| dc.description.abstract |
Under optimum conditions, starch at a concentration of 30% w/v liquefied by alpha-amylase in a 10-L scale-up reactor stirring with 2 impellers of a high efficiency type, the Ekato Intermig, at 200, 300 or 400 rpm (equivalent to the power inputs of 0.07, 0.25 and 0.06 W/kg, respectively). The viscosities of sugar dextrin solution during hydrolysis at those stirring speeds were 20, 17 and 12 mPas, respectively. The viscosities of samples at all speeds were ~3-4 mPas at 2 h and 2.5 h and ~1-2 mPas at 3 h. Viscosity curves showed the characteristic of shear thinning. At 300 and 400 rpm, the flow regime was turbulent after 1 h of liquefaction and at 200 rpm it was turbulent after 2 h. The highest reducing sugar concentration of 38.14 mg/mL with an DE (Dextrose Equivalent) value of 28.14 was obtained from stirring at 400 rpm. Following liquefaction, sugar dextrin was further saccharified by glucoamylase with the optimum conditions for 20 h at the same impeller speeds above. The viscosity of sugar samples at all speeds was between 1.2 and 1.6 mPas. The fluid flow regime was turbulent for all agitation speeds. The hishest reducing sugar concentration of 253.09 mg/mL with an DE value of 98.57 was obtained from stirring at 300 rpm. Hydrolysis of cassava starch in a 10-L stirred tank reactor here can be scaleable. |
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