Numerical simulation of coil-helix transition processes of gelatin

Gelatin is widely used in food, pharmaceutical, and photographic industries due to the coil-helix transition, whereas the structural inhomogeneity considerably affects its essential properties closely connecting with the industrial applications. The spatially structural inhomogeneity of the gelatin caused by the uneven and unstable temperature field is analyzed by the finite element method during the cooling-induced coil-helix transition process. The helix conversion and the crosslinking density as functions of time and spatial grid are calculated by the incremental method. A length distribution density function is introduced to describe the continuous length distributions of two kinds of triple helices. The results show that the crosslinking density and the length distribution of triple helices are dependent on the thermal histories. And the spatially structural inhomogeneity is more distinct when the initial gelatin concentration and the convective heat transfer coefficient increase. The present work is helpful for optimizing the fabrication conditions of gelatin. (C) 2009 Elsevier Ltd. All rights reserved.