Why Glycerol Ester of Rosin Continues to Be a Safe Additive

GEWR is produced by the reaction of food-grade glycerine with refined wood rosin at temperatures in the 260-280°C range. After the required acid number range has been reached, the product is purified by countercurrent steam stripping.

The above definition of GEWR is based entirely on the original wood rosin process that has been in continuous operation to this day. Its approval for use in beverages was the basis for the successful development and approval of GEWR as a beverage-weighting agent.

The wood rosin purification process was developed specifically for the longleaf/slash crude rosin originating in the southeastern United States. Since the extractives in pine stump wood have a wide range of structures and polarity, the composition of the wood rosin product will depend on the specific pine species and the extraction and refining solvents chosen—in other words, the pine species and extraction process determine the chemical identity of the rosin, which means the process for any new GEWR needs to be well defined, thoroughly documented, and understood by the regulatory authorities.

GEGR: Gum rosin is produced by tapping living pine trees. The oleoresin exudate is collected, filtered, and distilled to remove turpentine, leaving gum rosin as the product. This rosin is sourced from a variety of pine species in China, Brazil, Indonesia, Mexico, Vietnam, and other countries. GEGR is produced in a manner similar to GEWR, although manufacturing processes and final product form may vary significantly depending on the supplier.

Much compositional variability is found in gum rosin sourced from different pine species and geographical locations. Use of GEGR as a beverage-weighting agent has been complicated by incomplete compositional and toxicological data. Understanding the composition of a natural raw material like rosin is critical in order to meet regulatory standards.

Regulatory Approvals

Food additive safety is verified by national and international regulatory agencies. The regulatory process has been a key driver in the successful development of the BWA market.

The FDA approved GEWR for use in beverages in the early 1960s. During the review and approval process, a suggestion was submitted that the product be referred to by the broader term of “glycerol ester of rosin.” Since available data didn’t support this proposal, this suggestion was rejected, and “glycerol ester of wood rosin” was adopted. This was an early acknowledgement that the source of the feed rosin was important and that all glycerol esters of rosin could not be considered equivalent based on superficial similarities. The FDA ultimately approved GEGR use in beverages in 2005, followed by Health Canada in 2010, but multinational regulatory agencies have not followed suit due to incomplete compositional and toxicological information.

The Joint FAO/WHO Expert Committee on Food Additives (JECFA) carried out a comprehensive evaluation of GEWR produced from P. palustris and P. elliottii beginning in 1974. JECFA took a conservative approach to evaluating and approving this material as a food additive, and the original manufacturer of GEWR initiated a long-term program of analytical and toxicological testing at JECFA’s request. From the beginning, JECFA emphasized the need to more fully characterize the material from which the glycerol ester of rosin was prepared, including specifying the species of pine tree used. The rigorous evaluation process culminated in 1991 with specifications for GEWR under International Numbering System (INS) 445.

In 2008, FDA requested that JECFA consider the extension of INS 445 approvals to GEGR. The basis was a claim of chemical equivalence between GEGR and GEWR to justify relying on the extensive toxicological testing done on the original GEWR product. JECFA maintained a consistent, science-based approach in its evaluation of this request. During evaluation of the GEGR petition, the committee noted that the chemical composition of GEGR varies depending on the pine species, geographical differences, and the techniques used in the processes of rosin production. JECFA noted that limited data was available on the variability of the resin acid composition of GEGR in commerce and that complete information on the composition and ester distribution of GEGR had not been submitted. Therefore, officials were not able to claim similarities to GEWR. JECFA was unable to establish specifications and an allowable daily intake for GEGR due to the lack of information.