Effects of the timing and amounts of leavening during processing of wheat flour tortillas

Abstract

Changes in dwell time and pressure of the hot-press yielded tortillas with substantially different attributes. Thick tortillas were prepared using low pressure and long dwell time. Thin and larger diameter tortillas were prepared using higher pressure and/or longer press times. Volume and opacities were similar except when extreme low or high dwell times and pressures were utilized. Thicker tortillas corresponded to shorter shelf stability. The effects of the rates of reaction of several leavening acids and 4 grades of sodium bicarbonate (NBC) on flour tortillas were determined. An increase in dough and tortilla pH was observed in treatments with the same acid but faster NBC, indicating that smaller particle size NBC dissolves and reacts earlier in processing. Tortillas with increased volume also had increased height, diameter and opacity. Tortillas with more volume or height had shorter shelf stabilities. Higher opacities were observed in tortillas containing fine NBC and lower opacities with coated NBC. Some combinations of the acid with NBC enhanced tortilla attributes. Treatments with coated citric acid were unique because they were thick, and had increased diameter, opacity, volume, and shelf stability. SALP with coarse NBC yielded unique tortillas with decreased height and increased diameter and opacity. Slower acids dissolved some during mixing and nucleated the dough with gas bubbles sufficiently to yield opaque tortillas. During dough resting, dividing and rounding, some insoluble leavening compounds need to be retained to allow for later chemical neutralization and reaction during baking. The gas produced early during baking was not completely retained as evidenced by less opaque tortillas. The effects of the amount of leavening (optimum, 33% less than optimum, and 50% more than optimum) on tortilla properties were evaluated. Tortilla height increased with the amount of leavening. Increased leavening increased opacity with the high amount of leavening resulting in the most opaque tortillas for all the acids. Greater amounts of leavening, however, adversely affected storage stability. Increased amounts of leavening resulted in tortillas with increased opacity, decreased diameter, shorter shelf-life and less rollable tortillas; while decreased amounts of leavening resulted in tortillas with decreased height, volume and opacity.