Gelatin is the denatured form of collagen, the main component of skin, bone, and connective tissues of animals. Its special properties are a sharp sol-gel transition, low sol viscosity and high effectiveness as a protective colloid.
For properties of aqueous mixtures of gelatin with other biopolymers, the character of aggregates of a-chains is important: the entropy of mixing is reduced when gelatin chains are limited in their mobility by aggregation.
SEC-MALS was used to study the aggregation behavior of gelatin solutions as a function temperature without using denaturing agents, such as urea or SDS. In addition to the usual concentration detection by refractive index, optical rotation detection was applied to detect any changes in the degree of helicity of the gelatin chains.
The effect of temperature on the molar mass distribution suggests the existence of a monomer-dimer equilibrium between gelatin chains (the shoulder corresponding to the monomer was 90–100 kDa and the one corresponding to the dimer was ca. 200 kDa). The results explain the different behavior of these gelatins in mixtures with other biopolymers.
The ratio of the refractive index and the optical rotation was constant for MM <ca. 400 kDa and is independent of temperature. No involvement of helix formation could be detected.
This note graciously submitted by R.H. Tromp and C. Olieman, NIZO Food Research, Kernhemseweg 2, 6718 ZB, Ede, The Netherlands.
DAWN®, miniDAW®, ASTRA®, Optilab®, DynaPro®, Protein Solutions® and the Wyatt Technology logo are registered trademarks of Wyatt Technology Corporation. ©2011 Wyatt Technology Corporation.
Wyatt Technology Corporation