Development of glucomannan-chitosan interpenetrating hydrocolloid networks (IHNs) as a potential tool for creating satiating ingredients

• pH behaviour of KGM:chitosan (Ch) blends depends on hydrocolloids ratio and Ch Mw.
• Low Mw Ch creates stronger interactions with KGM.
• Interpenetrating hydrocolloid networks (IHNs) are formed with high Mw chitosan.
• The IHNs with greater KGM content displayed better pH-dependent behaviour.
• These compositions can thus be potentially used as satiating ingredients.

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 Na2CO3-promoted interactions was observed when applied to the films (solid state) or incorporated into the hydrocolloid solutions.

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