Pregelatinization

Starches, used first in the late 1930s for filtration control (71), are stiU in use in the 1990s. Com starch is most commonly used in the United States. Potato starch is also used in the United States but primarily in Europe and elsewhere. Both com and potato starches are pregelatinized before dispersion in water (72). The API specifications for drilling fluid starch are listed in Table 8 (73). 

Nonfood Uses. Native com starch is principally used in nonfood appHcations in mining, adhesives, and paper industries. Pregelatinized starch is chemically unmodified, but it is physically modified. Pregelatinized starches are used to decrease water losses in oil-weU drilling muds, in cold water-dispersable wallpaper pastes, and in papermaking as an internal fiber adhesive. 

Starch monophosphates are quite useful in foods because of their superior freeze—thaw stabiUty. As thickeners in frozen gravy and frozen cream pie preparations, they are preferred to other starches. A pregelatinized starch phosphate has been developed (131) which is dispersible in cold water, for use in instant dessert powders and icings and nonfood uses such as core binders for metal molds, in papermaking to improve fold strength and surface characteristics, as a textile size, in aluminum refining, and as a detergent builder. 

A slurry of the starch is cooked in the presence of a heat-stable bacterial endo-a-amylase. The enzyme hydrolyzes the a-l,4-glycosidic bonds in pregelatinized starch, the viscosity of the gel rapidly decreases, and maltodextrins are produced. The process may be terrninated at this point. The solution is purified and dried, and the maltodextrins are utilized as blandtasting functional ingredients in dry soup mixes, infant foods, sauces and gravy mixes, etc. 

Starches are also sometimes pregelatinized to make them easier to dissolve during product manufacture. 

Pregelatinized starch Hydroxypropyl cellulose Calcium phosphate... 

Polydrill is a sulfonated polymer for filtration control in water-based drilling fluids [1775]. Tests demonstrated the product s thermal stability up to 200° C and its outstanding electrolyte tolerance. Polydrill can be used in NaCl-saturated drilling fluids as well as in muds containing 75,000 ppm of calcium or 100,000 ppm of magnesium. A combination of starch with Poly drill was used successfully in drilling several wells. The deepest hole was drilled with 11 to 22 kg/m of pregelatinized starch and 2.5 to 5.5 kg/m of Polydrill to a depth of 4800 m. Field experience with the calcium-tolerant starch/Polydrill system useful up to 145° C has been discussed in detail [1774]. 

Allen et al. (2007) produced puffed snack foods with com starch and pregelatinized waxy starch, WPC and instantized WPC, and protein concentrations of 16%, 32%, and 40% and showed that the air cell size, extru-date expansion ratio, and water solubility index decreased proportionally as protein and com starch levels increased. Protein concentration significantly affected total soluble protein, water absorption index, and water-soluble carbohydrate. A covalent complex between amylase and protein formed in the presence of cornstarch, but protein-protein interactions appeared with the presence of low levels of pregelatinized waxy starch. 

Starch is often cited as a filler, but it is more commonly used in its dry state as a disintegrating agent. However, modified starches such as StaRx 1500 and National 1551 (partially hydrolyzed, or pregelatinized starch) are marketed for direct compression and appear to offer the advantage of substantial mechanical strength and rapid drug release. 

Fig. 17 Effect of powder bed height, piston height, and compression force on plug ejection force in an instrumented Zanasi LZ-64 automatic capsule-filling machine (pregelatinized starch lubricated with 0.005% magnesium stearate). Note that the first point of each curve is precompression. Piston height (mm) , 15 -jlf, 14 , 13 , 12. Powder bed height (mm) heavy line, 30 light line, 50. (From Ref. 51.)...

Prefiring, of ferrites, 22 72 Prefixes, 27 398, 399 Preformed silver halide grains, as photocatalysts, 29 345-346 Pregelatinized starches, 4 722 p-region, 23 36-37... 

A. water. They include cellulose ethers, pregelatinized starches, polyethylene oxides, alginates, carrageenans, polyacrylamide, carboxyvinyl polymers and polyvinyl alcohol. 

Te Wierik, G. H. P, Eissens, A. C., Bergsma, J., Arends, A. W., Lerk, C. F. (1997b). A new generation of starch products as excipient in pharmaceutical tablets. It. High surface area retrograded pregelatinized potato starch products in sustained-release tablets. J. Contr. Re/., 45,25-33. 

Charge in a suitable stainless steel double-cone blender, sucrose, sodium phosphate, xanthan gum, sodium cyclamate, sodium saccharin, gly-camil, and starch pregelatinized. 

Modification of physicochemical property of the existing excipient has been the most successful strategy in the development of new excipients in the past three decades (24). This model has been successfully adopted for the introduction of excipients with better performance grades, such as pregelatinized starch, croscarmellose sodium, and crospovidone (25). However, the quantum of functionality improvement is limited due to a restricted range of possible modifications. 

Method C. Proceed as Method B using the pregelatinized amylase treatment only. 

Pregelatinized Starches. Suspensions of starches and starch derivatives can be gelatinized/cooked and dried to yield a variety of products that can be dispersed in cold water to yield pastes comparable to those obtained by cooking granular starch products. These products are made for convenience of use. 

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