Characteristics of nixtamalised maize flours produced with the use of microwave heating during alkaline cooking.

Whole, ground and abrasively dehulled grains from both normal (H-34 and H-34) and quality protein (QPM and QPMa) maize were mixed with water contents of 70, 95 and 100 g kg and calcium hydroxide concentrations of 0.0, 0.3, 0.5 and 2.0 g kg and heated (operating frequency 2.450 MHz, high-power setting) for 10, 15 and 20 min in a commercial microwave oven. The cooked grain was then oven dried and milled to obtain nixtamalised maize flour (NMF). The protein contents and test weights of QPM were higher than for the normal hybrids. The highest yields of masa and tortillas were found for the normal hybrids, and these samples did not show significant differences, as compared with the commercial nixtamalised flour (CNMF) used as control, with respect to masa firmness and adhesiveness and tortilla tensile strength. The cutting force of tortillas from hybrid H-30 and QPM did not show significant differences from the control. The highest values of tortilla rollability were found for the control followed by hybrid H-34. The values of residual cooking liquor for microwave-heated samples were lower than for the control. Ground or dehulled maize grain gave sticky masa and poor mechinical characteristics. Tortillas from whole grain showed good characteristics of texture and consistency of masa, and the tortillas were subjectively similar in colour, flavour and rollability to the tortillas prepared with CNMF. These results indicate a potential use of microwave energy to produce NMF for tortillas and derivatives. © 2000 Society of Chemical Industry.