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Agency Response Letter GRAS Notice No. GRN 000336

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CFSAN/Office of Food Additive Safety

August 24, 2011

Ton van Dongen
Purac Biochem b.v.
Arkelsedijik 46
P.O. Box 21
4206 AA Gorinchem
The Netherlands

Re: GRAS Notice No. GRN 000336

Dear Mr. van Dongen:

The Food and Drug Administration (FDA) is responding to the notice, dated April 5, 2010, that you submitted in accordance with the agency's proposed regulation, proposed 21 CFR 170.36 (62 FR 18938; April 17, 1997; Substances Generally Recognized as Safe (GRAS); the GRAS proposal). FDA received the notice on April 16, 2010, filed it on May 5, 2010, and designated it as GRAS Notice No. GRN 000336.

The subject of the notice is epsilon-polylysine (polylysine). The notice informs FDA of the view of Purac Biochem b.v. (Purac) that polylysine is GRAS, through scientific procedures, for use as an antimicrobial agent in a wide variety of food categories at levels of up to 0.025% by weight. Purac revised the intended uses of polylysine in GRN 000336 to exclude uses in meat and poultry products in an amendment dated May 13, 2011. The amended uses are listed in Table 1.

Table 1: Intended Uses of Polylysine in Food
Intended Food Use Use Level (% by weight)
Alcoholic beverages 0.01
Wine 0.005
Cake batter and cheesecakes 0.01
Muffins and popovers 0.01
Pancakes and waffles 0.025
Pies (not fruit) 0.025
Sweet pastries 0.01 - 0.025
Energy, fitness, sports, and isotonic drinks (ready-to-drink) 0.025
Gelatin, rice, and sugar cane-based beverages 0.025
Soft drinks 0.025
Cheese-based mixtures 0.025
Cottage, ricotta, and cream cheese 0.025
Feta, mozzarella, and Mexican cheese 0.025
Processed cheese and cheese spreads 0.025
Coffee and coffee beverages 0.025
Tea and tea beverages 0.025
Pickles, olives, and pickled products 0.025
Cream substitutes 0.025
Imitation cheese 0.025
Egg-based dishes 0.025
Reduced-fat or fat-free margarine-like spread 0.005
Salad dressings (regular and low-fat) 0.025
Fish and shellfish-based foods 0.025
Eggs 0.025
Fish and shellfish 0.025
Frozen fruit bars and sorbet 0.025
Gelatin 0.025
Pie fillings 0.025
Puddings, custards, and mousses 0.025
Grain-based dishes 0.025
Pastas 0.025
Fat-based sauces 0.01
Gravy 0.025
Tomato-based sauces 0.025
Chocolate-flavored drinks 0.01
Cream 0.01
Eggnog 0.01
Sour cream and dips 0.025
Yogurt 0.01
Peanut butters and sauces 0.025
Meat substitutes 0.025
Soy products 0.025
Fruit-flavored drinks and ades (ready to eat) 0.025
Fruit smoothies 0.025
Nectars 0.025
Prepared fruit and fruit mixtures 0.025
Dry beans and bean-based prepared foods 0.025
Potato- and sweet potato-based foods (excluding French fries) 0.025
Vegetable-based prepared foods 0.01 - 0.025
Tomato-based juices 0.025
Soups (excluding canned) 0.025
Sweet syrups and toppings 0.025

As part of its notice, Purac includes the report of a panel of individuals (Purac's GRAS panel) who evaluated the data and information that are the basis for Purac's GRAS determination. Purac considers the members of its GRAS panel to be qualified by scientific training and experience to evaluate the safety of substances added to food. Purac's GRAS panel considered the identity of polylysine, its method of manufacture, specifications, exposure, and safety studies. The information considered by Purac's GRAS panel included published studies pertaining to the safety of polylysine that had been cited in a previous GRAS notice for polylysine.[1] The panel reports that an updated literature search did not identify any information that would contradict previous conclusions about the safety of polylysine. Purac's GRAS panel concludes that polylysine, manufactured in accordance with good manufacturing practice (GMP) from suitable food grade ingredients, is GRAS when used as an antimicrobial agent in the specified food categories.

Purac describes generally available information about the identity and composition of polylysine (Chemical Abstracts Service Registry Number 28211-04-3). Polylysine is a homopolymer of L-lysine consisting of 25-35 lysine units, linked by amide bonds between the carboxyl groups and epsilon-amino groups, with a molecular weight of approximately 4700 kilodaltons. According to the notice, the antimicrobial effect of polylysine depends on its molecular size; effective inhibition of microbial growth requires polylysine to have at least nine lysine residues. Purac intends to market two formulations of polylysine, a 50:50 mixture of polylysine and maltodextrin powders and a 25% w/v solution of polylysine in water. The notice provides specifications for purity, heavy metals, lead (≤ 1ppm), and microbial contamination for each formulation, and also provides data for each formulation from three batch analyses consistent with these specifications.

Polylysine is manufactured by fermentation of the nonpathogenic and nontoxigenic microorganism Streptomyces albulus subspecies lysinopolymerus. Purac states that the fermentation is conducted according to current GMP using common and suitable food grade raw materials. Following fermentation, the microorganism is removed by membrane filtration and the polylysine in the filtrate is purified using multiple ion-exchange resins and activated charcoal. The product is concentrated by evaporation of the liquid and then spray dried to obtain the final powdered product.

The notice describes the intended use of polylysine as an antimicrobial agent at levels ranging from 0.005 to 0.025% in a variety of foods. Purac estimates the all-eaters 90th percentile daily intake of polylysine from the intended uses to be 520 milligrams (mg) per person or 8.4 mg per kilogram of bodyweight per day (mg/kg bw/d).[2] Purac states that polylysine does not occur naturally in the diet.

Purac discusses safety studies on polylysine that include absorption, distribution, metabolism, and excretion (ADME) studies; acute, subchronic (90-day), and chronic (2-year) oral toxicity and carcinogenicity studies; a reproduction and teratogenicity study; and a mutagenicity study. Purac cites a peer-reviewed English-language publication that encompasses these studies, including both previously unpublished data as well as data published only in Japanese journals.

Purac discusses the ADME studies and concludes that absorption of ingested polylysine is very low. While a small fraction is cleaved into individual lysine molecules and incorporated into proteins or further metabolized, almost all polylysine is excreted from the body within 48 hours and systemic exposure is minimal.

Purac discusses the results of acute, subchronic, and chronic toxicity studies in Sprague-Dawley rats. Polylysine is known to taste bitter at high concentrations. Purac notes that reductions in body and organ weights associated with poor palatability were observed at the high intake level in the subchronic study. These effects were also observed at the high intake level during the midpoint but not the end of the chronic study. The authors did not report notable histopathological effects in either study. Purac concludes that these results indicate that polylysine intake of at least 1060 mg/kg bw/d, the middle dose of the 2-year chronic toxicity study, resulted in no adverse effects. Purac also states that the 2-year study did not identify any evidence of carcinogenicity and that a separate reproductive study at comparable exposure in rats did not identify any adverse effects. Finally, Purac states that the ingredient is in common use in Japan and no reports of any allergenic reactions or other adverse effects associated with the use of polylysine in food were found in the literature. Purac notes that polylysine, being an epsilon-linked polymer of a single amino acid, is unlikely to be allergenic. Purac concludes that the available toxicological studies support the safety of polylysine under the intended conditions of use.

Standards of Identity

In the notice, Purac states its intention to use polylysine in a variety of food categories, including a number of foods for which standards of identity exist, located in Title 21 of the Code of Federal Regulations. We note that an ingredient that is lawfully added to food products may be used in a standardized food only if it is permitted by the applicable standard of identity.

Potential Labeling Issues

Section 403(k) of the Federal Food, Drug, and Cosmetic Act (FD&C Act) provides that a food shall be deemed to be misbranded if it bears or contains any chemical preservative, unless it bears labeling stating that fact. Section 403(i)(2) of the FD&C Act provides that a food shall be deemed to be misbranded unless its label bears the common or usual name of each ingredient. Section 403(a) of the FD&C Act provides that a food shall be deemed to be misbranded if its labeling is false or misleading in any particular. Purac's use of polylysine constitutes use as an antimicrobial agent. Therefore, the ingredient statement on labels of food products that contain polylysine must comply with the labeling regulations that implement sections 403(k) and 403(i)(2) of the FD&C Act. For example, 21 CFR 101.22(j) requires that the food to which a chemical preservative is added bear a label declaration stating both the common or usual name of the ingredient and a separate description of its function. Further, food that is subjected to any form of preservation, except as provided in 21 CFR 101.95(c), may not be labeled as "fresh." If Purac has any questions about the appropriate labeling of this food ingredient, Purac should contact the staff in the Office of Nutrition, Labeling, and Dietary Supplements, Division of Food Labeling and Standards.

Section 301(ll) of the Federal Food, Drug, and Cosmetic Act

The Food and Drug Administration Amendments Act of 2007, which was signed into law on September 27, 2007, amends the FD&C Act to, among other things, add section 301(ll). Section 301(ll) of the FD&C Act prohibits the introduction or delivery for introduction into interstate commerce of any food that contains a drug approved under section 505 of the FD&C Act, a biological product licensed under section 351 of the Public Health Service Act, or a drug or a biological product for which substantial clinical investigations have been instituted and their existence made public, unless one of the exemptions in section 301(ll)(1)-(4) applies. In its review of Purac's notice that polylysine is GRAS under the intended conditions of use, FDA did not consider whether section 301(ll) or any of its exemptions apply to foods containing polylysine. Accordingly, this response should not be construed to be a statement that foods that contain polylysine, if introduced or delivered for introduction into interstate commerce, would not violate section 301(ll).


Based on the information provided by Purac, as well as other information available to FDA, the agency has no questions at this time regarding Purac's conclusion that polylysine is GRAS under the intended conditions of use. The agency has not, however, made its own determination regarding the GRAS status of the subject uses of polylysine. As always, it is the continuing responsibility of Purac to ensure that food ingredients that the firm markets are safe, and are otherwise in compliance with all applicable legal and regulatory requirements.

In accordance with proposed 21 CFR 170.36(f), a copy of the text of this letter responding to GRN 000336, as well as a copy of the information in this notice that conforms to the information in the GRAS exemption claim (proposed 21 CFR 170.36(c)(1)), is available for public review and copying at

Mitchell A. Cheeseman, Ph.D.
Acting Director
Office of Food Additive Safety
Center for Food Safety
and Applied Nutrition

[1] The polylysine that is the subject of GRN 000336 is manufactured by the Chisso Corporation (Chisso). In GRN 000135, Chisso notified FDA of the firm's view that polylysine is GRAS, through scientific procedures, for use as an antimicrobial agent in cooked rice or sushi rice at levels up to 0.005%. In a letter dated January 16, 2004, FDA stated that it had no questions about Chisso's conclusion that the intended uses were GRAS. GRN 000336 incorporates many parts of GRN 000135 and relies on the same references to support Purac's conclusions. The intended use described in GRN 000135 is subsumed within the new use category of "grain-based dishes" at levels up to 0.025%.

[2] This estimate does not reflect the removal of meat and poultry uses as communicated by the notifier on May 13, 2011, and is therefore conservative. In GRN 000135, Chisso estimated the 90th percentile intake from the intended uses in cooked and sushi rice at 15 mg or 0.25 mg/kg bw/d.

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