Interactions between xanthan gum and phenolic acids

Area of Science:

• Food science and colloid chemistry.
• Physicochemical interactions in complex food systems.

Background:

• Phenolic acids like gallic and caffeic acid are common in food.
• Xanthan gum is a widely used food polysaccharide.
• Understanding their interactions is crucial for food texture and stability.

Purpose of the Study:

• To investigate the molecular and colloidal interactions between gallic acid, caffeic acid, and xanthan gum.
• To correlate system stability with pH and polysaccharide-polyphenol concentrations.
• To elucidate the role of noncovalent interactions in macroscopic properties.

Main Methods:

• Preparation and analysis of binary gallic acid-xanthan gum and caffeic acid-xanthan gum systems.
• Construction of global stability diagrams.
• Fluorimetry for thermodynamic analysis.
• Shear and extensional rheometry for macroscopic behavior.
• pH-dependent stability measurements.

Main Results:

• Caffeic acid-xanthan gum interactions are primarily pH-independent volume exclusions.
• Gallic acid interacts with xanthan gum, particularly at pH 7, enhancing colloidal stability.
• Gallic acid induces xanthan gum aggregation, influencing system structure and stability.
• Rheological and stability data reveal distinct interaction mechanisms for each phenolic acid.

Conclusions:

• Xanthan gum's role in structuring and de-structuring complex systems with phenolic acids is clarified.
• The study provides a physicochemical framework for understanding xanthan gum's oral functions, including texture.
• Specific interactions depend on the type of phenolic acid and environmental conditions like pH.