The Spaniards first brought the word
"cake") to Mexico; the Mexicans, in turn, used it to
describe their flat corn and flour cakes. The bread staple of the Mexican
diet, all tortillas were originally made from the pulp of ground corn, the
native grain of the New World. When the Spanish brought wheat to the New
World, white flour tortillas became prevalent. Corn tortillas, now mostly
machine-made, still hold the highest nutritional value. Cut into wedges
and deep fried, these flat cakes became tortilla chips. After tortilla
products were first introduced in the United States by Latin Americans
living in the southwestern states, the popularity of new food item spread
rapidly. Tortilla chips can come in many different sizes and shapes, such
as triangles, rounds, and rectangular strips. The seasonings of tortilla
chips can vary greatly, and they can be eaten with a variety of salsas and
The basic method of tortilla and tortilla chip production has changed
little since ancient times. Traditional tortilla preparation involves
cooking the corn in pots over a fire, steeping (soaking) for 8 to 16
hours, pouring off the cooking liquor or nejayote, and washing the
nixtamal (the end product of the cooking, steeping, and washing/draining
process). The nixtamal is then ground into masa (dried and ground corn
flour) with hand-operated grinders or metates (grinding stones). The masa
is either hand-molded or molded using a tortilla press to form thin disks,
which are then baked on a hot griddle called a
One of the most important industrial advancements has been the production
of dry masa flour, a shelf-stable product. This dry flour has become
popular because it meets standards for certain applications, reduces
requirements for energy, labor, floor space, processing time, and
equipment, and is convenient and easy to use. When compared with fresh
masa flour, however, foods made from dry masa flour tend to be less
flavorful and the cost per unit is higher. Smaller manufacturers that
supply local restaurants with tortilla chips usually use dry masa flour,
while larger manufacturers use fresh masa flour that is produced on-site.
Tortilla chips are made using yellow corn, white corn, flour, whole wheat,
or blue cornmeal. Coarse masa is used in making corn tortilla chips. Masa
consists of corn that has been soaked in a food-grade lime and water
solution to break down the hulls; the kernels are then ground into flour.
Frying oil, salt, and various seasonings complete the list of main
ingredients. Other ingredients, such as preservatives, emulsifiers, gums,
and acidulants, are used mainly in the United States to improve shelf life
and to maintain certain properties of the product. The characteristics of
the raw material determine the tortilla chips' quality, cooking
parameters, and color.
Preparing the masa (dough)
1 The first major process in tortilla chip manufacturing is the
production of coarse masa or dough. In a typical mixture, 2.5 to 3.0
liters of water, 1 kilogram of 12 percent moist com, and 0.01 kilogram
of food-grade lime (usually quicklime or hydrated lime) are
added together in a large industrial cooker. The lime is used primarily
as an aid in removing the pericarp (hull or skin) during cooking and
steeping. The lime also helps to increase the product shelf life by
controlling microbial activity, and it affects the flavor, aroma, color,
and nutritional value of the chips.
To make tortilla chips, manufacturers first mix the raw
ingredients—water, moist corn, and lime—to form the
masa or dough. Next, the mixture is heated in a large kettle such as
a Hamilton kettle, which is heated indirectly by steam. After
steeping, which allows water to be absorbed, the solution is washed
and pumped onto a conveyor belt for transport to the grinder.
2 This mixture is then batch-cooked in either a Hamilton steam kettle or
a vertical closed cooker. The Hamilton kettle is indirectly heated by
steam, and the grain contents are mechanically agitated. It is designed
for cooking at or near the boiling point of the lime-water-corn
solution. An elaborate agitation system ensures the uniform transfer of
heat by condensing steam through the kettle wall and into the
limewater-corn solution. The capacity of these steam-jacketed kettles
ranges from 300 to 595 pounds (136 to 270 kilograms). The vertical
closed cooker uses direct steam injection to heat and agitate the
lime-water-corn solution in a large tank, which serves for both cooking
and steeping. Additional agitation is accomplished with compressed air.
Because this system is designed for cooking at temperatures well below
the solution boiling point (185 degrees Fahrenheit or 85 degrees
Celsius), the cooking time is longer than in the Hamilton steam kettles.
The capacity of the vertical cookers ranges from 3,000 to 6,000 pounds
(1,360 to 2,730 kilograms). Cooking time can vary greatly from a few
minutes to a half hour, depending upon which system is used. In general,
temperatures above 155 degrees Fahrenheit (68 degrees Celsius) are
considered to be the optimum cooking temperatures. Cooking depends on
the characteristics of the corn and
the interaction of time, temperature, lime concentration, cooking
vessel size, and agitation. Nixtamal used for fried products is
generally cooked less than nixtamal used for table tortillas.
3 Immediately after cooking, the solution is quenched (rapidly cooled)
to about 154 to 162 degrees Fahrenheit (68-72 degrees Celsius). This
lower temperature decreases water absorption during the steeping process
and the cooking time of the nixtamal. The result is a more consistent
masa, which absorbs less oil during frying.
4 The grain is then steeped for 8 to 16 hours in the cooking vat (if a
vertical cooker was used) or transferred to a holding vat (if a Hamilton
steam kettle was used). The steeping process allows water to be
absorbed, which helps to disintegrate the hull and soften the kernel.
During the steeping process, the temperature is dropped to 104 degrees
Fahrenheit (40 degrees Celsius).
5 After steeping, the solution is pumped into the washers. The cooking
liquor is drained off, and the resulting nixtamal is washed with
pressurized water or spraying systems. Most of the pericarp and excess
lime is removed during this step. Washing in commercial processes is
done in two types of equipment: the drum washer and the
"lowboy" system. A drum washer consists of a conveyor that
transports the nixtamal into a rotating perforated cylinder with
internal flights and water sprayers located within the drum. After
spraying, the nixtamal passes into a drain conveyor, where the excess
water is removed. The lowboy system consists of a receptacle equipped
with internal screens and sprayers. The washed nixtamal is continuously
removed from the bottom of the receptacle by an inclined belt conveyor.
In both systems, a conveyor transports the washed, drained nixtamal into
a hopper, which then feeds the stone grinder. The end result, using the
typical corn and lime mixture, will be 54 ounces (1.53 kilograms) of 47
percent moist nixtamal.
6 The washed nixtamal is then ground using two matched carved stones,
one stationary and the other rotating at about 500 to 700 rpm. The
stones are usually composed of lava or volcanic materials, although they
can also consist of synthetic materials made of aluminum oxide (Ak203).
For optimum efficiency, the lava stones must be frequently recarved; the
synthetic stones last longer and require less recarving. A typical stone
is 10 centimeters thick and 40 centimeters in diameter and has radial
grooves. The grooves become more shallow as they approach the perimeter
of the stone. The number, design, and depth of the grooves in the stones
vary with the intended product: stones carved for the production of
table tortillas have more shallow grooves to produce a finer masa,
whereas coarser masa for tortilla chips comes from deeper-grooved
The grinding or milling starts when a screw conveyor at the base of
the hopper forces the nixtamal through a center opening and into the
gap between the stones, where shearing occurs. The material travels
outward from the center to the perimeter of the stones. Water added
during milling cools the stones, prevents excessive wear, and reduces
the masa temperature. For a grinder with a capacity of 600 kg/hr,
about 0.6 to 1.2 liters of water per minute (0.16-0.32 gpm) is added.
This amount of water increases the masa moisture content to the
optimum for sheeting. Like the grinding stones, the moisture content
depends upon the resulting product. The masa particle size is the
result of several interacting factors: degree of nixtamal cooking;
size and depth of the grooves in the grinding stones; gap or pressure
between the grinding stones; amount of water used. during milling; and
the type of corn used. The grinding breaks up the kernel structure and
promotes "plastic" and cohesive properties in the masa.
Once the masa is produced, it is important to use it immediately or to
protect it against moisture loss. After grinding, the resulting
mixture will be 1.65 kilograms of 51 percent moist coarse masa.
7 Next, actual chips are produced using the coarse masa, which is
kneaded and mixed into plastic masa by mixers and extruders and then fed
to sheeter rolls. The plastic masa is sheeted into a thin layer, which
is then cut or forced into a specific configuration; the thickness of
the sheet determines the final product weight. The sheeting starts when
the masa is fed onto a pair of smooth rollers, usually
coated with Teflon, one rotating counter-clockwise and the other
clockwise. The gap between the rollers is adjustable, so that products
of different thicknesses can be produced. The masa is forced between the
rolls and separated by wires located on the front and back rolls. The
back wire cleans the sheeted masa from the back roll and allows it to
adhere to the front roll, and the front wire or wires strip the masa
pieces from the roll. The cutter rotates underneath the front roll.
Different cutter configurations (triangular, circular, rectangular,
etc.) are used for various products. Copper or plastic bands surround
the end of the first roll and help to recycle excess masa. The masa
pieces leave the front roller on a discharge belt, which feeds directly
into the oven.
The washed solution is ground using two matched carved stones, one
stationary and the other rotating. From there, the resulting coarse
masa is cut into actual chips. The masa is fed onto a pair of smooth
rollers, usually coated with Teflon, one rotating counterclockwise
and the other clockwise. The masa is forced between the rolls, cut,
and discharged into the oven for baking. After frying and seasoning,
the chips are packaged accordingly.
Baking and cooling
8 A three-tiered gas-fired oven is used to bake the formed masa.
Generally, the chips are baked at temperatures ranging from 500 to 554
degrees Fahrenheit (260-290 degrees Celsius), with the baking time
varying from 35 to 50 seconds. Baking enhances the alkaline flavor and
reduces moisture and oil absorption during frying.
9 The tortilla chips are then cooled by moving through a series of open
tiers or cooling racks. The chips are sometimes cooled for up to 20
minutes before frying to produce a more uniform consistency and to
reduce blistering during frying. During this cooling process, the chips
lose additional moisture (up to 3 percent), and the moisture within each
chip becomes more evenly distributed.
Frying and seasoning
10 The next step involves frying the chips using oil temperatures
ranging from 338 to 374 degrees Fahrenheit (170-190 degrees Celsius) for
50 to 80 seconds. The frying temperature and time depend on the type of
product. Tortilla chips made from yellow corn require a lower frying
temperature and a longer time than chips made from white or blended
white and yellow corn. For example, corn chips made from yellow corn are
fried at 320 degrees Fahrenheit (160 degrees Celsius), while those made
from blended white and yellow corn are fried at temperatures up to 410
degrees Fahrenheit (210 degrees Celsius) for 60 to 90 seconds. Most of
the commercial fryers used are the continuous type with direct or
indirect heating elements. Indirect-fired fryers are more expensive but
more efficient, with lower operational costs. Modern fryers are designed
to filter out fines (very small pieces) continuously
and be easy to clean. These commercial fryers are available in sizes
that can process from 160 to 1,360 kg/hr (353-3,000 lbs/hr). The process
yield, using the typical corn/lime mixture, will be 0.96 kilograms (2.1
pounds) of tortilla chips, with 22 to 24 percent oil and less than 2
11 The salt and seasonings are applied immediately after frying while
the chips are still hot. The hot chips are conveyed into an inclined
rotating cylinder, where a liquid seasoning mix is sprayed on them.
Generally, the liquid mix consists of hot oil, salt, seasonings, and
flavoring and coloring agents. Upon cooling, the oil crystallizes,
forming the seasoning coat. Salt can also be deposited on the chips as a
liquid spray or by a granulated salt dispenser positioned over the
conveying belts after the tumbling operation. The amount of salt usually
added to tortilla chips is about 1 to 1.5 percent by weight.
Cooling and packaging
12 The tortilla chips are then cooled to ambient temperature and
immediately packaged in moistureproof bags. Because fried products are
very hygroscopic (they readily absorb and retain moisture), delayed
packaging can cause a loss of crispness. The cooled tortilla chips, with
about 1.5 percent moisture, are conveyed into a bagging machine. This
machine automatically weighs and deposits them in a bag, which is then
The quality control aspect of tortilla chip production is essential so
that the chips can reach the customer at their freshest. The major
parameters controlled during tortilla chip production are: temperature and
relative humidity of corn silos and storage rooms for ingredients and
products; the cooking, quenching, steeping, baking, and frying times and
temperatures; types of grinding stones and their adjustment during
milling; moisture content of the corn, nixtamal, masa, and, finally, the
tortilla chips; operating condition of the equipment (such as the cooker,
sheeter, oven, fryer, cooling rack, packaging equipment, etc.); frying oil
and product deterioration; and the sanitation of equipment and personnel.
The future trends for the corn and tortilla chip market are toward
thinner, lighter, and smaller chips. Recently, tortilla chips made from
white corn, whole wheat flour, and the blue cornmeal of the Southwest have
become available and increasingly popular. Combinations of masa flour with
wheat, legumes, and other flours will lead to interesting new products.
New products fried with oils containing more unsaturated fatty acids or
made from nutritionally improved corn will enhance the image of tortilla
chips. Modified frying and new baking techniques that produce foods with a
texture like that of fried foods will be used to make lower calorie
snacks. The industry will move toward higher-speed production lines, more
automation, better quality control, and higher labor and equipment
It is estimated that the consumption of tortilla chips will continue to
increase in the United States. Corn and tortilla chips are becoming
popular in other areas of the world as well. Corn chip plants have been
started in Australia, the People's Republic of China, India, Korea,
and other countries. Experiencing a 50 percent increase in wholesale sales
during the past five years, corn and tortilla snacks are rapidly moving
into main-stream popularity. Future growth, however, depends on the
industry's ability to keep pace with changing consumer demands.
Where To Learn More
Booth, R. Gordon.
Van Nostrand Reinhold, 1990.
Gleason, Carolyn J.
Handbook of Mexican American Foods: Recipes, Nutritional Analysis,
Diabetic Exchanges & Common Practices.
Intercultural Development Research Association, 1982.
Matz, Samuel A.
Snack Food Technology.
Pan-Tech International, 1993.
Sparks, Pat and Barbara Swanson.
St. Martin's Press, Inc., 1993.
Wise, Victoria and Susanna Hoffman.
The Well-Filled Tortilla Cookbook.
Workman Publishing, 1990, pp. 32-33.
de Lisser, Eleena. "Tortilla Chips Tempt Snackers With
Wall Street Journal.
May 6, 1993, p.B1.
"Thin Tortilla Chips,"
October 19, 1992, p. 109.
Mack, Toni. "Tortilla Wizard,"
July 20, 1992.
Serna-Saldivar, S. O., M. H. Gomez, and L. W. Rooney.
"Technology, Chemistry, and Nutritional Value of Alkaline-Cooked
Advances in Cereal Science & Technology.
1990, pp. 243-307.