is the hardened sap of a handful of species of Acacia tree grown in several countries in northern sub-Saharan Africa, most notably Sudan and Senegal. The sap is harvested by cutting holes in the bark of the tree; after waiting approximately 6 weeks, enough sap will have been exuded for collection. Gum arabic is heavily used in the food and beverage industry as a stabilizer or thickener and falls into the class of substances known as hydrocolloids (others include gelatin and agar agar). The properties that make it useful in food processing have also led to its use in brewing, primarily as a foam stabilizer/head retention agent, but also in fining agents to assist with beer clarification. There has also been at least one claim that a gum arabic solution can also improve beer flavor by stabilizing aromatic compounds in the beer, adding sweetness and coating a drinker’s mouth.

Gum arabic’s use as a head retention agent comes in two forms: as a solution sprayed onto green malt, which is then used in combination with nontreated malt, and as a powdered or flaked form of gum arabic that can be added later during the brewing process (gum arabic is soluble in cold water, but its solubility increases at warmer temperatures).

Gum arabic’s use as a head retention agent/foam stabilizer has been largely overtaken by polypropylene glycol alginate. That shift occurred at least in part because the levels of the active substances in gum arabic can vary widely from harvest to harvest, whereas PGA—being more heavily processed—can be produced to tighter specifications.

See also additives.