What is added to corn to make it digestible?

November 14, 2025 •

4 min read

For centuries, indigenous peoples in Mesoamerica knew that simply cooking corn was not enough to unlock its full nutritional potential and avoid deficiencies like pellagra. It was an ancient technique called nixtamalization, or treating corn with an alkaline substance, that revolutionized its use and answered the question of what is added to corn to make it digestible.

Quick Summary

The digestibility of corn is enhanced by nixtamalization, a process of cooking corn kernels in an alkaline solution such as food-grade lime or ash. This treatment breaks down the tough outer hull, releases nutrients like niacin, and allows the corn to be ground into a dough called masa.

Key Points

Nixtamalization is key: Cooking corn kernels in an alkaline solution, like lime (calcium hydroxide), is the traditional method to make it digestible for humans.
Alkaline treatment breaks down the hull: The process softens the tough outer pericarp of the corn kernel, allowing for easier digestion and nutrient absorption.
Niacin is unlocked: Nixtamalization releases bound niacin, a vital nutrient, from the corn, which prevents deficiency diseases like pellagra.
Industrial processes use enzymes: For animal feed, enzymes like alpha-amylase and mechanical methods such as steam-flaking are used to improve corn's digestibility and energy yield.
Untreated corn is less nutritious: Consuming unprocessed corn does not allow for full absorption of its nutrients due to the indigestible hull and bound niacin.
Processed corn becomes masa: Nixtamalized corn can be ground into masa, a pliable dough used to make tortillas and tamales, which is not possible with untreated cornmeal.

Nixtamalization: The Ancient Solution

Nixtamalization is the primary method for making corn digestible, a process discovered thousands of years ago in Mesoamerica. It involves cooking and soaking dried corn kernels in an alkaline solution. This simple but critical step dramatically transforms corn, addressing several key issues related to its nutrition and texture. The most common alkaline substance added for this purpose is food-grade lime, or calcium hydroxide.

The Chemistry Behind Nixtamalization

When corn is cooked in a highly alkaline solution, a series of chemical changes occur that make the kernel more useful and nutritious:

Breaks Down the Pericarp: The alkaline solution, with the aid of heat, dissolves the hemicellulose in the kernel's cell walls. This softens and loosens the tough outer skin, known as the pericarp or hull. Once loose, the pericarp can be easily washed away.
Unlocks Niacin: Niacin (Vitamin B3) in untreated corn is bound to a complex carbohydrate, making it largely unavailable for human absorption. Nixtamalization frees this niacin, preventing deficiency diseases like pellagra, which plagued European cultures that adopted corn without this critical processing step.
Increases Nutrient Absorption: The process also makes other nutrients, like certain amino acids and minerals, more bioavailable. For example, calcium is absorbed from the lime, enriching the corn's mineral content.
Improves Texture and Grinding: Nixtamalized kernels become softer and can be ground into a cohesive, pliable dough called masa. This dough is essential for making tortillas, tamales, and other classic corn-based foods. Untreated cornmeal will not form a proper dough.
Reduces Mycotoxins: Nixtamalization helps to significantly reduce levels of harmful mycotoxins, which are toxins produced by fungi that can contaminate corn crops.

Modern vs. Traditional Nixtamalization

While the underlying principles remain the same, the application of nixtamalization has evolved from a traditional, household chore to a large-scale industrial process. A traditional method might involve soaking corn in a solution of wood ash, but modern industrial methods primarily use food-grade lime. In either case, the treated kernels are rinsed and processed further.

Mechanical Processing and Enzymes

For products where nixtamalization is not used, or as an additional step, other methods help increase corn's digestibility. These methods are particularly relevant for animal feed but also play a role in human food production.

Mechanical Breakdown

Simply breaking the corn kernel can increase its digestibility, primarily by exposing the starchy endosperm to digestive enzymes.

Grinding or Rolling: Reduces the corn into smaller particles like flour or grits. This increases the surface area, making the starch more accessible to digestive enzymes. The finer the grind, the greater the digestibility.
Steam-Flaking: A process that involves treating corn with steam and then rolling it into flakes. The heat and moisture gelatinize the starch, making it highly fermentable and digestible. This is a very common method for animal feed production.

Enzymatic Treatments

In some industrial applications, particularly for animal feed, specific enzymes are added to break down corn more efficiently. These enzymes can be added during processing or even incorporated into the corn hybrid itself, as is the case with some specialized livestock corn.

Alpha-Amylase: This enzyme is added to break down starch into smaller sugars, improving energy utilization. Studies have shown that adding alpha-amylase during extrusion of corn for piglets can significantly enhance nutrient digestibility and growth performance.
Multienzyme Preparations: Some feed producers use a cocktail of enzymes to enhance the digestibility of various corn components, including starch and non-starch polysaccharides. This can improve overall nutrient absorption in animals.

Comparison of Processing Methods


Feature	Nixtamalized Corn (Hominy/Masa)	Unprocessed Corn (Fresh or Dried)	Mechanically Processed Corn (Ground/Flaked)
Key Additive	Alkaline solution (lime/ash)	Water only	None, but processing aids digestion
Main Action	Alkaline cooking and steeping	Cooking (boiling, roasting)	Physical breakdown (grinding, rolling)
Nutritional Impact	Frees niacin, adds calcium, reduces mycotoxins	Niacin largely unavailable; potential mycotoxin risk	Increases starch availability, but doesn't add nutrients or address niacin deficiency
Digestibility	Highly digestible for humans and animals	Indigestible cellulose hull remains; low nutrient bioavailability	Improved starch digestibility due to increased surface area, but depends on fineness
Culinary Use	Masa for tortillas, tamales; whole hominy for stews	Corn on the cob, popcorn	Cornmeal for cornbread, grits
Final Product	Masa dough, hominy	Sweet corn, popcorn	Cornmeal, grits, corn flour

Conclusion

When considering what is added to corn to make it digestible, the answer largely depends on the intended purpose. For human consumption, particularly in traditional cultures that depend on corn as a staple, the essential addition is an alkaline solution, like calcium hydroxide (lime), through the nixtamalization process. This critical technique not only makes corn digestible but also significantly enhances its nutritional value by releasing bound niacin. For animal feed, the primary methods involve physical and enzymatic treatments, such as grinding, flaking, and adding supplemental enzymes like alpha-amylase, to maximize energy absorption from the starch. In all cases, processing is key to unlocking corn's full potential, whether it's through a timeless alkaline bath or modern industrial methods. To learn more about the ancient roots of this practice, refer to the informative work on nixtamalization by PuraVeda.

Frequently Asked Questions

Unprocessed corn kernels have a tough, fibrous outer shell called the pericarp, which is made of cellulose. The human digestive system cannot break down this cellulose, meaning the inner parts of the kernel are not fully digested.

Nixtamalization is an ancient Mesoamerican process where dried corn is cooked and soaked in an alkaline solution, traditionally made with lime (calcium hydroxide) or wood ash.

The alkalinity of the lime solution dissolves the corn's tough outer hull, softens the kernel, and releases bound nutrients like niacin, making them more available for absorption by the body.

Masa harina is a flour made from nixtamalized corn. After being treated with an alkaline solution, the kernels are ground into a dough called masa, which is then dried and ground into flour.

The main health benefits include enhanced bioavailability of niacin (preventing pellagra), increased calcium content, and the reduction of mycotoxins.

No, commercially produced corn tortillas are typically already made from masa harina, which means the corn has already undergone the nixtamalization process.

Yes, in industrial settings, especially for animal feed, specific enzymes like alpha-amylase may be added to corn during processing (like extrusion) to increase starch digestibility.