Tree sap: a plant-based gelatine alternative?

Researchers from the University of Ottawa have presented gum tragacanth as a plant-based alternative to gelatine for creating edible films.

“Gelatine has unique properties and its use is versatile,” said study author Ezgi Pulatsu. “To fully replace gelatine, we must replicate its microstructure and understand its function in different applications.”

Gelatine’s gel-like structure and transparency are just two of its qualities that a plant-based alternative must replicate. Gum tragacanth, a by-product of the sap in certain legume plants, is promising in both of these characteristics.

To test this, Pulatsu’s team developed films containing different concentrations of gelatine and gum tragacanth — some constructed with alternating layers, others a mixture of the two — and monitored their survivability in water and saline solutions. They found the optimal combination of gum tragacanth and gelatine for maintaining the gelatine’s gel-like behaviour was a 3-to-1 ratio of the two, respectively. However, gum tragacanth’s inclusion leads to a more porous film, making it prone to penetration by water or saline solutions.

Gels were created with different ratios of gum tragacanth to gelatine (top) to compare their properties to those of gum tragacanth (bottom left) on its own and of gelatine (bottom right) on its own. Image credit: Ezgi Pulatsu.

Though gum tragacanth cannot replace gelatine completely just yet, the researchers are continuing their work on developing a fully plant-based alternative. Pulatsu said one path forward is to improve gum tragacanth’s suitability on its own through various chemical and structural modifications that can increase its mechanical and barrier properties, but noted that even a partial replacement is a step forward.

“Partial replacement of gelatine will reduce animal-based product use,” Pulatsu said. “Our efforts in the full replacement of gelatine are ongoing.”

Specific applications will each have their own challenges to consider. For example, replacing gelatine in lollies requires special attention to gum tragacanth’s impacts on sweetness, texture and transparency, while brittleness and flexibility are key factors for when gelatine in used in food packaging.

The research findings have been published in Physics of Fluids by AIP Publishing.

Top image credit: iStock.com/Almaje