The glass transition temperature (T-g) and change in heat capacity (Delta C
-p at T-g) of processed wheat gluten samples, including wet (casting) and d
ry processes (thermal treatment, mixing, thermomoulding and mixing followed
by thermomoulding) were determined by modulated differential scanning calo
rimetry (MDSC) as a function of water content. An increase of T-g and a dra
stic decrease of Delta C-p were observed when gluten was dry processed. Cas
ting process gave a film with calorimetric properties close to those of nat
ive gluten. The molecular size distribution of proteins in native and proce
ssed glutens was measured by size exclusion chromatography. The thermomould
ing and the use of chemical cross-linker during casting resulted in a drast
ic drop of SDS-soluble proteins. In contrast, mixing of gluten, even using
high specific mechanical energies, gave only a slight polymerisation of the
proteins. Therefore, except for treatments where a high temperature was ap
plied to gluten, the modification of calorimetric parameters accounting for
reticulation phenomena was not related to the SDS-insoluble protein conten
t. T-g, Delta C-p and protein SDS extractability could account for differen
t kinds of protein networks. (C) 2000 Elsevier Science Ltd. All rights rese
rved.