Brea Tree (Cercidium praecox) Exudate Gum

BERTUZZI, MARÍA, A.; SLAVUTSKY, ANIBAL M.

Emerging Natural Hydrocolloids: Rheology and Functions

John Wiley & Sons, Ltd.

Año: 2019; p. 347 - 369

Brea gum is the exudate from the Brea tree (Cercidium praecox) that is widespread in arid and semiarid regions of the American continent. Brea tree grows in poor soils and can help with degraded environment restoration. Brea gum is obtained through cuts or incisions on the bark. Its chemical composition is based on a β-(1??4) xylan backbone heavily substituted by short branch chains containing neutral sugars and uronic acids and their ethers. In water solution, the molecule acquires spherical form and presents high solubility and a rheological behaviour practically Newtonian with moderate viscosity at high concentrations. Brea gum contains 4 to 10% of proteins that influence its functional properties. The gum is suitable as a stabilizer for systems containing high insoluble solids. It acts as a good emulsifier and stabilizer of oil-in-water emulsions and favours foam formation and stabilization. Besides, brea gum forms dense edible films with high water solubility, hence their mechanical and barrier properties are strongly affected by ambient relative humidity. Clay nanoparticle incorporation in the film matrix reinforces the structure and reduces the effect of humidity on the film properties. In bread making, an addition of 0.5% of brea gum to wheat flour increases the moisture of the crumb. The food safety of this hydrocolloid has been demonstrated and it was approved as a food additive. According to its physicochemical and rheological properties, this gum could be used as a substitute for arabic gum or similar gums in several applications.