3. Results and discussion
3.1. Solegel transition at constant or increasing temperature
At temperatures below 30 C, gelatin macromolecules undergo a
conformation coil/helix transition (rigid form). As a result, its
aqueous colloidal solutions transforms to gels if the gelatin concentration exceeds some critical threshold (Izmailova et al., 2004;Ross-Murphy, 1997). Such a sol /gel transition happens due to
formation of intermolecular hydrogen bonds between carboxyl
oxygen and amid hydrogen in polypeptide chain (at high content of
glycineeprolineehydroxyproline amino acids). Beside, gelatin
macromolecules loss solubility at cooling owing to their transition
into the rigid helix conformation. These processes lead to phase
decomposition and formation of a spatial network structure based
on a biopolymer phase with the presence water entrapped
(Gilsenan&Ross-Murphy, 2000).