Alpha Amylase for Paper and Board Starch Coating Viscosity Control
Controlled alpha amylase hydrolysis converts cooked starch into precisely thinned coating fluids for surface sizing, size press, and board coating — improving runnability and surface quality.
Surface sizing and coating starch applied to paper and board must meet narrow viscosity windows to run reliably on film presses, size press rolls, coater blades, and curtain coaters. Native cooked starch at high concentration is far too viscous and unstable for direct application — it requires controlled thinning (conversion) to reach the target viscosity and maintain it reliably across the application temperature range of 55–75°C. Alpha amylase for paper starch coating is the precision tool for this conversion, hydrolyising cooked starch to a defined degree that achieves target viscosity without over-thinning or batch-to-batch variation.
Our Bacillus amyloliquefaciens–derived alpha amylase for paper and board coating converts cooked corn, tapioca, or potato starch at concentrations of 12–25% dry solids in the starch cooking vessel. Enzyme is added to the hot cooked starch at 85–95°C and held for a controlled time (typically 10–30 minutes) until the target Brabender viscosity or Brookfield viscosity is reached. The reaction is then stopped by raising temperature (enzyme inactivation at 100°C) or by rapid cooling. This enzymatic conversion method is more precise and reproducible than acid-thinning methods, which can produce inconsistent viscosity and surface sizing performance.
The converted starch is then applied to the paper web at the size press or surface sizing station, typically at 65–80°C. The starch penetrates the paper surface, improving internal bond strength, pick resistance, IGT strength, and printability. For pigment coating applications, enzyme-converted starch is used as a co-binder in blade or curtain coating formulations where its lower viscosity allows higher pigment loading without sacrificing binder distribution.
Paper mill procurement and technical teams evaluate alpha amylase for starch conversion on control of viscosity endpoint, reproducibility between batches, compatibility with calcium carbonate pigments and starch types, and food-grade or industrial-grade documentation. We supply COA, TDS, and relevant safety data per lot. MOQ 25 kg; bulk pricing for paper mill contract supply.
Surface Sizing Starch Conversion on Film Press
Film press sizing requires starch at precise viscosity (Brookfield 50–150 mPa·s at 60°C) for consistent film split and uniform coat weight. Cooked starch at 15–20% DS is treated with alpha amylase (0.02–0.10 kg/t dry starch) at 85–90°C for 15–25 minutes under controlled agitation. Enzyme inactivation is achieved by holding at 95–100°C for 5 minutes before the starch is pumped to the film press. Consistent enzyme dosage and reaction time are essential to maintain the viscosity specification within ±10 mPa·s across production shifts.
Starch Co-Binder for Blade Coating
In pigment-coated paper and board production, enzyme-converted starch serves as a co-binder alongside latex in the blade coating formulation. Converted starch at viscosity 20–80 mPa·s is blended with pigment (calcium carbonate, kaolin) and binder at up to 8–12 parts per 100 parts pigment. The lower viscosity of enzyme-converted starch, compared to oxidised or acid-thinned starch, allows higher total solids in the coating mix and better blade rheology. This contributes to smoother coating surfaces and improved ink holdout in offset and inkjet printing grades.
Board Starch Adhesive for Corrugating
Corrugated board adhesive requires cooked starch with controlled viscosity for reliable application at the corrugator. Alpha amylase is used in some corrugating board operations to reduce viscosity of carrier starch in the Stein Hall adhesive formula, improving metering and wetting of the corrugating medium flutes at high machine speeds. Precise control over enzyme dosage and reaction time prevents over-thinning, which would reduce bond strength. This application is particularly relevant in lightweight board grades where adhesive viscosity affects structural performance.
Packaging Board Internal Sizing
Internal sizing of food-grade paperboard with converted starch improves water resistance and reduces water absorption (Cobb value) without requiring synthetic sizing agents. Alpha amylase–converted starch at 10–18% DS is added to the wet-end furnish or size press as a functional coating. This is particularly important for food packaging board where regulatory restrictions limit the use of some synthetic sizing chemicals, making enzyme-converted starch an effective and clean-label alternative.
| Parameter | Value |
| Activity range | 50,000 – 200,000 U/g (multiple grades) |
| Optimal pH | 5.5 – 7.0 |
| Optimal temperature | 70°C – 95°C |
| Form | Light brown powder or amber liquid |
| Shelf life | 12 months (sealed, cool, dry place) |
| Packaging | 25 kg drums / 30 kg jerricans |
Frequently Asked Questions
How does alpha amylase thin starch for paper coating?
Alpha amylase hydrolyses internal α-1,4 bonds in cooked starch chains, reducing molecular weight and therefore viscosity. The process is controlled by enzyme dosage, reaction temperature, and time. Small doses produce modest viscosity reduction (mild conversion for surface sizing); higher doses produce more extensive hydrolysis for low-viscosity coating applications. By adjusting dosage and stopping the reaction (via heat inactivation at 100°C), paper mills can hit specific Brookfield or Brabender viscosity targets reproducibly — batch after batch — across different starch types and concentrations.
What viscosity target should I aim for in surface sizing?
Surface sizing viscosity targets depend on the application system. Film press applications typically require 50–150 mPa·s (Brookfield, spindle 1, 60 rpm, at 60°C). Size press applications may accept up to 300 mPa·s. Blade coating starch co-binder requires 20–80 mPa·s at application temperature. Your paper machine technical team will have a viscosity specification for the target coat weight and coating speed. We recommend confirming the viscosity target and then calibrating enzyme dosage against your starch type and cooking system in laboratory trials before plant-scale rollout.
Is enzyme conversion better than acid or oxidative thinning?
Enzymatic thinning with alpha amylase offers more precise viscosity control, better batch-to-batch reproducibility, and a narrower molecular weight distribution in the converted starch compared to acid or hypochlorite thinning methods. It avoids the corrosion and safety concerns of acid handling and the colour formation and yellowing associated with oxidative thinning. The resulting enzyme-converted starch typically has better coat coverage, improved retention, and cleaner wastewater compared to chemically thinned starch. The main requirement is careful control of enzyme dosage and reaction time to hit the viscosity target consistently.
What starch types can alpha amylase be used with for paper coating?
Bacillus-derived alpha amylase for paper coating is compatible with corn starch, tapioca starch, potato starch, and wheat starch — the four most common starch types used in paper surface sizing and coating. Different starch types have different intrinsic viscosity profiles after cooking, so the enzyme dosage needed to hit a target Brookfield viscosity will vary between corn and potato starch, for example. We recommend running viscosity calibration curves for each starch type in use before setting a fixed dosage for production.
Request Alpha Amylase for Paper Starch Conversion
Specify substrate (flour, mash, starch slurry, fabric, coating), process temperature, pH, and target DE or dosage. We will advise on powder vs liquid and standard vs thermostable grade, ship a free 100 g sample with COA, and quote bulk pricing within 24 hours.
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