Dextrins (Pyrodextrins & Maltodextrins)

Properties and Applications

Dextrins are a group of lower molecular weight carbohydrates obtained by heating starch in the presence of acid and moisture which results in slight depolymerization (hydrolysis) of the starch. Dextrins are more water-soluble than unmodified starch and when dissolved in water produce less viscose solutions. Depending on the reaction conditions such as temperature, time, type and concentration of acid catalyst, a number of different dextrins can be produced. They can be broadly categorized as pyrodextrins and maltodextrins according to the method of dextrinization. Pyrodextrins are prepared from acid hydrolysis and heat treatment whereas maltodextrins are  prepared from acid hydrolysis followed by enzymatic hydrolysis of the acid hydrolysate.¹ The three most important grades are

• White dextrins - prepared by hydrolyzing starch at low temperature for a shorter duration

• Yellow dextrins - prepared by hydrolyzing starch at higher temperature for a longer duration

• British Gum - prepared at high temperatures in the absence of acid catalyst

British gums are much darker in color than yellow dextrins and are very soluble in both cold and hot water whereas
white dextrins are only slightly soluble in cold water but are very soluble in hot water. Both yellow and white dextrins have a much lower solution viscosity than British gum.

Dextrins are non-toxic, fully biodegradable and eco-friendly. They are extensively used as low-cost watersoluble adhesives and binders for paper products such as remoistenable envelope adhesives, wallpaper and cardboard glues, and consumer tapes. These adhesives cure through the loss of water. Only white dextrins and only small amounts of it are used in food and pharmaceuticals. They function as film formers, binders, thickeners and tackifiers.

Manufacturers & Distributors

¹Reference: United States Patent 2012/0035355A1