ABSTRACT
Introduction ........................................................................................................ 377
Material and Methods....................................................................................... 379
Aqueous Food Pastes Composition ........................................................ 379
Determination of Mean Molecular Weight ............................................ 379
Solid Support Surfaces .............................................................................. 379
Detachment Tests ....................................................................................... 379
Glass-Transition Temperatures ................................................................ 380
Results and Discussion ..................................................................................... 381
Effect of Molecular Weight on Self-Detachment................................... 381
Effect of Composition on Self-Detachment............................................ 382
Conclusions......................................................................................................... 385
Acknowledgments ............................................................................................. 385
References ........................................................................................................... 385
During water removal by evaporation, many substances, including proteins
and sugars, can be converted to an amorphous state. The temperature at
which this transformation takes place is called the glass-transition
temperature (T
), which involves the transition of a liquid-like structured
material from an “elastic” or “rubbery” state to a solid “vitreous” one (Roos
and Karel, 1991; Roos, 1995). The main consequence of glass transition is an
exponential decrease in molecular mobility and free volume as well as
changes in the mechanical and electrical properties below T
(Roos and
Karel, 1991; Roos, 1993). The free volume, which corresponds to the volume
not occupied by material, represents the space available for the free
movement of molecules. Below T
, molecular mobility reduces diffusion,
affecting the reaction rates and food deterioration (Roos, 1995).
