Maize milling facts for kids

Maize milling is how we turn maize (also known as corn) into food that's safe and tasty to eat. This can be done using big machines in factories or smaller machines and even by hand in homes.

First, the maize kernels are cleaned. Then, they are "conditioned" by soaking them in water. This helps to easily remove the outer skin (called the seed coat or pericarp) from the inside part (the endosperm). After this, the maize is ground into different types of flour or meal.

Cleaning and Conditioning Maize

Cleaning maize is a very important first step. It means taking out anything that isn't a maize kernel. This includes things like husks, straw, dust, and sand. We also remove anything too big or too small, or lighter than a maize kernel.

It's also important to remove poisonous seeds. And we take out things that could harm the milling machines, like metal pieces or stones.

What is Conditioning?

Conditioning means adding just the right amount of water to the maize. This makes the outer layer, called the bran, easier to peel off. When the maize is milled, the bran comes off in flakes. This makes it simple to separate the bran from the flour using a sifter. Adding moisture also helps to increase the weight of the final product.

How Maize is Milled and Sifted

After cleaning and conditioning, the maize is ready for milling. There are a few ways this can happen:

• Using Roller Mills: Many modern mills use roller mills to grind the maize. These machines have special rollers that crush the kernels. In a large maize milling factory, several roller mills work together. The first mills might remove the maize skin. Later mills grind the maize into smaller pieces, making fine flour. The larger pieces then go to the next mill for more grinding.
• Sifting the Meal: While the maize is being ground, machines called sifters separate the different parts. They can be double bin sifters or square plan sifters. Sifting helps to separate the fine flour from the bran. It also sorts the ground maize by size, making sure the flour is of good quality.

Packing the Final Products

Once the maize is processed, it becomes different products like flour or grits. These products are different based on how finely they are ground. For packing, special machines are used. These machines can automatically pack the flour into bags of different sizes, such as 5 kg, 10 kg, 25 kg, or 50 kg.

Getting the Best Quality Maize Meal

To get the best quality maize meal, a few things are important:

• Removing the Germ: First, the germ (the part of the kernel that would sprout) is removed before milling. This process is called de-germination.
• Using Roller Mills: Grinding the maize with roller mills usually gives better quality than using hammer mills or plate mills.
• Sifting is Key: Sifting is a very important part of the process. It helps to separate the different parts of the maize and ensure the flour is fine and smooth.

Types of Sifters

Different types of sifters are used depending on the size of the mill and the fineness needed:

• Turbo Sifters: These sifters are good for separating larger pieces. They have steel screens and can handle a lot of maize quickly. They are often used in smaller mills or to sort maize after de-germination.
• Rotary Sifters: These sifters use nylon screens and can sift very finely. They are used in smaller mills where very fine screening is needed.
• Mini Plan Sifters: These are good for medium-sized mills (from 1 to 2.5 tons per hour). They can sift a good amount of maize and produce very fine flour.
• Plan Sifters: These are used in very large mills (2.5 tons per hour and more). They can handle a huge amount of maize and provide very fine screening.

Mill Layouts

Large industrial mills can be built on one, two, three, or more levels. Using more levels helps to use gravity to move the maize between the different machines, like mills and sifters. This makes the process more efficient.

Sometimes, a small mill (processing 500-1,000 kg per hour) might be placed inside a shipping container. This is useful for special situations, like when there isn't a proper building, or if the mill needs to be moved often, or if it's in a very remote area.