Dextrins, production

This enzyme [EC 3.2.1.10] (also referred to as oUgo-1,6-glucosidase, sucrase-isomaltase, and limit dextrinase) catalyzes the hydrolysis of l,6-o -D-glucosidic linkages in isomaltose and dextrin products generated from starch and glycogen via a-amylase. See also Sucrase... 

This view has prevailed in many countries. In the U.S.S.R. lead azide entered (industrial production in 1929 (Bagal [1]). Between 1920 and 1930 a considerable amount of work was dedicated to the production of lead azide which would, be less hazardous to manufacture and thus dextrinated product was manu-... 

As indicated in the introduction to this chapter, one of the major advances which affected the civil and military technology of lead azide occurred with the development of the dextrinated products. Today these continue to play the most significant role in civilian industry and are still used for some military applications. 

In the manufacture of lead azide. ATS uses the Meissner process in which lead acetate is added to sodiiun azide and precipitated at a temperature of 30-40°C. This is described as a continuous process, and in this respect it contrasts markedly with the processes which are used in the United States and Great Britain. A further contrast is that they manufacture only a little CMC-stabilized material, concentrating their efforts on the production of pure or dextrinated products. In fact, in the last three years there had been no production of CMC material, as they are quite satisfied with the dextrinated product. A sketch of the process which they use for manufacture by the Meissner process is shown in Figure 14. 

Table III shows the properties of the resultant dextrin products. The...

The term, dextrins, refer to starches which were depolymerized and then restractured to form short, highly branched or cyclic polymers. These polymer products are dextrorotatory, thus the name dextrins. The primary mechanisms for dextrin production include a depolymerization step, by acid or enzymes... 

Available chromatographic, spectroscopic and chemical methods for the characterization and quantitative determination of amylo-dextrin products are reviewed, discussed and evaluated. The analyses of amylodextrins are of vital importance to researchers involved, for example, in the characterization of novel starch degrading enzymes and starches of novel rheological properties and the rationalization of structure/ function relationships of amylases. 

Fig. 4.2 Graph DTA thermogram of pure and dextrinated a-LA showing exceptional thermal stability of the dextrinated product (heating 5 °C min , 5 mg samples, static air atmosphere, open test tube)...

A wide variety of special malts are produced which impart different flavor characteristics to beers. These malts are made from green (malt that has not been dried) or finished malts by roasting at elevated temperatures or by adjusting temperature profiles during kilning. A partial Hst of specialty malts includes standard malts, ie, standard brewers, lager, ale, Vienna, and wheat caramelized malts, ie, Munich, caramel, and dextrine and roasted products, ie, amber, chocolate, black, and roasted barley. 

The adhesives (qv) used to form tube seams and bag bottoms include unborated dextrin, borated dextrin, casein, latex—casein, latex, poly(vinyl acetate), vinyl acetate copolymers, and hot-melt materials (10,27). Dextrin and casein adhesives are more commonly used in the production of grocery sacks vinyl acetate-type adhesives are commonly used in ah paper multiwah bags. The hot-melt adhesives are typicahy used to tack the phes of the multiwah bag together and to form the seam and bottom joints when polymer film phes or coated paper phes are used in bag constmction. 

Pyrotechnic mixtures may also contain additional components that are added to modify the bum rate, enhance the pyrotechnic effect, or serve as a binder to maintain the homogeneity of the blended mixture and provide mechanical strength when the composition is pressed or consoHdated into a tube or other container. These additional components may also function as oxidizers or fuels in the composition, and it can be anticipated that the heat output, bum rate, and ignition sensitivity may all be affected by the addition of another component to a pyrotechnic composition. An example of an additional component is the use of a catalyst, such as iron oxide, to enhance the decomposition rate of ammonium perchlorate. Diatomaceous earth or coarse sawdust may be used to slow up the bum rate of a composition, or magnesium carbonate (an acid neutralizer) may be added to help stabilize mixtures that contain an acid-sensitive component such as potassium chlorate. Binders include such materials as dextrin (partially hydrolyzed starch), various gums, and assorted polymers such as poly(vinyl alcohol), epoxies, and polyesters. Polybutadiene mbber binders are widely used as fuels and binders in the soHd propellant industry. The production of colored flames is enhanced by the presence of chlorine atoms in the pyrotechnic flame, so chlorine donors such as poly(vinyl chloride) or chlorinated mbber are often added to color-producing compositions, where they also serve as fuels. 

Starch pyrodextrins and British gums have the abiUty, in aqueous dispersion, to form films capable of bonding like or unlike materials. Thus, they have uses as adhesives for envelopes, postage stamps, and other products. These dextrins are used in glass-fiber siting to protect the extmded fiber from abrasion, and as binders for metal core castings, water color paints, briquettes, and many other composite materials (qv). 

After 30 hours, the maximum and critical fermentation is underway and the pH must remain above 4.0 for optimal fermentation. However, accompanying bacterial contamination from various sources such as yeast contamination, improper cleaning procedures, slow yeast growth, or excessive temperatures can result in a pH below 4.0. The remaining amylase enzymes, referred to as secondary conversion agents, are inactivated and can no longer convert the dextrins to maltose. Under these circumstances, the fermentor pH continues to drop because of acid production of the bacteria, and the pH can drop to as low as 3.0. The obvious result is a low ethanol yield and quaUty deterioration. 

Maltodextrins [9050-36-6] are mixtures of saccharides with average DE values of <20 (12). They are rather soluble, have a bland taste, and are widely used in foods. A dextrin is a product obtained by depolymerization of a polysaccharide. 

The yield was highest with starch or dextrin, intermediate and about the same with sucrose, glucose, maltose and lactose and poorest with glycerol. Kanamycin was produced by media containing soybean meal, peanut meal, cottonseed meal, corn steep liquor, peptone, yeast extract or meat extract, with or without sodium nitrate. Commercially available soybean meal was recognized to be one of the best nitrogen sources. The addition of corn steep liquor, peptone, yeast extract or nitrate to the soybean meal promoted the production of kanamycin. 

Only the hydrophobic and steric terms were involved in these equations. There are a few differences between these equations and the corresponding equations for cyclo-dextrin-substituted phenol systems. However, it is not necessarily required that the mechanism for complexation between cyclodextrin and phenyl acetates be the same as that for cyclodextrin-phenol systems. The kinetically determined Kj values are concerned only with productive forms of inclusion complexes. The productive forms may be similar in structure to the tetrahedral intermediates of the reactions. To attain such geometry, the penetration of substituents of phenyl acetates into the cyclodextrin cavity must be shallow, compared with the cases of the corresponding phenol systems, so that the hydrogen bonding between the substituents of phenyl acetates and the C-6 hydroxyl groups of cyclodextrin may be impossible. 

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