Uniform TitleUnderstanding the origins of stickiness in wheat flour tortillas and devising strategies to reduce it
NameRathod, Jigarbhai H. (author), Kokini, Jozef (chair), DAUN, HENRYK (co-chair), Takhistov, Paul (co-chair), Rutgers University, Graduate School - New Brunswick,
DescriptionThis thesis aimed to determine the factors which affect stickiness in wheat flour tortilla products based on a phase/state-change approach and measurement of water activity and surface properties. Strategies were considered to reduce stickiness of flour tortillas by adding GRAS ingredients and modifying processing conditions.
Commercial wheat tortillas with a wide range of stickiness were selected and equilibrated to different water activity levels (0.12-0.97). Moisture sorption isotherms were developed. Differential scanning calorimetry and mechanical spectroscopy were used to characterize the phase behavior and freezable water, wide-angle x-ray scattering to understand the effect of crystallinity, contact angle measurements to determine the surface hydrophobicity. An objective instrumental test technique was developed using a texture analyzer to quantify the stickiness in tortilla samples. X-ray microtomography was used to measure tortilla cellularity. Tortillas were prepared with Xanthan gum, carboxymethylcellulose, glycerol and propylene glycol. To understand the effect of processing conditions on stickiness, tortillas were prepared using different combinations of dough resting times, baking temperatures and cooling times after baking.
Sticky tortilla showed lower glass transition temperature compared to non-sticky tortillas but both were in rubbery state at room temperature. Higher product Aw resulted in increase in surface energy which in turn caused an increase in instrumental stickiness scores as hypothesized. The polar component of surface energy was found to have a good correlation with stickiness. The sticky tortillas showed low crystallinity as compared to non-sticky tortillas. Tortillas containing 0.5 % gums and 4 % glycerol showed increased water retention, decreased water activity, reduction in surface free energy and lower freezable water. Addition of glycerol reduced the water activity from 0.94 to 0.91. Tortillas baked at 450° F were stickier than tortillas baked at 350°. Rupture force to extend tortillas increases with increase in storage time and temperature. Storage of tortillas at lower temperatures retains freshness as was shown by reduced rupture force values.
NoteIncludes bibliographical references (p. 134-136).
CollectionGraduate School - New Brunswick Electronic Theses and Dissertations
Organization NameRutgers, The State University of New Jersey
RightsThe author owns the copyright to this work.