Anionic starches are modified starches that have negatively charged functional groups, typically carboxylate or sulfate groups, introduced into the starch molecules. This modification changes the properties of the starch, making it more water-soluble and negatively charged, which can have a significant impact on its functionality in various applications.
The anionic modification of starch is achieved by using different reagents, such as sodium hydroxide or sodium periodate, to introduce the negatively charged groups onto the starch molecules. The degree of modification can be controlled by adjusting the reaction conditions, such as the concentration of the reagents or the reaction time.
Applications
Anionic starches have a wide range of applications in various industries, including papermaking, textiles, and food. In the papermaking industry, anionic starches are used as wet-end additives to improve the strength and water resistance of paper, as well as to enhance the retention of fillers and other additives. Anionic starches can also be used as surface sizing agents to improve the surface strength and water resistance of the paper.
In the textile industry, anionic starches are used as sizing agents to improve the handling and processing of the fibers and to provide stiffness and body to the fabric. Anionic starches are also used as finishing agents to improve the wrinkle resistance and durability of the fabric.
In the food industry, anionic starches are used as thickeners, stabilizers, and emulsifiers in a wide range of products, including sauces, soups, dressings, and baked goods. Anionic starches can also be used as fat replacers, which can reduce the calorie content of foods while maintaining their texture and mouthfeel.
Overall, anionic starches are versatile and important modified starches that have found many applications in various industries due to their unique properties and functionality.