The effects of added wheat proteins on processing and quality of wheat flour tortillas

Abstract

Specific proteins improve quality of flour for breadmaking but protein composition in tortilla flour has not been investigated. Selected wheat protein fractions can separately modify dough resistance and extensibility. This may yield tortillas with increased diameter, opacity and stability. Tortillas were prepared using laboratory-scale, commercial equipment with fixed processing parameters. Dough and tortilla properties were evaluated using a texture analyzer and subjective methods. Tortillas were stored in plastic bags at 22⁰C for 28 days. The effects of ten wheat proteins (donated by Midwest Grain Products, Inc; at 3.0 baker's percent) on processing and quality of flour tortillas were determined. Mixograph parameters varied but were not significantly affected by added wheat proteins. Dough absorption, mixing time, and cysteine level were adjusted slightly to attain uniform dough for tortillas. Wheat protein fractions added to pastry, tortilla and bread flours did not significantly affect tortilla weight, moisture, pH, opacity or specific volume, except for glutenin and vital wheat gluten, which decreased opacity in pastry flour tortillas. Protein fractions yielding improved tortilla properties and stability were FP600, FP6000, FP5000 and Gliadin in pastry and tortilla flour. Addition levels of selected wheat proteins were evaluated in weak protein tortilla formulas. Addition of 1% FP5000 or PF6000 improved tortilla stability. Calcium peroxide was added to the formula to better incorporate added protein fractions in a reduced-oxidized dough system. A combination of 7.5 ppm calcium peroxide with 1% Gliadin resulted in tortillas with improved shelf stability. Bread-making quality of wheat flour is correlated with the insoluble polymeric protein fraction. The insoluble polymeric proteins in flour correlated with smaller diameter and improved rollability score at 12 days of storage for tortillas made from different wheat flours. The insoluble proteins correlated only with tortilla stability for tortillas prepared with added wheat protein fractions to flours with different protein strengths. Several wheat protein fractions improve storage stability of tortillas, while retaining good tortilla properties. This was not related to the insoluble protein amount; however the more insoluble proteins in flour caused smaller diameter tortillas.