The aim of this study was to understand the interactions taking place between konjak glucomannan (KGM), a soluble dietary fibre with extraordinarily high water-holding capacity, and chitosan, a pH-sensitive biopolymer, to promote the development of physically crosslinked interpenetrating hydrocolloid networks (IHNs). These IHNs could be useful for the design of satiating ingredients that would swell at gastric pH values. Initially, cast films from blends of KGM and chitosan were developed to study swelling ability and molecular organization through gravimetric studies, small-angle X-ray scattering (SAXS), wide-angle X-ray scattering (WAXS) and Fourier transform infrared spectroscopy (FTIR). The effects of chitosan molecular weight, KGM:chitosan ratio and neutralization with sodium carbonate were also analysed. Freeze-dried samples from the hydrocolloid blend solutions were also studied for comparison purposes. The rheological behaviour of these solutions was characterized and could be adequately explained by the interactions established during the formation of the IHNs, thus providing useful information for developing novel satiating ingredients. Interestingly, a different mechanism of NaCO-promoted interactions was observed when applied to the films (solid state) or incorporated into the hydrocolloid solutions.

Synchrotron experiments were performed at NCD beamline at ALBA Synchrotron with the collaboration of ALBA staff. Laura G. Gómez-Mascaraque is recipient of a predoctoral contract from the Spanish Ministry of Economy and Competitiveness (MINECO), Call 2013. M. J. Fabra is recipient of a Ramon y Cajal contract from the Spanish Ministry of Economy and Competitiveness. We are also grateful to the Spanish Ministry of the Economy and Competitiveness for financial support (AGL2012-36753-C01) and gratefully acknowledge the financial support of EU FEDER funds.