Hydrolyse starch

Hydrolysis by acids. Place 15 ml. of starch solution in a boiling-tube, add I ml. of cone. HCl, mix well and place in a boiling water-bath for 20 minutes. Cool and add 2 drops of iodine solution to i ml. of the solution no blue coloration is produced. On the remainder, perform tests for glucose in particular show that glucosazone can be formed. Neutralise the excess of acid before carrying out these tests. (Note that a more concentrated acid is required to hydrolyse starch than to hydrolyse the disaccharides, such as sucrose.)... 

Starch hydrolysates Starch industry Starch-iodine Starch-lipid complex... 

Acrylate and low-molecular-weight acrylic acids are effective slime depressants/disper-sants. Suspendol PKK and PC improved separation efficiency between zinc and iron oxides. Starches, mainly hydrolysed starch and cooked starch, are effective depressants in the treatment of oxidized zinc ores that contain iron oxides and Fe-hydroxides. 

Pancreatic amylase hydrolyses starches to maltose and oligosaccharides. Final digestion of carbohydrates takes place in the brush border of the epithelial cells. Oligosaccharides are hydrolysed to monosaccharides and reabsorbed. Proteins are hydrolysed to peptides by pepsin, trypsin and several other proteolytic enzymes from the pancreas. The brush border attaches proteases which hydrolyse the di- and tripeptides to amino acids and absorbs them. 

Cellulose and derivatives (CMC, MC, HPC, HPMC) Stffl h and derivatives (fractionated nylose, mnylopectin, modifred propylated, acetylated..., hydrolysed starch dextrins, maltodextrins, glucose syrups, pregelatinized starch)... 

Hazes caused by starch mainly occur when unripe or prematurely ripe fruit is processed, but can be avoided by preventive use of enzymes that hydrolyse starch. 

The enzymes used for this type of digestion in Analytical Chemistry are mainly hydrolytic enzymes, the catalytic effect of which is based on the insertion of water at a specific bond of the substrate. The hydrolytic enzymes used in analytical applications include lipases (which hydrolyse fats into long-chain fatty acids and glycerol) amylases (which hydrolyse starch and glycogen to maltose and to residual polysaccharides) and proteases (which attack the peptide bonds of proteins and peptides themselves). 

Although enzyme usage was in fact widespread, the first recognition of an enzyme was reported in 1833. It was found that malt extract contained a substance that splits (hydrolyses) starch into glucose. This substance was named diastase and is now knovm as amylase . 

Invertase hydrolyses cane sugar. Amylase hydrolyses starch. 

Gel layers are prepared from hydrolysed starch for electrophoresis (Sigma St. Louis, MO, Serva Feinbiochemica, Heidelberg, FRG) by suspending in the gel buffer, degassing the mixture and heating it to the moment when viscosity drops... 

Starch-Modifying Enzymes Starch is one of the most abundant carbohydrates in terrestrial plants and the most important polysaccharide used by humankind. This polymer is normally processed and used in a variety of products such as starch hydrolysates, starch or maltodextrin derivatives, fructose, glucose syrups, and cyclodextrins [148, 149]. In addition, starch is widely used as a raw material in the paper industry, in polyol production, and as economic substrate for many microbial fermentations [149]. Starch consists of a large number of glucose units that can be linearly attached as hehcal amylose [ 99% a-(l-4) and 1% a-(l-6) bonds] or branched as amylopectin [ 95% a-(l-4) and 5% a-(l-6) bonds] [69]. In nature, four types of starch-converting enzymes exist (i) endoamylases (ii) exoamylases (iii) debranching enzymes and (iv) transferases. 

The next relevant discovery was made in 1910, when it was noted that some enzymes are blocked by substances whose molecular structure resembles that of the normal substrates. Thus amylase, which normally hydrolyses starch, is inhibited by glucose (see Section 9.1). Again, malonic acid 9.3) competitively inactivates the enzyme succinic dehydrogenase by displacing the normal substrate, succinic acid 9.4), from the enzyme (Quastel and Wooldridge, 1927). A similar phenomenon in physiology is the toxic action of carbon monoxide... 

Starch occurs as a flour-like white powder, which is insoluble in cold water after its extraction from plants. Native starches contain between 15 and 45% of crystalline material. Starch crystallite, starch nanocrystal, microcrystalline starch and hydrolysed starch all refer to the crystalline part of starch, which are obtained by different extents of acidic hydrolysis. We will focus on starch nanocrystals. Cellulose nanocrystals are 100% crystalline materials, but starch nanocrystals consist of 45% crystalline portion. 

Examples of Le.used commercially are proteases (in detergents, and for making cheese and other food products), carbohydrases (for hydrolysing starch, con-... 

It may be mentioned here to complete the picture that Bamsey [556] has employed the hydrolysed starch , used by Smithies for starch gel block electrophoresis, for thin-layer chromatographic separation of proteins. The starch gel layer is poured, giving a layer about 1.5 mm thick. Further experimental details may be taken from the original article. 

Mixed esters of hydrolysed starch have been prepared in pyridine using anhydrides as acylating agents. The mixed esters are hydrophobic and organic-soluble, but may be readily solubilized in aqueous base through the half-ester groups. The solutions show surface activity which varies according to the type and extent of substitution. 

Active immobilized enzyme use in column 549 form for continuous conversion of partially hydrolysed starch to D-glucose Active immobilized enzyme 389... 

Fig. 6.2A-C. Scanning electron micrographs of a median cross section of a wheat grain to show modification of the endosperm after (A) 1 day and (B) 2 days. (C) shows the partially hydrolysed starch grain in the sub-aleurone endosperm of grain modified for 4 days. In (A) a region of weakness has been arrowed where the endosperm is becoming modified close to the aleurone (A) layer. In (B) the aleurone layer remains adhered to the seed coat. From Fincher and Stone, 1974 [50]...

Much of the resistant and slowly hydrolysed starch is fermented by bacteria in the colon, and a proportion of the products of bacterial metabolism, including short-chain fatty acids, may be absorbed and metabolized. As discussed in section 7.3.3.2, butyrate produced by bacterial fermentation of resistant starch and non-starch polysaccharides has an antiproliferative action against tumour cells in culture, and may provide protection against the development of colorectal cancer. 

An exo-enzyme (mol. wt. 5.4 x 10 ) isolated from Aerobacter aerogenes has been purified to homogeneity by disc electrophoresis, ion-exchange chromatography, and gel filtration. The enzyme is stable over a wide range of pH, and at its optimum pH (6.80) and temperature (50 °C) it hydrolysed starch, amylose, and amylopectin to maltohexaose, but it did not hydrolyse cyclohexa- or... 

Glucoamylases.—Although the molecular weight and the carbohydrate content of Aspergillus awamori glucoamylase were reduced on treatment with subtilisin, most of the enzymic activity was retained. The modified enzyme was less stable and its ability to hydrolyse starch was diminished. 

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