MX2008007911A - Continuous production of masa flour and whole-corn flour for grain-based foods, using a novel precooking - Google Patents

Abstract

A process and apparatus for the continuous production of masa and whole- corn flour for grain-based foods, includes a preconditioning of clean corn, grinding the moisturized corn to produce fine and coarse grind fractions, sieving the fine grind and aspirating from both fractions a light-bran fraction as animal feed, remilling the coarse grind for further bran extraction and admixing the sifted fine grind with lime to produce a limed grind, low-moisture precooking of a stream of limed corn particles in another stream of saturated steam to obtain a partial starch pregelatinization and protein denaturation degree, venting and separating the moist-heated corn particles, conditioning the segregated fine grind to soften and swell the endosperm, germ and bran fractions, hot- air drying the tempered fine grind and stabilizing for extended shelf-life, cooling the dried fine grind with clean air;grinding the agglomerated particles, classifying and separating the fine grind so produced from the coarse grind while the latter fraction is further remilled and screened to obtain a pregelatinized flour for tortilla and corn-based foods and an instant flour for whole-grain foods.

Description

CONTINUOUS PRODUCTION OF MASS FLOUR AND WHOLE CORN FLOUR FOR GRAIN-BASED FOOD, USING A NOVELED PREPARATION FIELD OF THE INVENTION The present invention relates to a hydrothermal process for the preparation of new corn flours and, more particularly, it refers to a precooking process with low continuous humidity applied to the production of pregelatinized dough for flour based corn and instant whole corn flour for the preparation of grain-based foods.

BACKGROUND OF THE INVENTION The production of high quality corn dough and flours can be achieved by conventional and modern techniques (dry and wet milling) only if the food grade corn has the following characteristics: uniformity in grain size and hardness, low number of cracks due to tension and damage to the grain, and ease of pericarp removal during the lime-water cooking process. The five general classes of corn - corneo, pigeon, tender, toothed and sweet - are based on grain characteristics. Since toothed corn is a derivative of corneal corn crosses, it can REF .: 194088 show significant differences in the relationship of corneous to tender endosperm caused by genotype and environmental factors. A common classification of corn based on endosperm quality and commercial production distinguishes its types: 1) sweet with < 1% for processed vegetables, 2) inflated with 1% for making, 3) tender with 12% for food, 4) corneo with 14% and 5) serrated with 73% for animal feed / feed. The ratio of corneal endosperm (hard and translucent) to tender (soft and opaque) can average about 1-2: 1 in yellow and white toothed corn (Pomeranz et al., 1984 and González, 1995). It is known that food grade corn (U.S. No. 1 and 2: USFGC, 1996) must be partially cooked before it is formed into the final products, in order to cause it to be a new precooked corn meal. White grain corn may contain: 11.0-11.5% moisture, 72.2-73.2% amylaceous / non-starchy polysaccharides, 9.8-10.5% protein, 3.7-4.6% fat and 1.1-1.7% ash. For example, a sample of dry milled corn could produce, on a weight basis, 74.8-76.2% total endosperm, 18.9-20.5% germ and 3.3-6.3% bran. Mature grain corn (Watson, 1987, FAO, 1993) has four separable components, on a dry weight basis: tip (0.8-1.1%), pericarp (5.1-5.7%) and aleurone (2.0-3.0%), endosperm (78.3-81.9%) and germ (10.2-11.9%). In wet or dry milling processes, the separated bran includes the pericarp layer, the tip layer, the aleurone layer (isolated with bran) and adherent pieces of amyloid endosperm as well (FAO, 1993). A bran of native corn contained dietary fiber (57-76%), certain starch (4-22%), proteins (5-8%) and fat (2-7%) originating from endosperm tissue and glycoprotein as well (Saulnier et al. 1995 and Hromadkova et al., 1995). In the dry milling process, the primary product is isolated pieces of tender and corneous endosperm, which are recovered through progressive grinding, sifting (or classification) and aspiration processes. To recover starch by wet milling, the granules within the endosperm cells must be released from the protein matrix (gluten) by treating corn (or endosperm) with an alkaline or acid reducing agent (preferably sulfur dioxide or lactic acid) in a soaking process. A husked corn (with 18 MM-Btu / ton-corn) through refining by wet milling can produce: 55% starch (or 58% sugar or 15-30% dry ethanol), 20% feed for animals (fiber / protein), 5% gluten semolina (protein), 25 oil and 18% corn steep liquor (food or fermentation substrate). A modular wet mill unit (mini-biorefinery: MBR) can produce products from high value from the operation of low-value fuel ethanol (33% yield at $ 660 dollars / ton or >$ 18 USD / MM-Btu). Corn accounts for around 40% of the cost of total ethanol production ($ 300 dollars / ton) and energy of around 33% (gas or oil). Energy recovery and renewable energy have provided more than 80% of the increasingly higher energy requirement in the United States since 1973 ($ 0.25 USD / MM-Btu). However given the current high prices for natural gas ($ 3.50 USD in 2000 and $ 6 to 12 USD during 2005: oilergy.com), no realistic price reduction will occur without concerted international and national programs and incentives to encourage more rapid adoption of efficient and renewable energy (biofuel and hydrogen) as well as natural gas. The success and cost effectiveness of this integrated approach has been proven by the redesign or continuous improvement of industrial processes: reduce / recycle / resell waste, reduce energy use and emissions (Acee, 1997). Nixtamalized corn flour (NCF) is produced by the stages of alkaline cooking (heating and soaking) of maize, washing, wet milling of nixtamal and drying, thus producing corn masa flour. At the industrial or commercial level, the grinding or dehydration process are major cost factors. This precooked flour is sifted and mixed for different applications of product and is usually supplemented with additives before packaging it for packaged corn or tortilla-based or commercial table-top foods. In a commercial operation, the loss of corn solids has been calculated at 5-14% depending on the type of corn (hard or soft) and the severity of the cooking, washing and drying process (Jackson et al., 2001 and Bressani, 1990) . Industrial corn or processed dough properly simplifies the production of tortilla products, because the client eliminates management techniques required for wastewater treatment, assurance, handling and processing of corn for tortillas and snacks. However, a pregelatinized corn flour could have the following quality and cost limitations: high cost, lack of flavor / aroma and poor texture. Most of the commercial dough flours for the same applications (totopo / taco and tortilla) had different physical, chemical and filling properties. The coarse meal (> 35, 20 meshes) had a lower peak viscosity and the fine meal (> 120,100 meshes) showed a higher peak viscosity, suggesting that the coarse flours (totopo / taco) hydrate more slowly (longer peak time) and develop less viscosity than fine flours (Almeida-Domínguez et al., 1996). Since the market for corn / tortilla snacks ($ 4.5 billion dollars in retail sales in popular-flavored snacks) in 2001) and Mexican foods continue to grow, the difference in quality and price will become closer between industrial dough flour and traditional dough. New formulations in baked goods (Maseca® Regular-yellow: 5-20% and <60 mesh) and processed (Maseca® Normal-70% white flour and <45 mesh) continue to expand such as tortilla-based snacks. corn and corn flour ravioli prepared from nixtamalized corn flours (US patent 6,491,959 and Erempoc, King and Ramírez, 1997). Third generation (3G) cereal foods include the extrusion cooking stages, followed by cooling, resting and drying to make "cereal granules" which are expanded when frying or baking to make foods based on nixtamalized corn (snack) based on new mass in US Patent 5,120,559 and hypercholesterolemia reducing snack in US 20040086547). Another example is breakfast cereals made by baking grains or whole particles (wheat, barley, rye, oats, rice or corn), followed by cooking, tempering, crushing, forming into "biscuits" and baking or roasting food based on cereal (CA 2015149). The most important biochemical changes during nixtamalization are: an increase in the calcium level with an improvement in the Ca to P ratio; a reduction in insoluble dietary fiber and protein zein; a reduction in thiamine and riboflavin; an improvement in the leucine to isoleucine ratio, reduced niacin requirement; Niacin release from the pericarp / aleurone / endosperm and industrial leachate of ferulic acid (1,500 to 1,900 ppm: Sánchez, Ramírez and Contreras, 2005), insecticides, fungicides and residual mycotoxins in the alkaline soaking liquor or "nejayote" (FAO, 1993) and Sustain, 1997). The microflora of the fermented and nixtamalized corn flour can produce a fermentation in the spontaneous solid state to produce a "sour dough" (pH < 5) called "Pozole" (from the Nahuatl: "pozolli" or spongy). It is a fermented probiotic food that involves at least five bacterial and yeast groups which include the natural flora of a freshly made dough (or nixtamalized cornmeal) and that is consumed as a thin drink (drink or cold gacha) by the population indigenous peoples of southeastern Mexico (Ramírez and Steinkraus, 1986). The main result of a lactic fermentation is an endosperm protein / zein dispersion and an increase in the release of starch during the subsequent grinding of an acid fermented corn drink or gacha such as: Ghanaian kenkey, ogi- Nigerian industrial, Kenyan Uji and South African mageu-industrial ("yogurt-type corn products" Steinkraus, 2004). A bran of corn treated with industrial lime (Maseca® brand) contained 4-5% alcohol-toluene extract (unsaponifiable matter) with a content total sterol of 860-900 ppm (notification GRAS-61, 2000) and this represents around 50% of a germ content of dry milled corn (Arbokem-Canada, 2000). New baked foods that contain whole grains may qualify to carry labels with the following or other related health statements: a) "The development of cancer depends on many factors: Feeding a diet low in fat and high in grain products, fruits and vegetables that contain dietary fiber may reduce your risk of some cancers "(21 CFR 101.76); and b) "The development of heart disease depends on many factors: Eating a diet low in saturated fat and cholesterol and high in fruits, vegetables and grain products that contain fiber can reduce blood cholesterol levels and reduce your risk of heart disease" (21 CFR 101.77 and 81: FDA / DHHS, 2004). Whole grains or foods made from them contain all the essential parts and nutrients that occur naturally from the whole seed. If the grain has been processed (eg, cracked, crushed, rolled, extruded, lightly pearled and / or cooked), the food should provide approximately the same rich balance of nutrients as that found in the original grain seed. There are marked differences between corn tortillas against wheat tortillas and bread in relation to: its physicochemical flour composition, ingredients, dough cooking and cooking process. The products based on wheat and grains use wheat / grain flour without bran and degerminated (training ingredient). The dough used to make bread and similar products always contains more ingredients than corn tortilla dough. Examples include texture modifiers (butter, salt and sugar / syrup), fermentation agents (sodium bicarbonate and / or yeast) and characterization agents (flavoring / spices, gums and antimicrobial additives). The base ingredients for corn tortilla include a nixtamalized whole wheat flour (US 4,513,018) or corn flour precooked with lime (Maseca® brand), with water and antimicrobial or functional additives that can be mixed before the dough is prepared for the cooking and packaging of seven days of useful life (US patent 6,764,699). Most diseases are caused by an incorrect lifestyle and diet. Current eating habits make people sick and weak, shorten their life expectancies and deteriorate mental and spiritual health (Know Thyself -prevent ion is better than cure and heal th is weal th: SSSB, 1995). A list of some potentially allergenic ingredients (food labeling regulations of the United States, 2005) includes: 1) cereals containing gluten and products of the same (the Celiac disease causes chronic intestinal inflammation and malabsorption of nutrients that is induced by prolamines rich in prolamin and glutamine from wheat, barley, rye and oats), 2) soy and its products, 3) milk and dairy products, including lactose and 4 ) sulfur dioxide and sulfites at concentrations of more than 10 ppm. Approximately 5% of the American population suffers from food allergies, and in Europe adults (3%) and children (8%) are affected. A grinding or spraying process involves two different break mechanisms, in particular: a) fragmentation (impact / cut or compression), an operation that results in daughter particles that are approximately the same size as the mother particle and b ) Surface erosion (abrasion / attrition or friction), another operation that affects the generation of fine particles during the initial stages. The existence of these phenomena was evident from the characteristic bimodal size distribution curve and the progressive change in the relative weight of large and fine particle populations (Becker et al., 2001 and Peleg et al., 1987). The method of reducing the size of the disk mill (abrasion) and the paddle mill (impact) are a little different. Within the disk mill, corn particles break along lines of weakness by impact and shear forces; the resulting particles are typically not very small and with poor uniformity of particle size. The particles milled with the paddle mill are forced against an abrasive ring by the paddle disc rotating at high speed; in this way pieces of the material wear out of the global material. Another factor is the shape of the particles which in turn influences the absorption of water and the swelling behavior of the apparent viscosity curves. Significant variations in these rheological curves can be due to several factors: size distribution (bimodal / unimodal), shape and chemical composition of the particle (starch / dietary fiber and protein) that can be changed during the precooking (thermal) and grinding operations (mechanics) . In raw corn particles (US 400 to 45 mesh with 75% starch, 8% protein, 5% dietary fiber and 1% fat) which were ground with paddle mill, the largest particles (> 60) meshes:> 250 μm) produced a lower peak viscosity (at 95 ° C) and longer peak time (at 95 ° C) compared to smaller particle profiles (Becker et al., 2001). They also found that the paddle mill caused some damage to the almison along with protein denaturation caused by heat (with temperatures <50 ° C). This mechanical damage can increase the degree of gelatinization with a lower apparent viscosity than corn particles not milled and ground with discs.

A higher protein content (3 times or 2.4% vs. 0.7%) was measured in the medium vane particles (120 to 70: 170 μm-medium mesh) affecting a low peak viscosity (at 95 ° C) that the particles of medium disk by diluting not only its starch content but also denaturing its endosperm protein. The dehydrated dough prepared by removing the nixtamal germ resulted in lower peak and final viscosities than both dehydrated maize and nixtamal masses. The dehydrated dough prepared from white corn (stone mill) resulted in a lower viscosity than the nixtamal (Martínez-Bustos et al., 2001). The addition of soy protein in corn-based flours reduced the peak viscosity because the starch was diluted in the corn-legume formulation for tortilla and tamale / arepa foods (Tonella et al 1982 and Ramírez 1983). Corn flour Azteca Milling L.P. (Becker et al., 2001: Maseca® brand <60 mesh with 68% starch, 9% protein, 8% dietary fiber and 4% fat) was used to make a medium product extruded from corn, using a thermomechanical extrusion process, and the peak and final viscosities recorded were 5-10 times lower than those for the native particles, respectively. The degradation of starch to oligodextrins can be increased by raising the extrusion temperature and reducing the moisture level in the starch. Food extruders can considered as high temperature and short time cookers (<5 min.), in which granulated starch (particles / flour) having a moisture content of 10-30% is first compressed into a compact mass and converted into a amorphous mass and melted by high pressure, heat (60-135 ° C) and mechanical shear during processing. A new extrusion (at 85-90 ° C) using fine-grained flour (Azteca Milling: Maseca® brand with 8% total fiber) produced a snack with a unique cookie-like structure (faster break with the same strength) and more texture crunchy (Chen et al., 2002 and US patent 5,368,870). Not only did they detect a higher partial gelatinization in the dough flour (30-50%) attributed to the drying of the dough (20-30%), but also a more viscous and gelatinized extruded medium product granule (> 90% gelatinization) (ready to fry: 10-12% water) or tortilla totopo (ready to eat: 1-2%). A similar corn-based tortilla totopo used a pregelatinized corn flour in an amount of 8 to 65% of the total flour formulation (Maseca® Regular yellow: with a degree of gelatinization of 20% -60%). A low fat and baked product (> 5-15% bran) can also be produced with a crisp / non-floury texture with an omelette flavor (U.S. Patent No. 6,491,959). The first heat / moisture investigations where an excess of water content was used (suspensions or starch slurries: > 30%) or where the water content was below 30% (without free water in solid paste) the type of humidity is clear (Stute, 1992). However, in some investigations it is not clear whether it was a tempering treatment (low temperature and long time: 50-65 ° C and> 10 h with> 50% water) or heat / humidity (high temperature and short time (95-110 ° C and <120 min with 15-30% water) The first published viscosity curves showed a lower peak viscosity with a higher gelatinization temperature (peak viscosity temperature) and - depending on the degree of hydrothermal treatment - at lower grades a higher low and at higher degrees a lower low A degree of reduced gelatinization (ie, low swelling capacity) of the starch granules leading to a higher low (This tempering effect was used to prepare a mash starch or "pregelatinized potato starch" Stute, 1992), while at higher degrees of modification the swelling is inhibited to such an extent that the decrease is lower (this effect heat-humidity is used to elaborate "partial pregelatinized whole wheat flours" or instant flours with 15% to 99% degree of gelatinization; Messager, 2002). The filling with water-soluble colloids with water (low solids from 7% to 39% or high moisture content of 61-93%), such as cereals, starches and cellulose derivatives can be achieved in the form effective using direct steam injection (high pressure saturated steam, ranging from 4.22 kg / cm2 to 14 kg / cm2). Mix-jet cooking of a corn-starch paste or suspension (10-800 microns) is instantly heated to above the gelatinization / gelation temperature (150 ° C filling temperature for 1 to 8 minutes) and mixed vigorously suspend the granules in water / steam rapidly swelling starch to achieve hydration, dissociation and dispersion of their polymer chains to form a fluid solid (Perry, 2000). On the other hand an extrusion of corn starch or a steam jet cooking of starch-corn followed by drying in a drum (150 ° C) with low water content (20%) at elevated temperatures (175 ° C and 140 ° C) ) gave both a molecularly dispersed / broken and completely molten starch. Extruded corn starches absorb water at room temperature to form pastes made of soluble starch and swollen endosperm with little degradation to oligodextrins (Shogren et al., 1993). Therefore, the terms tempering (treatment of high humidity below the gelatinization temperature) and heat-humidity or semi-drying (treatment with low humidity above the gelatinization temperature) describe completely different changes within the starch granule. They can cause a physical modification of starches with different degree of gelatinization or denaturation, or any other damage with respect to size only by controlled moisture and heat processing. Various methods for mass industrial production include traditional and steam cooking (ie, low temperature and long time) cooking with accelerated steam (ie, high temperature and short time) and extrusion cooking (i.e., high temperature and short time), with lime cooking of the whole or ground corn kernel. Maize dough includes cooked corn either in its wet commercial product (fresh dough) or dry (dough or nixtamalized dough) for tortilla and derivatives. Nixtamalization (corn with lime) is derived from Nahuatl nextli: ash or lime and tamalli: corn masa. The nixtamalization, or treatment with heat and lime, involves the alkaline cooking when boiling corn in water (1-2% lime). Corn flour processors can generate added value from their industrial operations in three approaches: development of new products from new hybrids, increase in yield (Reduction of solid waste and residual water from nixtamalization - "nejayote": nextli áyoh-atl or light gacha with lime) of traditional products from corn, and reduce energy and water at a lower unit cost. In northern South America, particularly in Colombia and Venezuela, food grade corn is processed with dry milling technology without wastewater and it also converts to a pre-cooked steam degerminated flour (US patent 3,212,904 and EP 1,142,488 A2) or without bran (EP 0,883,999 A2 and US patent 6,326,045) for traditional corn foods. Its consumption is mainly in the form of an "arepa", which is a thick and cooked flat or ovoid and non-fermented cake made from dry ground corn flour. In other South American countries, corn grits (arepa or polenta) and corn flour are used for different pastry foods (mixtures for empanadas and cakes), gacha (atolli: "atole" or thin gacha) and snack foods (FAO, 1993). Steam cooking of whole corn grain begins with steam injection in a corn suspension in lime-water (corn to water ratio of 1: 2-3 and 1-2% lime on a corn basis). The steam is injected to partially gelatinize the corn starch (at 70-95 ° C for 20 to 100 minutes). The grain cooked with lime (nixtamal) is allowed to soak overnight (> 10 h at 40 ° C) and then washed and milled with discs to cut, knead and mix the ground nixtamal and form a dough. Additional water is added during grinding with discs to cool the mill and increase the humidity level. A drying step followed by grinding and sifting will produce a dry dough flour for tortilla and totopo. Tortillas are the main edible corn product in North and Central America. It's a thin, flat cake, round, unfermented and cooked (flat cornmeal bread) made from fresh dough or corn dough prepared from industrial nixtamalized corn flour (NCF). It should be mentioned that an omelette, when processed manually and mechanically and without additives of any kind, has a maximum shelf life of 12 hours at room temperature (patent of US Pat. No. 3,730,732). With cooking with accelerated steam (MX 993,834, US 4,594,260, US 6,344,228 and US 6,387,437), pressure steam was injected into an aqueous suspension (corn to water ratio of 1-1.5: 0.3-1 and 0.3-1.5% of lime) generally it can vary between 0.0703 to approximately 1.75 kg / cm2 (at 70-140 ° C) for a period of time from 1 to 40 minutes. The nixtamal is washed and cooled to about 80 ° C, and then soaked for about 60 minutes. The nixtamal soaked wet or wet is continuously ground by impact and dried by vaporization by cooking or partial pregelatinization (patent of US Pat. No. 2,704,257). After classifying the masa meal an increase in water absorption (yield) and peak viscosity (viscoamilograph) will depend on the particle size distribution. These prior art methods for industrial mass production include short precooking and soaking times with less soluble residues (1.2-2.7% chemical oxygen demand: Alvarez and Ramírez, 1995, and Duran-de-Bazúa, 1996) and solids total (-1.5-3.5%: 50-60% dietary fiber, 15-20% ash, 15% starch, 5-10% protein and <5% fat). The extrusion cooking (Bazúa et al., 1979, US 5,532,013, US 6,265,013 and 6,516,710) of whole or dehulled corn flour has been tested by extruding a mixture of semolina / flour, with lime (corn to water ratio of 1: 0.3 -0.6 and 0.2-0.25% lime on flour) and water in an extruder cooker or horizontal worm conveyor until a homogenous dough or semolina vaporized during heating is uniformly 1 to 7 minutes at 60-130 ° C (> 1.40 kg / cm2). The cooled corn masa or semolina (40-70 ° C) is further dehydrated in hot air (US Pat. No. 3,859,452), milled and hocked to produce a partially husked or whole corn meal. Roasting corn (200-260 ° C, 5-12 minutes) can depolymerize, by dextrinization, and reduce the swelling potential of corn starch and cereal at a low water content (9-10%). Three recent innovations have been published (WO Pat. 2004/008879, US Pat. No. 6,516,710 and MX / PA / a / 2001/012210) for the preparation of a nixtamalized or instantaneous corn flour by means of a hot-moisture cooking, without wastewater production ("nejayote"), unlike the traditional wet process mentioned above. They obtained a corn feed using a steam injection during a short warm-up time of husked corn or ground corn in such a way that its starch and protein were pre-cooked. Although the prior art methods described above are capable of partial cooking of whole corn or broken whole, an industrial application continues to use not only low humidity with a short time precooking of the husked corn and ground corn but also with a minimum requirement of water and energy that produces a dough flour and whole corn was not yet available in the market at the time of the invention.

BRIEF DESCRIPTION OF THE INVENTION Accordingly, an object of this invention is to provide a complete departure from the prior art precooking methods of thermal and mechanical processing of dehulled corn and ground corn to thereby carry out gelatinization and partial denaturation during the production of whole corn flour and dough. Another objective is to produce this instant corn dough and flour using a continuous low moisture precooking that is not only efficient in water and energy consumption but also less expensive than the prior art accelerated methods for the preparation of pregelatinized corn flours and instantaneous.

Another objective is to produce dough flour for tortilla and flour based on corn and whole corn for cereal and grain-based foods where this flour is relatively uniform in its biochemical content and physicochemical properties. The above and other objects and advantages of the invention are achieved by means of a new continuous process applied to the production of pregelatinized and instant maize flours for tortilla and cereal-based foods, which modalities comprise the following steps: moisten the grain clean whole to precondition; grind the moistened grain to produce fine and coarse grinding fractions; sieve the fine grinding and aspirate from both milling fractions a fraction of light bran as animal feed; remove coarse grinding for removal of additional bran; mix the fine sifted grind with lime powder to produce a lime grind; Preheat with moisture-heat a stream of corn particles in another stream of saturated steam to obtain a desired degree of starch pregelatinization and protein denaturation; ventilate the residual steam and separate precooked fine particles; temper fine grinding to soften and swell the endosperm, germ and bran fractions; drying with conditioned air the fine conditioned grinding and stabilizing it for extended useful life while extracting hot exhaust air; cool with clean air while discarding the moist air from dry fine grinding; grind the agglomerated particles; sieve and separate the fine grind produced in this way from the coarse grind while the last fraction is further stirred and hovered to obtain a dough flour and whole corn flour for corn and grain based foods.

BRIEF DESCRIPTION OF THE FIGURE This invention can be understood from the following description of preferred embodiments when read with the attached figure 1 in which is a schematic flow sheet illustrating the continuous and industrial process using a low moisture precooking of corn husked and ground corn for the preparation of a whole corn flour and dough for grain-based foods.

DETAILED DESCRIPTION OF THE INVENTION Referring first to Figure 1, one embodiment of the present invention is illustrated in flowchart form. Includes a preconditioner 1; a primary mill 2; a sifter 3 with an associated vacuum cleaner; a mixer 4; a precocedor of low industrial humidity 5; a cyclone 6; a conditioner 7; a heater 8; a dryer 9 with a fan; a cooler 10 with a fan associated; a secondary mill 11 and a sorter 12. A whole corn kernel, which has been released from broken corn and foreign material by dry cleaning (sifting and suction), is fed to a preconditioner 1, where the cleaned corn is continually sprinkled with water for 1 to 3 minutes - to moisten and soften evenly the fractions of bran, germ and endosperm. Corn moisture is adjusted from about 10-12% to about 16-18% while using a corn to water ratio of 1: 0.12 to 1: 0.24. The moistened grain is passed through a primary mill 2, which breaks and separates the bran by loosening it of the grain, detaches the germ and grinds the grain coarsely into two fractions. The large-sized portion of broken corn is known as the coarse grinding fraction ("glue fraction", and some of it can be isolated as large flake-forming particles) composed of endosperm, germ and pericarp-bran, while the Small size portion is described as the fine grinding fraction composed of endosperm, germ and aleurone-bran which is also known as "pass material". This whole wet milled corn obtained in this way is then directed to a sifter 3 with an associated vacuum cleaner where three fractions are separated, in particular, the smaller fine grinding which is thereafter fed to a mixer 4, the larger coarse grind (more than 16 to 20 meshes) which is recycled to the primary mill 2 for further grouting, and the light bran which is isolated with air flow as a by-product of corn (containing 14 % -16% humidity). This fraction of segregated and light bran (more than 16 to 20 mesh) can represent 4% -16% and 1% -3% of the total weight of clean corn to produce a whole-grain flour (dough) and a whole corn flour , respectively. The finest sieved grind (which represents 90% and 98% average of the total weight of the input corn, respectively) is transported further to a mixer 4, in which it is mixed with food-grade hydrated lime in an amount of about 0.20% and 0.020% by weight to produce a dough and a whole corn meal, respectively. After finishing the mixing stage, the fine grinding with lime and partially with lime (containing 16% to around 18% moisture) is transferred to an industrial low humidity precooker 5, whose design is known per se, in where saturated steam is injected under pressure into a stream of fine corn particles as they enter the hydrothermal precooker (venturi throat), instantly heating and wetting the fine particles to the desired temperature. The temperature is controlled when adjusting the pressure of the injected steam, and preferably around 150 ° C to about 170 ° C. The fine particle stream is further hydrated and dispersed at elevated temperatures (90 ° C to 100 ° C) for about one second to about five seconds, the residence time being adjusted by the corn flow velocity through the precooker hydrothermal (venturi mixing tube or low pressure flow tube). Preferably the vapor pressure is from about 4.9 kg / cm2 to 6.3 kg / cm2 to control the steam flow rate and ensure that the precooking temperature is set for a fixed corn flow rate. By this means, precooked fine grinding is increased to a moisture content of 20% to about 22%. Its amyloid / aleurone endosperm is not only partially gelatinized, but its germ and bran proteins are also denatured using this moisture-heat treatment for new flours. The pre-cooked fine grinding with steam is then passed to a cyclone 6 where the residual steam (80 ° C to 85 ° C) is vented and separated from the precooked fine grinding. The fine particles heated with moisture are further tempered in a low humidity conditioner 7, in which the fine grinding is tempered for 30 to 60 minutes and 70 ° C to 75 ° C to effect a reabsorption of moisture of between 1% and 3%. This stage removes heat and diffusion barriers and allows the condensed steam and added lime soften and swell the endosperm, germ and bran fractions. Subsequently, this conditioned precooked fine grinding is passed through a dryer 9 with a fan, the design of which is known per se, so that it is mixed with hot air coming from a heater 8 with which a fuel, such as gas Natural, and clean air are used for combustion. The conditioned material is then dried by high temperature vaporization from 190 ° C to 260 ° C for a short time of 2 to 6 seconds with the ventilated residual hot air (80 ° C to about 95 ° C with 18% to 21% moisture) . The drying stage causes stabilization for extended useful life (> 4 months) and also gives the flour a typical aroma of "toasted" and "corn with lime / nixtamalized". The corn flour is dried to produce a moisture content of 13% to about 15% depending on the desired particle size. If desired, whole cornmeal can be pregelatinized by additional heat to 9% to 13% moisture to make an instant whole corn flour used as a base ingredient for cereal in whole grain foods. Warm moisture-laden air is removed from the dried corn material through a cooler 10 with an associated fan, thereby further reducing the moisture content with clean ambient air, from 9-15% to 7-12%, depending on the desired shelf life of the dough ((10-12%) or whole wheat flour (7-9%) During the stages of precooking processing at low temperature, tempering, drying and cooling, some degree of agglomeration will occur of particles and the larger corn particles will have to be swirled to achieve a uniform product specification.After further extraction of moisture, the cooled and dried material is fed to a secondary mill 11, where the agglomerated material is milled in two fractions, in particular, a fine milling ("steps") and a coarse milling ("tails"). The ground material is directed to a classifier 12 with suitably configured screens (below 20 to 120 meshes) where the milling The fine material is segregated as corn flour and the coarse grinding is further recycled to the secondary mill 11 and is subsequently re-ground.The regrind is further sifted to produce a homogeneous corn flour for dough (below 20 to 100 meshes) or whole corn (below 40 to 120 meshes), respectively. The following table gives an average biochemical composition of whole and partial-whole corn flours: whole corn for grain foods (<40 to 120 mesh) and corn food dough (<20-100 mesh). Raw ground corn (<20 to 80 meshes) used for flour.

Table 1 Biochemical content (g / 100 g): * new maize flours Flours of whole corn and dough (partial-whole) they contain both granules of the endosperm fractions, germ together with pericarp and aleurone-bran producing a large fraction (<40 to 20 mesh) and small / medium (<120 to 100 mesh) of a bimodal size distribution. In addition there is a potential in corn flour yield of 98% and 90% of the total weight of precooked corn with low moisture compared to the continuous processes of arepa / polenta and dough that produce 65-85% to 88-95% , respectively (U.S. Patent Nos. 6,326,045 and 6,516,710; U.S. Patent Nos. 6,344,228 and 6,387,437). If the grain has been processed (eg, cracked, crushed, rolled, extruded, lightly pearled and / or cooked), the entire food product must provide approximately the same essential parts and nutrients that occur in the original grain seed. Maize is wet or dry milled (without leaving fiber) and traditional nixtamalized corn loses fiber during its wet / alkaline precooking. Therefore the new maize flours produced by the present method have, on average, a higher nutritional value compared to conventional methods, with higher fat (2.5-3 times), dietary fiber (2-3 times: together with ferulic antioxidant as a biomarker of whole grain feed, 4-7 times) and protein composition (1.3 times) than commercial dry milled flours (coarse flour / fine flour: no bran / no germ) used in corn-based foods (INCAP, 1961). Whole grain products conserve both bran and germ by providing phenolic antioxidants (trans / cis-ferulic, vinyl and caffeic) and phytic acid that acts independently / synergistically with dietary fiber to reduce risk (30% with 3 servings / day) it will depend on coronary arteries, colon cancer and diabetes (Decaer et al 2002, Millar et al 2000 and Ou et al 2004). Approximately 69% of the phenolics present in yellow sweet corn are insoluble bound forms (1700 ppm on dry basis), with the ferulic antioxidant being the main compound esterified to xylan side chains (700, 1000-1800 ppm in white / yellow corn) : Martínez-Bustos et al., 201, Rosazza et al., 2004 and Adom and Liu, 2002). In this method, the new low moisture precooking results in a reduction of 40% to 80% in water and energy consumption with minimum residual costs correspondingly, as compared to industrial dough flour methods (US Patents Nos. 6,516,710 and 6,344,228, MX / PA / a / 2001/012210). The precooking at low fresh moisture (20% to 22%) using a low addition of lime (0.02% and 0.20%) not only helps partially hydrolyze the starch / dietary fiber and protein granules but also allows a reduction of 50%. % to 80% in lime if a flour for instant whole corn was produced for introduce new flavors and beverages of whole grain. A definition of whole grain corn by the FDA has been requested (AACC, 2005) in such a way that a whole grain nixtamalized corn flour has a dietary fiber content of 7.3% to 9.6%. The following table shows the physicochemical properties of whole and partial / whole corn flours: whole corn for grain foods (<40 to 120 mesh) and corn food dough (<20-100 mesh). Raw ground corn (<20-80 mesh) used for flour.

Table 2 Physicochemical properties; * New grain flour Whole maize flours and whole (partial-whole) flours may include coarse particles (<40 to 20 mesh) and fine / intermediate (<120 to 100 mesh). The large granules are pieces of pericarp-bran, endosperm and germ. The small and medium size are mainly pieces of amyloid endosperm, germ and aleurone-bran. Thus, a bimodal size distribution and biochemical composition affect both not only the physicochemical properties (apparent viscosity and adhesiveness: US patent 3,788,139) in corn but also its yield (water absorption) for grain foods. In this method, the yield for dough flour is higher than whole wheat flour or raw flour, because the low moisture precooking treatment causes partial starch gelatinization and protein denaturation. However, its viscosity of dough has less than crude flour but more viscosity of whole corn indicating a low degree of modification for a pregelatinized flour. On the other hand, a high degree of modification for an instant flour was detected for a viscosity of low yield and viscosity of whole corn showing both treatment effects with heat-humidity and semi-dry heat.

Example 1 Preparation of corn-based foods using a pregelatinized dough flour 1) For use in the preparation of snacks and tortillas: The pregelatinized dough and the whole partial meal made from the present method can be rehydrated with warm water of a ratio of weight from 1: 1.0 to approximately 1: 1.4 for a high yielding mass (50% to 55% final moisture) used in the preparation of industrial corn snacks and commercial cooked tortilla foods. Transferulic was the predominant dietary fiber antioxidant and could be released during wet processing, especially with alkaline compositions, and during baking. The dough flour contained approximately 9% on average dietary fiber and 800 ppm of transferulic content (or expressed as 1280 μmoles Trolox equivalent / 100 g: Decaer et al., 2002) and was 50% lower than raw flour (flour of nixtamalized corn Maseca® brand had an average of 8% dietary fiber: US patent 6764,699). This pregelatinized partial-whole flour had a higher ferulic content than corn flour mixed in dry (209 ppm) and flour without similar bran (wheat / oats: 59/55 ppm: Soeuleki et al., 1982 and Rosazza et al., 1995 ). Ferulic acid is a known phenolic antioxidant, which is an effective free radical scavenger (lipophilic and hydrophilic fibers as μmol Trolox-equivalent). It has been reported that ferulic could protect low density lipoproteins from oxidative damage, exhibiting anti-inflammatory properties, inhibited chemical carcinogenesis (in mouse skin) and lipid peroxidation. It is estimated that per capita corn tortilla consumption in Mexico and Central America is around 240 grams / day (8 tortillas or 150 grams of flour), equivalent to at least 30% of the daily caloric intake (AACC, 2001).

Therefore, a tortilla dough will provide around 1. 2-1.5 gram fibers / serving and three portions of tortilla (56 grams of dough flour: USDA-SR16) would supply at least 15% of the daily fiber value of the FDA (25 grams). The Food Guide Pyramid (2005) suggests eating half the whole grains (51 grams or servings of grain / day with 4.5 cups of fruits and vegetables / day for a 2000-calorie diet: Mypyramid.gov). In addition, a lower intake of energy-dense foods (high in fat / protein and high in sugar or high in starch and soft drinks (highly sugar-free) will also reduce total daily calories to maintain a healthy weight.

Example 2 Preparation of grain-based foods using instant whole corn flour 2) For use in whole-grain foods as a cereal-based ingredient: the instant and whole meal obtained from the above mentioned process can be mixed uniformly with 45% by weight. 49% by weight of grain meal to thereby increase its ingredient formulation from about 70% to about 80% dietary fiber and from 800% to about 1,400% ferulic antioxidant contents. Whole flour can be rehydrated with warm water from a weight ratio of 1: 0.7 to approximately 1: 1.1 for a low yielding corn mass (40% to 50% final moisture) used in food preparation. industrial wheat base and grain base. Cereal bran contains significant amounts of ferulic phenolic acids. Its potential health benefits and potentials have been related mainly to its antioxidant activity (absorbance capacity of oxygen radicals-ORAC as Trolox equivalent μmoles / 100 g: Decaer et al., 2002). The instant whole flour had about 11% dietary fiber and approximately 1,400 ppm trans-ferulic content (2240 μmoles T.E. or vitamin E analog) and was similar to raw corn indicating minimal alkaline hydrolysis. A new wheat aleurone (6,600 μmol of T.E. 46% fiber and 5,000 ppm ferulic, Ou et al., 2004) can increase wheat flour (with an addition of 20%) antioxidant content. Therefore, the food industry has an opportunity to provide a functional base food (reduced risk of a disease with polyphenols as a defense against the declaration of type B oxidants: Consensus Document, 1999) instead of a product-based statement maintaining at the same time its useful life (> 4 months). The challenge is to make these corn-based foods (along with low fat / cholesterol diets) more attractive than refined grains and to communicate to the population their healthiest attributes. Several epidemiological studies have consistently defined whole grains as those foods that comprise > 25% by weight of whole grain or bran (Liu, 2003). However, the FDA specifies that whole grain products such as those that meet the criterion of 51% -61% definition of whole grain by weight on wheat (12.5% fiber), barley (10% fiber), oats ( 11% fiber), rice (3.5%) and nixtamalized corn (> 73%) is still pending (Anderson 2004, AACC, 2005). Examples of flours and whole grain foods generally accepted are: amaranth, barley, brown and colored rice, buckwheat, bulgur, corn (sweet and inflated) and whole corn semolina, spelled / farro, grain, kamut and spelled, oats and whole oats, quinoa, sorghum, triticale, whole rye, whole or cracked wheat, wheat berries and rice wild. Grains of corn and rice are gluten-free to prevent celiac disease (approximately 0.8% of the US population has been diagnosed: csaceliacs.org and enabling.org) and certain grains near corn are safe for celiac patients to eat ( millet, sorghum / milo, tef and ragi from Africa and Asia According to FAO / WHO (2000) a gluten-free food ingredient must contain <2000 ppm (db) for sensitive people (< 10 mg of prolamin / day: CX / NFSDU 00/4). The Food Allergy Labeling Act and Consumer Protection Act (FALCPA) will be effective for any food labeled in 2006. This new law essentially asks for simple, non-allergenic labels on the food labels (wheat, milk, egg, fish, crustaceans, shellfish, nuts, peanuts and soybeans: Food Safety Magazine, 2005). Therefore, this whole grain flour can be better used as a cereal base and functional ingredient during the standard processing of reduced gluten foods (soft / hard wheat, barley, rye and oats) and based on grains such as: bar ( fruits), biscocho, biscuit, salty biscuit, snack (tasty and 3G), flat bread (pita), flour tortilla (table and ciabatta omelette), yeast roll, pancake, pie, pancake, bulgur, pasta, dumplings, noodles, porridge (cereal drink made with water / milk and flavorings). This whole corn flour can also be used in traditional and new gluten-free foods such as: a) an instant drink (gacha) made of ground toasted flour with pinole flavored with sugar and cinnamon / orange, b) the atole is prepared with flour and water with sugar / honey and cinnamon / anise and c) mestizo-chorote / pozole is made by mixing water and dough with ground roasted cocoa beans or with sugar / coconut (Maya "Popul Vuh": Ixmucane took white and yellow corn and made food and drink from which man's fat and flesh was made, Sarabia, 1975). From the above, it will be apparent that it is possible to prepare pregelatinized and instant maize flours with a new continuous process that is efficient due to the precooking of low humidity and heat treatment that produce a dough flour for food and flour based on corn and whole corn for grain-based foods, in which some of the nutrients, water and energy losses that would have been present but by the characteristics of this invention are avoided. It should be understood that the modalities of this invention illustrated herein and described in detail and with published references, are by way of illustration and not limitation. Other changes and modifications may be made by those skilled in the art without departing from the spirit of this invention. It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention.

Claims (20)

CLAIMS Having described the invention as above, the content of the following claims is claimed as property:

1. A process for making whole wheat flour and dough for grain-based foods from clean corn grain, characterized in that it comprises continuously and repeatedly carrying out the following stages: preconditioning the clean corn kernel with sprinkled water to partially wet the fractions of bran, germ and endosperm of clean maize grain to produce moistened whole corn kernel; grind the whole corn grain moistened by removing the portions of bran from it and grind the whole corn grain moistened to create fine and coarse grinding fractions; sieve and aspirate the fine and coarse grinding fractions to remove a fraction of light bran from them; mix with lime the finest grinding sifted and sucked to obtain a fine grinding with lime; Preheat with moisture-heat a stream of fine grinding with lime in a stream of saturated steam to a temperature of 150 ° C to 170 ° C to carry out partial starch gelatinization and protein denaturation; Ventilate fine grinding with steam while allowing steam to escape; temper precooked and separated fine grinding to partially hydrate the endosperm and swell starch and protein granules thereof, producing hardened corn particles; hot air drying the hardened corn particles in a warm air stream for additional pregelatinization and removing residual hot air, producing dried corn particles; cool and dry dry corn particles further with clean ambient air while ventilating moist air; grind the chilled and dried corn particles into fine and coarse fractions, and remove the coarse grinding fraction and collect a pregelatinized dough under 20 to 100 mesh suitable for tortilla and corn-based foods.

2. The method of compliance with the claim 1, characterized in that the sieving step separates the fine grinding fraction, under 16 to 20 meshes, from the coarse grinding fraction, the fine grinding comprises the endosperm, germ and aleurone-bran fractions, the coarse grind comprises the endosperm, germ and pericarp-bran fractions.

The method according to claim 2, characterized in that the grinding and pulverizing step further comprises: aspirating the fine and coarse grinding fractions to isolate a fraction of light maize bran; recycle the coarse grinding, suction and remove the coarse grinding, sucked and recycled.

4. The method according to claim 1, characterized in that the collection stage further comprises collecting an instant whole corn flour under 40 to 120 mesh suitable for grain-based foods.

5. The method of compliance with the claim 4, characterized in that the dough and whole corn flours represent 90% and 98% yield of the total weight of clean maize grain, respectively.

6. The method according to claim 5, characterized in that the precooking uses lime in an amount of 0.20% and 0.02% by weight of the clean maize grain to obtain, respectively, a dough flour and a whole corn flour suitable for corn and grain-based foods.

7. The method of compliance with the claim 1, characterized in that the step of precooking with moisture-heat includes the step of injecting the saturated steam under pressure into the stream of fine grinding with lime upon entering the fine grinding with lime in the precooker, instantaneously heating and hydrating particles of the grinding fine with lime to a moisture content of 20% to 22% for 1 to 5 seconds.

The method according to claim 1, characterized in that the drying step with hot air is carried out at a temperature of 190 ° C to 260 ° C for a time of 2 to 6 seconds, while removing moisture from tempered corn particles to a content of 15% to 9%.

The method according to claim 7, characterized in that the precooking with low humidity comprises a reduction of 40% to 80% in the consumption of energy and water compared to a comparable process.

The method according to claim 1, characterized in that it comprises the additional steps of: rehydrating the pregelatinized dough with hot water of a weight ratio of 1: 1 to about 1: 1.4 to form a dough and make the less one of corn-based foods with dietary fiber and ferulic antioxidant using partial whole flour.

11. The method according to claim 6, characterized in that it further comprises the steps of: mixing the instant whole corn flour with 45% to 49% by weight of flour without bran and degerminated, to produce a whole grain flour; rehydrate the instant flour with lukewarm water of a weight ratio of 1: 0.7 to approximately 1: 1.1 to form a corn dough and make at least one of wheat-based and grain-based foods with increased dietary fiber and antioxidant content ferulic using whole flour as a cereal base and functional ingredient.

12. A process for making flour, characterized in that it comprises the steps of: providing clean corn grain; precondition the clean corn kernel with sprinkled water to produce moistened whole corn kernel; grind the whole corn grain moistened by removing the portions of bran from it and grind the whole corn grain moistened to create fine and coarse grinding fractions; sieve and aspirate fine and coarse grinding fractions; mix the fine grinding fraction sifted and sucked with lime to produce a fine grinding with lime; Precook with moisture-heat the fine milling with lime by injecting a stream of saturated steam; ventilate pre-cooked fine grinding with steam; temper fine grinding with precooked lime to partially hydrate the endosperm and swell the starch and protein granules thereof, producing hardened corn particles; drying the warm corn particles with warm air, producing dried corn particles; cool and dry dry corn particles further with clean ambient air while ventilating moist air; grind the cooled and dried corn particles to create fine and coarse fractions, and collect from the fine fraction a pregelatinized dough under 20 to 100 mesh suitable for tortilla and corn-based foods.

13. The method according to claim 12, characterized in that the sifting and suction lid comprises removing a light bran fraction

14. The method according to the claim 12, characterized in that the saturated steam of the precooking stage with moisture-heat has a temperature in the range of 150 ° C to 170 ° C.

15. The method according to claim 14, characterized in that the precooking stage with heat- moisture carries out a partial starch gelatinization and protein denaturation.

16. The method according to claim 12, characterized in that the hot air drying step produces additional pregelatinization.

17. The method according to claim 12, characterized in that the step of grinding the dried and cooled corn particles also includes removing the coarse grinding fraction.

18. The method of compliance with the claim 12, characterized in that the grinding and pulverizing step further comprises: aspirating the fine and coarse grinding fractions to isolate a fraction of light maize bran; recycle the coarse grinding, suction and remove the coarse grinding, sucked and recycled.

19. The method according to claim 12, characterized in that the picking step also comprises collecting an instant whole corn flour under 40 to 120 mesh suitable for grain-based foods.

20. The method according to claim 12, characterized in that the step of precocción with humidity-heat includes the stage of injecting the saturated steam under pressure in the stream of fine grinding with lime upon entering the fine grinding with lime in the precooker, instantly heating and hydrating the fine grinding particles with lime to a high content of humidity from 20% to 22% for 1 to 5 seconds.