Starch protein complexes

Electrophoresis of proteins on starch thin layers,969 starch columns,970 and starch gels971,972 has been reviewed. Partition chromatography of ribo-nucleosides on starch973 and the possibility of making plastics from starch and proteins974 have also been discussed. The effect of protein-starch complexes on the staling of bread was discussed by Hampel.975 All of these studies suggest the formation of starch-protein complexes. 

To isolate proteins involved in protein-starch conq)lexes, soluble proteins were removed from extrudates with SDS/p-ir rcaptoethanol the insoluble residues were then treated with a-amylase to digest any starch present and release any proteins that had been bound. In separate analyses, the entire extrudate was treated with glucoamylase to remove starch and proteins were extracted. Protein was quantified by Kjeldahl analyses and protein glucosamine contents were measured as one form of protein-starch complex (4). 

Figure 11, Protein-starch complexation in wheat flour extrudates as measured by glucosamine contents of SDS-soluble proteins and proteins released from insoluble residue by amylase. Extrusion runs are various combinations of 18, 21, and 24% moisture 145, 160, and 175 die temperature and 300, 375, and 425 rpm screw speed. Adapted from (4) with permission. Copyright American Assoc, of Cereal Chemists, 1996.

Feedstuffs consist largely of complex polymers (e.g. proteins, starches, fats) that must be hydrolyzed to the constituent building blocks before they can be absorbed and made available to the host. The digestibility of many plant proteins is inherently lower compared to proteins from animal tissues. This is particularly true for the structural proteins (Carbonaro et al, 2000 Mariotti et al, 1999). As a consequence, amino acid scores for many plant proteins often do not reflect true availability to the host (Mariotti et al, 2001). 

Carbohydrates form the major structural components of the cell walls. The most common form is cellulose which makes up over 30 per cent of the dry weight of wood. Other structural forms are hemicellulose (a mixed polymer of hexose and pentose sugars), pectins and chitin. Apart from contributing to the structure, some polymers also act as energy storage materials in living systems. Glycogen and starch form the major carbohydrate stores of animals and plants, respectively. Carbohydrate structure, like that of nucleic acids and proteins, is complex, and various levels of structure can be identified. 

XI. Starch Complexes with Macromolecules 1. Starch-Protein Complexes... 

Several observations indicate the formation of starch-protein complexes. For instance, starch precipitates serum proteins of rabbit, horse, sheep, and chicken.962 This observation seemingly indicates that the complexation has a rather universal character. On the other hand, the type of bonding of proteins from Triticum durum and Triticum sativum is specific for each of these varieties.963 The observed effects may not be associated with complex formation, but they can instead be attributed to the destruction of micelles by dehydration, followed by agglomeration.964 As in the case of starch complexes with sugars, the effect of proteins and cellulose derivatives on starch gelation can be assumed to be the result of the competition for water in solution. As a consequence, swelling is perturbed.965-968... 

The caryopses of grasses and cereals are anatomically complex. The starch endosperm of the caryopsis is surrounded by the aleurone layer and pericarp, both of which can be partly or completely removed, along with the embryo, by the abrasive process known as pearling, which removes the bran. The flour obtained by milling a pearled grain consists of protein, starches, and a low proportion of endospermic hemicellulose and non-endospermic hemicellulose from the bran. 

Condensed tannins, the polymerized products of flavan-3-ols and flavan-3,4-diols, form complexes with proteins, starch and digestive enzymes and may cause a reduction in the nutritional value of foods (Chung et al 1998). In fruit extracts, the tannins may cause precipitation in the presence of proteins. The high ability of the condensed tannins to form complexes with other food components reduces the extractability of those constituents from grapes and berries. 

Condensed tannins, flavan-3-ols (catechins) and flavan-3,4-diols (leucoanthocyanins) can form complexes with important nutrients as proteins, starch and digestive... 

To standardize how enzyme activities are expressed, the Enzyme Commission of the lUB proposed that the unit of enzyme activity be defined as the quantity of enzyme that catalyzes the reaction of 1 pmol of substrate per minute and that this unit be termed the international unit (U). Catalytic concentration is to be expressed in terms of U/L or kU/L, whichever gives the more convenient numerical value. In this chapter, the symbol U is used to denote the international unit. In those instances in which there is some uncertainty about the exact nature of the substrate or when there is difficulty in calculating the number of micromoles reacting (as with macromolecules such as starch, protein, and complex lipids), the unit is to be expressed in terms of the chemical group or residue measured in following the reaction (e.g., glucose units, or amino acid units formed). 

Zaleska, H., Ring, S., and Tomasik, P., Electrosynthesis of potato starch whey protein isolate complexes, Carbohydr. Polym., 45, 89, 2001b. 

Most stains consist of colored substances of natural origin belonging to the polyphenol, carotenoid, or chlorophyll class. Artificial food colorants, cosmetic ingredients, and decorative dyes complete the stain portfolio. Very often stains are complex mixtures of spilled food preparations or beverages. Combined with oils, fats, or other organic material, such as proteins, starch, or waxes, the properties of stains are quite different from those of isolated dyes. Only a small proportion of all stains is fixed on surfaces by physical adhesion. On fibers, in particular, strong interactions often result in covalent bond formation. This process is more important on cotton than on synthetic fabrics. 

Digestion Chemical process whereby complex chemical compounds such as proteins, starches, and complex carbohydrates are broken down into smaller, simpler molecules such as amino acids and simple sugars. 

Uses Starch complexing agenL protein complexing agent, softener in yeast-leavened bakery prods. conditioner in dehydrated potatoes RegiMory FDA 21CFR 172.844... 

Ethanol. Accurate projections of ethanol costs are much more difficult to make than are those for methanol. Large scale ethanol production would impact upon food costs and have important environmental consequences that are rarely cost-analyzed because of the complexity. Furthermore, for corn, the most likely large-scale feedstock, ethanol costs are strongly influenced by the credit assigned to the protein by-product remaining after the starch has been removed and converted to ethanol. 

Molecular Interactions. Various polysaccharides readily associate with other substances, including bile acids and cholesterol, proteins, small organic molecules, inorganic salts, and ions. Anionic polysaccharides form salts and chelate complexes with cations some neutral polysaccharides form complexes with inorganic salts and some interactions are stmcture specific. Starch amylose and the linear branches of amylopectin form inclusion complexes with several classes of polar molecules, including fatty acids, glycerides, alcohols, esters, ketones, and iodine/iodide. The absorbed molecule occupies the cavity of the amylose helix, which has the capacity to expand somewhat to accommodate larger molecules. The starch—Hpid complex is important in food systems. Whether similar inclusion complexes can form with any of the dietary fiber components is not known. 

In addition to plastics materials, many fibres, surface coatings and rubbers are also basically high polymers, whilst in nature itself there is an abundance of polymeric material. Proteins, cellulose, starch, lignin and natural rubber are high polymers. The detailed structures of these materials are complex and highly sophisticated in comparison the synthetic polymers produced by man are crude in the quality of their molecular architecture. 

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