1. Starch can be desalted with enzymes, while tapioca starch is difficult to be degraded by amylase.
2. The alpha-amylase may be inactivated by hydrogen peroxide and other oxidants at a pH between 4-10.5. In practical applications, some modified starches are added to the viscosity reducer of the original starch. The viscosity reducing agent is generally a peroxide. Generally, ammonium persulfate is used in many applications. These peroxides are prone to inactivation of amylase during desizing.Most of the industrial oxidized starch is sodium hypochlorite as an oxidant. The residual sodium hypochlorite also causes the inactivation of the amylase.
3. Metal ion Fe/Cu/Mn inhibits amylase
Hydrochloric acid is used in some modified starch production processes. The container used is typically an iron container. Metals are inevitably introduced into the starch during starch production. In the production process of amide-modified starch, copper chloride is used as a catalyst, which also causes residual copper ions in the modified starch.When the printing and dyeing plant is equipped with amylase working fluid, the rust in the cast iron water pipe, the metal ions in the container, etc. are all easy to introduce metal ions into the desizing process of the amylase. These metal ions inhibit the catalytic decomposition of starch by amylase to varying degrees.
4. To know if there is any fungicide in the slurry. Fungicides can deactivate enzymes.
5. The anionic surfactant has an inhibitory effect on amylase, and in particular, the chelating dispersing agent significantly reduces the desizing effect of the amylase.
6. Different modified starches have different rates of amylase decomposition
The decomposition rate of esterified starch such as acetate starch or phosphate starch is close to that of the original starch. The decomposition rate of oxidized starch is second, and the decomposition rate of cationic starch is the smallest. The phosphate starch produced by the dry process contains a large amount of phosphate. Since phosphate has metal complexation, it also has an adverse effect on amylase.
Conclusion: In the actual production process, some printing and dyeing factories carry out simple hot water washing before the enzyme desizing, and the desizing effect is obviously improved. For example, after the singeing is extinguished by three-layer hot water, the amylase is padded on the cold-rolled pile equipment; or after the hot water is washed in the jigger, the enzyme is desizing.
There are two reasons for the hot water washing to improve the desizing effect: 1 Washing removes residual impurities such as oxides, metal ions, bactericides, preservatives and the like against the amylase, and the peroxide also retreats during the washing process. 2 High temperature water washing has a puffing effect on starch, and is more conducive to the catalytic decomposition of amylase.