Corn tortillas are a traditional staple food throughout Mexico and Central America where iron and other micronutrient deficiencies affect large segments of the population, particularly women and children. Tortillas, which represent nearly 50% of energy intake for some populations, are high in natural inhibitors of iron and zinc absorption, particularly phytates. They also contain relatively low levels of several other key micronutrients (B vitamins and folic acid).
SUSTAIN’s initiative to fortify these much loved and widely consumed products with essential micronutrients is beginning to change children’s lives one meal at a time, in ways the kids don’t notice, their mothers appreciate, and neighborhood tortilla millers take pride in.
Tortilla production in Mexico dates back to ancient Mesoamerican civilizations. The present day commercial manufacture of tortillas in small neighborhood mills (molinos de nixtamal) throughout Mexico essentially utilizes the traditional production process. Corn is cooked and soaked in lime to produce nixtamal (the Aztec word for the slurry of soaked and softened maize kernels). Nixtamal is ground into “masa de maíz“ (corn dough). The masa is rolled, molded into thin patties and baked on a clay or metal grill. Nixtamal can also be dried to produce corn masa flour (harina de masa), a convenience product introduced in the 1940s that is rehydrated for use in commercial and home-based tortilla production. These two manufacturing methods each account for roughly half of the commercial tortilla market in Mexico (although estimates of market shares vary).
Corn masa flour gained widespread use in tortilla production by the late 1980s, opening an attractive avenue for fortifying a widely consumed food product with micronutrients. It has been technically feasible to enrich the flour with micronutrients for some time. Yet Mexico’s “molinos de nixtamal” had no way of enriching their fresh masa.
With the majority of tortillas manufactured in Mexico produced from fresh masa in small neighborhood mills, a large segment of the population was missing out on the benefits of micronutrient fortification.Background
SUSTAIN began to explore the potential for fortification of widely consumed products in Central America with technical assessments in 1996 and 1997 of iron fortification practices at wheat mills in El Salvador, Guatemala, Nicaragua and Honduras. The SUSTAIN team also visited two manufacturers of corn masa flour.
In 1998, industries representing corn and wheat millers in Mexico signed a groundbreaking agreement with the government to voluntarily fortify both wheat and corn masa flour with iron, B-vitamins, zinc and folic acid. Anticipated progress towards enforceable regulatory action stalled—among other issues, the choice of an appropriate iron fortificant became a sticking point for all parties to the agreement. One major issue was the lack of information on the efficacy of the most commonly used iron fortificants (elemental iron powders), which are favored by industry because of their relatively low cost and minimal impact on food vehicles. Both industry and government representatives asked SUSTAIN to help address this situation.
In response, SUSTAIN convened a panel of world-renowned research scientists, physicians and industry specialists to review nearly 45 years of research on elemental iron powders, and to discuss how to interpret conflicting bioavailability data. The Monterrey (Mexico) Workshop proved to be a highly effective step toward clarification. Drawing on its findings and recommendations, SUSTAIN drafted the Guidelines for Iron Fortification of Cereal Food Staples an interim tool to help program planners select and use optimal iron fortificants for public health programs.Fortifying masa tortillas
By 2002, manufacturers of corn masa flour had seen their market share plateau, thus considered the inclusion of molinos de nixtamal (which produce the fresh masa) in fortification programs a prerequisite for their own participation. But how could the molinos de nixtamal fortify their dough?
The National Institute of Public Health in Mexico (Instituto Nacional de Salud Publica, INSP) and SUSTAIN formed a working group of representatives from industry, the research community, and government to bring relevant expertise to bear on this problem. A fortification system suitable for small masa mills had to fit into the existing milling process without significant changes to manufacturing methods. It had to be reproducible, easily learned/operated and engender little or no increase in manufacturing or product costs. The added micronutrients must be distributed homogenously in the masa and survive baking. For commercial success, the new product had to be indistinguishable from the traditional tortilla Mexicans love.
SUSTAIN sponsored laboratory and pilot studies of masa fortification using both liquid and dry premixes and “super-fortified” flour (for operations that use a mix of masa and corn masa flour). A dry premix proved most cost effective and technically feasible and yielded positive results with respect to micronutrient uniformity and consumer acceptability. Several reformulations of the dry premix were needed to identify iron sources that did not negatively affect tortilla color. The final premix was made with electrolytic iron, in addition to zinc, folic acid, niacin, riboflavin and thiamin. Electrolytic iron is preferred by industry due to its low cost and minimal impact on the food vehicle. Acceptance of tortillas with electrolytic iron was confirmed by consumer sensory tests carried out in partnership with the National Institute of Nutrition in Mexico (Instituto Nacional de Nutritión). Because it is considered to be about half as bioavailable as ferrous sulfate, it was added at twice the level recommended for ferrous sulfate.
Considerable work went into identifying a prototype dosifier and adapting it for use in metering out micronutrients in tortilla mills. The unit had to be relatively low in cost, but sturdy/robust enough to perform in the moist environment of the mills and easy to operate. After evaluating potential alternatives, a small and affordable dosifier manufactured by the Mexican firm Probst was identified, installed in pioneer mills in Mexico City and Guadalajara, and successfully operated in pilot and extended commercial trials. Tests indicated that the dosification yielded consistent levels of micronutrients (based on iron as a marker) in consecutive production runs.
The chosen method is cost effective, easy to use and has a minimal impact on the manufacturing process. It dramatically improves the nutritional value of the tortillas without changing their appearance and taste. An extended trial in selected mills confirmed that the procedure is commercially viable, and that consumers educated about the nutritional benefits provided by fortified tortillas become loyal customers.
Pioneer mill owners and employers took pride in offering their customers—and their own families—a healthier product at no added cost. Consumers learned about its enrichment through nutritional education and promotion campaigns at mill sites and community centers. School children who enjoyed an interactive nutrition lesson disguised as an art contest came up with the logo for the fortified tortilla.
A number of progressive mill owners have expressed interested in the fortification of their product, and SUSTAIN hopes to secure funding to develop a sustainable business model for expanding the fortification system to other mills and neighborhoods throughout Mexico and Central America.
To read more about this initiative and the pioneer mills click Enriching Children’s Lives, One Meal at a Time
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