U. S. Food and Drug Administration
Center for Food Safety and Applied Nutrition
December 15, 1999

FOOD CODE SECTION: 3-501.17 Ready-to-Eat, Potentially Hazardous Food, Date Marking.

ISSUE: Are all cheeses required to be date marked when the processor's package is opened and the product, in whole or in part, is repackaged or wrapped for sale or service or for later use in a food establishment?

DISCUSSION: The Food Code specifies that ready-to-eat, potentially hazardous food prepared and held refrigerated for more than 24 hours in a food establishment must be marked at the time of preparation to indicate the date by which the food shall be consumed or discarded. It further stipulates that refrigerated, ready-to-eat, potentially hazardous food prepared and packaged by a food processing plant shall be clearly marked, at the time the original container or package is opened in a food establishment, to indicate the date by which the food shall be consumed or discarded.

The dating provision was introduced into the Food Code because of the potential for growth over time of psychrotrophic organisms such as Listeria monocytogenes and Yersinia enterocolitica in refrigerated, ready-to-eat foods. Refrigeration does not prevent growth of these organisms. However, the rate of growth is slowed as the temperature decreases. Dating requirements are set forth to minimize a potential hazard attributable to the growth of psychrotrophic organisms during extended periods of refrigeration.

Several inquiries have been received regarding the necessity of date marking hard and semisoft aged cheese and pasteurized process cheese when the processor's package is opened and the product is, in whole or in part, repackaged or wrapped for sale or service or for later use in a food establishment. It was suggested that there is evidence showing that date marking certain refrigerated cheeses is unnecessary.

In view of the inquiries and evidence that were presented, FDA issued a letter on April 5, 1999 suggesting that regulatory agencies use their discretionary authority and defer enforcement action regarding date marking of aged hard cheeses. Specifically, the letter advised that FDA would issue an interpretation relating to the Food Code provision of date marking hard cheeses that are aged for at least 60 days. In addition, it was stated that a more inclusive list of aged cheeses would accompany the interpretation.

Following issuance of the letter, a review of the published literature was conducted.

The review showed that many soft cheeses exhibited the capability to support growth of L. monocytogenes.¹ Further, a number of soft cheeses have been implicated in foodborne illnesses.²

However, in addition to refrigeration, there are several factors in certain cheeses that may further control growth of pathogenic organisms. These factors may include the presence of organic acids, preservatives, or competing flora; pH; water activity; or salt concentration. When two or more of these are combined, the resultant effect is an additional hurdle to the outgrowth of pathogens of concern. It is precisely this effect that makes it possible to safely store some refrigerated cheeses beyond either one of the two Food Code criteria for date marking (i.e., 7 days at 41°F or 4 days at 45°F).

On the other hand, there is a considerable body of evidence showing that certain cheeses do not support the growth of pathogens during the aging process and subsequent storage although survival of the organisms is possible.^{3, 4, 5, 6} Also, evidence supporting the contention that growth of L. monocytogenes is inhibited during refrigerated storage can be found in inoculation studies conducted on various cheeses.⁷

Cheeses that do not support growth of L. monocytogenes include hard or semisoft cheeses such as Cheddar and Romano or Colby and Swiss, and various pasteurized process cheeses. Hard cheeses are manufactured with a moisture content not exceeding 39 percent as specified in 21 CFR 133.150 and semisoft cheeses contain more than 39 percent but less than 50 percent moisture as specified in 21 CFR 133.187. Pasteurized process cheeses (manufactured according to 21 CFR 133.169 and labeled as containing an acidifying agent) were also shown to inhibit growth of L. monocytogenes.

A list of some cheeses that are and are not exempt from the date marking provisions is attached.

INTERPRETATION: Hard and semisoft aged cheeses and pasteurized process cheese, each manufactured according to 21 CFR 133 as specifically cited above and maintained under refrigeration, are exempt from the Food Code's date marking provision relating to refrigerated, ready-to-eat, potentially hazardous food.

/ s /	/ s /	/ s /
Robert L. Buchanan, Ph.D. Senior Science Advisor Center for Food Safety & Applied Nutrition	Elizabeth L. Harden Team Leader Retail Food & Interstate Travel Team	Raymond D. Beaulieu Author Retail Food & Interstate Travel Team

REFERENCES:

1. Growth of Listeria monocytogenes in Camembert and other soft cheeses at refrigeration temperatures. Jonathan P. Back, Sarah A. Langford and Rohan G. Kroll. Journal of Dairy Research, Vol. 60, 1993. Pages 421-429.

2. Cheese-Associated Outbreaks of Human Illness in the United States, 1973 to 1992: Sanitary Manufacturing Practices Protect Consumers. Sean F. Altekruse, Babagaleh B. Timbo, John C. Mowbray, Nancy H. Bean, and Morris E. Potter. Journal of Food Protection, Vol. 61, No. 10, 1998. Pages 1405-1407.

3. Behavior of Listeria monocytogenes During the Manufacture and Ripening of Cheddar Cheese. Elliot T. Ryser and Elmer H. Marth. Journal of Food Protection, Vol. 50, No. 1, 1987. Pages 7-13.

4. Behavior of Listeria monocytogenes During the Manufacture and Storage of Colby Cheese. Ahmed E. Yousef and Elmer H. Marth. Journal of Food Protection, Vol. 51, No. 1, 1988. Pages 12-15.

5. Survival of Salmonella in Cheddar Cheese. Charles H. White and Edward W. Custer. J. Milk Food Technol. Vol. 39, No. 5. 1976. Pages 328-331.

6. Source and Persistence of Salmonella muenster in Naturally Contaminated Cheddar Cheese. D. S. Wood., D. L. Collins-Thompson, D. M. Irvine and A. N. Myhr. Journal of Food Protection, Vol. 47, No. 1, 1984. Pages 20-22.

7. Growth and Survival of Listeria monocytogenes in Market Cheeses Stored at 4 to 30°C. Constantin Genigeorgis, Marius Carniciu, Dan Dutulescu, and Thomas B. Farver. Journal of Food Protection, Vol. 54, No. 9, 1991. Pages 662-668.

List of Some Hard and Semisoft Cheeses Exempt from Date Marking
Examples of Hard Cheeses Containing not more than 39% moisture (21 CFR 133.150)	Examples of Semisoft Cheeses Containing more than 39%, but not more than 50% moisture (21 CFR 133.187)
Asiago medium Asiago old Cheddar Gruyere Parmesan and Reggiano Romano Sap sago	Asiago fresh and soft Blue Brick Caciocavallo Siciliano Colby (not more than 40% moisture) Edam Gorgonzola Gouda Limburger Monterey, Monterey Jack Muenster Pasteurized process cheese Provolone Roquefort, sheep's milk blue-mold Swiss and Emmentaler

Cheeses that are NOT exempt from the Food Code provisions for date marking include soft cheese such as Brie, Camembert, Cottage, Ricotta, and Teleme.