The formation of botulinal toxin relative to spoilage of fresh whole tomatoes was investigated at 13 and 23°C under passively modified (MA) and controlled atmospheres (CA) and air. Tomatoes were subsurface inoculated with a composite of type A and proteolytic and nonproteolytic type B strains of Clostridium botulinum spores. Some were also inoculated with Alternaria mold spores. MA (1.0–2.9% O2) was passively established by a combination of product respiration and package permeability. CA was established by placing tomatoes in continuously flushed (1% O2, 20% CO2, balance N2) Plexiglass plastic containers. Tomatoes were tested for botulinum toxin by the mouse assay at the time when they first became inedible based on predefined stages of decay rather than specific storage times in order to determine the relationship between spoilage and botulinal toxigenesis. All tomatoes became inedible according to the established criteria within 17 to 46 d depending on the storage temperature and atmosphere. Botulinum toxin was not detected in the 24 composite samples of inedible tomatoes (representing 99 tomatoes) which were tested at the time they first became inedible. Toxin was detected in four of five additional composite samples (representing 10 tomatoes) which were held 2 to 9 d beyond the time they were first determined to be inedible. These data indicate that MA-packaged tomatoes can become toxic but only after becoming severely spoiled beyond the point of being organoleptically acceptable. The risk of botulism from consumption of extended shelf life whole tomatoes appears to be insignificant.
2Dow Chemical Company, Consumer Products Research, 1603 Building, Midland, Michigan 48674
3Department of Food Science and Nutrition, University of Minnesota, St. Paul, Minnesota 55108
4Department of Epidemiology and Preventative Medicine, University of California, Davis, California 95616
5Dow Chemical Company, Department of Toxicology, 1803 Building, Midland, Michigan 48674
6Department of Microbiology, ABC Research Corporation, 3437 SW 24 Avenue, Gainesville, Florida 32607
7Food Research Institute, University of Wisconsin, 1925 Willow Drive, Madison, Wisconsin 53706.