Ingredient Information

Function

Ester gum is a resin that is produced from the reaction of glycerol (syrup used for sweetening and preserving food) with rosin (dark brown resin derived from the stumps and sap of pine trees). It is used in beverages as an emulsifier (prevents separation of fluids) and a weighting agent. It is also used in chewing gum bases as a masticator.

Ester gum is amber in color and comes in flake or rock forms. It can readily oxidize, especially in the flaked form, due to increased surface area. It has a pH of 6.5, a softening point of 90°F and a density at 25°C g/cm3 of 1.08. It is also almost odor free. Since it is an emulsifier, it is soluble in organic and inorganic solutions. However, the more oxidized the gum, the less soluble it becomes. Some of the solvents it is highly soluble in are citrus oil, essential oils, hydrocarbons (including aromatic compounds), terpenes (found in the resins of plants), esters (which create the fragrances and flavors of many flowers and fruits), and ketones (organic compounds having a carbonyl group linked to a carbon atom).

The reason ester gum works well as a weighting agent is its density; it is slightly higher in density than water and has strong emulsification properties. This makes it ideal for use in citrus-flavored beverages to weigh down the oil and create a more homogenous mixture. It can also create a “cloudy” appearance. Both glycerol ester (of gum rosin) and glycerol ester (of wood rosin and gum rosin) are approved for use in gum and beverages by the FDA.

Other Use and Industries

Ester gum is also used in ink, paint, varnish, adhesive, packaging, and other non-food items. It is considered a natural compound and can be used to make synthetic or natural products. It works well in many applications because of its solubility, adhesiveness, and stability.

Health Effects

Ester gum has been evaluated for bio-availability and toxicity in rats. Initial studies have shown that it is not readily bio-available or toxic. Moreover, the gum appears to not be digestible or absorbable by the human body. On another note, there have been a few studies showing skin sensitivity to ester gum. These findings were short term and could not rule out other factors. It appears that ester gum has no positive or negative effect on human health, but the FDA still concluded that better, longer studies on this substance need to be performed. Even so, it is approved for food use at certain levels.

Origins

Wood rosin is esterified (converted into ester) with glycerol to create ester gum. Due to the structure of the rosin, high temperatures are used for the reaction. The high temperatures also make the final product more stable. The wood rosin is obtained by three methods.

The first method is to obtain the rosin from pine stumps. The rosin is extracted by a solvent and then is further refined. This has been a common method for creating food-grade ester gums and is approved for use by the FDA. The second method is by collecting the sap of a pine tree and purifying it to strip the volatile compounds and leave the rosin. The last method involves oil, but is not used currently for food-grade ester gum.

Once the esterfication has taken place, there will be extra glycerol. As such, the manufacturing of ester gum will also produce mono-glycerides, diglycerides and triglycerides. The excess glycerol is removed by vacuum distillation, the remaining ester gum is sprayed with steam until there is no longer an odor, and then it is dried.

The use of ester gum became popular with orange-flavored carbonated drinks. The ester gum kept the oil flavor base in suspension and created a cloudy appearance to the beverage that consumers found appealing. Work on this began in the late 1960’s.