Modified starch is an additive prepared by treating starch or starch granules, causing the starch to be partially degraded. Modified starch is used as a thickening agent, stabilizer, or an emulsifier. Apart from food products, modified starch also find use in paper manufacturing, Pharmaceuticals, Textiles and various other industrial applications. Starches are modified to increase their stability against excessive heart, acid, and freezing to change their texture or to lengthen or shorten gelatinization time.
Cationic starches represent a unique class of high performance starch derivatives which have gained commercial acceptance because of their affinity towards negatively charged substrate such as cellulose, aqueous suspensions of minerals and slimes and biologically active macromolecules. They have already found extensive use in the paper manufacture in which they function as internal binders and retention aids for various fillers and emulsions and are added to the paper furnish before the sheet is formed. They are effective for improving such physical properties of paper as bursting and tensile strength, elongation, fold endurance, and pick resistance. Usually 0.5% to 1% addition of cooked cationic starch, gives the same improvement in the paper as does 1.5% to 2% addition of corn starch. Other benefits of the cationic starches are improved drainage on the wire, better sheet formation and enhancement of the sizing efficiency of an alum rosin size. Cationic starches also improve the retention of fillers such as titanium dioxide, clay, calcium carbonate which are frequently incorporated in the furnish to improve the opacity of high grade printing papers, fine writing papers, light weight papers such as bread wraps, glassine, etc. With increasing filler retention, the sheet loses strength because inert fillers reduce the number of sites for fiber to fiber bonding. Because cationic starch acts both to improve strength properties and filler retention. Its use gives high strength properties at higher level of filler retention.