Enzymatic process for nixtamalization of cereal grains

Details Enzymatic process for nixtamalization of cereal grains Enzymatic process for nixtamalization of cereal grains

2000-08-22

2002-08-06

Hendricks, Keith (Department: 1761)

Food or edible material: processes, compositions, and products

Fermentation processes

Of farinaceous cereal or cereal material

C426S052000

Reexamination Certificate

active

06428828

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to the fields of making flour and dough, used for producing flat breads such as tortillas, roti; snacks such as corn chips, tortilla chips; fried puffed snacks, half-product and related products, from the component parts and whole portions of cereal grains, grain materials, and non-cereal materials such as dry edible beans, oilseeds, tubers, bananas, carrots, and related materials. More particularly, this invention relates to a method for the production of flour and dough through the use of an enzymatic digestion process whereby component parts and whole portions of cereal grains, grain materials, and non-cereal materials such as dry beans, tubers and other food materials can be used as the starting material. The method of this invention imparts advantageous qualities to the resulting flour and dough such that it can be conveniently processed and sheeted, cut or extruded using common food processing equipment to produce a variety of foods and related products produced therefrom.
BACKGROUND OF THE INVENTION
Corn tortillas, tortilla chips, corn chips, taco shells, and burrito wraps and other related products are prepared by sheeting, cutting and baking and/or frying of corn dough pieces. These products are prepared from corn masa flour, which is instant masa flour which has been produced from nixtamalized corn or corm meal and rehydrated with water to form a dough, or stone ground corn dough/masa, which is dough or flour prepared by stone grinding of nixtamalized corn.
Traditionally, the production of instant masa flour or fresh corn masa dough material involves the process of nixtamalization. Nixtamalization involves the following essential steps: whole kernel corn is cooked at a temperature below or at boiling for a period of time in a medium which usually contains an alkaline agent, such as water containing lime [Ca(OH)
2
]. The time and temperature of the cook often depends upon the hardness of the grain. Harder grain requires longer cook time and/or higher temperatures. Thereafter the cooked corn is allowed to steep (soak) for a period of time in the liquid, for example for about three to about fourteen hours. After steeping, the cook/steep liquor, which is the liquid medium in which the corn was cooked and steeped and is also known as nejayote, is drained and the retained grain is washed to remove the alkaline agent and other solubilized/dispersed materials. The processed (cooked and steeped) grain is known as nixtamal. Nixtamal is stone ground in a traditional stone grinder to produce fresh corn dough also known as masa. To produce instant masa flour, nixtamal is coarsely ground, dehydrated and milled into flour often referred to as instant masa flour. Instant masa flour can be conveniently re-hydrated by the addition of water to make masa dough. Stone ground fresh masa or instant masa flour dough is sheeted, cut baked and/or fried in oil to produce tortillas, tortilla chips, corn chips, taco shells and related products.
The preferred grain for use to produce tortillas and related products is corn or corn meal. With corn the alkaline cooking and steeping loosens the pericarp or outside bran layer of the corn kernel from the endosperm so that water can reach the starch and the pericarp can be removed.
Conventional nixtamalization processes for producing fresh masa dough or instant masa flour have several disadvantages. For example, the time required for steeping places production limits on equipment and increases the space requirements for the manufacturing facility. Additionally, the process uses large amounts of water and generates large quantities of effluent waste water that must be treated prior to disposal. The waste water from the traditional nixtamalization is highly alkaline as large amounts of alkaline lime solution are used to cook, steep and hydrate whole kernels of corn. The highly alkaline waste streams (pH approximately 9-12) also have a high biological and chemical oxygen demand (BOD/COD) values and are a potential pollutant because of their composition and characteristics. Nejayote also contains large amounts of dissolved pericarp, soluble/dispersed starches and other corn material that cannot be ecologically discharged into water ways or municipal waste water systems. Nejayote has a chemical oxygen demand (COD) of approximately 2500 mg/liter, a biological oxygen demand (BOD) of approximately 8100 mg/liter and a suspended solids content of approximately 20,000 mg/liter. Nejayote also contains approximately 310 mg/liter of nitrogen and approximately 180 mg/liter of phosphorus.
Commercial alkaline corn facilities discharge alkaline wastewater in large sedimentation tanks or lagoons for disposal. The wastewater cleaning operation is accomplished by sedimentation and microbial degradation of corn solids. The wastewater, due to its alkalinity and solids content, cannot be directly discharged in the environmental water streams before proper neutralization and clean-up. Generally, the manufacturing facility must bear the cost of treating the waste water prior to discharge.
Alkaline waste and wastewater disposal is a major concern during commercial nixtamalization. Alkaline cooking, steeping and washing of the corn solids causes partitioning of corn solids between corn material and waste water. Loss of corn solids i.e. yield loss during nixtamalization and cost of effluent processing are considerable. In a commerical operation, corn solid loss has been estimated to vary between 5 to 14% depending on the type of corn. (Katz et al., (1974)
Science
184:765; Khan et al., (1982)
Cereal Chem.
59:279-284). The effluents generated during alkaline cooking of corn known as nejayote are potential pollutants because of their composition and characteristics.
In recent years a number of processes have been developed for improving the efficiency of nixtamal and masa flour production. Many of these processes attempt to shorten the cooking or steeping time or vary the concentration of additives to increase production rates. One example is disclosed in U.S. Pat. No. 5,558,898 to Sunderland. This patent discloses a process for producing masa flour where the whole grain is partially cooked in a hot alkaline solution to partially gelatinize the starch and loosen the bran. Thereafter, the grain is debranned, flash dried and milled.
Further developments in the production of masa and masa flour use ground corn or corn flour as the starting material instead of whole corn. These processes typically treat the ground corn with water at elevated temperatures to hydrate the corn in less time than with conventional steeping. An example of such a process is disclosed in U.S. Pat. No. 5,532,013 to Martinez-Bustos et al. In this process whole corn flour is mixed with lime and water and heated to 60 degrees to 95 degrees Celsius in a cooker-extruder to partially cook the mixture. The partially cooked mixture is then discharged through a die to a cooling chamber and thereafter extruded through a nozzle.
Other processes of producing masa from ground corn are disclosed in U.S. Pat. Nos. 5,395,637 and 5,401,522 to Reeg. The disclosed processes form a mixture of corn flour, water and lime and heat the mixture slightly above the gelatinization temperature and then cool below the gelatinization temperature to only partially gelatinize the starch. The process disclosed in U.S. Pat. No. 5,652,010 to Gimmler discloses a similar method where the mixture is hydrated below the gelatinization temperature of the corn starch with subsequent gelatinization at controlled temperatures to only partially gelatinize the hydrated corn particles. The upper limit of the heating temperature is selected to carefully control the gelatinization of the starch.
The above-noted processes for producing nixtamal and masa flour have not completely overcome the deficiencies of the traditional masa production process. There remain concerns about product quality and production rate. Accordingly, there is a continuing need in the industry for an improved process of prod

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