Starch/carrageenan mixed systems: Penetration in, adsorption on or exclusion of carrageenan chains by granules?

This study focused on the understanding of starch/carrageenan interactions. Seven carrageenan samples and a modified waxy maize starch were used. Two types of blends were made: starch was pasted in carrageenan solutions or swelled starch granules were mixed with carrageenan solutions. For each blend, the carrageenan concentration in the continuous phase was determined by indirect titration that permitted to evaluate the percentages of carrageenan trapped by starch granules. The presence of carrageenan in the continuous phase was shown to impact the swollen starch granulesʹ sizes and characteristics. The level of viscosity in the continuous phase was shown to depend on the starch/carrageenan interactions but also on the released amylopectin concentration. Starch pasting was shown to be unnecessary to promote interactions as the same percentage of trapped carrageenan was found when put into contact with starch granules either before or after swelling. Carrageenans were found to be both excluded and adsorbed on starch granules. The level of adsorption of carrageenan on starch granules seemed to be promoted by low-negatively-charged carrageenan and by low-molecular-weight carrageenan.