Starch anionic

Anionic polymers Anionic starches Anionic surfactants... 

Like the natural gums, starches need to be cooked in water to form dispersions for addition to the papermaking system. Various techniques have been developed for cooking starches rapidly (see Starch). In general, anionic starches are used with alum, which aids in starch retention. The cationic and usually the amphoteric starches are self-retaining. 

Surface Sizing. Surface sizing is generally used for modification of other properties of paper or paperboard such as printabiHty, smoothness, porosity, coefficient of friction, opacity, surface strength, anti-linting or coating holdout. Anionic starch is perhaps the most common additive or co-additive used for surface sizing. 

In starch chemistry and technology, extrusion is used for cooking as well as for preparation of starch complexes with such guest molecules as gluten6511 and lipids.651 Acylation of starch with cyclic anhydrides of dioic acids on extrusion has been demonstrated the reaction provides anionic starches.651... 

Anionic starches are obtained by reaction with phosphoric acid and alkali metal phosphates or by derivatization with carboxymethyl groups.30,31 This modification is primarily used to introduce amphoteric properties into cationic com starch for application on the wet end of the paper machine. Anionic starches with carboxymethyl substitution are used as thickeners in coating colors or as binders in coatings for specialty paper grades. Oxidized starches are inherently anionic but without thickening action. Potato starch already carries sufficient natural anionic charge to provide amphoteric properties after cationization.32... 

Anionic starches, obtained by carboxymethylation of corn starch, provide improvements in film strength, pick resistance, opacity and air-leak density. They are used... 

Specific interactions between starch and proteins were observed as early as the beginning of the twentieth century. Berczeller996 noted that the surface tension of aqueous soap solutions did not decrease with the addition of protein (egg albumin) alone, but it did decrease when starch and protein were added. This effect was observed to increase with time. Sorption of albumin on starch is inhibited by bi- and trivalent ions and at the isoelectric point. Below the isoelectric point, bonding between starch and albumin is ionic in character, whereas nonionic interactions are expected above the isoelectric point.997 The Terayama hypothesis998 predicts the formation of protein complexes with starch, provided that starch exhibits the properties of a polyelectrolyte. Apart from chemically modified anionic starches (such as starch sulfate, starch phosphate, and various cross-linked starch derivatives bearing ionized functions), potato starch is the only variety that behaves as a polyelectrolyte. Its random phosphate ester moieties permit proteins to form complexes with it. Takeuchi et a/.999-1002 demonstrated such a possibility with various proteins and a 4% gel of potato starch. 

Synthetic complexes of starch with proteins have rather limited applications, in contrast to protein complexes with anionic starches. This problem has been reviewed several times by Tolstoguzov et al1039-1041... 

Formation of inclusion complexes of starch becomes a more common method of protecting some volatile, as well air-sensitive, food components (microencapsulation). Such complexes are essential for food texturization and overall stabilization. Cationic starches are used as detergents and cellulose pulp components, whereas anionic starches readily form complexes with proteins (Schmitt et al 1998). The latter are attempted in utilization as biodegradable plastics and meat substitutes. 

Anionic starches include carboxymethyl starch and starch phosphate esters. Starch phosphates were first produced commercially in 1960. They were used extensively in Europe in acid systems, being retained in the sheet by alum. Then-addition to the papermaking system requires a minimum of 1% alum (dry fibre basis) in the beater stock and a pH in the range of 4.3-6.0 [4]. These starches proved hugely successful in replacing the native (unmodified) beater starches then in use. 

The use of anionic starches in the wet-end declined rapidly following the introduction of cationic starches and their use almost ceased with the subsequent move to neutral sizing. There has been a revival of interest in anionic products for use in dual-starch systems [5]. 

The sequential use of anionic and cationic wet-end starch was described as early as 1975. In an acid furnish, anionic starch would be added first, adsorbed onto the fibre by alum, and then a cationic starch was added. A reversed addition sequence has been proposed for alkaline papermaking systems [8]. There are numerous patents covering sequential additions of oppositely charged starches [17,18]. 

This was a very important debunking of the myth that increased cationicity in starch leads to enhanced paper strength (extension of this logic would be that anionic starches are debonding agents). 

Other anionic flocculants comprise polyoxybenzyl cw-butenedioic acids, alginic acids, humic acids, anionic starchs, and mannogalactan. Other cationic flocculants mainly involve in guanidines, cationic starchs, and polyamines. 

A completely different PEC system for the loading and release of hydrophobic drugs like dihydroxyanthraquinone (DHA) was introduced by Wenz and coworkers [143]. They prepared PEC nanoparticles ( >h > 130 nm) of anionic starch and... 

Thiele C, Auerbach D, Jung G et al (2011) Nanoparticles of anionic starch and cationic cyclodextrin derivatives for the targeted delivery of drugs. Polym Chem 2 209-215... 

Tomasik P., Wang, Y.J., and Jane, J.L. (1995) Facile Route to Anionic Starches-Succinylation, Maleination, and Phatalation of Corn Starch on Extrusion, Starch/Starke, 47, 96-99... 

Advances in Carbohydrate Chemistry and Biochemistry, Vol. 51. New York Academic Press, p. 243-320. Tomasik P, Wang YJ, Jane J-L. 1995. Facile route to anionic starches. Succinylation, maleination and phthalation of com starch on extrusion. Starch/Starke 47 96—99. 

Tomasik P, Wang YJ, Jane JL, (1995) Facile route to anionic starches , Starch/starke, v47 96-99. 

C. is a - starch ether in which some or all of the available hydroxyl groups of the starch have been etherified by carboxymethyl groups (- anionic starch),... 

The reaction will proceed in aqueous suspension, but the ether formed becomes swellable in cold water if DS becomes >0.1. Therefore, the process is mostly run in aqueous organic solvents such as methanol, ethanol, isopropanol, acetone. After the reaction, the unswollen and undissolved c. is filtered off, washed and dried. Usually DS is 0.2-0.6. Carboxymethylation enhances die hydrophilic character of - starch polysaccharides (- anionic starch). 

Among this group of f, starch is the most used, either as such or as derivative ( cationic starch - anionic starch). Guar gum and derivatives, as well as animal - glue (gelatin), are also of some importance. Albumin is used for clarifying wine. 

For practical uses see - anionic starches, car-boxymethyl starch, - cationic starches, - cross-linked starches, - hydrophobic starches, - oxidized starches, - starch industrial applications. 

The reaction can be performed in a belt dryer, by spray-drying or by extrusion. The esters formed with a low DS (<0.1) belong to the - anionic starches. They exhibit enhanced paste viscosity, clarity, freeze-thaw reversibility and reduced - ret-rogradation. The pastes are c stically thinned at acidic pH, in the presence of salts and high cooking temperatures. Stabilization is achieved by crosslinking. 

Anionic Starches Anionische St ke Annual Einjahrig Antibiotics Antibiotika Antistatic Agents Antistatika Aiachidic Add Arachinsaure Arachidonic Add Arachidonsaure L-Ascorbic Add L-Ascorbinsaure Atropine Atropin Avocado Avocado Azelaic Add Azelainsaure... 

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