The May edition of the Journal of Food Protection discusses a study to investigate the adequacy of the 60-day minimum aging to reduce the numbers of viable pathogens and evaluate milk subpasteurization heat treatment as a process to improve the safety of Cheddar cheeses made from unpasteurized milk.

The FDA Standard of Identity for Cheddar cheeses requires pasteurization of the milk, or as an alternative treatment, a minimum 60-day aging at 2 degrees C for cheeses made from unpasteurized milk, to reduce the number of viable pathogens that may be present to an acceptable risk.

As part of the study, Cheddar cheese was made from unpasteurized milk inoculated with a five-strain cocktail of acid-tolerant Escherichia coli O157:H7.

The study confirms previous reports that show 60-day aging is inadequate to eliminate E. coli O157:H7 during cheese ripening. Sub-pasteurization did result in E. coli O157: H7 reduction.