Effects of chemical leavening systems on the opacity of whole wheat flour tortillas
T. LIU (1), G. G. Hou (2), S. L. Book (3), L. Marquart (4). (1) Univ of Minnesota, St Paul, MN, U.S.A.; (2) Wheat Marketing Center, Portland, OR, U.S.A.; (3) ICL Food Specialties, St. Louis, MO, U.S.A.; (4) University of Minnesota, Saint Paul, MN, U.S.A.
Translucency, a lack of opacity, is generally a defect in tortillas. Chemical leavening is a neutralization reaction, which can affect not only the opacity, but also other physical and chemical properties of tortillas. The objectives of this research were to evaluate the effects of types and amounts of leavenings (acids and base), hot press temperature and dough temperature on the opacity and other quality properties of whole-wheat tortillas. Whole-wheat flour tortillas were produced with three different leavening acids, three levels of sodium bicarbonate (1%, 1.5% and 2%), three levels of hot press temperature (320°F, 350°F and 380°F), and two levels of dough temperatures (25°C and 35°C). Encapsulated fumaric acid was used to lower tortilla pH. Whole-wheat tortillas were analyzed for weight, diameter, thickness, moisture, color, pH, opacity and texture at one day and 45 days after baking. Sodium aluminum phosphate (SALP) produced more opaque tortillas than sodium acid pyrophosphate-28 (SAPP-28), followed by sodium aluminum sulfate (SAS). Increased amount of leavenings improved opacity, while dough temperature and hot press temperature did not significantly affect opacity. In addition, higher hot press temperature produced lighter, thinner but bigger diameter tortillas. Higher amount of leavenings produced smaller, thicker and brighter color tortillas. SALP produced largest diameter and lightest weight tortillas. Tortillas made with SAS had the largest breaking force, while tortillas with SALP had the smallest breaking force as determined by TA-XTPlus Texture Analyzer. After 45 days of storage at room temperature, all tortillas showed decreased breaking force. The results indicated that the type and amount of leavenings were the major influencing factors for the opacity of whole-wheat tortillas.
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