I have been continuing to plug away at researching the mystery of the “60 day rule.” Here is another article questioning the rationale of the rule:

Behavior of Escherichia coli O157:H7 during the manufacture and aging of gouda and stirred-curd cheddar cheeses manufactured from raw milk


Journal of Food Protection

D’Amico, Dennis J.; Druart, Marc J.; Donnelly, Catherine W.


This study was conducted to examine the fate of Escherichia coli O157:H7 during the manufacture and aging of Gouda and stirred-curd Cheddar cheeses made from raw milk. Cheeses were manufactured from unpasteurized milk experimentally contaminated with one of three strains of E. coli O157:H7 at an approximate population level of 20 CFU/ml. Samples of milk, whey, curd, and cheese were collected for enumeration of bacteria throughout the manufacturing and aging process. Overall, bacterial counts in both cheese types increased almost 10-fold from initial inoculation levels in milk to approximately 145 CFU/g found in cheeses on day 1. From this point, counts dropped significantly over 60 days to mean levels of 25 and 5 CFU/g in Cheddar and Gouda, respectively. Levels of E. coli O157:H7 fell and stayed below 5 CFU/g after an average of 94 and 108 days in Gouda and Cheddar, respectively, yet remained detectable after selective enrichment for more than 270 days in both cheese types. Changes in pathogen levels observed throughout manufacture and aging did not significantly differ by cheese type. In agreement with results of previous studies, our results suggest that the 60-day aging requirement alone is insufficient to completely eliminate levels of viable E. coli O157:H7 in Gouda or stirred-curd Cheddar cheese manufactured from raw milk contaminated with low levels of this pathogen.

  • L.E. Peterson

    Excellent timing for the release of these findings (Dec 1, 2010). Maybe it will help motivate FDA to revise the 60 day rule and use it only as a standard of identity for raw milk cheese.

  • John Munsell

    I also would like to continue plugging away at the non-scientific foundation of USDA-style HACCP, and that forcing the same failed system on FDA (such as was in S 510) will not promote public health.
    Who cares if the 60-day rule is inadequate, as the above extract reveals? Cheese makers, just like the large beef slaughter plants, accumulate “scientific articles” which allegedly prove the efficacy of their kill floor HACCP programs and cheese production processes. Confronted with a plethora of scientific articles which ostensibly prove the abattoirs’ ability to achieve Zero Tolerance mandates, who can criticize this veritable array of “proof”?
    USDA/FSIS introduced HACCP as a Trojan Horse, all the while hiding the horse’s contents, which was deregulation of the industry, liberating the regulators to assume a “Hands Off” non-involvement role. Even though FDA might be funded to hire additional inspectors, such new hires would quickly be forced to do what FSIS inspectors do: audit company-generated paperwork! Indeed, do NOT inspect cheese or meat; merely audit paperwork. Part of the paper chase is to review scientific reports accumulated by the “audited” facility, which justify their HACCP decisions.
    Consumer interests are best achieved via implementation of Pillsbury’s truly science based HACCP protocol, or jettison USDA-style HACCP and replace it with something meaningful. This conundrum was not addressed by S. 510; hopefully, a replacement bill will cover all these bases.
    John Munsell

  • fred b

    Thank you for the continued research, Bill. This is the type of thoughtful and educational materials I have come to expect from your blog. Since I felt it necessary to tweak you for the inflammatory comments at the beginning of this cheese debacle, I should also compliment you on your staying with the problem to uncover the true scientific bases involved.