MX2007002681A - Continuous nixtamalization process by high pressure. - Google Patents

Abstract

The present invention is related to improvements in a continuous nixtamalization process by high pressure, wherein the products to be obtained therewith are nixtamalized masa and instantaneous nixtamalized flour, preferably from maize, also obtaining further products derived from the nixtamalization of other cereals. The invention describes a continuous nixtamalization process using clean technology, where the effluents level such as residual water is reduced as well as the power consumption and the process time. The process basically consists in the grain nixtamalization in a cylindrical-shaped cooker at a high pressure and an interval of from about 1.05kg/cm2 to about 20 kg/cm2, having a tilted position of from about 25°C to about 45°C, the cooking time ranging from about 5 min to about 20 min, the lime concentration being of from about 0.3% to about 1°; the product is cooked by direct steam and/or jacket steam. The obtained nixtamal is maintained within other resting cylinder, and subsequently milled in a disc mill for the manufacture of flour, or milled in a disc or stone mill for the manufacture of masa. The present invention allows nixtamalized flour and masa to be obtained with optimum and homogeneous physicochemical and rheological characteristics, including additives for the production of tortillas and further products derived from nixtamalization.

Description

CONTINUOUS PROCESS OF NIXTAMALIZATION BY HIGH PRESSURE FIELD OF THE INVENTION The present invention is related to the improvement of the process of nixtamalization by high pressure and obtaining various products obtained from nixtamalization, such as nixtamalized flour, nixtamalized dough, preferably corn, sorghum and other cereals. As well as the improvement in the obtaining of several products derived from the processing of the flour and the nixtamalized mass such as tortillas, tortilla toasts, nachos, and other products obtained from the nixtamalization by high pressure.

ANTECEDENTS OF THE INVESTIGATION The tortilla is the basic food in the population of our country and the grain of corn is the fundamental raw material for its elaboration. It is estimated that the per capita consumption of tortilla in rural areas exceeds 125 kg, and in the poorest communities of the country the per capita consumption of the tortilla can reach 200 kg (National Chamber of the industrialized corn 2003). These products and the nixtamalization technology have entered the markets of the United States of North America, some countries in Europe and Asia that look for foods with these characteristics and alkaline flavors. The technology for the elaboration of the tortillas has been transmitted from generation to generation following basically the same steps and procedures used by the Aztecs, the industrial process has improved and modernized some stages but this still has several disadvantages, such as high energy consumption, water and generating alkaline effluents to the environment, which are reflected in higher production costs (Vaqueiro et al 1986, Martínez-Bustos et al 1996, San Martín et al 2003, Moreno et al 2003 and Cortés et al 2005). The traditional nixtamalization process consists of mixing a part of corn with two or three parts of a suspension of calcium hydroxide (lime) at a concentration of approximately 1%, this mixture is heated to a temperature of 90 ° C during a period of time from 30 to 50 min depending on the type and variety of corn (Martínez-Herrera &Lachance 1979), afterwards it is subjected to a resting phase of 10h-14h. After the lapse of time, the liquid called nejayote (residues of the nixtamal wash) is decanted; the nixtamalized corn goes through a washing system until the seed covers are removed from the corn grain and the residual lime, which decreases the amount of fiber, protein, lipids and other constituent of the grain, in the dough and tortillas made by this process (Cory &Bruce et al., 1997, Martínez-Bustos et al., 2001). The industrial process of nixtamalization can be batch or continuous, consists of cooking 1 part of corn grain in approximately 3 parts of water conditioned with 1% of Ca (OH) 2 at temperatures of 70 to 95 ° C for 40- 55 min in these conditions the grain of corn reaches an approximate humidity of 36%; the cooked grain is washed by means of water under pressure until all the surplus is eliminated, later it goes through a milling process until obtaining flour with high humidity, which passes through a flash dryer and a mill until it generates a fine particle flour. The traditional process of nixtamalization of corn is still the only process that uses many mills of the small and large industry for the production of both dough and nixtamalized flours, however this process has a number of disadvantages because it requires a long time at rest, high energy consumption, the use of large volumes of water that later become highly polluting waters which cause a significant ecological impact and a high cost of production. The research carried out seeks to reduce these problems, such as the Manuel Jesús Rubio U.S. Pat. No. 3,730,732 (May, 1973) adding alkaline substances soluble in water (nejayote) in the previous process of nixtamalization increases the yield in the dough and produces a decrease in waste in the process. But tortillas tend to harden and become stiffer during storage. Another process such as the Mexican patent No. 125, 285 of Celorio (April 25, 1972) performs the grinding of the whole grain and the flour obtained is mixed with dry lime. Then it is heated in a closed chamber and by the heat generated nixtamalization is achieved without the addition of water, this process gives poor results due to the little homogeneity of the nixtamalization and consequently in poor rheological characteristics (elasticity, plasticity and texture properties) of the mass obtained. The patent MX 007630 (April 06, 1990) of M. C. Vaqueiro & P. Reyes (US Pat. No. 4,594,260), produces nixtamalized flour, after separating the husk from the grain which is nixtamalized with 4% to 10% lime (ratio to the grain is 0.4% to 1%) after the husk it is washed and mixed with the endosperm without nixtamalizing to produce the nixtamalized flour. The results are poor in the rheological properties of the dough obtained and consequently of the tortillas. The patent MX 189541 (August 05, 1998) of C. O. Diez de Sollano, proposes the traditional nixtamalization in countercurrent where the nejayote is used for washing the grain, preheating and pre-nixtamalizing the grain for the process of nixtamalization. The proposal contributes to a saving in energy consumption, but does not solve the other problems (excess water consumption and generation of tributaries) of the traditional method. MX patent 208246 (U.S. 6.025,011) by Raleigh J. Wilkinson & Reffrey R. Short. III (2000), performs the degermination and grinding of the grain to then nixtamalize the fractions separately, the coarse fractions and then the fine fraction, to then mix these two fractions, applying vacuum for the final grinding drying and obtaining nixtamal and nixtamalized flour . The process uses water and lime that are heated between 71 ° C and 100 ° C, preferably at 99 ° C, for an approximate time of 15 min. The temperature must be kept below the gelatinization temperature of the starch. U.S. Patent 6,068,873 (May 30, 2000) by R. M. Deirue and M. D. Burianek claims a continuous process of nixtamalization of ground corn grain in different fractions and mixtures that can be made of broken grain into small fragments of corn, germ, and husk. These mixed fractions are first hydrated to a humidity of 20% with water at 60 ° C for a time of 5min to 4h and then the fractions of the corn grain are cooked inside a cylinder with direct steam in indirect, through the jacket of the cylinder, at a temperature of 92 ° C for a time of 1 to 10 min, depending on the mixture can obtain various products derived from corn.

Patent WO 01/87076 of FA Sánchez de la Cámara (2001) developed a process of nixtamalization and dehydration with the broken grain up to a size of 4 to 4.5 mm, then it is nixtamalized with a lime suspension between 0.6% and 1.0% and volume of water from 35% to 65% in relation to corn, is cooked at 70 ° C for a time of 35min to 120 min with continuous agitation. Before finishing this process, 350 g of glycerin, 350 g of gum arabic (stabilizer), 400 g of H2S2O3, 200 g of T1O2 and 400 g of CaCl2 are added. The tortillas obtained by this process were similar to those of the traditional process. In the patent MX 209251 (July 26, 2002) a modification to the Vaqueiro patent (1990) is proposed where it nixtamalizes the shell and the endosperm separately and then performs the mixing of the two components to obtain a homogeneous mass. J. D. Figueroa Cárdenas et al. (2002) through the MX patent. 210991 (U. S. Pat. 2003 / 0198,725) establishes a clean and rapid process of nixtamalization for the production of fresh corn dough to make tortillas, instant flours and their derivatives. The method indicates to solve the waste problem, nixtamalizando corn ground grain with a particle size between 0.1 mm to 5 mm, with a suspension of 0.3% to 0.55% of lime for a time that varies from 5 min to 5 h to a temperature lower than 75 ° C and ambient pressure. The proposed hydration time is too long and the energy consumption by the various stages involved makes the process less feasible and very expensive.

The processes that use high pressure as a unit operation for the nixtamalization of corn are: In the process indicated by Mendoza (1975) (US Patent 3,859,452) it uses temperatures in a range of 80-120 ° C (47.39 kPa to 316.3 kPa) cooking of corn flour is done inside a steam chamber with agitator in the lower part to homogenize both the air and the corn flour previously conditioned with lime, the temperature is gradually raised until reaching the boiling point, later the flour It is transferred to a cooling chamber, finally it is ground.

Bedolla and Rooney, (1982) nixtamalized corn grain by applying high pressures, to decrease the time used during traditional nixtamalization, however the high pressures do not favor all the reactions that are generated during nixtamalization as the grain occurs a strong gelatinization, modifying the physicochemical characteristics of the mass obtained under these conditions. The nixtamalization in this process is carried out in a container at pressures of 5-25 pounds / in2 in an approximate time of 20 min, later the cooked grain is washed and cooled to 77 ° C and left to rest for 60 min with stirring each 10 minutes. Then the grain is ground, the texture of the resulting dough by this method is very sticky and difficult to mold, so this method has not been implemented by the industry. Patent MX 006624 (August 30, 1985) by Manuel Jesús Rubio deals with the installation and improved method for the processing of corn grains, in this proposal dry corn kernels are heated between 135 to 150 ° C for 12min to 18min then They are cooled with water containing lime for 5min to 15min until they have a humidity of 18% to 26%, then they are ground to the desired granulometry, again they are hydrated and cooked until they form a nixtamalized mass from which the tortillas are formed. Also Manuel Jesús Rubio in 2001 with the patent US 6,326,045 establishes a method for the production of arepas and tortillas with precooked and dehusked corn. The precooking is performed by rolls heated with internal steam and the broken grain is cooked by both the internal pressure of the rolls and by the direct steam from 70 to 98 lb / in2 at temperatures of 154 ° C to 162 ° C, by time 40min to 100min The production of tortillas is made with precooked corn flour to which the husk and germ were completely removed, applying lime at 0.3% in relation to the flour and forming an instant mass. Another modification of the patent previously proposed by the same author M. J. Rubio et al. (2001) which consists of adding, during steaming, acids or substances such as sodium bisulfite, metabisulfite and sodium sulfite to hydrolyze the shell and reduce losses by washing and processing the nixtamalized flour as described in previous patent.

In the U.S. patent 6,344,228 M. J. Rubio et al. (2002) establishes a continuous method for the production of nixtamalized corn flour by an accelerated process of cooking under pressure (7 to 10 lb / in2), with lime suspension of 0.3%, for a time of 17min to 25min and temperature of 1 10 ° C to 1 14 ° C. The moisture content reached is 35% to 37% and a pH of 11 to 12. After this cooking the nejayote is washed and removed, for the second wash the water of the first wash is used, then the grain is conditioned with water for 150min at 2 0min reaching a humidity of 38% to 39%. Subsequently, by a feed screw is led to a first mill then it is dried and sieved, the fine particles are separated and packaged, but the coarse particles are ground again to the desired granulometry. The patent US 6,387,437 of Martínez Bustos et al. (2002), proposes a method of nixtamalization at high pressure of the whole grain to obtain flour and mass of nixtamalized corn and other products, the continuous nixtamalization is carried out at pressure of 0.5 to 5.2 atmospheres, with temperatures of 95 ° C to 140 ° C in a team where the cocido is made in total immersion of the grain, then it is ground in a hammer mill and dried to obtain the nixtamalized flour from where it is hydrated to obtain the dough and with it to make the tortillas. The patent WO 2005/036985 of C. Cummings Ibarra (2005), claims as an invention the process and improved apparatus for nixtamalization and various uses, where in a closed tank with agitation dry grains are subjected to vacuum (0 mm Hg to 9.92 mm Hg) to open the pores of the grain that is then cooked with an alkaline suspension suctioned by the vacuum, the tank is pressurized (0 kg / cm2 to 6 kg / cm2) and heated (0 ° C to 100 ° C) and the nixtamalization is carried out for a time of 45 min. After that cooking the product is dehydrated again under vacuum and drained from the tank to be ground. The process does not generate effluents but the energy consumption is too high compared to the traditional process. From the reviewed background we find that it has not been possible to develop a technology that replaces the traditional nixtamalization process, since the results both in the mass and in the tortilla do not meet the physicochemical and rheological characteristics (indicated above) required by the consumers, which is why new alternative processes must be generated to replace and / or improve the traditional process without affecting the final quality characteristics of tortillas and other products derived from the nixtamalization process. Therefore, this improvement of the inventiveness of the continuous process of nixtamalization by high pressure is considered, taking into account the demands of energy, water consumption, time of process to obtain a clean technology.

BRIEF DESCRIPTION OF THE INVENTION In summary form, the present invention consists of improving the continuous process of nixtamalization by high pressure to produce flour and nixtamalized dough, which can be preferably made from corn, sorghum and other cereals. For this purpose the grains of cereals go through a cleaning stage where, through screens, the foreign material, dust and other materials are removed, after being cleaned, it is transported to the feeding silo of the nixtamalizer cooker, the cooker is placed in an inclined position with an angle of variation of 25 ° to 45 ° with respect to the base of the plant, which operates with a pressure that varies between 1.05 Kg / cm2 and 2.0 Kg / cm2, the cooking time is from 5min to 20min, with a lime concentration from 0.3% to 1%, is cooked with direct steam and / or jacket steam. The cooked grain is transported by the cooker itself preferably through an endless screw disposed in its interior towards another stabilization cylinder, also inclined with an angle of variation of 25 ° to 45 °, the grain is stabilized for 10 to 30 minutes and It can be cooled by a lower temperature fluid through a jacket. For the production of nixtamalized dough and flour, the hydrocolloids of guar, or gum arabic and / or xanthan gum in a concentration of 0.1 to 1.5%, sorbitol, or polypropylene glycol, or 0.1 to 2% glycerol in the stabilization cylinder are added. Ground preferably in stone mill or discs. For the production of flour after having added the additives indicated above, the grain is preferably ground with a disc mill and then transported to the flash dryer. The dry flour is sifted, where it is separated into Different particle sizes and flour with particle size greater than that required is again ground in a hammermill until the appropriate size is obtained for the production of tortillas. The production of nixtamalized corn flour can also be carried out without adding the additives in the stabilization stage, the nixtamal being transported to the disc mill and then the flour is dried in flash dryer to be subsequently sieved. Separating the fine flour from the coarse flour, the flour of larger particles are again ground in a hammer mill until fine particles are obtained. The nixtamalízada flour with particle size suitable for the production of tortillas is mixed with gums and food-grade additives, such as guar gum hydrocolloids, or acacia and / or xanthan in a concentration of 0.1 to 1.5%, sorbitol, or polypropylene glycol, or glycerol from 0.1 to 2%, and then stored for later use in the production of tortillas. When other products derived from nixtamalization are required, the appropriate particle size for each product is modified in the milling process.

BRIEF DESCRIPTION OF THE IMAGES This invention will be described in detail according to the graph presented below. Figure 1. Presents a schematic flow chart of the continuous process, incorporating the steps according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED INCORPORATIONS With reference to figure 1 where the steps of the continuous process of nixtamalization are represented, in the form of a flow diagram, and incorporated in the present invention, where a grain cleaner (1) is included; a silo (2); a feeder (3); a nixtamalizer cooker (4); a resting tank (5); a primary mill (6); a feed silo (7); a flash dryer (8); a cyclone (9); a sieve (10); a secondary mill (11); a mixer (12).

The different stages of the process of the present invention are described in detail below. The grain cleaner (1) removes, through a sieving system incorporated within the same equipment, foreign material and smaller particles to the grain, such as sticks, straws, stones and fine dust that adheres to the grain during the harvest and transport. The clean grain is transported to the grain processing silo (2) that regulates the feed to the cooker (3) through a rotary valve while maintaining a controlled flow of the grains. The high pressure cooker (4) performs the process of nixtamalization at high pressure between 1.05 Kg / cm2 and 2.0 Kg / cm2 by direct injection of steam into the cylinder or by indirect heating through the jacket. The clean grain is introduced into the cooker (4) which has a cylindrical shape, the feed being regulated through valves (3) that allow the grain to be introduced without losing steam or internal cylinder pressure. By another access of the high pressure cooker (4) the lime and water suspension is introduced in a concentration of 0.2% to 1.5% in relation to the corn kernel. The ratio of water with lime to the grain is maintained at approximately 0.5 to 1 part of water for 1 part of corn. The nixtamalization is carried out for an approximate time of 5min to 20min depending on the hardness of the grain. The boiling cylinder (4) transports the grain in its interior through a helical screw, the cylinder (4) has an approximate inclination between 25 ° and 45 ° with respect to the base of the plant, so that the grain is maintained in contact with the alkaline suspension more or less time, the speed of rotation is controlled electronically, through frequency inverters so that the grain is nixtamalized at the time indicated above; the output of the nixtamalized grains from the other end of the boiling cylinder (4) are removed at a flow controlled by another valve that allows the nixtamalized grains to be removed and prevents the loss of steam or internal cylinder pressure. During continuous cooking, the grain absorbs the alkaline suspension and this decrease is controlled by the fresh addition of the suspension to the inside of the cylinder through centrifugal pumps, maintaining the water ratio for the grain.

The nixtamalized grain is led to the resting cylinder (5) and stabilized so that equilibrium is reached and cooled for the next stage. This cylinder also has an approximate inclination of 25 ° to 45 ° with respect to the base and the grain is transported in its interior through a helical screw, this section is made at ambient pressure. The resting time is regulated electronically in order to maintain a constant flow in nixtamal production, which can last from 10min to 30min. When necessary, the cooked or nixtamal grain is cooled by the circulation of a fluid with a lower temperature through a jacket provided in this cylinder. In this stage the hydrocolloids, which can be guar gum, or xanthan gum, or gum arabic, or carboxymethyl cellulose in a proportion ranging from 0.1 to 1.5%, sorbitol, or polypropylene glycol, or glycerol in a range that varies from 0.1 and 2%. The nixtamalized grain with the rest and additives is deposited in a silo that feeds the primary mill (6), depending on the final product to be obtained if the production is nixtamalized mass is selected a stone mill or discs where it is ground to form the nixtamalized mass .

When it is going to obtain nixtamalized corn flour from the settled corn, which may or may not have additives and stabilizers, it is ground by a primary mill (6), then transported pneumatically to a feed silo (7) of the flash dryer (8), In this equipment, an air extractor and a gas burner are incorporated, which heat the system to a working temperature that varies from 150 ° C to 200 ° C. The wet flour obtained from the primary mill (6) is dried in the flash dryer (8) for a residence time to obtain a residual humidity of the flour from 7% to 9%. The dry nixtamalized flour is transported to (cyclone battery) the cyclone (9), separators of flour and hot air, the hot air before being released into the environment passes through air filters and then is returned to the flash drying system (8) to the entrance of wet flour to save energy in this stage. The flour collected by the cyclone (9) is transported to a sieve (10) to select the fine flour, which must have a suitable granulometry for the formation of tortillas. The dry coarse flour is ground by a secondary mill (1 1) of hammers, fine mesh to reduce the particle size, the ground flour is then transported to the sieve (10) to obtain fine flour. If the fine flour had no additives in step (4) it is mixed with dry additives in the mixer (12) with hydrocolloids and stabilizers and preservatives indicated above to be then packaged. The addition of additives in the stage of rest and stabilization of the nixtamalized grain, are necessary to provide a homogenous mass with good characteristics for the production of tortillas, achieving an increase in shelf life and improving the yield of tortillas per kilo of mass.

Table N ° 1 Comparative advantages with other processes of nixtamalization Processes Consumption of Consumption of Generation of Characteristics water energy effluents of the tortilla, Traditional texture 3 parts of High consumption by high Excessive generation Texture and water for 1 use of effluent water (2.5 rheology good corn water parts in relation to 1 corn) Industrial 1.8 to 2 parts High consumption by high Excessive generation Water texture and water for effluent use (1.5 good rheology 1 corn water parts in by utilization ratio 1 corn) of additives High 0.8 to 1 part Energy consumption Does not generate effluents or Texture and water pressure for less than traditional are minimal. rheology no 1 of adequate corn. Continuous 0.8 to 1 part Less consumption of Does not generate effluents or Texture and High water for energy efficiency are minimal. good rheology Maize 1 pressure in the milling and longer life of heat transfer shelf

Claims (1)

1. CLAIMS Considering the invention as a novelty, the content of the following clauses is claimed as exclusive property: 1. Continuous process of nixtamalization by high pressure for cereals, preferably corn to produce flour and nixtamalized mass, which consists of the following stages; a) the maize grain first passes to a cleaning stage, after it is transported, it is transported, to a b) process silo and by gravity it is moved, to a c) feeding system, d) of the nixtamalizador cooker, the cooker is placed in an inclined position with an angle of variation of 25 ° to 45 ° with respect to the base of the plant, which operates with a pressure that varies between 1.05 Kg / cm2 and 2.0 Kg / cm2, the cooking time is 5min at 20min, with a lime concentration of 0.3% to 1%, it is cooked, with direct steam and / or jacket steam, the cooked grain is transported by the cooker itself through an endless thyme arranged inside to another e) resting or stabilizing cylinder, also inclined with an angle of variation of 25 ° to 45 ° with respect to the base of the plant, the grain is stabilized during 10min to 30min and can be cooled by a lower temperature fluid through a jacket; for the production of dough, food-grade gums or hydrocolloids are added to this cylinder for rest or stabilization; also for the production of nixtamalized corn flour, gums or food-grade hydrocolloids can be added at this stage of rest of the grain, after rest the nixtamal or cooked grain is ground, f) in stone mill or discs for the formation of dough and for the production of flour is ground preferably in disc mill and then pneumatically transported, g) to the dryer feed silo and certain flow is introduced, h) to the dryer, using a flash dryer, which has a system for separating flour particles that are transported by the flow of hot air, i) being separated through cyclones, the dry flour is removed from the bottom of the cyclone , and j) the particle size is selected through a sieve, the flour that has fine particles passes to the final stage and the flour with coarse particles is ground again, k) in a mill preferably of hammers until obtaining fine particles, I ) in a mixer, the dry and fine flour that was not added in the resting stage with additives, in this stage dry mixing is done with gums or food grade hydrocolloids, and then it is stored and packed, for later Use in the production of tortillas. 2. Continuous process of nixtamalization by high pressure claimed in 1 point c) where the cereal can be cooked only with direct steam or initially cooked with direct steam and then to maintain the temperature or pressure of cooking is done with the heat generated by the steam indirect through the jacket. 3. The continuous process of nixtamalization by high pressure claimed in 1 clause c) where the tilt of the high pressure cooker cylinder has an inclination of 25 ° to 45 °, controls the immersion time of the grain in the alkaline suspension together with the speed of rotation of the transport screw, the speed of the motors being regulated through inverters of frequency in a range of 10 Hz to 60 Hz. 4. Continuous process of nixtamalization by high pressure where the gums or hydrocolloids used in the stage At rest or stabilization are guar gum, or gum arabic, or carboxymethyl cellulose and / or xanthan in concentration of 0.1% to 1.5%, and sorbitol, or polypropylene glycol, or glycerol from 0.1 to 2%, but are used in this stage can be used in the stage of dry mixing with the fine flour, also of the gums or hydrocolloids can be used only one additive, or two additives, or a proportional mixture of various additives for the manufacture of tortillas. Continuous process of nixtamalization by high pressure claimed in 1 clause f) where the nixtamalized grains are ground in a mill, preferably discs for obtaining corn flour, this type of mill can grind cereals with enough humidity without diminishing its performance while maintaining the capacity of the entire process. Continuous process of nixtamalization by high pressure claimed in 5 where the nixtamalized flour and mixed with additives in the resting stage depending on the granulometry of 0.42mm to 0.177mm and 0.25mm to 0.149mm obtained in the first and second grindings may be used for the elaboration of other food products, such as chips, toasts and other fried foods. Continuous process of nixtamalization by high pressure claimed in 1 clause f) where it is indicated that after the nixtamalized grain is reposed and additives were added, for the production of nixtamalized mass during grinding with stones or disks, it must be also add a quantity of water so that the moisture content is between 45% to 50% for the adequate formation of nixtamalized mass. Continuous process of nixtamalization by high pressure according to the previous claims where the cereal can be selected among corn, sorghum, wheat, oats and legumes such as beans and soybeans. They can also be mixed between cereals in proportional parts and cereals with legumes, corn is preferably used for the present invention.