Enzymatically modified starch for paper surface sizing: Enzymes with different action modes and sites

Area of Science:

• Biochemistry
• Materials Science
• Pulp and Paper Technology

Background:

• Enzymatically modified starch is a key surface sizing agent for enhancing paper quality.
• Limited enzyme options exist for starch modification, primarily focusing on α-amylases.

Purpose of the Study:

• To evaluate various commercial enzymes for starch modification in paper surface sizing.
• To explore the enzymolysis mechanism and its impact on paper properties.

Main Methods:

• Starch modification using α-amylase (CSTWA), β-amylase (CSTWB), pullulanase (CSTWP), glucoamylase (CSTWG), and compound enzyme (CSTWAB).
• Comprehensive determination of paper performance and sizing agent properties.
• Molecular characterization of modified starch to understand enzymolysis.

Main Results:

• Enzymatic hydrolysis is most effective before starch gelatinization.
• β-amylase (CSTWB) and pullulanase (CSTWP) modified starches yielded higher paper strength due to suitable viscosity and molecular mass distribution.
• Glucoamylase (CSTWG) and compound enzyme (CSTWAB) resulted in excess low-molecular-mass molecules, reducing sizing effectiveness.

Conclusions:

• Pullulanase and β-amylase demonstrate superior potential as surface-sizing agents compared to α-amylase.
• Enzyme selection and hydrolysis conditions are critical for optimizing starch-based paper sizing agents.