Coffee changes how xanthan gum thickens and lubricates liquids

Adding instant coffee to xanthan gum solutions changes the thickener’s flow and lubrication behavior in ways that could matter for designing drinks for people with dysphagia, according to a study published in Food Science and Biotechnology in 2026. Researchers Juneha Bak, Hyunji Kim and Jiwon Jeon examined the tribo-rheological properties of 1.0% xanthan gum in instant coffee systems at several coffee concentrations.

The study found that adding coffee markedly decreased the intrinsic viscosity of xanthan gum. At coffee concentrations of 1.0% or higher, the power-law exponent β fell below 1.0, which the authors interpret as chain contraction and a transition to a more ordered molecular conformation. All samples in the study showed shear-thinning behavior, meaning their viscosity decreased as they were stirred or flowed faster.

Higher coffee concentrations also enhanced the viscoelastic properties, apparent viscosity, and structural recovery after shear compared with xanthan gum alone. Temperature behavior differed as well: xanthan gum by itself showed what the authors describe as atypical temperature-dependent viscosity, whereas coffee-containing systems at concentrations of 1.0% or above showed a gradual decrease in apparent viscosity as temperature increased.

Tribological analysis, which measures how the samples behave under lubrication, showed that increasing coffee concentration shifted the boundary-to-mixed lubrication transition toward lower sliding speeds. The authors conclude that coffee-induced conformational changes in xanthan gum substantially influence its tribo-rheological properties, linking molecular structure directly to how the thickened liquid flows and lubricates surfaces.

Because the study examined model instant coffee systems in the laboratory, the reported effects apply to the tested xanthan gum and coffee concentrations rather than to commercial beverages generally.

Subject of Research: Effects of instant coffee concentration on the rheological and lubrication properties of xanthan gum solutions

Article Title: Effect of coffee concentration on rheological and lubrication characteristics of xanthan gum

Article References: Bak, J., Kim, H., & Jeon, J. (2026). Effect of coffee concentration on rheological and lubrication characteristics of xanthan gum. Food Science and Biotechnology. https://doi.org/10.1007/s10068-026-02340-4

Image Credits: AI Generated

DOI: 10.1007/s10068-026-02340-4

Keywords: xanthan gum, instant coffee, rheology, tribology, lubrication, shear-thinning, viscosity, dysphagia, thickened beverages, food science, Effect, coffee