Continuous enzymatic liquefaction of starch for saccharification
A process was explored for continuous enzymatic liquefaction of corn starch at high concentration and subsequent saccharification to glucose. The process appears to be quite efficient for conversion of starch to glucose and enzymatic liquefaction and should be readily adaptable to industrial fermentation processes. Preliminary work indicated that milled corn or other cereal grains also can be suitably converted by such a process. Essentially, the process involved incorporation of a thermostable, bacterial alpha-amylase for liquefaction and, subsequently, of a glucoamylase into the continuous mixer under conditions conductive to rapid enzymatic hydrolyses. Also studied was the effect on substrate liquefaction of variables such as starch concentration (40-70%), level of alpha-amylase (0.14-0.4%, dry starch basis), temperature (70-100 degrees C), pH (5.8-7.1), and residence time (6 and 12 minutes). The degree of liquefaction was assessed by determining 1) the Brookfield viscosity, 2) the amount of reducing groups, and 3) the rate and extent of glucose formed after glucoamylase treatment. Best liquefaction processing conditions were achieved by using 50-60% starch concentration, at 95 degrees C, with 0.4% alpha-amylase, and a 6 minute residence period in the mixer. Under these conditions, rates and extents of glucose obtained after glucoamylase treatment approached those obtained in longer laboratory batch liquefactions. The amount of glucose formed in 24 hours with the use of 0.4% glucoamylase was 86% of theory after a 6-min continuous liquefaction, compared to 90% for a 30-min laboratory batch liquefaction (95 degrees C, 0.4% alpha-amylase). (Refs. 15).
- Research Organization:
- Northern Regional Research Center, Agricultural Research Service, US Dept of Agriculture, Peoria, IL 61604
- OSTI ID:
- 6248332
- Journal Information:
- Biotechnol. Bioeng.; (United States), Vol. 24
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
STARCH
ENZYMATIC HYDROLYSIS
AMYLASE
GLUCOSE
MAIZE
SACCHARIFICATION
SUBSTRATES
ALDEHYDES
CARBOHYDRATES
CEREALS
CHEMICAL REACTIONS
DECOMPOSITION
ENZYMES
GLYCOSYL HYDROLASES
GRAMINEAE
GRASS
HEXOSES
HYDROLASES
HYDROLYSIS
LYSIS
MONOSACCHARIDES
O-GLYCOSYL HYDROLASES
ORGANIC COMPOUNDS
PLANTS
POLYSACCHARIDES
REAGENTS
SACCHARIDES
SOLVOLYSIS
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