Inability of Pediococcus pentosaceus to Inhibit Clostridium botulinum in sous vide Beef With Gravy at 4 and 10°C

The ability of Pediococcus pentosaceus to inhibit Clostridium botulinum toxigenesis in minimally heat-treated, vacuum-packaged sous vide-type beef with gravy was investigated. The bacteriocinogenic strain P. pentosaceus ATCC 43200 and the nonbacteriocinogenic strain P. pentosaceus 43NP1 were coinoculated with proteolytic and nonproteolytic C. botulinum types A and B spores into minimally processed meat with gravy. Toxin was present in samples inoculated with C. botulinum alone by day 31 at 4°C and by day 6 at 10°C. When coinoculated with C. botulinum, neither strain of Pediococcus was capable of significantly delaying the appearance of toxin. Although an enzyme-linked immunosorbent assay method for botulinal toxin was useful for screening toxin-positive samples, a high proportion of false negatives was revealed by confirmatory mouse bioassays. This research confirms that, if botulinal spores are present, sous vide beef does present a botulinal hazard, even when kept under adequate refrigeration.