Dextrins viscosity

Hydroxyethylstarch is widely used with synthetic latexes in the surface sizing of paper and as a coating binder. For these uses, the hydroxyethylstarch is acid-thinned, oxidized, or dextrinized. Hydroxypropylstarch is used in foods to provide viscosity stabiHty and to ensure water-holding during low temperature storage. 

The degree of polymerization of the reducing dextrine dropped rapidly to 10 and then slowly to 4. These findings are in accord with the observations of many investigators that the amylase of Aspergillus oryzae causes a very rapid decrease in the viscosities of its substrates and a very rapid disappearance of products which give color with iodine. 

JACS 68, 374(1946) CA 40, 3634(1946) (Nitration of dextrin starches with N2O5 in presence of Na fluoride) 5) G.V. Caesar et al, JACS 69, 617-21 (1947) CA 41, 3680(1947) (MW detns intrinsic viscosities of nitric triesters of dextrins corn starches)... 

Initial work began with testing various starches for encapsulation properties. Low viscosity, stable starch dextrins were first evaluated versus gum arabic for encapsulation efficiencies. Dispersions of corn and tapioca dextrins were used to encapsulate single fold orange oil. 

The starch dextrins match the viscosity and stability of the gum arabic when placed in solution, however other properties such as emulsifying and emulsion stabilizing properties are poorer in the dextrins. We believe that the emulsifying properties inherent in gum arabic are partially responsible for its encapsulating abilities. 

Gum arabic, standard starch dextrins and laboratory prepared low viscosity starch octenylsuccinates were used for all encapsulation work. 

Emulsions of lemon oil stabilized with gum arabic, a conventional starch dextrin and a low viscosity starch octenylsuccinate were spray-dried and evaluated for encapsulating efficiencies. Oil retentions and surface oil determinations were made according to the Materials and Methods section. TABLE 3 demonstrates the superiority of the starch octenylsuccinate in flavor retention and surface oil to gum arabic and a starch dextrin (5) ... 

As can be seen from the data in TABLE 5 the low viscosity starch octenyl-succinate closely matches the oxidation resistance of gum arabic. This product would offer improved shelf-life over a standard starch dextrin and similar stability to a gum arabic encapsulated flavor. 

Fig. I. Single-drum dryer (atmospheric). Dryers of this type may be dip or splash fed (not shown), or, as shown, equipped with applicator rolls. The latter is particularly effective for drying high-viscosity liquids or pasty materials, such as mashed potatoes, applesauce, fruit-starch mixtures, gelatin, dextrine-type adhesives, and various star dies. The applicator rolls eliminate void areas, permit drying between successive layers of fresh material and (omi me product sheet gradually. While single applications may dry to a lacy sheet or flakes, the multiple layers generally result in a product of uniform thickness and density with minimum dusting tendencies. (Bujiovak Division, BlawKnox Food Chemical Equipment. Inc)...

Measurement of the Viscosity.—This can be carried out either on the solution prepared in the cold or on that prepared in the hot. In the former case, 100 grams of the dextrin are shaken with 500 c.c. of distilled water at 17-5° until the whole of the soluble part has dissolved, the liquid being filtered through a dry filter and the filtrate tested in the Engler viscometer (see Vo I, p. 352). In the second case, the solution is prepared in the hot and the viscosity measured when cold. The value obtained is compared with that given by a standard dextrin under the same conditions. 

Starch pastes irradiated with 130,000 V, 15 mA X-rays lost their viscosity, and there was concurrent decrease of iodine-binding ability and pH. Other properties measured after such treatment point to dextrinization and oxidation of starch.78-79 Other results of such irradiation is the cleavage of phosphoric acid esters from glucose units of potato starch. This effect is observed at 50,000 V and 8 mA as well as at 150,000 V and 12 mA. The effect of X-ray irradiation is similar in this respect to irradiation with 7-rays, whereas neither sonication with ultrasound nor exposure to UV light evoke such effects.5 Starch irradiated by X-rays, contains free radicals, and thus the presence of free radicals in starch provides evidence of previous irradiation. 

Converted starches, also called thin-boiling starches, are produced by degradation of the starch chains into small segments. They can be cooked in water at higher concentrations than native starches. Low-viscosity starches are needed in applications where a high solid starch paste with a pumpable and workable viscosity is required. There are four classes of commercial converted starches dextrins (hydrolysis in solid-state) acid-modified starches (hydrolysis in a slurry) oxidized starches and enzymically depolymerized starches. 

Dextrins are produced by dry heating (roasting) starch in the presence of an acid catalyst. They are produced in a range of viscosity and color specifications. Dextrins are primarily used as adhesives in paper conversion, such as laminating and envelope production. A low-viscosity dextrin is used in Europe as a total chlorine free (TCF) coating binder for application on TCF paper. 

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