Ester Gum is a food additive used as an emulsifier and stabiliser to keep oils in suspension in water. It is common in soft drinks and eyeliner pencils. Food additives are substances added to food to preserve flavour or improve its taste and appearance.

Used in beverages and chewing gum, it is prepared from resin acids of wood rosin harvested from the stumps of the longleaf pine. Rosin is a solid form of resin obtained from pines and some other plants, mostly conifers, produced by heating fresh liquid resin to vaporize the volatile liquid terpene components. It is semi-transparent and varies in color from yellow to black. At room temperature rosin is brittle, but it melts at stove-top temperatures. It chiefly consists of different resin acids, especially abietic acid.