Starch Hygiene

The importance of starch hygiene in starch preparation systems.

Poor starch hygiene results in :-
Molecular breakdown
Loss of binding power
Variations in strength properties
Variations in retention
Variable coating viscosity
Surface sizing problems

Increased microbiological activity stems from :-

• More closed water systems in mills
• Ideal higher temperatures for growth
• Bigger machines / higher production speeds

The microbiological activity of the bacteria can be so fast that one can sometimes measure differences in viscosity within minutes.

Mill example (cationic wet-end starch 3.3% solution).

Viscosity after jet-cooker ~120 mPas.
Viscosity after 15 m3 storage tank ~100 mPas.

Addition point to the machine (150 m pipeline from the storage tank) ~ 1 mPas
i.e. fully degraded (= "water") 1-2 mins. later

This fast degradation by bacteria led to lost filler/fines retention, decreased machine speed, etc..

How to avoid problems :-

Proper design of starch preparation systems

Regular maintenance and cleaning of the starch preparation system

Storage temperature about 60ºC

Biocide use in cooked starch solutions