Tree sap: a plant-based gelatin alternative?

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

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

Gelatin’s gel-like structure and its transparency are just two of its qualities that a plant-based alternative must replicate. Gum tragacanth, a byproduct 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 gelatin 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 gelatin for maintaining the gelatin’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 gelatin (top) to compare their properties to those of gum tragacanth (bottom left) on its own and of gelatin (bottom right) on its own. Image credit: Ezgi Pulatsu.

Though gum tragacanth cannot replace gelatin completely just yet, the researchers continue 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 gelatin will reduce animal-based product use,” Pulatsu said. “Our efforts in the full replacement of gelatin are ongoing.”

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

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

Top image credit: iStock.com/Almaje