Publication no. C-2004-0712-05R |  VIEW ARTICLE

Glass Transition Behavior and Rheological Properties of Surfactants and Gluten-Surfactant Mixtures.

Imad Toufeili (1,2) and Jozef L. Kokini (1,3). (1) Department of Nutrition and Food Science, American University of Beirut, Riad El-Solh 1107 2020, Beirut, Lebanon. (2) Center for Advanced Food Technology, Department of Food Science, Rutgers, The State University of New Jersey, P.O. Box 231, New Brunswick, NJ 08903-0231. (3) Corresponding author. Fax: 961-1-744460. E-mail: <toufeili@aub.edu.lb> Cereal Chem. 81(5):582-588. Accepted February 12, 2004. Copyright 2004 American Association of Cereal Chemists, Inc.

Diacetyltartaric acid esters of monoglycerides (DATEM) and sodium stearoyl lactylate (SSL) displayed thermal events corresponding to glass transition temperature (T(g)) and melting of crystalline domains, while monoglycerides (MG) exhibited an endothermic peak corresponding to melting of crystalline structures when heated in a differential scanning calorimeter. The plasticizing effect of water on T(g) of gluten exhibited little apparent change in DATEM, MG, or SSL (gluten-surfactant 10:1), in the moisture range of 6.5–21.3% as shown by mechanical spectrometry and differential scanning calorimetry. Gluten-surfactant mixtures showed higher G(prime) and apart from gluten-SSL, which displayed higher tan delta (G(double prime)/G(prime)) at <2.51 rad/sec, lower tan delta values than gluten in the frequency range of 0.1–100 rad/sec. DATEM and SSL softened the gluten network before cross-linking reactions, while MG shifted the onset of cross-linking reactions to higher temperatures at moisture contents of 30–40%. Complete vitrification of the gluten network occurred at higher temperatures, at the indicated moisture contents, in the presence of surfactants. Softening of the matrix and the delay in cross-linking of gluten, in the presence of surfactants, might allow for greater expansion of doughs during baking with concomitant increase in loaf volumes.