A process was explored for continuous enzymatic liquefaction of corn starch at high concentration and subsequently saccharification to glucose. The process appears to be quite efficient for the 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 could be suitably converted by such a process.
The process involved incorporation of a thermostable, high-temperature alpha-amylase for liquefaction and, subsequently, of glucoamylase into a continuous mixer under conditions conducive to rapid enzymatic hydrolyzes.
Since the start of the 19th century, starch has been broken down to glucose with the use of acids. With the advent of enzymes, starch hydrolysis has moved away from acids to enzymes. Enzymatic starch conversion depends upon the enzymes used and physical properties of starch used in the conversion process. The process can be broadly classified into two steps via Liquefaction and Saccharification.
In liquefaction, a starch suspension containing 40-45% dry matter is gelatinized by raising the temperature to steam levels and then liquefied by the addition of enzymes. Thermostable Alpha amylases hydrolyze the starch matter to maltodextrin which contains mainly oligosaccharides and dextrins. Maltodextrins are further converted in the next step called saccharification.
Saccharification is carried with the help glucoamylase enzymes which can hydrolyze starch completely to glucose along with maltose and isomaltose as by-products. Xylanase Enzyme may be used in the liquefaction process to reduce the viscosity of the mash by breaking down xylan’s which are native hemicelluloses in plant matter. Dextranase Enzymes are used in the Sugar Cane industry for hydrolysis of Dextrans, which pose many fundamental problems in the processing of cane and extraction of juice.