Phosphorus starch phosphate content

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

To explain the variation in the phosphate content of starches, it is postulated that some plants contain a specific phosphatase such an enzyme would have to possess unusual powers of penetration, since R-en-zyme, for example, cannot attack the interior of an amylopectin molecule. Moreover, a considerable proportion of the phosphorus would be situated in outer chains there is no evidence for this. (5) The formation of waxy-type starches is attributed to a low activity of the debranching enzyme caused by the presence of an inhibitor(s) to the debranching mechanism or by a deficiency of the debranching enzyme. Waxy-type starches should, therefore, contain a higher degree of branching than that actually observed (about 5%). 

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],... 

Of the esters, starch phosphate is produced by reaction with phosphorus oxychloride, polyphosphates, or metaphosphates a cross-bonded product results. Total degree of substitution is determined by measuring the phosphorus content, and the mono- to disubstitution ratio can be calculated by potentio-metric titration. Allowance is made for the natural phosphorus content of the starch. Treatment of starch with acetic anhydride produces starch acetate, which has improved paste stability over native starch. The acetyl group is very labile, and hydrolyses readily under mild alkaline conditions. When a known amount of alkali is used, the excess can be titrated and the ester function measured. This is not specific, however, and a method based on an enzymatic measurement of the acetate has been developed in an ISO work group. The modified starch is hydrolyzed under acidic conditions, which releases acetic acid and permits filtration of the resulting solution. Acetic acid is then measured by a commercially available enzyme test kit. Both bound and free acetyl groups can be measured, and the method is applicable... 

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. 

Anionic dyes readily adsorb on starch (Tables XXXIX-XLIII).802 However, there is evidence that this rule is violated in the case of potato starch.802-803 The simplest intepretation of this fact has been presented in terms of the phosphate groups present in potato starch. A relationship exists between the phosphorus content in potato starch and the sorption capacity of that starch for Methylene Blue. The sorption follows the Langmuir isotherm. Extrapolation of the result to 0% phosphate leads to the conclusion that no Methylene Blue would be adsorbed on phosphate-free starch.804 Methylene Blue is better adsorbed on potato starch, but is also... 

As some fractions of the limit dextrins produced by the common amylases have a much higher phosphorus content than starch, the author assumed that the substitution with phosphoric acid is one of the anomalies postulated as the cause of the limit dextrin formation. That the phosphoric acid acts in this way is evident from the investigations of Posternak, who isolated a tetraose phosphate from a mixture of limit dextrins. On acid hydrolysis this gave D-glucose 6-phosphate. 

Most amylases have only a slight action on the phosphate groups. As mentioned before, the 3-dextrin from potato starch contains all the phosphorus of the starch. This is in accordance with the fact that the phosphorus is concentrated in the amylopectin. A /3-dextrin from arrow-root starch had a phosphorus content of 0.051 % while the starch itself had 0.019%. Since the /3-dextrin corresponds to 40% of the starch, it is evident that here also all the phosphorus is left in the /3-dextrin. 

Samec and coworkers have differentiated between the fractions on the basis of phosphorus content. Undoubtedly, organic phosphate is associated primarily with the B-fraction of potato starch, contributing polarity to that component. In the case of corn starch, the distinction is not as sharp, since the total phosphorus content is very much lower. Also, it is possible to separate the B-fraction of corn starch into subfractions of high and low phosphorus content, and these do not differ materially in. solubility behavior or alkali lability. Thus phosphorus is believed to constitute only a minor difference between the fractions. 

In Asia, oriental noodles play an important role in the diet. Similar to pasta products, oriental noodles manufactured from wheat flours are considered an important source of calories. Practically all the caloric load is supplied by starch and gluten proteins. Alkali noodles contain significant amounts of potassium carbonates, bicarbonates, and phosphates used to impart typical flavors, aroma, texture, and colors. These salts increase sodium, phosphorus, and potassium levels. Wonton or egg noodles contain higher protein content, quality, and overall nutritional value due to the addition of whole eggs. 

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