Tortilla

Well known dishes with tortillas are:

• Quesadilla: Grilled tortilla with cheese
• Burrito: Rouled, stuffed tortilla
• Enchilada: A sort of lasagne meal made from tortillas
• Fajita: grilled meat on a tortilla

The wheat tortilla is the best-known tortilla, while the maize tortilla is interesting for people with a gluten intolerance, because the maize tortilla does not contain gluten. These tortillas are also more nutrient. The maize tortillas are sometimes called tacos, however, the name taco is often associated with the fried version in u-shape.

Because the production processes of the wheat and maize tortilla are significantly different, both processes will be described below.

Production Wheat tortilla

The wheat tortilla can be produced in several ways, resulting in the division of hand-stretched, squeezed and punched tortillas. The hand-stretched tortilla has a more powdery structure due to the remaining flower on the surface, and is dryer and firmer. These tortillas are becoming less popular because of the intensive labour process. Therefore only the process of the squeezed and punched tortillas will be described below.

Squeezed tortillas are globally the most popular. These tortillas have a smooth surface, remain fresh for a longer period of time and absorb less fluid of the possible fillings. This tortilla can also be frozen and defrosted without damaging the product. This can not be done with the punched tortilla which has a damaged gluten network due to the processing of the dough. These punched tortillas contain less fluid and are therefore more fragile. They also have a sticky taste in your mouth and have flour on the surface, just like the hand-stretched tortillas.

Raw materials

Wheat tortillas consist mainly of wheat flour, water, fat and salt. The wheat flower for the squeezed tortillas contains less proteins and gluten than the flower for the punched tortillas. The fat, liquid or solid, is added to improve the dough quality. The tortillas become softer and more flexible due to the fat which decreases retrogradation. Usually 1 to 2% salt is added to enhance the flavour and the gluten network. In other countries than Mexico, ingredients like baking powder and emulsifiers are often added to improve the flavour and texture and prolong the freshness. An oxidation agent must also be added to the punched tortillas, because the dough of these tortillas is stretched during the production process.

Mixing

The process starts with the production of a dough. To produce the dough, the ingredients are mixed, creating a good form- and stretchable dough. When the squeeze technique is used, the mixing takes place at a temperature between 32 and 38°C. A further developed and cooled dough is needed for the punched tortillas, so the mixing for these tortillas takes place at a lower temperature between 28 en 32°C.

Resting

Before the dough is processed, it is left to rest for approximately 20 minutes.

Shaping

Squeezing
The shaping starts with the division and creation of dough balls. The weight of the dough balls depends on the desired size of the tortilla. It is very important that the dough is accurately divided, in order for the tortillas to have consistent shapes. The dough balls are then placed in a warm and moist environment for 2 to 20 minutes, so the gluten network can relax. This step in the process is very important, because it makes the tortillas less transparent and guarantees longer freshness. A loading machine is used to place the relaxed dough balls on a moving band which transports the balls to the pressure plates. Both the moving band and the pressure plates have a temperature between 175 and 230°C. The pressure plates shape the dough balls into tortillas.

Punching
The dough for the punched tortillas is pumped to a moving band, where it is unfolded to a thin layer of approximately 0,5 to 2,5 mm thick. This thin layer of dough is then placed under a mold to give the tortillas their desired shape. The remaining dough is transported back to the dough pump and processed again.

Selecting

The pressed tortillas have a less consisting shape, therefore a selecting machine is placed after the pressure plates. The tortillas of lower quality, like tortillas with holes or transparent spots, are selected and removed.

Baking

Once the tortillas are shaped, they are, depending on their thickness and desired colour, baked during: - Squeezed: 25 to 40 seconds at a temperature between 190 and 260°C. - Punched: 20 to 25 seconds at a temperature between 220 and 260°C. The baking takes place in a gas oven with 3 floors.

Cooling

To prevent the tortillas from sticky together and the growth of micro-organisms, the tortillas are transported on a moving band after the baking and cooled to a temperature below 32°C.

Wrapping

After the cooling, the tortillas are wrapped in plastic bags by means of a wrapping machine. Some manufacturers choose to separate each tortilla with a sheet of paper. This is also done automatically.

Production Maize tortilla

The production process of the maize tortilla is mostly corresponding to the production of tortilla chips. Both processes will therefore be described below. Tortilla chips can be seen as maize tortillas which are cut in triangles and fried. This snack can then be seasoned with different spices and if one wishes to, eaten in combination with several dips.

Raw materials

The three basic ingredients for maize tortillas and tortilla chips are maize, salt and water. For the production of tortilla chips, vegetable oil and several spices are also important. To prolong the freshness of the tortillas after production, preserving agents are added during the grinding or the shaping. Preserving agents do not need to be added to the tortilla chips if these are, without intermediate storage, fried immediately. When tortillas are stored, their flexibility is increased by means of gumming.

Instead of producing the maize mass himself, a producer can choose a dried maize mass, to which only water needs to be added. However, the entire process will be discussed below.

Cooking

The production process starts with the cooking and soaking of the grains of maize in a claciumhydroxidesolution of approximately 1% in a closed, vertical kettle. This method is also called nixtamalisation. The whole is heated and mixed at the same time by using direct steam injections and compressed air. Grains of maize with a moisture content of approximately 12% are used. The whole is cooked at a temperature of 85°C during 15 to 45 minutes, depending on the maize characteristics, kettle size and stirring speed. The cooking time for tortilla chips is generally shorter than the time for maize tortillas.

Soaking

For the production of tortilla chips, the temperature of the cooked maize is rapidly decreased until below 72°C before the soaking. Due to the lower temperature the maize absorbs less water and consequently the product contains less oil. This is because a higher moisture content corresponds with a higher amount of water that leaves the chips during the deep-frying and a higher amount of oil which is then taken in by the product. After the cooking, and possible cooling, the whole, also called nixtamal, is soaked in the vertical kettle in the hot calciumhydroxide during 8 to even 16 hours. During this process the temperature slowly decreases to 40°C. Due to the cooking and the soaking in calciumhydroxide, the chaff lets loose and the core becomes soft. The maize can then be grinded more effectively and the availability of among others niacin and tryptophan increases. This part of the production process also helps to develop the smell and taste of the tortillas and decreases the amount of mycotoxins.

Washing

After the soaking, the formed nixtamal is pumped towards washing drums. In these drums the calciumhydroxidesolution is removed from the nixtamal and washed by means of a powder dispenser. The whole is then brought to a draining conveyer-belt, where a large part of the water is removed until the moist content is approximately 50%.

Grinding

The nixtamal, which is cooled down because of the washing, is grinded between splined volcanic or synthetic stones, of which one stationary and the other rotates with 500 to 700 rotations per minute. The pattern, number and dept of the grooves depends on the product which is being produced. The grooves are deeper for tortilla chips than for maize tortilla, so that a coarse mass is created. The bigger parts prevent the formation of bubbles as the steam which is formed during baking and deep-frying can escape. During the grinding, water is added to the mass to prevent the temperature of the stone and mass from increasing too much and to reduce wear. Due to the friction of the stones a part of the grains of starch stiffens, and the nixtamal becomes a whole and stays a whole during the following processes.

Shaping

It is important that the mass is immediately processed further after the grinding, in order to prevent dehydration. After another possible mixing step the mass is being lead to a supply mechanism, after which the whole is pressed to a thin layer between two with Teflon coated and in opposite direction turning rollers. The thickness of the layer depends on the distance between the two rollers. The grinded dough is then placed under a mold, so that tortillas of the desired measurement are formed. The remaining dough is guided back to the dough pump and processed again.

Baking

The shaped discs of triangles are guided to a gas oven with 3 floors by means of a maasband. Both products are baked during 30 to 45 seconds at a temperature between 260 and 300°C. Because of the baking less oil is absorbed by the tortilla chips during the deep-frying.

Cooling

Maize tortilla
Just like the wheat tortilla, the maize tortillas are guided over a conveyer-belt after the baking and cooled to a temperature below 32°C during 2 to 5 minutes. This methods prevents the tortillas from sticking together and the growth of micro-organisms.

Tortilla chips
Before the deep-frying the tortilla chips are cooled up to 20 minutes to prevent the formation of bubbles during the deep-frying and to obtain a homogeneous consistence. This cooling step also ensures that additional fluid can vaporize and that the fluid in the chips is distributed equally.

Deep-frying

The tortilla chips are baked in a continues deep-fryer during 20 to 90 seconds at a temperature between 170 and 190°C. Time and temperature depend on the type of maize. Yellow maize, for example, is fried longer at lower temperature than white maize. In general a mix of these types of maize is used.

Flavouring

Immediately after the deep-frying the tortilla chips are guided to a turning, sloping cylinder, in which salt or a liquid mixture of spices is sprayed over the chips. This mixture generally consists of hot oil, salt, spices and food additives. If only salt is included, usually 1 to 1,5% of salt is added.

Wrapping

Maize tortilla
After the cooling, the maize tortillas are wrapped in plastic bags by means of a wrapping machine. Some manufacturers choose to separate each tortilla with a sheet of paper. This is also done automatically.

Tortilla chips
Before the wrapping, the flavoured tortilla chips are cooled to room temperature. The oil which is crystallised because of the cooling, forms a coating for the applied mixture of spices. The tortilla chips are wrapped immediately after the cooling, to ensure the chips stay as crispy as possible. The cooled chips are guided to a wrapping machine, which automatically weighs the desired quantities, deposits the chips in a bag and closes it. Before the bag is closed, nitrogen is injected in the bag to physically protect the chips and prevent oxidation.