Foods are complex systems where proteins (P) and polysaccharides (PS) play a major role as structural and nutritional agents. Their structural organization in food determines the textural and sensory qualities of foods. In addition to the intrinsic properties of P and PS (molecular weight, structural conformation, charge, etc.), interactions with other constituents in the food also direct their assembly and influence their functionality. Coupled gels were made with β-lactoglobulin (βlg)-xanthan gum (XG) or Lysozyme (Lys)- XG with in situ acidification with glucono delta-lactone (GDL) (reaching pH 4.4 or 7 respectively), in quiescent condition. The gel strength, microstructure (porosity) and water holding capacity were determined for several biopolymer concentrations and ratios. At similar concentration and ratio (0.3 wt%, ratio 0.5), both gels exhibited different gel strengths. Softer gels were found for Lys-XG compared to the βlg-XG (76 vs 342 Pa). The residual net charge at pH 7 is -20 mV for LYS-XG compared to -50 mV for βlg-XG. Both gels can retain high amounts of water (&gt; 300g / g biopolymer). The gelation mechanism was identified for the βlg-XG system where βlg aggregates along the XG chains and could be considered as a crosslinking agent. The main limitation of these systems being a gel dissolution at neutral pH due to disruption of electrostatic interactions. Heat treatment stabilization was investigated and allowed to introduce these gels in neutral pH systems. The spectrum of P and PS functionality may be broaden using associative interactions and this will enable food scientist to design products with desired structure and texture.

Functionality of protein-polysaccharide hydrogels

253rd National Meeting (2017)

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