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Modification of starch granules to produce specific products. J. F. ROBYT. Laboratory of
Carbohydrate Chemistry and Enzymology, Iowa State University, Ames, IA 50011.
Starch granules have been modified in acidic (0.36%-6.0%, w/v HCl)
alcohols (methanol, ethanol, 2-propanol, and 1-butanol) at various temperatures (5°-65°C). These
modifications give new kinds of limit dextrins, whose degree of polymerization (d.p.) can be controlled by
controlling the conditions--type of alcohol, concentration of acid, temperature, and concentration of
starch--to give a wide range of d.p. values from 2000 to 25. Modifications have also been made using mixtures of
two alcohols with volume ratios of 90:10 to 10:90 in 10-volume increments. Starch granules have been
modified with specific enzymes in situ reactions to give products that are 100% retained
inside the granule. Starch granules containing 10-50% w/w D-glucose, with 100% retention inside
the granule, have been prepared by an in situ reaction of glucoamylase. Starch granules containing
3-4% w/w cyclomaltodextrins, with 100% retention inside the granule, have been prepared by an in
situ reaction with isoamylase and cyclomaltodextrin glucanosyltransferase.
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