Corn Starch

Corn Starch: How it Travels from Farm to Table

Corn starch is a versatile ingredient that is commonly used in many recipes, from homemade sauces and gravies, to desserts like meringues and puddings. While you may recognize the little blue box of cornstarch in your cupboard, you probably don’t consider how this beloved starch goes from farm to table. This blog post aims to shed some light on the fascinating, science-backed process which takes corn starch, or maize starch, from the fields to our dinner plates.

What is Corn Starch?

A cornerstone of many kitchens, cornstarch is derived from corn kernels through a process called wet milling. This type of milling involves soaking the kernels in water to begin separating out their starch content, which is then dried and finely ground into powder.

Corn Starch Components

Corn starch is a polysaccharide, made up of two types of polymers: amylose and amylopectin. Amylose is a linear glucose polymer, and amylopectin is a branched form of this polymer. Together, these polymers form a granular structure which gives cornstarch its unique properties.

The Science of Growing Corn

Before cornstarch can travel to our dinner plates, it must first be grown and harvested. Corn, or maize, is an annual grass that is native to North America and is one of the most widely cultivated cereal grains in the world. It is a deep-rooted crop that requires warm temperatures and plenty of moisture to grow. The corn plant goes through several stages of growth, and by the time it is ready to be harvested, it can reach up to eight feet in height.

Harvesting and Drying

Once the corn is mature and ready for harvest, the kernels are picked and dried. This is necessary not just to prevent spoilage, but also to maintain the high starch content of the kernels. A dry kernel contains around ? of its starch content, compared to less than ½ of a wet one. Drying is done with either air drying or mechanical drying and can take a few days to weeks, depending on the weather conditions.

Going Through Wet Milling

After the kernels are dried, they enter the first stage of wet milling - soaking. During this process, the hard outer husks of the kernel are removed, revealing the soft and starchy germ which enables further milling. The next step is a process called grinding, or slurry making. During this stage, the kernels are ground to a paste and mixed with hot water to form a slurry. This slurry is then passed through a process called hydrolysis which separates the starch molecules from smaller particles like protein and fiber.

Centrifuge Separation

In the third stage of the wet milling process, the starchy water produces in the previous step is put into a centrifuge, a rotating cylinder which spins at varying speeds to separate out the starch from other unwanted materials. Once this is complete, the starch is ready to be dried and ground into a powder.

Starch Drying

The next step is drying the starch. This is a critical step to make sure the cornstarch remains stable during storage and transport. There are several methods typically used to dry the starch, including pulsed air, microwave heating, freeze-drying, and spray drying. It’s also possible to use a combination of these methods. Spray drying is the most commonly used method since it can ensure a fine powder and eliminate pathogens, lowering the risk of food contamination.

Tests, Safety, and Packaging

Before the cornstarch is packed and shipped out, the manufacturer runs a series of tests to make sure that the final product meets safety and quality standards. These tests look for moisture content, starch solubility, and other characteristics.

Finally, the starch is packaged in either airtight bags or boxes and stored for transportation. In the U.S., cornstarch is transported via trucks and is tracked as a food commodity with the USDA's Grain Inspection and Feed Program.

From Farm to Plate

After the cornstarch has been fully processed, packaged, transported, and tested, it is delivered to the distributor and eventually sent to grocery stores or restaurants. From there, it finally arrives at your dinner plate.

Whether it’s used to thicken a stew or make a fluffy cake, cornstarch has certainly come a long way to make its way to your kitchen. The entire process of creating and transporting cornstarch relies heavily on both science and technology, and it is truly fascinating to consider the effort that goes into making a seemingly simple ingredient.