88C-3 |
Prediction of the glass transition temperature of dry proteins and the effect of various plasticizers |
B. CUQ1, S. Guilbert1, and N. Gontard2. (1) Ecole Nationale Supérieure Agronomique de Montpellier, Institut National de la Recherche Agronomique, 2, Place P. Viala, Bât. Administratif, Cedex 1, Montpellier, 34060, France, (2) GBSA, Univ. Montpellier II, CC 023, Place Eugene Bataillon, Montpellier, 34095, France The glass transition behavior of food proteins is a critical parameter in the transformation process and can be used to predict textural properties and physicochemical stability during storage. The glass transition temperature (Tg) of various proteins (wheat gluten, corn gluten and fish myofibrillar proteins) has been studied as a function of the content of various plasticizers (water and plasticizers of variable polarity). Measurements of Tg were done by using modulated differential scanning calorimetry and dynamical mechanical thermal analysis. The Tg of dry proteins (without any plasticizer) have been estimated by using the Matveev equation. The calculation is based on the additive contributions of structural parameters. Predicted values are closed to the respective measured values. The general plasticizing effect of selected plasticizers broadly followed the Couchmann-Karasz and the Kwei models. The plasticizing efficiency was generally found to be proportional to the molecular weight and inversely proportional to the percent of hydrophilic groups of the plasticizer. Migration rate of the plasticizers in the polymer was related to their physicochemical characteristics. Prediction of glass transition behavior (in a dry state and under various conditions of plasticization) of food proteins can be obtained by using the Matveev equation and the Couchmann-Karasz and the Kwei models.
Session 88C, Food Engineering: Physical and Chemical Properties
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