STADEX® 77 Corn Dextrin

White dextrins are used extensively in making adhesives for paper converting. They are frequently employed in combination with starches and other ingredients such as borax, alkaline materials, fillers, latices, resins, salts, humectants, preservatives, and defoamers. The proper selection of a dextrin for a specified application is important to the formulation of an effective adhesive.

• Carton/Case
• Sealing Bag Bottom
• Bag Seam
• Tube Winding
• Laminating
• Wall Covering
• Flat Gumming
• Envelope Seam
• School Paste
• Corrugating Carrier

In paper making, STADEX white dextrins are used at the size press or calendar stack for sizing specialty grades such as transparentizing parchment. They are especially useful in paper sizing when thin viscosities are required, and may also be used in paper coating mixtures as thin viscosity adhesives or water holding agents.

In the baking of breads and rolls, certain white dextrins can be used as dough improvers. In a related application they have been found useful in adding crispness to batters for breading fish and poultry.

Some white dextrins are used as binders in panning and extruding confections, and in binding spices, seasonings, colorings, etc. to food surfaces, e.g. dry roasted nuts.

In textile finishing, white dextrins are used as sizing or weighting agents to produce desired hand. They also aid in stabilizing reduced vat dye solutions to give proper color to dyestuffs, and may be used with print thickeners for screen and roller printing to improve print quality. In plisse printing, certain white dextrins act as thickeners in the caustic soda solutions used. Cord polishing formulas often employ dextrins to lay fibers and improve feel, while the sizing of fiberglass is accomplished with a minimum of migration. In this application, dextrin allows clean burn off.

STADEX white dextrins are useful in a large number of products requiring a liquid or dry binder. Typical examples include salt blocks and other function blocks, tablets and bars. They are also used as binders or fillers for functional coatings in high value items like garden seeds. In some fermentation processes, white dextrins have been utilized as a source of nutrients.

Although each dextrin demonstrates individual characteristics and differ in their selections, most of the STADEX canary dextrins can be used in adhesives for flat gumming and envelope seams. They may also be used to extend potato or tapioca dextrins in envelope seam or seal adhesives, and with waxy starches and animal glues in gummed tapes.

STADEX canary dextrins may be used to supplement white dextrins in carton and case sealing, and in tube winding and laminating adhesives to improve overall performance. They are compatible with latices and other materials commonly used in making prepared or ready-to-use adhesives.

Many of the STADEX canary dextrins demonstrate characteristics and properties which make them ideal for certain applications. The water absorbency of STADEX 124, for example, makes it an outstanding binder in ceramic greenware. Another dextrin, STADEX 140, is excellent as an adhesive for wall coverings, while STADEX 128 is recommended as a core binder for foundry castings and as an adhesive in leather pasting.

The mining industry makes use of STADEX canary dextrins as foam control agents to improve the efficiency of certain ore separation processes and, in the textile industry, they may be used as blanket adhesives when screen-printing fabrics.

Their use in foods includes the addition of certain canary dextrins to improve the handling quality of products such as frozen eggs. They may also be used as a functional adjuvant in certain drink mixes.

STADEX dextrins are available in 50 lb. packages in multi-walled, polylined paper bags.

Basic Properties
Dextrins are basically similar in structure to the parent starches from which they are derived. Viewed under the microscope, granules of starch and dextrin are of the same general size, though some fracturing and peeling of the dextrin granule is apparent. (See Insets A and B)

                  A. Corn Starch                                                 B. Corn Dextrin

When starch is heated in the presence of acid, the conversion to dextrin products begins. There is usually some residual moisture present at the start of the reaction. The moisture level, the acid concentration and the temperature of the reaction controls how much the starch structure is changed into dextrin over time. The viscosity of the dextrin paste will be thinner than that of the starch paste at the same solids level. The dextrin can therefore be cooked at a higher solids content to achieve viscosity parity. Generally, the viscosity increase of a dextrin paste upon cooling is less than that of its parent starch. This improved stability is an important feature of the STADEX dextrins.

As the dextrin conversion continues, heat tends to drive the residual moisture out of the reaction. Now a competing reaction called repolymerization (REPOL) begins at a significant rate. This is an acid catalyzed dehydration reaction that reconnects chains through glycosidic linkages, most of which are foreign to starch. Because some of these newly formed bands are different from the linkages normally found in starch, the properties of the dextrin become less like starch as the REPOL level becomes elevated. Most significantly, viscosity stability improves as REPOL increases. In other words, starch retrogradation decreases as REPOL increases. Other attributes of REPOL include increased water solubility and decreased caloric content (for food applications).

The other major property change, which occurs during dextrinization, involves an increase in the water solubility of the dextrin. Compared to starch granules, which show little or no solubility, dextrins are partially to almost completely soluble in water at room temperatures depending on the degree to which they’ve been hydrolyzed. (It should be noted that “water solubility” is not the same as “pregelatinization or precooking”, and even though some dextrins are highly water soluble, they must be cooked at elevated temperatures to completely develop their adhesive properties.)

Another obvious change that occurs during the conversion of a starch to a dextrin is its change in color. With roasting, the low to moderately converted white dextrin begins to turn off-white in color, frequently developing a buff tone. As the conversion process proceeds to produce a dextrin that is even more water soluble, it becomes more yellow in color and is commonly referred to as a canary dextrin. Color is not a significant contributor to dextrin functionality. In general, color formation in dextrins is most rapid during high rates of repolymerization. Color has been used in the past as an indirect measure of repolymerization and, therefore viscosity stability. Unfortunately, there are other mechanisms for color formation that do not parallel the repolymerization rate, making color an unreliable measure of viscosity stability. Primient measures the amount of REPOL directly by molecular weight analysis.

The product classification covering white dextrins includes a large number of products and a broad range of properties. It is generally marked by extremes of conversion from those that are only lightly converted to those that approach the very highly converted character of the canary dextrins.

In dry form, white dextrins are white to off-white in appearance, and when compared to powdered starch, their dispersion time in water is greater. (Smooth suspensions can be developed in room temperature water if good agitation is used.)

When cooked, fresh pastes are light to dark buff in appearance, depending upon the degree of conversion. As the pastes cool to room temperature they turn opaque, becoming nearly white.

Low conversion white dextrins have little viscosity stability, and when cooled, thicken or set-back to form soft gels. By contrast, high conversion white dextrins cook up to form pastes that congeal less, are more fluid, and exhibit better viscosity stability. (See Tables I, II, and III.)

Borax is the additive most commonly used to improve the performance of white dextrins as adhesives. It increases paste viscosity, improves viscosity stability, increases tack, and promotes quick drying. Because of the commercial importance of the borax response with dextrins, a special, borated viscosity test has been developed by the Primient as an added measure of control during production.

These borated viscosities (based on flow properties) are performed on in-process and finished STADEX dextrins. Table III illustrates the effect of borax on the viscosities of STADEX dextrins.

Canary dextrins range in appearance from pale yellow to buff in color. Their cooked pastes, which are somewhat darker than the dextrins themselves, have better clarity than pastes made from white dextrins. Films of canary dextrins exhibit a very high degree of clarity.

The water solubilities and other data pertaining to STADEX canary dextrins are shown in Tables II and III. Most of these products are highly converted and approach complete solubility in water. As a group, the outstanding viscosity stability of the STADEX canary dextrins allows them to be used at relatively high solids levels – up to 55 to 60 percent on a dry basis.

The borax response of the canary dextrins is similar to that exhibited by the typical white dextrin; there is pronounced thickening, improved stability, and increased tack. 

Storage conditions to achieve maximum shelf life : Store at ambient temperature and humidities. Storage in a cool, dry area will increase shelf life.