Cereal Chem 68:578-582   |  VIEW ARTICLE

Starch Characterization of Nixtamalized Corn Flour.

M. H. Gomez, R. D. Waniska, and L. W. Rooney. Copyright 1991 by the American Association of Cereal Chemists, Inc. 

Commercial nixtamalized corn flours used to prepare tortilla and tortilla chips were analyzed for particle size distribution, composition, and functionality. Changes in starch crystallinity, solubility, and kernel microstructure were evaluated in commercial samples of raw corn, alkaline-cooked and steeped corn (nixtamal), ground nixtamal (masa), and nixtamalized corn flour (NCF). The coarse, intermediate, and fine particle size fractions of NCF had similar chemical composition and distribution of anatomical parts. Starch in the large particles of NCF was less damaged during grinding and was more soluble after autoclaving and sonication. Starch in the intermediate and smaller particle size fractions was more mechanically damaged, gelatinized, and retrograded, as indicated by decreased starch solubility (after autoclaving and sonication). NCF drying, the last thermal operation during processing, caused partial starch gelatinization and retrogradation, decreasing starch crystallinity. Thus starch functionality was modified during NCF preparation, which negatively affected the rheological characteristics of rehydrated NCF; that is, it decreased the cohesiveness and plasticity of the NCF and the shelf life of baked products, so that tortillas became stale sooner.