Impact of high pressure homogenisation (HPH) on inulin gelling properties, stability and development during storage

The impact of different high pressure homogenisation (HPH) treatments on long-chain inulin gelling properties was investigated. Magnetic stirred inulin-water dispersions (6, 9 and 12 wt% inulin) were subjected to rotor-stator homogenisation at 5000 rpm during 5 min and high pressure homogenised at 103, 207 or 296 MPa with two different homogeniser configurations and for a single cycle. The results obtained from backscattering, water holding capacity and rheological measurements demonstrated HPH reduced the critical minimum concentration needed to obtain homogeneous gel structures to 9 wt% inulin. The ability of HPH processing to disperse inulin particles and reduce agglomerates sizes with increasing pressures improved the inulin crystallisation behaviour, inducing the development of stronger interactions and consequently improving the development of the particulate gel. However, the application of very high homogenisation pressures at 296 MPa, negatively affected the gel structure and yielded weaker gels with poorer water retention capacities. The after-valve homogenising cell (HC) configuration had also an impact on the inulin-water dispersions gelling properties. The HC lengthening produced, in general, stronger and more water retaining gels. The combination of processing parameters (pressure level and HC configurations) could be used to obtain gels with specific rheological properties.