Why is calcium hydroxide in tortilla chips? The nixtamalization story

October 23, 2025 •

3 min read

For thousands of years, Mesoamerican civilizations used a cooking process called nixtamalization to unlock the nutritional power of maize. This ancient technique, which involves soaking corn kernels in an alkaline solution containing calcium hydroxide, is the very reason for the distinct flavor, ideal texture, and boosted nutritional profile found in modern tortilla chips.

Quick Summary

Calcium hydroxide is the key ingredient in nixtamalization, an ancient corn preparation method. It fundamentally changes corn's properties, enhancing texture and flavor while boosting the nutritional content, particularly niacin, and improving food safety.

Key Points

Nixtamalization: The primary reason calcium hydroxide is used is to prepare corn in a process called nixtamalization, an ancient Mesoamerican technique.
Nutrient Bioavailability: The alkaline solution unlocks bound niacin (vitamin B3), making it available for absorption and preventing diseases like pellagra.
Enhanced Texture: Nixtamalization softens the corn's outer hull, or pericarp, and alters the starch to create a workable, cohesive masa dough.
Increased Calcium: The corn kernels absorb calcium from the lime-water, increasing the overall calcium content of the final product.
Improved Safety: The process is highly effective at reducing the presence of harmful mycotoxins like fumonisins and also mitigates the formation of acrylamide during frying.
Distinct Flavor: Calcium hydroxide imparts a characteristic flavor and aroma to corn products that is fundamental to authentic tortillas and chips.

The Ancient Technique: Nixtamalization

Nixtamalization is a pre-Columbian process that permanently altered the nutritional landscape of maize-based diets. The term itself comes from the Nahuatl language, combining words for 'ashes' ($nextli$) and 'cooked maize dough' ($tamalli$). This is because the earliest practitioners, including the Aztecs and Maya, discovered they could cook and steep corn kernels in a water-based alkaline solution derived from wood ash, or in modern times, food-grade calcium hydroxide. This simple yet revolutionary step is what transforms raw corn kernels into the versatile, nutritious nixtamal from which masa dough is made. That same masa dough is then used to create tortillas, tamales, and, of course, tortilla chips.

The nixtamalization process typically involves cooking dried corn kernels in an alkaline solution, often between 70-90°C, followed by steeping for several hours or overnight. After steeping, the kernels are washed to remove the outer skin (pericarp) and excess alkaline solution before being ground into masa dough. This masa is then used to make tortillas or tortilla chips.

Key Functional Roles of Calcium Hydroxide

Calcium hydroxide, also known as 'cal' or slaked lime, plays several crucial roles in creating the characteristics of a tortilla chip. Its alkaline nature facilitates chemical changes essential for the process.

Here are some of its primary functions:

Pericarp Removal: The alkalinity helps remove the tough outer skin of the corn kernel, resulting in a more tender product.
Masa Cohesiveness: Calcium ions strengthen the protein network in the corn, helping to create a pliable masa dough that can be shaped without crumbling.
Flavor and Aroma: Nixtamalization contributes to the distinct flavor and aroma associated with authentic Mexican corn products.
Reduced Acrylamide: Calcium cations can help reduce the formation of acrylamide during the frying process by controlling pH and affecting the Maillard reaction.

The Nutritional Revolution of Corn

Before nixtamalization, diets heavily reliant on corn could lead to pellagra, a niacin deficiency disease. Calcium hydroxide fundamentally improves corn's nutritional profile.

Enhanced Nutrient Availability

Niacin (Vitamin B3): The process significantly increases the bioavailability of niacin. It releases niacin bound in raw corn, making it digestible and preventing pellagra.
Calcium Content: Corn kernels absorb calcium from the solution, substantially increasing the final product's calcium content.
Reduced Antinutrients: Nixtamalization lowers levels of phytic acid, improving the absorption of minerals like iron and zinc.
Protein Digestibility: The digestibility of corn protein is enhanced, increasing the availability of tryptophan, which the body can convert to niacin.

Mycotoxin Reduction

Nixtamalization is effective in reducing mycotoxins like fumonisins and aflatoxins that can contaminate corn, improving food safety. This is achieved through extraction and chemical changes to the toxins.

Nixtamalized vs. Non-Nixtamalized Corn Products

Comparing nixtamalized and non-nixtamalized corn products highlights the impact of calcium hydroxide and the nixtamalization process.


Feature	Nixtamalized Corn Products (Tortilla Chips, Tortillas)	Non-Nixtamalized Corn Products (Cornbread, Polenta)
Texture	Soft, cohesive, and pliable; masa dough holds its shape and makes for a sturdy chip.	Dry, crumbly texture; ground cornmeal requires other ingredients to bind effectively.
Flavor	A distinct, earthy flavor often described as richer and more complex.	Simple, starchy corn flavor; can be bland by comparison.
Niacin (Vitamin B3)	Bioavailable and easily absorbed, preventing pellagra.	Bound and mostly indigestible, with little to no bioavailability.
Calcium Content	Higher calcium content due to absorption from the alkaline solution.	Low calcium content, same as raw corn.
Mycotoxins	Levels of mycotoxins like fumonisins are significantly reduced.	Mycotoxins are retained and can be concentrated in certain milled fractions.
Masa Formation	Easily forms a dough for shaping into chips or tortillas.	Does not form a cohesive dough; results in a gruel-like consistency.

Conclusion: More Than Just a Chip

Calcium hydroxide is a vital ingredient in tortilla chips due to its role in nixtamalization, an ancient technique that dramatically enhances corn's flavor, texture, and nutritional value. This process makes essential nutrients like niacin available and improves food safety by reducing toxins. The next time you enjoy a tortilla chip, consider the historical and scientific significance of this ingredient and process.

For more insight into the historical and scientific importance of nixtamalization, the International Maize and Wheat Improvement Center (CIMMYT) offers extensive resources.

Frequently Asked Questions

Nixtamalization is the process of cooking and soaking corn kernels in an alkaline solution, typically water mixed with calcium hydroxide, which softens the corn, enhances its nutritional value, and improves its flavor and texture.

Yes, food-grade calcium hydroxide is safe for consumption in the small, regulated amounts used during nixtamalization. Regulatory bodies like the U.S. FDA have approved its use as a food additive.

In raw corn, most niacin is in a bound, indigestible form called 'niacytin'. The alkaline environment of nixtamalization chemically frees this bound niacin, making it available for the human body to absorb and use.

It helps soften the corn kernels by loosening the outer pericarp, and aids in the gelatinization of starch. This results in a cohesive masa dough that produces the firm yet crisp texture characteristic of tortilla chips.

Yes, during the cooking and steeping process, the corn kernels absorb calcium from the calcium hydroxide solution, leading to a significant increase in the product's calcium content.

Nixtamalization significantly reduces harmful mycotoxins that can contaminate corn crops. Additionally, the process can help mitigate the formation of acrylamide, a potential carcinogen, when the chips are fried.

The recipe for nixtamalization was not transmitted with corn to Europe, resulting in populations that relied heavily on unprocessed corn developing pellagra, a disease caused by niacin deficiency. This highlights the critical importance of the process.