INSTABILITY OF PATULIN IN CHEDDAR CHEESE

When 50 μg/g patulin was added to Cheddar cheese and stored at 5° and 25°C for varying time periods, the toxin became undetectable by chemical and biological means. Less than 27% of the added toxin was detected after 3 hr and less than 16% after 48 hr. The reaction was not affected by storage temperature or the presence of microorganisms and thus appeared to be chemical in nature. A patulin producing strain of Penicillium patulum grew well on Cheddar cheese at 5° and 25°C, but patulin production was not observèd at 5°C, and only small, variable amounts of patulin were noted at 25°C. The patulin formed at 25°C on the cheese was authentic as shown by UV absorption maxima and high pressure liquid chromatography, and it possessed biological activity against Bacillus megaterium and Clostridium perfringens . Potassium sorbate, vacuum packaging and coating cheese with paraffin wax all pre vented growth of P. patulum on retail size pieces of cheese stored at 5° and 25°C. A heat‐sealed wrapping on large (20 lb) blocks of cheese also prevented growth of this organism on cheese stored at 12°C for 6.5 wk.