the aid of a crosslinking agent because the enzyme contained a specific binding site for chitin. Continuous production of high glucose concentrate from a highly concentrated alpha-amylasetreated gelatinized starch substrate (about 45% total solids) was undertaken successfully with the use of a column-packed chitin-immobilized amylase. The activity of the column was stable for more than 20 days of continuous operation and the product was found to be only glucose with an average dextrose equivalent value of more than 97%. The final product showed no isomaltose or panose contamination, indicating that the immobilized amylase had no transglucosidation activity. The immobilized amylase was most active in the conversion of gelatinized starch to glucose at 55 degrees C and pH 2.5 to 5.0. Drying the chitin-immobilized amylase resulted in the decrease of activity and shortening of storage life, whereas a storage life of up to 80 days was attained without affecting its original activity when kept under moist condition at 4 degrees C.
Laboratory of Applied Microbiology, Department of Agricultural Chemistry, Kyushu University 46, Fukuoka 812, Japan.
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Hayashida