Characterisation of psyllium husk with different sizes and their effects on gel properties of surimi.

Summary: Psyllium husk has attracted increasing interest in food applications due to its well‐known health benefits. Size reduction is an important mechanical operation used to tailor the functional properties of materials. In this study, the physicochemical properties and colloidal stability of the PHPs with different sizes were characterised by particle size distribution, zeta potential, Fourier transform infrared (FT‐IR) and X‐ray photoelectron spectroscopy (XPS). Furthermore, the size effects of psyllium husk on surimi gel properties were investigated in terms of the gel strength, water‐holding capacity (WHC) and water distribution. The results found that milling changed the monosaccharide composition and increased the diffraction intensity of psyllium husk powder (PHP) without disrupting the β‐glycosidic linkages. Furthermore, the XPS results suggested that smaller samples showed more exposed surface functional groups. The PHP3 group with average size of d (0.5) = 259.50 μm exhibited the highest absolute zeta potential. The viscosity and zeta potential of PHP correlated positively and negatively with the gel strength of surimi, respectively. Moreover, the micronized PHP also contributed to the increase in immobilised water content and uniform water distribution in surimi gels. The high viscosity and colloidal stability of psyllium husk (PHP3 group) contributed to the improved mechanical properties of surimi gels. This work provides a valuable reference for the potential use of psyllium husk in quality improvement of surimi products through size control. [ABSTRACT FROM AUTHOR]