HYDROLYSIS OF STARCH WITH IMMOBILIZED GLUCOAMYLASE - A COMPARISON BETWEEN 2 TYPES OF EXPANDED-BED REACTORS

Glucoamylase (E.C.3.2.1.3) covalently immobilized onto chitin particles (dst = 0.37 mm) was examined in two types of continuous bench-scale reactors (180 mL) fed with hydrolyzed manioc starch (15%, w/v): a two-phase reactor (liquid expanded-bed) and a threephase reactor (air expanded-bed). Several conditions of continuous operation were investigated, varying the biocatalyst load (16.7, 37.2, and 54 g/L) into the reactor and the hydraulic residence time. The best results were achieved with the two-phase reactor, which operated continuously for 20 d and showed a decrease of only 6% in conversion (starch to glucose). Conversion levels of 96% were obtained with a hydraulic residence time of about 4 h. A simple mathematical model was able to describe the experimental results of the two types of reactors considering biocatalyst deactivation. © 1990 Humana Press Inc.