Starch chemically modified

Most manufacturing technologies consist of treating native starches in a reactor with temperature and agitation controls. Generally, a starch slurry with approximately 35% solids and adjusted to a certain pH is treated with chemicals to promote the desired reactions. In most instances, gelatinization and starch solubilization is avoided so as to prevent the disruption of the starch granule. 

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Obtaining Different Properties in the Starch. One method of obtaining a starch with different properties is the biological method of using a different type of plant. The best example of this is waxy maize, which yields a starch that is nearly pure amylopectin. The other method is to chemically modify the starch. Chemically modified starch is normally declared as modified starch . A whole range of modified starches are available. There is of course no bar to chemically modifying a starch from a special source. 

Dextrose, obtained from starch, is the raw material for sorbitol and other sugar alcohols and polyols. Isolated starch (usually from corn) can be chemical modified and is used in large amounts as an inexpensive binder in the textile and paper industry. Chemically modified starch can be used as super-absorbers or in polymer manufacturing. 

In the manufacture of paper, starch-based adhesives are used either to strengthen the paper base or for coating the surface of the paper. Raw starch is unsuitable for either purpose. To achieve sufficient adhesive power with raw starch would require the application of a solution that was far too thick for practical use. Instead, chemically modified starch, with a much lower viscosity in solution, is used. As an economical alternative to modifying the starch with aggressive oxidizing agents, the starch can be treated with enzymes ( df-amylases) to obtain the same thinning effect... 

Adebowale, K. O., Lawal, O. S. (2003). Functional properties and retrogradation behaviour of native and chemically modified starch of mucuna bean (Mucuna pruriens). J. Sci. Food Agric., 83, 1541-1546. 

Singh, J., Kaur, L., McCarthy, O. J. (2007). Factors influencing the physico-chemical, morphological, thermal and rheologieal properties of some chemically modified starches for food applications - A review. Food Hydr., 21, 1-22. 

Starch is an abundant, inexpensive polysaccharide that is readily available from staple crops such as com or maize and is thus is mostly important as food. Industrially, starch is also widely used in papermaking, the production of adhesives or as additives in plastics. For a number of these applications, it is desirable to chemically modify the starch to increase its hydrophobicity. Starch modification can thus prevent retrodegradation improve gel texture, clarity and sheen improve film formation and stabilize emulsions [108], This may, for example, be achieved by partial acetylation, alkyl siliconation or esterification however, these methods typically require environmentally unfriendly stoichiometric reagents and produce waste. Catalytic modification, such as the palladium-catalyzed telomerization (Scheme 18), of starch may provide a green atom-efficient way for creating chemically modified starches. The physicochemical properties of thus modified starches are discussed by Bouquillon et al. [22]. 

Starch—different kinds (potato, corn, and wheat starches) and many kinds of chemically modified starches (oxidized starches, phosphated distarch phosphate, etc.)... 

Table 12.8 Specification of chemically modified starch for food applications according to Thai regulations... 

Because consumers have become more mindful of what is in their diet, and because in the European Economic Community chemically-modified starches must be labeled as such, there has developed an interest in starches that have only been heated to achieve the process tolerance and short texture of a lightly-crosslinked starch. Such developments in modifying the properties of starch without chemical derivatization are discussed in two chapters. 

These regulations are likely to lead a conventional food manufacturer to adopt a tailored approach to organic recipe development. As an example, a careful scanning of the Regulation will show that only non-chemically modified starch is allowed, whereas very highly specific chemically modified starches are the norm in conventional processing. This is likely to mean that the development process will have to include examination of non-chemically modified alternatives. Another example is chopped tomatoes, normally used in recipe dishes in the conventional industry, which are treated with calcium in order to retain their texture this is not an option available to the organic manufacturer. 

Fig. 56.—Water solubility of tapioca starch and chemically modified starch extruded without and with 2% addition of fatty acids. C2, acetic acid C 2, dodecanoic acid C 4, tetradecanoic acid C,A, hexadecanoic acid C18, octadecanoic acid C18 i, oleic acid C 8 2, linoleic acid CaSL, calcium octadecanoyl lactate GMS glyceryl monooctadecanoate GMP, glyceryl mono-hexadecanoate Am, Amidan and Dm, Dimodan (mixtures of GMS and GMP). (Reprinted with permission of C. Mercier, R. Charbonniere, J. Grebaut, and J. F. de la Gueriviere, Cereal Chem., 57 (1980) 4-9.)...

The main drawback to the widespread use of polymer-polymer aqueous two-phase extraction has been the high cost of fractionated dextran. Crude dextran has been used with some success for the purification of enzymes but is much too viscous for many applications. Conversely, polymer-salt systems have relatively low viscosities, separate rapidly, and are inexpensive. Unfortunately, they lack selectivity and cannot be used for affinity partitioning in most cases since the high salt concentrations interfere with the protein-ligand interaction. The starch derivatives are reasonable alternatives for bottom phase polymers but have been hampered by low solubilities and the tendency for gel formation. Tjemeld has reported that chemically modified starches i.e. hydroxypropyl starch... 

Dextrin Chemically modified starch, raw material for dextrin glue. 

The analytical approach described showed to be suitable when ones aim to discriminate maize flour samples from whole and degermed maize, an issue thought to be important for the food, cosmetic, and pharmaceutical industries regarding the usage and quality control process of that raw material. Similarly, the classification of maize landraces according to their starch traits is considered technologically relevant in order to optimize the usage of non-chemically modified starches in industrial process, for instance. 

In spite of recent developments and research in synthetic polymers applied in pharmaceutical field, biomaterials, particularly polysaccharides like starch, cellulose, gums and mucilages, have a greater role to play in pharmaceutical formulation development. It is concluded from the discussion in this entry that because of some limitations at the molecular level, there is a need to modify the parent structure of starch to make it available for pharmaceutical and other industrial uses. Physically and chemically modified starches showed very promising results in the delivery of therapeutic agents. The modified starches have enormous potential to be used in drug delivery because of its easy modification and biodegradability. 

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