Glycerol Ester of Rosin: The Pine Ingredient in Fanta and Fresca

Glycerol ester of rosin (also called ester gum, or E 445 in the EU) is a food additive made of glycerol esters of resin acids from pine rosin. In the United States, the FDA regulation that permits it names one use: adjusting the density of citrus oils used to make beverages, at no more than 100 parts per million of the finished drink. On Open Food Facts, it appears in the ingredient listings for Fanta Orange and Fresca.

Key takeaways:

• Glycerol ester of rosin (ester gum, E 445) is a mixture of glycerol esters of resin acids from pine rosin; the EU version must come from wood rosin extracted from aged pine stumps.
• In the United States, FDA regulation 21 CFR 172.735 permits it specifically to adjust the density of citrus oils in beverages, capped strictly at 100 parts per million.
• Open Food Facts listings show the additive in Fanta Orange and Fresca Grapefruit Citrus; Sprite's listing does not include it.
• In 2023, EFSA set an Acceptable Daily Intake (ADI) of 10 mg/kg body weight per day and found no safety concern at permitted levels; JECFA's ADI for wood rosin esters is 0 to 25 mg/kg body weight per day.

What is glycerol ester of rosin (E 445)?

Glycerol ester of rosin is listed in the EU as E 445, and ester gum is a synonym. According to evaluations by the European Food Safety Authority (EFSA), glycerol esters of wood rosin (GEWR) consist of a complex mixture of tri- and diglycerol esters of resin acids. These resin acids are a mixture of isomeric diterpenoid monocarboxylic acids with the empirical formula C20H30O2, chiefly composed of abietic acid.

Physically, the purified substance forms a hard, yellow to pale amber-colored solid. It is insoluble in water and soluble in acetone. The functional uses listed in the specification are emulsifier, density adjustment agent (flavouring oils in beverages), stabiliser and chewing gum base component.

If the E number is what caught your eye, E Numbers Explained: The EU Code for US Additives shows how EU codes map to US ingredient names.

How is glycerol ester of rosin made?

In the European Union specification (Commission Regulation (EU) No 231/2012), glycerol esters of wood rosin are strictly obtained by the solvent extraction of aged pine stumps, followed by a liquid-liquid solvent refining process.

EFSA notes that purification depends on the end use: for chewing gum base the rosin is purified by steam stripping, while for adjusting the density of citrus oils for beverages it is purified by a countercurrent steam distillation process. The US regulation likewise says the additive "is purified by countercurrent steam distillation or steam stripping."

A significant regulatory gap exists between the United States and the European Union regarding raw material sources. Under FDA regulation 21 CFR 172.735, manufacturers may utilize wood rosin, gum rosin (an exudate from living pine trees), or tall oil rosin (a byproduct of kraft paper pulp manufacturing). In contrast, the European Union's E 445 definition excludes gum rosin and tall oil rosin entirely.

EFSA's food additives panel looked at the other two sources as proposed additives for use "as a stabilising and emulsifying food additive in certain beverages to a maximum level of 100 mg/l": glycerol esters of gum rosin in 2010 and glycerol esters of tall oil rosin in 2011. For both, it concluded that "the available data are too limited to conclude on the safety" at the proposed uses and use levels. For tall oil rosin, the only toxicological data were two acute oral toxicity studies, and the panel "could not conclude that GETOR is chemically equivalent to GEWR." These are data gaps in the EU file, not evidence of harm, and the Open Food Facts listings for Fanta Orange and Fresca do not say which rosin they use.

What is glycerol ester of rosin used for in food and sodas?

The US regulation is short. It says glycerol ester of wood rosin, gum rosin, or tall oil rosin "is used to adjust the density of citrus oils used in the preparation of beverages whereby the amount of the additive does not exceed 100 parts per million of the finished beverage." Fanta Orange and Fresca are both citrus-flavored sodas, but their Open Food Facts listings do not say what the ester does in either drink, or whether either drink contains citrus oils.

In the United States, FDA regulation 21 CFR 172.735 permits the additive under specific parameters: it must have an acid number between 3 and 9, a drop-softening point of 88 to 96 degrees Celsius, and a color of N or paler under Official Naval Stores Standards. The single use it names is adjusting the density of citrus oils in beverages, capped at 100 parts per million (ppm) of the finished beverage.

Under EU rules (as tabulated in EFSA's 2018 re-evaluation), authorized beverage applications for E 445 are similarly capped at 100 mg/L, restricted specifically to cloudy flavored drinks, cloudy spirit drinks, and cloudy flavored alcoholic beverages with under 15 percent alcohol. Outside of drinks, E 445 is authorized in the EU for the surface treatment of fresh citrus fruit (up to 50 mg/kg) and for printing on personalized hard-coated confectionery (up to 320 mg/kg).

Fresca's listing also includes acacia gum and carob bean gum; see Acacia Gum (Gum Arabic): What It Is and Why FDA Calls It Fiber and Locust Bean Gum: Is It Safe? What 4 Scanned Labels Show.

Is glycerol ester of rosin safe, and what do regulators say?

Glycerol ester of rosin has been reviewed by food safety authorities in the US, the EU and at the FAO/WHO level. Under US regulations, 21 CFR 172.735 designates it as an approved direct food additive rather than a Generally Recognized as Safe (GRAS) listing, establishing enforceable purity and usage restrictions.

Toxicological evaluations establish an Acceptable Daily Intake (ADI), measured in milligrams per kilogram of body weight per day:

• In 1994, the European Scientific Committee on Food (SCF) set an ADI of 12.5 mg/kg bw/day.
• In 1996, the Joint FAO/WHO Expert Committee on Food Additives (JECFA) set an ADI of 0 to 25 mg/kg bw/day by applying an uncertainty factor of 100 to a no-observed-adverse-effect level (NOAEL) of 2,500 mg/kg bw/day, "although there were no studies available on chronic or reproductive toxicity," as EFSA summarizes it. JECFA widened this to a group ADI covering gum rosin esters in 2009, replaced it with a temporary group ADI of 0 to 12.5 in 2011, and confirmed 0 to 25 for wood rosin esters in 2013.
• In a 2018 re-evaluation, EFSA's ANS Panel considered glycerol esters of wood rosin non-genotoxic based on the core battery of in vitro tests. It said the SCF's 12.5 mg/kg bw/day ADI should be temporary pending reproductive and developmental toxicity data, and restricted its assessment to wood rosin from Pinus palustris (longleaf pine) and Pinus elliottii (slash pine). The NOAEL it relied on, 2,500 mg/kg bw/day, was the highest dose tested in a 13-week rat study.
• In a 2023 follow-up assessment, EFSA's FAF Panel established an ADI of 10 mg/kg bw/day, applying an uncertainty factor of 100 to a NOAEL of 976 mg/kg bw/day from a newly available dietary reproduction/developmental toxicity screening study in rats.

EFSA's current ADI of 10 mg/kg bw/day is lower than JECFA's 0 to 25 mg/kg bw/day. The lower figure comes from the new rat reproduction data, not from any finding in beverages. EFSA's 2023 panel concluded there was "no safety concern for the use of GEWR (E 445), at either the maximum permitted levels or at the reported uses and use levels."

Who should be cautious and what are the potential side effects?

In its 2018 re-evaluation, EFSA reported that mean and 95th percentile exposure in its brand-loyal refined scenario "did not exceed the temporary ADI in any of the population groups."

The same opinion's human-data section notes case reports of perioral dermatitis linked to rosin in chewing gum. In one, an 8-year-old boy's patch test was positive for rosin among other allergens, and EFSA notes that "possible sensitivity to allergens other than rosin could not be ruled out." These reports concern chewing gum, not sodas.

The EU safety file also has limits. EFSA's 2018 panel could not assess glycerol esters of wood rosin from two other pine species, Pinus halepensis and Pinus brutia, because no composition, stability or toxicity data were provided, and its 2023 ADI is restricted to wood rosin from Pinus palustris and Pinus elliottii. EFSA's 2023 opinion also recommended revising the EU specification and lowering the limits for toxic elements.

How to spot glycerol ester of rosin on food labels

Two products covered here list the additive on Open Food Facts:

• An Open Food Facts listing for Fanta Orange soda (barcode 049000019162) lists it as the 7th of 9 ingredients: "CARBONATED WATER, HIGH FRUCTOSE CORN SYRUP, CITRIC ACID, NATURAL FLAVORS, SODIUM BENZOATE, MODIFIED FOOD STARCH, GLYCEROL ESTER OF ROSIN, YELLOW 6, RED 40".
• An Open Food Facts listing for Fresca Grapefruit Citrus Sparkling Soda Water (barcode 049000002485) lists it in the 10th position: "carbonated water, citric acid, concentrated grapefruit juice, potassium citrate, aspartame, potassium sorbate (to protect tasté), acacia gum, acesulfame potassium, natural flavors, glycerol ester of rosin, potassium benzoate and calcium disodium edta (to protect taste), carob bean gum. phenylketonurics: contains phenylalanine".

Neither listing discloses the amount present, which rosin (wood, gum or tall oil) is used, or the additive's function in the product. Neither shows a "2% or less" statement. Furthermore, Open Food Facts listings for products like Fanta Pineapple (barcode 049000545500) and Diet Coke (barcode 049000006582) contain empty ingredient fields, meaning their formulation details cannot be confirmed from that source.

For contrast, the Open Food Facts listing for Sprite (barcode 049000028928), a lemon-lime soda, does not include it: "carbonated water, high fructose corn syrup, citric acid, natural flavors, sodium citrate, sodium benzoate (to protect taste)."

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