Maize milling is the processing of

maize Maize ( ; ''Zea mays'' subsp. ''mays'', from es, maíz after tnq, mahiz), also known as corn (North American and Australian English), is a cereal grain first domesticated by indigenous peoples in southern Mexico about 10,000 years ago. Th ...

(corn) for safe and palatable consumption as

food Food is any substance consumed by an organism for nutritional support. Food is usually of plant, animal, or fungal origin, and contains essential nutrients, such as carbohydrates, fats, proteins, vitamins, or minerals. The substance is inge ...

. Processing can be by machine-milling in either large- or small-scale mills, or by hand-milling in domestic or community settings. The maize is first cleaned and then "conditioned", or "tempered", by soaking the kernels in water. This facilitates the separation of the seed coat and

pericarp Fruit anatomy is the plant anatomy of the internal structure of fruit. Fruits are the mature ovary or ovaries of one or more flowers. They are found in three main anatomical categories: aggregate fruits, multiple fruits, and simple fruits. Aggre ...

from the

endosperm The endosperm is a tissue produced inside the seeds of most of the flowering plants following double fertilization. It is triploid (meaning three chromosome sets per nucleus) in most species, which may be auxin-driven. It surrounds the embryo and ...

. Further processing consists of separating components of the grain, and grinding it into various grades.

Cleaning and conditioning

Cleaning and conditioning of the

is an important step in the process and refers to the removal of foreign material and all that is not maize kernels from the to-be milled grain that lowers the quality of the product such as

husk Husk (or hull) in botany is the outer shell or coating of a seed. In the United States, the term husk often refers to the leafy outer covering of an ear of maize (corn) as it grows on the plant. Literally, a husk or hull includes the protective ...

straw Straw is an agricultural byproduct consisting of the dry stalks of cereal plants after the grain and chaff have been removed. It makes up about half of the yield of cereal crops such as barley, oats, rice, rye and wheat. It has a number ...

dust Dust is made of fine particles of solid matter. On Earth, it generally consists of particles in the atmosphere that come from various sources such as soil lifted by wind (an aeolian process), volcanic eruptions, and pollution. Dust in homes ...

sand Sand is a granular material composed of finely divided mineral particles. Sand has various compositions but is defined by its grain size. Sand grains are smaller than gravel and coarser than silt. Sand can also refer to a textural class of s ...

, and everything too big or too small and lighter than a maize kernel. It also refers to the removal of poisonous seeds, and material harmful to the milling equipment such as

metal A metal (from Greek μέταλλον ''métallon'', "mine, quarry, metal") is a material that, when freshly prepared, polished, or fractured, shows a lustrous appearance, and conducts electricity and heat relatively well. Metals are typicall ...

and

stones In geology, rock (or stone) is any naturally occurring solid mass or aggregate of minerals or mineraloid matter. It is categorized by the minerals included, its chemical composition, and the way in which it is formed. Rocks form the Earth's o ...

Conditioning Conditioning may refer to: Science, computing, and technology * Air conditioning, the removal of heat from indoor air for thermal comfort ** Automobile air conditioning, air conditioning in a vehicle ** Ice storage air conditioning, air condition ...

refers to the addition of moisture to the

to allow the

bran Bran, also known as miller's bran, is the hard outer layers of Cereal, cereal grain. It consists of the combined aleurone and pericarp. Corn (maize) bran also includes the pedicel (tip cap). Along with cereal germ, germ, it is an integral pa ...

to be peeled off in flakes during milling with plate or roller mills, allowing easy separation in a

sifter A sieve, fine mesh strainer, or sift, is a device for separating wanted elements from unwanted material or for controlling the particle size distribution of a sample, using a screen such as a woven mesh or net or perforated sheet material. T ...

and, most importantly, to add mass to the meal.

Milling and sifting

Following this process, milling can commence and may take several forms: * Adopt the

roller mill Roller mills are mills that use cylindrical rollers, either in opposing pairs or against flat plates, to crush or grind various materials, such as grain, ore, gravel, plastic, and others. Roller grain mills are an alternative to traditiona ...

to grinding the grain, the

has single

, double

and pneumatic

, the mill adopt the grinding roller to work. In a complete maize milling plant, there are several

that work together, they have different functions, the first mill mainly peeling the maize skin, the second and third will grinding the

into granular size, and meanwhile to get some super fine

flour Flour is a powder made by grinding raw grains, roots, beans, nuts, or seeds. Flours are used to make many different foods. Cereal flour, particularly wheat flour, is the main ingredient of bread, which is a staple food for many culture ...

, and the granular sized product will go to the next mill to continue grinding. * While grinding time, use double bin sifter or square plan sifter to sift the meal from the

miller A miller is a person who operates a Gristmill, mill, a machine to grind a grain (for example corn or wheat) to make flour. Mill (grinding), Milling is among the oldest of human occupations. "Miller", "Milne" and other variants are common surname ...

, classification and sifting more super flour. In general, the sifting used to separate the flour and bran, also separate large size and small size to ensure flour quality.

Final product packing

After the

is processed, it will come out in different final products like

and

grits Grits are a type of porridge made from boiled cornmeal. Hominy grits are a type of grits made from hominy – corn that has been treated with an alkali in a process called nixtamalization, with the pericarp (ovary wall) removed. Grits are oft ...

. They are different from their granular size. For the packing, a Full-auto Flour Packing Machine is adopted, and the

is packed into 5 kg, 10 kg, 25 kg or 50 kg bags.

Best quality maize

The best quality

meal is therefore obtained by: De-germinating the

prior to milling Milling with rollers rather than

hammer mill A hammer mill, hammer forge or hammer works was a workshop in the pre- industrial era that was typically used to manufacture semi-finished, wrought iron products or, sometimes, finished agricultural or mining tools, or military weapons. The feat ...

s or plate mills/

disc mill A disc mill is a type of crusher that can be used to grind, cut, shear, shred, fiberize, pulverize, granulate, crack, rub, curl, fluff, twist, hull, blend, or refine. It works in a similar manner to the ancient Buhrstone mill in that the feedstock ...

s. Alternatively, if the budget is small, the whole

, after cleaning and conditioning, may be milled by means of the plate mill only and then sifted (without de-germination). A significant part of the bran and germ meal would then be sifted off, resulting in a Special Sifted meal - of lower quality than roller milled meal and higher quality than hammer milled meal. A further element of major importance is

sifting A sieve, fine mesh strainer, or sift, is a device for separating wanted elements from unwanted material or for controlling the particle size distribution of a sample, using a screen such as a woven mesh or net or perforated sheet material. ...

. Milling and

, form the very essence of grain processing. The sifters in every system should be one or more of the following: * Turbo sifters - two separation horizontally shafted with steel screens - high capacity but not sifting very fine - used in small capacity plate mill systems and as graders for samp and other primary grading after de-germinators. * Rotary sifters - three separation horizontally shafted with nylon screens - lower capacity but very fine screening - used in small capacity plate mill systems. * Mini plan sifters - relatively high capacity and very fine screening used as primary sifters for all

mills Mills is the plural form of mill, but may also refer to: As a name * Mills (surname), a common family name of English or Gaelic origin * Mills (given name) *Mills, a fictional British secret agent in a trilogy by writer Manning O'Brine Places Uni ...

of 1 ton per hour to 2.5 tons per hour. * Plan sifters in various sizes and numbers of passages: Very high capacity and fine screening - used in all

with capacity of 2.5 ton per hour and more. Industrial type mills can be constructed over one level, two levels, three levels or more, as existing buildings determine or as practical as the solution may be. High capacity mills normally require more levels to make use of gravity in moving product between mills and sifters. Another option to consider, is to place a small mill (500-1,000 kg/h) in a container. This is only recommended for special applications where buildings are problematic, where the mill needs to be moved from time to time to another location, where temporary power is used and where the mill is located in very remote areas.

References

as of 15 July 2010 {{corn Maize * Food processing