Starch Solubilisation
Enzymatic preparation of woven fabrics involves the targeted degradation of starch-based sizing agents applied during warp preparation. Modern finishing mills use alpha-amylase desizing to break down these insoluble starches into water-soluble dextrins before the scouring and bleaching stages. This biochemical reaction occurs without damaging the cellulose structure of cotton fibres.
The process stops when all accessible sizing compounds are fully digested and washed out, preventing chemical waste in downstream wet processing.
Reaction Temperature
Optimal performance of the liquid enzyme depends on maintaining a pH range between five and seven. Industrial alpha-amylase desizing requires specific thermal conditions to prevent the denaturation of the active proteins while ensuring high throughput. Steam chambers or pad-batch systems hold the wet fabric at seventy degrees Celsius to accelerate the molecular breakdown.
If the temperature exceeds eighty-five degrees Celsius, the catalyst fails.
Process Limit
Incomplete removal of the sizing agent creates a barrier to subsequent dyeing and finishing chemicals. Residual starch on the cotton yarn prevents uniform penetration of dyestuffs, which leads to streaky fabrics and uneven shades. Production teams check for this residue by applying a weak iodine solution to the treated fabric.
A blue stain indicates that starch remains.
Quality Check
Refractometer readings of the wash liquor provide a rapid measurement of the dissolved solids removed during the process. While the iodine test gives a qualitative visual indicator, gravimetric analysis of fabric weight loss yields the final commercial confirmation. This verification ensures the fabric is ready for the high-temperature alkaline baths of the scouring department.
