Starch hydrolytic

Acid Reversion in Relation to Isomaltose as a Starch Hydrolytic Product, A. Thompson, M. L. Wolfrom, and E. J. Quinn,/. Amer. Chem. Soc., 75,3003-3004 (1953). Chemical Interactions of Amino Compounds and Sugars. VII. pH Dependency, M. 

Inactive form of starch hydrolytic enzyme, Q -aiiiylase, was incorporated in starch matrix. Degradation of the starch matrix by ct-amylase when the incorporated enzyme was activated in the pre.sence of Intelligent biosensor for Kost, 1994... 

Two approaches are discussed for the preparation of enzymatically controlled drug delivery systems a calcium-responsive biodegradable drug delivery system based on a mixture of starch with HPMC (hydroxypropyl methyl cellulose ether) (biodegradable) and the starch hydrolytic enzyme, alpha-amylase, in its non-active form and a glucose responsive insulin delivery system based on the hydrogel poly(2-hydroxyethyl methacrylate-co-N,N-dimethylaminoethyl methacrylate), with entrapped glucose oxidase, catalase and insulin. In both systems, the sensitivity... 

Desizing by chemical decomposition is applicable to starch-based sizes. Since starch and its hydrophilic derivatives are soluble in water, it might be assumed that a simple alkaline rinse with surfactant would be sufficient to effect removal from the fibre. As is also the case with some other size polymers, however, once the starch solution has dried to a film on the fibre surface it is much more difficult to effect rehydration and dissolution. Thus controlled chemical degradation is required to disintegrate and solubilise the size film without damaging the cellulosic fibre. Enzymatic, oxidative and hydrolytic degradation methods can be used. 

It has been demonstrated [186] that the inclusion of polyacrylamide in either enzymatic or oxidative desizing formulations results in increased pick-up of the liquor by the sized warp yams. Desizing by hydrolytic degradation of starch during the traditional kier-boiling treatment using 3°Be sodium hydroxide liquor at 110 °C is now rarely encountered as it is a slow and expensive process [169]. 

Amylases are hydrolytic enzymes which catalyze the hydrolysis of starches and glycogens. In addition to their intrinsic importance in Now with Bureau of Human Nutrition and Home Economics, U. S. Department of Agriculture, Beltsville, Maryland. 

AKDs are waxy, water-insoluble solids with melting points around 50 °C, and ASAs are viscous water-insoluble liquids at room temperature. It is necessary to prepare them as stabilised emulsions by dispersion in a cationic polymer (normally cationic starch). Small amounts of retention aid and surfactants may also be present. Particle size distributions are around 1 fim, and addition levels around 0.1% (of pure AKD or ASA) by weight of dry fibre. This is an order of magnitude lower than the amount of rosin used in rosin-alum sizing (1-2%). Emulsions of AKD are more hydrolytically stable than ASA, and the latter must be emulsified on-site and used within a few hours. 

The other important function of the binder is its effect upon the rheological properties of the coating mix. Starch, which is widely used, is unsuitable for use in its unmodified form because its solution viscosity is generally too high and also because of the problem of retrogradation. It is usually modified by reducing its molecular weight by either oxidative or hydrolytic (sometimes enzymatic) procedures. 

Digestion of starch involves the hydrolysis of the bonds between the glucose molecules. Two classes of hydrolytic enzymes are required amylases and oligo- and di-saccharidases (Figure 4.5). The disaccharidases are also involved in hydrolysis of sucrose and lactose. 

How does the monosaccharide hydrolytic product of cellulose differ from the hydrolytic product of starch ... 

Starch derived from maize, potatoes, barley, cassava or other somces must be pretreated with hydrolytic enzymes (amylases, amyloglucosidase, proteases), which carry out liquefaction, saccharification and protein hydrolysis, respectively, before it can be fermented by yeasts and other microorganisms into potable or non-potable alcohol. Enzymes can be added in the form of malt (germinated barley) or koji (germinated rice), but this is expensive. Therefore, industrial enzymes have nearly totally replaced malt and koji as enzyme sources, thereby not only improving the economics but also the predictability of the process. 

Starch (amylose and amylopectin) hydrolysis along with ester-fication, etherification or oxidation have been previously discussed as available methods for producing starch derivatives with improved water dispersibilities and reduced retrogradation potential (, ). Since oxidative and hydrolytic reactions are simple, easily controlled chemical modifications, starch-derived polymers made by hydrolysis alone or oxidative and hydrolytic processes were developed and tested. 

On the basis of researches devoted to the products of paitial or total hydrolytic breakdown of methylated starch, the chain of a-D-anhydroglucose is thought to constitute the main element of the amylose and amylopectin molecules. These units are combined as in maltose, i.e. by means of a-glucosidic linkages formed between the carbon atoms 1 and 4 ... 

It is now supposed that gibberellic acid stimulates the hormonal production of a-amylase (and, probably, of /9-amylase and others) in the aleurone layer surrounding the endosperm starch-reserve. Gibberellic acid released 400 mg. equivalents of D-glucose per g. in 90 hours in wheat grains, with a maximum hydrolytic activity after 60 hours. The effect on /9-amylase was thought to be a release (to the extent of 85%) from the protein-bound, insoluble form.876... 

Gibberellic acid and (2,4-dichlorophenoxy) acetic acid increased the glycoside content of Omithogalum umbellatum, as measured by a biological assay of extracts. The active principle, strophanthidin, is one of the cardiac glycosides. 7 There is little reference in the literature to this type of work, but the hydrolytic effects of gibberellic acid on starch may shift the equilibrium toward phenyl glycoside formation in some plant species. 

Pectinases These enzymes carry out the hydrolytic degradation of the D-glycosidic linkage in pectins. The latter substances, also known as pectic substances, are polymeric components of plant cell walls and. like starch, are composed of sugar residues linked by glycosidic bonds. The chemistry is the same as that shown for the amylases previously described. The main application of pectinases is in the production of fruit juices, wines, and certain other food products. 

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