Hydrophobic starch is a modified starch that has been chemically altered to become water-resistant or hydrophobic. This type of starch is produced by reacting natural starch with a variety of reagents, such as octenyl succinic anhydride (OSA), 2,3-epoxypropyltrimethylammonium chloride (EPTAC), and various fatty acid derivatives, to introduce hydrophobic functional groups onto the starch molecule.
One of the most common methods of producing hydrophobic starch is through the reaction of starch with OSA. This reaction introduces octenyl succinic acid (OSA) groups onto the starch molecule, which have both hydrophobic and hydrophilic properties. The hydrophobicity of OSA-starch is determined by the degree of substitution, which is the number of OSA groups per glucose unit.
The properties of hydrophobic starch depend on the degree of substitution, the type of reagent used, and the type of starch that is modified. Generally, hydrophobic starch has improved water resistance, better dispersion in water, and improved emulsion stability. It is also more resistant to microbial degradation and can be used in a wider range of applications than natural starch.
Hydrophobic starch has a wide range of applications in various industries. It is commonly used in the papermaking industry as a coating agent to improve the water resistance of paper and paper products. It can also be used as an emulsifier and stabilizer in the food industry, as well as in the textile and adhesive industries. In addition, hydrophobic starch can be used as a carrier for controlled release of active ingredients in pharmaceuticals and agrochemicals.
However, despite its potential, hydrophobic starch is not commonly used in papermaking, as it is more expensive than other commonly used additives, such as polyvinyl alcohol (PVA) or carboxymethyl cellulose (CMC). Furthermore, the use of hydrophobic starch may require additional processing steps and equipment, which can add to the production costs.