Enzymatic Hydrolyses of Cassava Starch in a 200-L Pilot-Scale Stirred Tank Lysis Reactor

Abstract

Cassava starch at concentrations of 30 and 40% (w/v), and cassava root chip powder at a concentration of 30% (w/v) were liquefied and saccharified by α-amylase and glucoamylase at a 200-L pilot-Scale reactor stirring with two-stage high efficiency agitator, the Ekato Interming at 25, 50 or 75 rpm with powder inputs, εT, of 0.0005-0. 008, 0.0112-0.0125, 0.039-0.043 W/kg, respectively. Reducing sugar concentration and DE value increased as a function of reaction time. For all experimental conditions, higher reducing sugar concentration and DE values were obtained from hydrolyses of starch and cassava root chip powder at a higher speed of 75 rpm due to higher power input. A high agitation speed should be should be used for hydrolyses of starch or cassava root chip powder, especially at higher concentrations. Starch hydrolyses in a stirred tank at a higher speed i.e. ≥ 75 rpm for 100 L of feed stock or εT ≥ 0.04 W/kg and Re ≥ 20,000 (turbulent flow) should be done rather than working at low speeds to achieve high productivity. Peak viscosity of sugar solutions were between 2 and 7 mPas during liquefaction and between 1 and 3 mPas during saccharification, but high viscosity was obtained from hydrolyses of root chip powder. Fluid flow regime during hydrolyses at 25 and 50 rpm and hydrolysis of cassava root chip powder at all speed was mainly transitional, but it was turbulent at a higher speed of 75 rpm. Enzymatic hydrolyses of cassava starch and root chip powder using 200-L stirred tank lysis reactor here could be scaled-up using εT as a key factor.