Corn starch process

I've summarised the industrial process of making corn starch. This is a uphill task for me because of the numerous technical terms that i have to grasp. I had no choice but to google for these term, hoping that i can come up with alternative terms. So here it is

CLEANING
The corn has to go through a process called wet milling, the first step is to wash the corns twice. And at the same time, removing foreign particles and unwanted parts of the corn.

STEEPING
The corn is next soaked into large tanks of hot water for up to 50 hours. This step is for fermentation of the corn, sulphur dioxide is added at 1000ppm~2000ppm to control the fermentation. Steeping into sulphur dioxide enhances the fermentation because it inhibits unwanted micro organism while not affecting those that are required for fermentation.

STEEPWATER EVAPORATION
The water is drained and the kernels are dried by an evaporator. The steep water is recycled by making a concentrated fermentation liquid.

SO2 PLANT
Sulphuric acid is used for controlling microbial activities as well as to soften the corn kernels.


GERM SEPARATION
Next, the kernels are broken up by a mill and water is added to facilitate milling, this process forms a slurry. The germs should be released from the kernels without any damage to ensure none of the oil escapes.
The germs are separated from the slurry by a centrifuge and hydrocyclones. The germs are then washed and screened to remove any starch. The rest of the slurry are dried for further processing.

GERM DRYING
The water on the surface of the germs are removed by a tapered screw press. The semi-dried germs are then dried to approximately 4% moisture. Remaining fibre are removed and transported for storage.

FINE GRINDING AND SCREENING
After removing the germs, the dried slurry is then grounded to release starch and gluten from the endosperm. It goes through a fibre washing system to remove the starch and gluten. The product of this process is crude starch milk.

STARCH AND GLUTEN PRIMARY SEPARATION
The crude starch milk comprises of starch, gluten and other soluble. It’s processed by a safety strainer and de-gritting cyclone. Due to the different density of gluten and starch, centrifugal force can be used to separate them. Gluten enters the overflow while starch, the underflow.

STARCH REFINING
The crude starch milk is refined by washing with fresh water. By using strong hydroclones and centrifudge, the starch settles quickly. Again, this process can happen because of the different density of water, fibre and starch.
Impurities that are present together with the extracted starch are removed by sieve. This is the only known way to remove impurities from this last stage.

STARCH DEWATERING.
The extracted starch is then dewatered by passing through a peeler centrigudge. After this process, it is discharged to the moist starch hopper.

STARCH DRYING
From the hopper, the starch is fed into a flash dryer to dry in hot air. The dried starch with moisture of 12~13% is then sent for storage.[1]


[1]gmo corn - Google Search
http://home3.inet.tele.dk/starch/isi/starch/tm18www-corn.htm [accessed 25/6/08]