Paper surface sizing by Starch Modified with Alpha-Amylase: a review

Sizing is generally the use of hydrophobic materials to modify the constituent behavior to improve the physical and mechanical properties of the paper. Starch is one of the most important materials used for this purpose because of its cheapness and biodegradability. In this study, it is investigated methods of starch modification in chemical, physical and enzymatic ways, depending on its application. Then, it is stated chemical, physical and enzymatic modification of starch for paper sizing. Finally, it is stated enzymatic modification of starch with α-amylase for paper making, the advantages and limitations of enzymatic starch with α-amylase as compared to cationic starch as the most consumed type of starch for paper sizing. In general, it is preferred paper surface sizing with enzymatic starch over other types due to use of native starch at the site of consumption, lower prices of native starch and consumed α-amylase, no formation of halogenated organic compounds (AOX) which is in oxidized starch preparation and no need to use lateral chemicals to modified and consumption, the use of enzymatic starch for paper surface sizing in developments countries. Therefore, it is advised to paper industries and researchers in the country to investigate these modifications.