Gums and Stabilisers for the Food Industry 12
Structural properties of gelatin in mixture with sugar
Published:19 May 2004
S. Kasapis, I. M. A. Al-Marhoobi, M. Deszczynski, J. R. Mitchell, and R. Abeysekera, in Gums and Stabilisers for the Food Industry 12, ed. G. O. Phillips and P. A. Williams, The Royal Society of Chemistry, 2004, pp. 437-449.
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The structural behaviour of a well-characterized gelatin sample has been revisited to investigate the morphology of its network in the presence of sugar. This was then contrasted with the corresponding properties of the gelling polysaccharides agarose, κ-carrageenan and deacylated gellan reported earlier in the literature. Small deformation dynamic oscillation, large deformation compression testing, differential scanning calorimetry in plain and modulated mode, visual observations and transmission electron microscopy were used to identify the structural characteristics of the biopolymers. Characteristics ranged from the melt and the rubbery plateau through the transition region to the glassy state.
In contrast to the collapse of the polysaccharide gels at intermediate levels of cossolute, gelatin forms reinforced networks. The drop in polysaccharide network strength is accompanied by a decline in the enthalpy of the coil-to-helix transition, whereas the transition enthalpy is more pronounced in gelatin gels in accordance with their strengthening. Tangible evidence of the molecular transformations was obtained using microscopy, with polysaccharides disaggregating and dissolving in the saturated sugar environment. Gelatin, on the other hand, is visualized in an aggregated form thus producing a phase-separated topology with sugar. We feel that these are thought-provoking results for confectionery manufacturers aiming to replace the protein with gelling polysaccharides in product formulations.