Dextrins branched

In these a-amylase reactions, glucose is not the primary product. Glucose is formed as a secondary product in the hydrolysis of maltotriose, maltotetraose and branched dextrins. Using 14C-reducing end labeled maltodextrins, G3 to G8, Robyt and French19 showed that porcine pancreatic a-amylase has different specificities for hydrolyzing the different linkages of the maltodextrins. The different frequencies for... 

The doubly branched dextrins, 64,66-di-a-D-glucopyranosylmaltohexaose and 63,65-di -a-D-glucopyranosylmaltopentaose, isolated by Kainuma and French17 after action of porcine pancreatic a-amylase on waxy maize starch, established that the a-(l—>-6) branch linkages could be as close as having one glucosyl unit between them. No saccharides were found that indicated that the branch linkages could be adjacent to each other. 

Dextrins are the products of partial hydrolysis of starch. They are a complex mixture of molecules of different sizes. Those formed from amylose are unbranched chains, whereas amylopectins produce branched chains of glucose molecules. Erythrodextrins are larger branched dextrins that turn a reddish color on complexing iodine. 

Glycogen is a utUisable polysaccharide. In food, it is hydrolysed by hydrolases (a-amylase and fS-amylase) in the same way as starch. The branched dextrins formed are further broken down by isoamylase to maltose and glucose. 

FIGURE 3.3 Chemical structure of the main soluble sugars found in cereal grains, (a) Glucose, (b) Fructose, (c) Sucrose, (d) Maltose, (e) Maltotriose. (f) Linear dextrin, (g) Branched dextrin. 

Endohydrolysis that cleaves internal a-l,4-glycosidic bonds of starch in an essentially random fashion. It is a calcium dependent enzyme. The enzyme hydrolyzes amylose and amylopectin into Unear and branched dextrins. 

The gelatinized starch slurry is pumped to an enzymatic reactor for further treatment with a-amylase. The biocatalysis takes place at pH 6.5 and a temperature of 85°C-95°C for sufficient time to hydrolyze the starch into a 20-30 DE hydrolysate. The viscosity of the starch slurry lowers due to the formation of linear and branched dextrins (BBI International 2003, Coble et al. 1981, Lawton 2000, Madson and Monceaux 1995, Maisch 2003, Norman and Lutzen 1981, Scheller 1981, Sears 1995). 

Dextrin A short-chain polysaccharide of glucose units linked with a-1,4 (linear dextrin) and a-l,6-glycosidic bonds (branched dextrins) formed during the breakdown of starch. 

Pullulanase Also known as debranching enzyme. An enzyme that catalyzes the hydrolysis of a-l,6-glycosidic bonds of amylopectin and branched dextrins. 

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