The influence of iota carrageenan on water mobility and aging of agarose gels
2022
Descallar, Faith Bernadette A. | Wang, Aoran | Matsukawa, Shingo
Water exudation, water permeation, Young's modulus, and Pulsed-field gradient stimulated echo (PGSTE) ¹H NMR measurements were carried out to investigate the effect of iota carrageenan (IC) on the water mobility and aging of agarose gels. Mixed agarose/IC polysaccharide samples exhibited slower water exudation and water permeation than pure agarose gels at the same total polysaccharide concentration. These effects were attributed to the water-holding capacity of IC chains. These results held for all storage times investigated. The Young's modulus increased during the first three days of storage, supporting gradual integration of all agarose chains into aggregates and the elastic network. The microstructure of the gels was also studied with PGSTE ¹H NMR experiments to obtain the diffusion coefficient of pullulan (Dₚᵤₗₗ) added as a probe polymer. In pure agarose gels, Dₚᵤₗₗ increased with storage time, again indicating gradual integration of all agarose chains into aggregates and gel network. Conversely, Dₚᵤₗₗ in agarose with IC did not show a significant increase during storage, indicating that the diffusion of pullulan is affected more by IC chains, which are not integrated into the agarose network, than by the soluble agarose chains, which are integrated into aggregates and the network within several days.
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