Starch particles

Endosperm constitutes the main part of the corn kernel and consists of 85 to 90% starch, 8 to 10% protein, and a small amount of oil and other compounds. Corn endosperm can be divided into two distinct parts floury and horny endosperm. In floury endosperm, starch particles are round and are dispersed loosely in the protein matrix. In the horny endosperm, the protein matrix is stronger and starch particles are held more firmly. Starch granules are encased in the continuous protein matrix. The tighter setting in horny endosperm gives starch particles a polygonal shape. On average, the amount of horny endosperm in the corn kernel is twice that of the floury endosperm. However, this ratio is a function of the corn kernel protein content (Wolf et al., 1952). 

Due to the structure of the corn kernel (cutinized outer layer of the pericarp surrounding the corn kernel), the diffusion of water and chemicals inside the kernel is through a very specific pathway. Initial results with the use of enzymes during steeping (Figure 1) indicated that enzymes were not able to penetrate the kernels and break down the protein matrix surrounding starch particles. For enzymes to penetrate the corn kernel, it was necessary... 

Protein content of field peas is negatively correlated with lipid, cell wall material (CWM), sugar, and ash content and positively correlated with starch separation efficiency and protein separation efficiency in air classification of pea flour. The lower separation efficiency of low protein peas may be due to their high lipid and CWM content which makes disintegration of seeds and separation into protein and starch particles by pin milling difficult. It is suggested that peas with a specific protein content should be used in order to control the protein and starch fraction contents (18). 

Matsumara [23] noticed that starch particles exhibit slight exothermie properties during wetting, whieh was thought to cause localized stress resulting from the expansion of air retained in the tablet matrix. Unfortunately, this explanation, if valid, would be limited to a few substances such as aluminium silicate and kaolinite. List and... 

A very recent development is encapsulation of actives in colloidosomes [16, 41]. The method is analogous to liposome entrapment. Selectively permeable capsules are formed by surface-tension-driven deposition of solid colloidal particles onto the surface of an inner phase or active ingredient in a water-in-oil or an oil-in-water emulsion composed of colloidal particles. Initially synthetic polymer microparticles were used but more recently a natural alternative has been described based on small starch particles. After spray-drying, redispersible emulsions can be formed. 

Coprocessing of a-lactose monohydrate with cornstarch helped in improving its compressibility, and provided dual benefits of enhanced binding capacity and better disintegration potential, the attributes associated to starch (48). This effect was a result of binding of small starch particles together with a-lactose monohydrate crystals into compound particles. 

In iodimetry (titration with If), starch can be added at the beginning of the titration. The first drop of excess If after the equivalence point causes the solution to turn dark blue. In iodometry (titration of If), If is present throughout the reaction up to the equivalence point. Starch should not be added to such a reaction until immediately before the equivalence point (as detected visually, by fading of the If Color Plate 10). Otherwise some iodine tends to remain bound to starch particles after the equivalence point is reached. 

Adherent starch particles were prepared by partially swelling pregelatinized starch in 30% 2-propanol and/or solutions of inorganic salts. A pest control agent was stirred into the gelled mass, which was dried, broken up and ground. The material... 

The viscosities of the three hemicellulose adhesives and the starch control are given in Figure 4. The viscosity of the suspended hemicellulose adhesive was lower when compared at different solids contents than that of the starch control. It was, on the other hand, much higher than the viscosity of a raw starch suspension (30 cP at 35% solids). The higher viscosity of the raw hemicellulose adhesive is probably caused by the gel-like outer layer of the raw hemicellulose-suspended particles. The suspended starch particles showed no such surface gel effect, but remained totally undissolved. The viscosities of the cooked and raw-cooked hemicellulose adhesive were similar to those of the starch adhesive (Figure 4). 

At lower starch contents (i.e., less than 60%) the starch particles act as weak links in the plastic matrix and become sites for biological attack. The polymer matrix can therefore disintegrate into small fragments, but this does not mean that the entire polymer structure will actually biodegrade. 

Ball milling Various starches Fragmented starch particles had improved cold water binding properties and freeze-thaw stability Niemann and Meuser (1996)... 

Vacuum ball milling Cassava starch Micronized starch particles (8-24 pm) had reduced gelatinization temperature Che et al. (2007)... 

Jamialahmadi and Muller Steinhagen [1993] conclude that the theory and art of scale prevention in boilers has developed in a rather amorphous way. They cite the use of potatoes in 1821 for scale prevention in boilers. The origin of the technique was apparently that some labourers, wishing to cook their potatoes in the boiler, were distracted so that the potatoes were not retrieved. Some days later when the boiler was due to be cleaned, the operators were astonished to see that the heat transfer surfaces were unusually clean. The cleanliness was explained in terms of the starch particles from the potatoes that provided bulk nucleation sites and the creation of weaker deposits. 

Experimental studies by Fiiredi and Valentine at various frequencies involved the bunching and orientation of microscopic particles made of polystyrene spheres, aluminum or carbon particles, ion exchange resin beads, ferric oxide or potato starch particles in water, saline solutions, or in castor oils. Orientation effects appeared to be absent in the salt solutions, but to be accentuated in castor oil, relative to that in water especially at high frequencies. GrifBn and Stowell confirmed and extended the studies of Teixera-Pinta et on the bunching and orientational effects of... 

The biodegradability of starch in the plastic matrix mainly depends on the accessibility of starch to microbes and on the coimectivity of starch particles each other. Wool and Cole (8) described a simulation model based on percolation theory for predicting accessibility of starch in LDPE to microbial attack and add hydrolysis. This model predicted a percolation threshold at 30% (v/v) starch irrespective of component geometry and other influential factors. Two critical aspects, the bioavailability and the kinetics of the starch hydrolysis in the plastic matrix must be examined before such blends could be applied as controlled release formulation of pestiddes. The goal of this work was to develop a kinetic model describing the degradation and release of starch blended with hydrophobic plastics. 

To recover the starch, the corn kernels, for example, are pealed and then dipped in sulfuric acid at pH 3.5-4 for 40 h at 125°C. The corn kernels softened in this way are then coarsely ground and the corn nucleus removed by floatation, whereby the starch particles sedimentate. Fiber components are filtered off and the starch particles are removed from the remaining protein solution by centrifugation. The recovered starch particles are then washed and dried. Sixty percent of the starch is converted to starch syrup or dextroses by partial hydrolysis. The remaining 40% is used in the food industry or in the textile, paper, or detergent industry, partially as derivatives such as starch acetate or hydroxyethyl starch. 

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