Dextrin’s are normally prepared by roasting starch in the presence of acid which materially changes the character and properties of starch. Chemically they are intermediate between starch and sugars derived from starch.
Unlike starch, dextrins are soluble in water. The severity of the heat and acid treatment determines the degree of solubility, which is the basis for classifying or grading dextrins.
Finished dextrins are very fine, powder varying in colour from pure white to light yellow.As dextrins do not easily react with chemicals, they are specially suitable for application in the textile field. In textiles printing, they are used as thickeners. Free of grit and other impurities, which usually accompany lower grades of starch, they ensure that the copper rolls (used in printing) do not suffer from abrasion. In sizing, they are used with starch for increased adhesiveness. In finishing, they give desired feel and handle to the fabric.