Nutritional quality of nixtamalized corn masa flour: achievement through fortification with micronutrients

RESUMO

Results from a relatively large number of surveys show that carn (Zea mays) is one of the most important cereal grains for the nutrition of large groups of the Latin American population, particularly for Mexico, Central America, Colombia and Venezuela. In South America, corn is consumed in a number of ways as a decorticated, degermed precooked flour and one of the most popular forms is the arepa. In Mexico and in Central America, corn is also consumed in many different forms made by processing the grain by nixtamaliization. This process consists in cooking sound hard endosperm white or yellow corn with lime for 40 to 60 minutes, allowing a soaking period of 8-12 hrs, washing to remove the seed coat and excess lime, befor grinding into a dough which can be made into tortilla or dried into flour. Lime-treated corn flour represents the whole corn grain without the seed coat. Therefore, it has more protein, more fat and is of a better protein quality than the degermed corn flour consumed in South America. Furthermore, it is a very rich source of calcium due to the lime-cooking process. In rural areas of Mexico and of the Central American countries nixtamalization is carried out daily by the traditional process of using whole corn to produce a dough from which tortillas are made. In recent years industrialized lime-treated corn flour has become available in Central America, a product first introduced in Mexico some 50-60 years ago. The nixtamalization process, as done at home level, is relatively simple to carry our however, it is time cinsuming, requuires hard work and uses relatively large amounts of water. The industrial process is basically similar but with changes in cooking operations to decrease processing time, followed by dehydration and grinding, producing a convenient dry flour for the market. Intake of corn as tortillas in higher in rural areas than in urban areas. Tortillas contribute 39-65 per cent of the daily intake of calories in the rural areas of the Central American countries and 27 to 53 per cent of the daily protein intake. They also provide some amounts of calcium and vitamins B1 and niacin. During processing by the alkaline-cooking procedure, no major changes occur in the macro-nutrients. However, the losses in thiamine and riboflavin are significant...