Raman analysis of surimi gelation by addition of wheat dietary fibre

Raman analysis has been carried out to study the effects of Vitacel® wheat dietary fibre (WDF) during gelation of surimi. The main results reveal the following: (a) Vitacel® comprises natural cellulose I as major component; (b) hydration of WDF leads to νCH frequency upshifting and decreasing intensity. On the basis of these spectral features it is suggested that water transfer from protein to WDF can occur in surimi gels. WDF hydration can be interpreted in the sense that this fibre either takes water that is delivered from the gel protein upon heat-mediated formation of β-sheets and hydrophobic contacts and/or or acts as an active dehydrating agent. An increase of solvent-exposed hydrophobic side chains is observed in the sol phase, upon the addition of WDF, which may cause breaking of intermolecular protein hydrophobic contacts; a subsequent change upon WDF-containing gel formation is the reduction in the νCH intensity, which may be indicative of increasing hydrophobic WDF-protein contacts. Interestingly, these results constitute molecular data, to be considered when designing restructured fish products with these fibre ingredients.