Phosphorus, in starch

Lim, S. T., Kasemsuwan, T., Jane, J. L. (1994). Characterization of phosphorus in starch by 31P nuclear magnetic spectroscopy. Cereal Chemistry, 71, 468M72. 

Phosphorus in starch is found in different forms, mainly starch phosphate monoester, phospholipids, and inorganic phosphate. 31P NMR spectroscopy was used to identify each of these forms in alpha-dextrins prepared from starches of different sources.128 Quantitative analysis was possible in DMSO solution. 

Jane, J., Kasemsuwan, E, Chen, J. F., Juliano, B. O. (1996). Phosphorus in rice and other starches. Cereal Foods World, 41, 827-832. 

Phosphorus Content in Starch Phosphates and Degree of Substitution with Phosphoric Acid Moieties22... 

Almost all the starches investigated contain some phosphorus.124-126 In addition to phospholipids, phosphorus is also commonly found in starch as monostarch phosphate esters.6,7 Inorganic phosphate is present in some starches.124-126 Monostarch phosphate esters and phospholipids have different effects on starch paste properties.133,135 Monostarch phosphate esters, found in potato, shoti and other starches,6,7,136-140 increase paste clarity and paste viscosity.79 Little phosphate monoester is found in cereal starch.121,124,141,142 Phospholipids, found in normal cereal starches (e.g. wheat, rice and maize) decrease paste clarity and viscosity.133 31P-nmr spectroscopy has... 

Swinkels29 collected published characterization data for tapioca starch and compared it to that for other starches of commercial significance (Table 12.4). Tapioca starch is differentiated from other starches by its low level of residual materials (fat, protein, ash), lower amylose content than for other amylose-containing starches, and high molecular weights of amylose and amylopectin. The small amount of phosphorus in tapioca starch is partially removable30 and, therefore, not bound as the phosphate ester as in potato starch. It is also common to find protein and lipid values of zero, as reported by Hicks.31 The very low protein and lipid content is an important factor which differentiates tapioca starch from the cereal starches. 

Phosphate Determine the residual phosphate (calculated as P) in starch phosphate, distarch phosphate, and phosphated distarch phosphate as directed under Phosphorus, Appendix IIIB. 

Generally, the phosphorus content in starches is associated with different pasting properties, and it confers a larger ion binding capacity. In wheat and com starch, phosphorus is present largely or wholly as adsorbed phos-phatides (extractable with boiling 85% methanol) associated preferentially with the amylose fraction. 

The properties displayed by a starch triacetate, or by other starch esters are dependent upon the type and molecular weight of the starch or starch fraction used for the esterification. The properties may also be influenced by trace constituents or impurities such as compounds of nitrogen and phosphorus which are often observed in starch esters. While the nature of the nitrogenous constituent is not known, it has been demonstrated that much of the phosphorus of potato starch exists as a natural phosphoric ester of the amylopectin fraction. It is not surprising, therefore, that the phosphorus of potato starch is carried through an esterification and may influence the properties of the starch ester. The exact modifying effects of these components on the properties of starch esters, however, are still to be explained. 

Many starches contain small proportions of phosphorus which is not solvent-extractable but is present as phosphate ester of the C-6-hydroxyl group of a few n-glucose residues. Potato starch contains about 0.1% of phosphorus, most of which (0.08%) is present in the amylopectin component. Cereal starches may contain only 0.02% of phosphorus. The origin of the phosphorus in potato starch is not known. One possibility, wliich has not been examined experimentally, is that traces of n-glucose 1,6-diphosphate are incorporated into the polysaccharides by P-enzyme or by starch-UDPglucosyl transferase. 

Phosphoras structures and contents in starches vary with the botanical source, maturity and growing conditions of the plant. Most normal cereal starches contain phosphorus in the form of phospholipids, whereas phosphorus in root and tuber starches is in the form of starch phosphate monoesters [2],... 

Lead tetraacetate is added in small quantities, with stirring, to an ice-cold suspension of 11 g. of ethyl 3-(D-arabino-tetrahydroxybutyl)-5-methyl 4-furoate in 100 ml. of benzene plus 40 ml. of glacial acetic acid. Addition is stopped when there is a positive reaction with potassium iodide-starch paper. The mixture is stirred for a further ten minutes, filtered, and the benzene solution washed twice with water. The benzene layer is then dried with anhydrous sodium sulfate, filtered, and the filtrate evaporated to dryness. The residue (6 g.) is mixed with a solution of 7.5 g. of sodium hydroxide plus 20 g. of silver nitrate in 40 ml. of water, and heated for 40 minutes on a steam bath. The aqueous solution is filtered, acidified to Congo Red while being cooled with ice, and the crystals formed are removed by filtration, washed with ice-cold water, and dried over phosphorus pentoxide in the vacuum desiccator yield, 2.2 g. After recrystallization from water, the product has m. p. 234r-235°. 

All of the studies were conducted with weanling, male albino rats of the Sprague-Dawley strain (Holtzman company). The basal diet used for these studies consisted of casein, starch, vegetable oil, vitamin and mineral mixtures, and cellulose. The Wesson Modification of the Osborne-Mendel mineral mixture was used in all studies. This mineral mixture contained no zinc, but it was adequate in the other minerals required by the rat. Most of the non-zinc-supplemented diets used in the various experiments contained approximately 7 ppm zinc. The level of mineral mixture used in the basal diets was 4%, and based on the chemical composition of the mixture, the basal diets contained approximately 0.57% calcium and 0.41% phosphorus ... 

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