By Jeanne Yacoubou, MS
VRG Research Director

An online reader asked us: I heard aspartame was made by processing it with pig kidney enzymes. Is there any in the final product that you know of? Or is it like sugar- processed with an animal derivative but none is in the final product?

Aspartame is a non-nutritive sweetener used widely in thousands of foods and beverages. Common brand names include NutraSweet®, Equal® and AminoSweet®.

We looked into aspartame manufactures and found several reports indicating that an enzyme derived from a pig’s kidney could be used to manufacture aspartame. For example: http://chemwiki.ucdavis.edu/Biological_Chemistry/Food_Chemistry/Sweetners/Aspartame

In this link, the paragraph titled “Synthesis” contains the sentence: “In the synthesis of aspartame, the starting materials are a racemic mixture (equal quantities of both isomers) of phenylalanine, and aspartic acid. Only the L isomer of phenylalanine is desired for use. This L isomer may be separated from the D isomer by a chemical pretreatment, followed by a reaction with the enzyme porcine kidney acylase.”

Another source (http://archive.is/EzYz) refers to pig kidney enzyme used in aspartame manufacture.

The VRG located a patent application filed in 1987 by The Nutrasweet Company, a major manufacturer of aspartame, which indicates that pig kidney enzyme could be used in its manufacture: http://www.freepatentsonline.com/4892820.html. The pertinent paragraph reads as follows: “The particular enzymes employed to couple the amino acids or amino acid derivatives according to the present process are not critical. Any enzyme capable of coupling the desired amino acids and/or derivatives is acceptable. Mixtures of enzymes can also be employed. Suitable enzymes are those which affect the aminolysis of amino acid esters by amino acids and their esters to yield peptides. Specific enzymes include (1) peptidase E. described by Carter et al. Journal of Bacteriology, 159 (2), 453-459 (1984); (2) leucine aminopeptidase from pig kidney (E.C. 3.4.11.1); (3) alpha-aminoacylpeptide hydrolases; (4) peptidase E from Salmonella typhimurium TN 1246 and (5) dipeptide hydrolases.”

We contacted The NutraSweet Company and asked for a comment on this patent application. A Vice President in Quality and Technology at NutraSweet wrote to us in December 2013: “Our R&D developed many potential processes, but many were not commercialized. I can assure you that we do not use, nor have we used that technology, in fact all of our High Intensity Sweeteners are actually both Kosher and Halal Certified – and no animal products are utilized in our processes. The only company that I am aware of that used enzymatic processes is no longer in the sweetener business.”

A patent application filed in 2001 by the Holland Sweetener Company details an enzymatic process for aspartame production. Bacterial enzymes especially from E. coli were preferred: http://www.google.com/patents/US6617127

In a 2012 patent application by Genscript Nanjing, Pseudomonas bacteria were successfully used: http://www.faqs.org/patents/app/20120295294. This document gives a brief overview of the three general approaches used to manufacture aspartame: chemical synthesis, enzymatic synthesis and mixed-method synthesis (both chemical and enzymatic aspects).

A document showing detailed steps involved in one pathway to synthesize aspartame can be viewed here:
http://www.chemeng.queensu.ca/courses/CHEE323/lectures/documents/L12-Aspartame-Immobilization.ppt

The VRG also contacted Ajinomoto, maker of AminoSweet® (their brand name for aspartame). A Director of Sales at Ajinomoto told us by phone that “our aspartame is non-animal. Aspartame is produced through a fermentation process.” The Ajinomoto website states that “aspartame is made using a fermentation process to produce amino acids from a feedstock of molasses (a thick syrup from sugar cane or beet), soy and corn.”

In November 2013 Ajinomoto’s Director of Scientific and Regulatory Affairs wrote us that, “We, Ajinomoto Company as manufacturer of aspartame, do not use the same production method as mentioned in the patent. We do not use pig kidney enzyme to manufacture aspartame and therefore it would be suitable for use in vegetarian food applications.”

Niutang Chemical is one of the world’s largest manufacturers of aspartame. We spoke with representatives at their California office who told us that their ingredients are “artificial” and “no fermentation is involved.” A senior level employee in charge of technical and quality support called us in July 2013 and said that Niutang uses “no fermentation and no enzymes in their process [of making aspartame].”

The contents of this article, our website, and our other publications, including the Vegetarian Journal, are not intended to provide personal medical advice. Medical advice should be obtained from a qualified health professional. We often depend on product and ingredient information from company employees or company statements. Information does change and mistakes are always possible. Please use your own best judgment about whether a product is suitable for you. Further research or confirmation may be warranted.

For more information on sweeteners and other food ingredients as well as the processing methods used to make them, visit
http://www.vrg.org/ingredients/index.php. A print version of our Guide to Food Ingredients is available for purchase from this link for $6.