Starch phosphorus

Potato starch usually contains 0.01-0.6% (w/w) phosphorus. Although phosphorus is present at very low levels, it has a significant effect on the physicochemical properties of starch. Phosphorus is in part responsible for the high swelling power, paste stability, and resistance to enzyme hydrolysis of potato starch. Potato starches contain significant amounts of monophosphate esters... 

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. 

Bromine is a dark red volatile liquid with a pungent odour. The vapour attacks the eyes and mucous membranes. It combines spontaneously and with deflagration with phosphorus, arsenic and potassium and with many other elements when warmed. It bleaches litmus and turns starch paper orange/yellow. 

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 ... 

Overall, the large number of significant differences among the fractions of all three bean types, reveals that the various minerals studied were not equally distributed among the fractions, except for sodium, but rather that partitioning occurred. Consistent with the ash values obtained, the protein flour fractions of the three bean types contained larger amounts of Fe, Mg, P, Z, and K whereas the starch II fractions contained smaller amounts of these minerals and Ca and Cu than the other flour fractions. Phytic acid content ranged from 8.7-30.2 mg/g for navy flours, from 4.3-23.7 mg/g for pinto flours. Total phosphorus content correlated well with both phytic acid content and protein content. Phytic acid content was... 

It is interesting to note that a similar scheme for making synthetic rubber was put forward many years ago. This Heinemann synthetic rubber process was essentially the production of levulinic acid from starch, its conversion with phosphorus pentasulfide into methylthiophene (XXXVII), which is reduced to 1,3-pentadiene. 

Most potato starches are composed of a mixture of two polysaccharides, a linear fraction, amylose, and a highly branched fraction, amylopectin. The content of amylose is between 15 and 25% for most starches. The ratio of amylose to amylopectin varies from one starch to another. The two polysaccharides are homoglucans with only two types of chain linkage, a-(l 4) in the main chain and a-(l 6)-linked branch chains. Physicochemical properties of potato and its starch are believed to be influenced by amylose and amylopectin content, molecular weight, and molecular weight distribution, chain length and its distribution, and phosphorus content (Jane and Chen, 1992). 

The phosphorus content can be determined by wet oxidation of the starch with sulfuric (or nitric) acid and hydrogen peroxide followed by colorimetric estimation of the phosphomolybdate complex. A detailed procedure for gravimetric determination can be found in AACC method 40-57 (AACC, 2000). However, large sample sizes (2-5 g) are required in this method. 

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

St = Starch POCI3 = Phosphorus oxychloride STMP = Sodium tri-metaphosphate EPI = Epichlorohydrin. (Source Singh etal, 2007)... 

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

In all types of starch small amounts of phosphorus are present owing to the part played by phosphoric compounds in the enzymatic processes of starch formation. Disregarding a few exceptions,.starch consists of two fundamental components ... 

If the fused element be shaken up with a warm liquid until cold, it furnishes the so-called granulated phosphorus. J. L. Casaseca recommended alcohol of sp. gr. 085 in preference to water R. Bottger, human urine, or an aq. soln. of urea N. Blondlot, soln. of various salts, or sugar and H. Schiff, methyl alcohol, actone, aq, ammonia, soln. of gum, dextrine, glue, starch, ammonium carbonate, etc. 

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