Starch dextrin complexes

Like the simple formazans, the formazans of oxidized polysaccharides form complexes with heavy metal salts with ease. On warming the formazans of oxidized cellulose, starch, dextrin, dextran, or inulin with copper, cobalt, nickel, or uranium salt solutions, their characteristically-colored metal complexes are obtained. The presence of carboxyl groups in the polysaccharide formazans frequently facilitates complex formation. ... 

Smith and coworkers - have subjected starch dextrins to the classical techniques of structural carbohydrate chemistry. In one study, four commercial maize-dextrins were fractionated from aqueous ethanol to obtain a sub-fraction which was the most resistant to periodate oxidation. This material was then methylated, the product hydrolyzed, and the resulting methylated sugars analyzed by column chromatography. Table II shows the results. The complexity of the dextrin structure is shown by the fact that only components 1, 2, and 5 arise in any large proportion from the methylation of maize starch. It is of interest that no traces of a methyl... 

Two methods were used one is the iodine method that was used to determine dextrinization or the ratio of hydrolysis of the starch, and the other is the phenolphifaalein method lhat was used to determine CD formation. Starch-dextrinizing activity was determined in accordance with Fuwa (19) and Pongasawasdi and Yagisawa (20) with slight modifications. The reaction mixture containing 100 (iL of diluted enzyme aliquot and 300 pL of 0.5% soluble starch prepared in 0.1 M acetate buffer, pH 5.5, was incubated at 55 °C for 10 min. The enzyme reaction was stopped by the addition of 4.0 mL of 0.2 M HCl solution. Then, 0.5 mL of iodine solution (0.3 g/L I2 and 3.0 g/L KI) was added to form an amylose-iodine complex with residual amylose. The final volume was adjusted to 10 mL with distilled water. The absorbance of the blue color of the amylose-iodine complex was measured by spectrophotometer at 700 nm, and a decrease in absorbance was verified, when compared to a control tube with heat-inactivated enzyme. One unit of enzyme activity was defined as the quantity of enzyme that reduces the blue color of the starch-iodine complex by 10% per minute. 

Preparation of Cyclic Dextrins bv Acetylation. Other methods for isolating the cyclic dextrins have been used. An early procedure utilized the differences in solubilities of the dextrin acetates (45). An enzymolysate of starch and macerans amylase was prepared by methods similar to those described above. The cyclic dextrins were precipitated from this enzymolysate with a complexing agent and the dextrin complexes which formed were collected by filtration and air-dried. The mixture of dextrins was acetylated with acetic anhydride in pyridine. A preferential crystallization of the dextrin derivatives was used to separate the derivatives and the individual dextrin acetates were obtained. Deacetylation of the derivatives is required to obtain the crystalline dextrins. 

Among enzyme modified starch derivatives,cyclo dextrins behave as empty molecular capsules with the ability to entrap guest molecules of appropriate geometry and polarity.The included molecules are protected from surroundings light, heat,oxidation, etc. The flavor cyclodextrin com -plexes show the above advantageous properties while they are in the dry,solld state.On contact with water,cyclodextrin complexes release their flavor content. In Hungary,the spice flavor beta-cyclodextrin complexes have been on the market, since 1982. 

Samec3,5 has conducted comparative studies on the effects of various types of radiation on the properties of the dextrins produced and found notable differences. The origin of the starch seems to be a factor of minor importance, at least upon sonication with 995 kc/s and 120 W. Potato and arrowroot starch gave similar results.309 The action of ultrasound on starch gels produces complex changes.312,313 The mechanism of disintegration has been discussed by Sozaburo.314... 

Complexes with Dextrins, Polysaccharide Gums, Alginates, Pectins, and Starch Derivatives... 

Poly(vinyl alcohol) is utilized as a component of starch-based adhesives.11121114 Other patents report the use of partially oxidized starch,1115 dextrins,1116 dextrins and urea,1117 borax,1118 boric acid,1119 and vinyl methyl ether-maleic acid copolymers.1120 Other patents indicate the use of poly (vinyl alcohol) with partially hydrolyzed poly(vinyl acetate),1121 nonhy-drolyzed poly(vinyl acetate),1122 and poly(vinyl chloride).1123 A few patents have reported such poly acrylic additives as poly (acrylic acid)1124 and its salts,1125 poly(acrylamide),1126 1127 A-methylacrylamide or poly(A-acryl-amide),1128 and polyethyleneimine.1129 Polystyrene has also been used,1130 as well as more complex copolymers such as a maleic acid monobutyl ester-methyl vinyl ether copolymer, together with dextrin and polyacrylamide),1131 carboxylated ethyl acrylate-styrene zinc salt copolymer,1132 ethylene-methyl acrylate-vinyl acetate copolymer,1133 vinyl acetate-vinyl pyr-rolidone copolymer,1134 and ethylene-vinyl acetate copolymer.1135 Some adhesives are compounded with SBR latex1136 1138 and phenol-formaldehyde resins.1139... 

Although the Tilden-Hudson test is very useful it has certain drawbacks in precise work, (a) The exact time at which needles appear is difficult to determine, (b) Enzyme activity is slowed but not stopped by the addition of iodine solution in fact, it is possible to add starch to a mixture of enzyme and iodine solution and observe the gradual formation of the crystalline dextrin-iodine complexes, (c) The apparent activity depends very much on the presence of such foreign materials as salts, n-glucose, maltose, etc., which may be present in the enzyme solution. In some enzyme preparations which seem to have fair activity, the needles are never observed. 

Karrer reports data for barium, sodium, and potassium complexes with the Schardinger dextrins, starch, and other carbohydrates. None of these materials were reported to be crystalline and it would seem that they would be of no value as characteristic derivatives. 

Since the discovery of the Schardinger dextrins, these cyclic compounds have been of special interest as they relate to starch. In the case of complex... 

Dextrins are the products of partial hydrolysis of starch. They are a complex mixture of molecules of different sizes. Those formed from amylose are unbranched chains, whereas amylopectins produce branched chains of glucose molecules. Erythrodextrins are larger branched dextrins that turn a reddish color on complexing iodine. 

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