Starch enzymatic degradation

Gernat, C., Radosta, S., Anger, H., Damaschun, G. (1993). Crystalline parts of three different conformations detected in native and enzymatically degraded starches. Starch, 45, 309-314. 

As an example using NMMO solution, the spinning of fibers consisting of blends of cellulose with cationic starch was investigated for the purpose of improving moisture absorbability, dyeability, and enzymatic degradability compared with standard Lyocell fibers [69]. 

Potato taste is not characterized by one of the primary taste sensations. Especially sweet, sour or bitter notes are considered off-flavors. However, free amino acids and 5 -nucleotides are important compounds that convey an agreeable basic taste to potato products. The amino acids occur naturally in free form the 5 -nucleotides are liberated during the heat preparation of potatoes by a specific enzymatic degradation of RNA. Starch forms a matrix for all potato preparations. Although it is tasteless, is has an influence on taste quality due to textural characteristics, and due to its pronounced capability to form stable complexes with flavor compounds either in a thermal gradient or under isothermal conditions. 

The elimination of etherified starches is complex and related to the size of the particles. The smaller molecules, with a molecular weight of less than 50 000 daltons, are excreted unchanged by glomerular filtration. The larger molecules are metabolized to smaller molecules and distributed to various body tissues, where they may undergo hydrolysis in the reticuloendothelial system or enzymatic degradation by amylases. 

Cyclodextrins are manufactured by the enzymatic degradation of starch using specialized bacteria. For example, P-cyclodextrin is produced by the action of the enzyme cyclodextrin glucosyltransferase upon starch or a starch hydrolysate. An organic solvent is used to direct the reaction that produces P-cyclodextrin, and to prevent the growth of microorganisms... 

Maltose monohydrate is prepared by the enzymatic degradation of starch. 

Ishiaku, U.S. Pang, K.W. Lee, W.S. Mohd-Ishak, Z.A. Mechanical properties and enzymatic degradation of thermoplastic and granular sogo starch filled poly(epsilon-caprolactone). Eur. Polym. J. 2002, 38, 393-401. 

Eurther conversion (saccharification) to dextrose can be done using glucoamylase. Starch consists of polymeric linear a-1,4 linked dextrose units (amylose, 25 % of the starch) and polymeric mixed a-l,4/a-l,6 linked dextrose units (amylopectin, 75 % of the starch). Eor enzymatic degradation besides a-1,4 specific amylases also a-1,6 specific amylases (pullulanases) are required. A portion of the dextrose can be converted into fructose with a glucose isomerase yielding a high fructose com symp (MFCS). 

The enzymatic degradation of starch is applied on an industrial scale to the production of corn syrup (a solution of oligomers) and dextrose (glucose) by utilizing thermally stable endoenzymes that can operate in an aqueous medium at temperatures up to 70-90 ° [14]. These temperatures are desired because the starch granules rupture in water at about 60 °C. The use of enzymatic hydrolysis for the conversion of starch to sugars is a much cleaner (more selective) process than is an acid-catalyzed hydrolysis. 

While little more is known in detail about the mechanism of the enzymatic degradation reactions of cellulose and starch, it is likely that, in many cases, once an enzyme molecule associates with a polymer chain and causes the first chain cleavage, either by an exo- or an endo-cleavage, it remains associated with the fragmented chain, and it can catalyze the hydrolysis of several more units before dissociating. At present, however, little quantitative information is available about this type of process. 

They are prepared by enzymatic degradation of starch. The enzyme cyclodextrin glucanosyltransferase (CGT) from Bacillus macerans, Bacillus megaterium or other bacterial strains cut the starch helix and join both ends of such destruct forming a cyclic compound. Because enzymes are not very specific, the obtained mixture contains cyclodextrins from 6 to 12 glucose units. The main fractions are a-, (3- and y-cyclodextrins which correspond to 6, 7 and 8 glucose units. 

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