Production of cornstarch

In producing cornstarch, the corn is inspected and cleaned, then place in vats, where it is steeped in warm water containing a small concentration of sulfur dioxide for about 40 hr, to begin breaking the starch and protein bonds.

The kernel swells to more than double the size and increases its moisture content from about 15% to 45%. The softened kernels are next run through an attrition mill to break up the kernels.

If not previously degerminated the steeped kernels are passed through mills that separate the germ and loosen the hull. The germ is removed by density separation in a cyclone.

The mass is then passed through tanks of water where the germs (being lighter) float and are skimmed off. The remaining endosperm, containing starch, corn gluten and hulls is then finely ground in steel mills.

The finely ground material is then passed through sifters to remove hulls, the starch and gluten passing through. The starch is separate from gluten by centrifugation. The starch-gluten suspension is concentrated by centrifugation and the higher and lower densities of gluten and starch facilitate centrifugal separation, again in a cyclone.

The gluten is dried and the starch is washed and dewatered. With hydrocyclones and a centrifuge the starch settles and separates from the water and fibers.

The starch fraction is finally dried to yield the familiar cornstarch. Cornstarch can be used as such in manufacture foods or be further converted into corn syrup by the hydrolytic action of acid or starch-splitting enzymes.
Production of cornstarch

Manufacturing of popcorn

Almost all of the popcorn consumed throughout the world in grown in the United States.

Popcorn is ideally harvested when the moisture content of the grain is about 17%. Unlike most of other grains, the outer hull of the popcorn kernel is both strong and impervious to moisture and the starch inside consists almost entirely of hard, dense type.

Once the grain is harvested, it is slowly dried using aeration and low heat. This slow drying, low heat method is used to avoid kernel breakage and damage while reducing the moisture content to about 13.5 to 14% which is ideal for popping.

The kernels of popcorn are smaller than flint corn. When heated rapidly, they turn the moisture in the kernel, which has a moisture-proof hull, into a superheated pressured steam.

The pressure continues to increase until the breaking point of the hull is reached: a pressure of about 135 psi and a temperature of 180 °C. This pressure burst the outer shell and the entire inside of the kernel puffs into a mass of flaky starch.

Upon popping, the volume is 25 to 30 times greater than original kernel.
Manufacturing of popcorn