What enzyme products are needed in denim washing plants?

Enzyme treatment is one of the key processes in denim washing plants when producing effects such as distressing, aging, and softening. It can replace traditional stone washing and chemical rinsing, is more environmentally friendly and does not damage the fabric. The following are commonly used enzyme products and their functions:

1. Cellulase

Function: Decompose the cellulose fibers (cotton fibers) on the surface of denim, causing fading, fluffing (peach skin effect) and softening.

Type:

Acid cellulase (pH 4.5-5.5): Strong fading effect, suitable for medium to heavy distressing (such as "snowflake washing").

Neutral cellulase (pH 6-7): Milder, reduces indigo back-staining, and protects stitches.

Complex enzyme (containing cellulase + other enzymes): Improve efficiency, such as cellulase + laccase for decolorization of indigo denim.

Application:

Replace pumice stone (Stone Wash) for bio-stone washing (Bio-stone Wash).

Used together with pumice stone, it can reduce the amount of stone and reduce machine wear.

2. Laccase

Function: Oxidative degradation of indigo dye to achieve a simulated bleaching effect (no sodium hypochlorite required), which is environmentally friendly and does not damage the fiber.

Features:

Need to cooperate with a mediator (such as ABTS) to enhance the decolorization ability.

Can be used for "enzyme rinsing" to replace traditional chemical bleaching.

3. Amylase

Function: Remove the residual starch when denim is sizing, and improve the effect of subsequent enzyme washing (cellulase).

Application:

Usually used in the desizing stage, in combination with oxidative desizing or hot water desizing.

4. Catalase

Function: Decompose residual hydrogen peroxide (H₂O₂) to avoid affecting subsequent enzyme treatment or dyeing.

Application:

Used after the bleaching process to ensure the effect of subsequent cellulase or softener.

5. Protease

Function: Decompose protein impurities (such as natural wax in cotton fibers) and enhance fabric softness.

Application:

Rarely used alone, but often combined with other enzymes.

Example of enzyme treatment process

Desizing: amylase → hot water washing.

Enzyme washing: acid/neutral cellulase (+ pumice) → rinse (remove enzyme activity).

Bleaching (optional): laccase/hydrogen peroxide → catalase neutralization.

Softening finishing: silicone oil/soft oil.

Advantages vs. traditional process

Traditional process                     Enzyme treatment process

Stone washing (pumice)                 Biological stone washing (cellulase)

Sodium hypochlorite                    bleaching Laccase bleaching

Chemical desizing                      Amylase desizing

High water consumption/pollution         Water saving, reducing wastewater COD

Precautions

Temperature and pH control: Different enzymes have optimal activity ranges (such as cellulase usually 40-55℃).

Enzyme inactivation: After treatment, high temperature (80°C) or alkaline washing is required to completely terminate the enzyme reaction to prevent excessive damage.

Back-staining control: Neutral enzymes or anti-back-staining auxiliaries can reduce indigo reattachment (back-staining).

Enzyme treatment is an important technology for the denim washing industry to transform to green manufacturing. Reasonable selection of enzyme preparations can improve efficiency and reduce environmental burden.