Chapter 17 - Food Uses of Lime-Cooked Corn With Emphasis in Tortillas and Snacks

Abstract

Mature corn kernels, food-grade lime, and water are the three fundamental raw materials for the production of an array of food. Processing-wise, cleaned corn is lime-cooked for production of nixtamal that is ground into a cohesive dough or masa which is the backbone for production of many traditional and industrialized food such as traditional gruels, tamales, table tortillas, corn chips, and tortilla chips. Undoubtedly, the soft tortilla is the most relevant food in Mexico and other Latin American countries, whereas tortilla chips one of the most important salty snacks worldwide. Other additives such as hydrocolloids, emulsifiers, acidulants, and preservatives are commonly added to table tortillas in order to enhance both textural and microbial shelf lives. For production of snacks, oil, salt, and flavorings are additional ingredients which affect flavor, mouth feel, and sensory attributes. Table tortillas are obtained from three major processes: traditional, industrial fresh masa, and from dry masa flour (DMF). The traditional and industrial processes consist of cooking corn kernels in the presence of a lime solution for about 30–40min followed by overnight steeping for 8–16h. The lime-cooked nixtamal is washed to remove excess lime and then stone-ground into masa. The resulting masa is formed into tortilla discs which are baked in continuous gas-fired ovens. Industrial production of DMF is accomplished by lime-cooking, washing, nixtamal grinding, drying, sieving, regrinding coarse particles, resieving, classifying, and blending to meet certain requirements, especially in terms of particle size distribution, water absorption, and pH. DMF is reconstituted into masa by blending with water for a few minutes. Extruded corn chips and tortilla chips are considered as the second most important salty snacks after potato chips. These snacks are commonly produced from coarse masa obtained from nixtamal cooked to a lesser extent. For corn chips, the masa is extruded and cut into different configurations and deep-fat fried. For tortilla chips, masa pieces are baked before frying to reduce the moisture content, absorb less oil, and induce a firmer texture and stronger flavor. Table tortillas, corn chips, and tortilla chips are considered caloric food with intermediate protein quality and an adequate source of bioavailable calcium and most B-vitamins. Regular corn and tortilla chips provide at least twice as much calories comparted to table tortillas because they contain 36% and 24% oil and are practically devoid of moisture. For this reason, the snack industry is manufacturing light tortilla chips and fat-free baked tortilla chips.