Incidence of Clostridium botulinum in Vegetables Packaged under Vacuum or Modified Atmosphere

Because modified atmosphere-packaged (MAP) vegetables may provide an anaerobic environment conducive to Clostridium botulinum growth and toxin production, the incidence of C. botulinum spores in commercially available, precut MAP vegetables was determined. One-pound (454-g) packages of MAP vegetables were aseptically opened, added to freshly steamed and cooled sterile trypticase-peptone-glucose-yeast extract broth and incubated at 35°C for 7 days. Positive and negative controls were included with each sampling. After incubation the broth cultures were tested for toxicity by the standard mouse bioassay. Of the 1,118 MAP vegetable packages examined, one package each of shredded cabbage, chopped green pepper, and Italian salad mix contained C. botulinum type A spores. One additional salad mix (main ingredient, escarole) contained both C. botulinum type A and type B spores. Results indicated a low overall incidence rate (0.36%) of C. botulinum spores in commercially available precut MAP vegetables.