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Sensory, Mechanical, and Microscopic Evaluation of Staling in Low-Protein and Gluten-Free Breads

¹Department of Nutrition, Dietetics and Food Science, Brigham Young University, S221 ESC, Provo, UT 84602. ²Corresponding author. Phone: 801-422-6671. Fax: 801-422-0258. E-mail: oscar_pike@byu.edu ³Center for Statistical Consultation and Collaborative Research, Brigham Young University, 223 TMCB, Provo, UT 84602. ⁴Department of Integrative Biology, Brigham Young University, 401 WIDB, Provo, UT 84602.

Staling over a 120-hr period was compared in a gluten-free rice bread, a low-protein starch bread, and two gluten-containing breads (standard wheat and added-protein wheat) using quantitative descriptive analysis (QDA), critical stress values obtained by mechanical compression testing, and scanning electron microscopy (SEM). The gluten-free rice bread had the highest QDA scores for both moistness and overall freshness, whereas the low-protein starch bread had the lowest scores for both attributes. Differences in critical stress values over the 120-hr period demonstrated that the gluten-free rice bread had the greatest resistance to mechanical collapse, indicating the least structural damage, whereas the low-protein starch bread had the least resistance to mechanical collapse. Both wheat breads had QDA moistness and freshness scores, and critical stress values that ranged between the gluten-free rice and low-protein starch breads. SEM showed the formulation containing rice, egg and milk proteins, xanthan gum, and hydroxypropylmethylcellulose created a bicontinuous matrix with starch fragments, similar to gluten.