DETECTION OF ROPE SPOILAGE IN BREAD CAUSED BY BACILLUS SPECIES

Rope spoilage of bread by eight Bacillus isolates obtained from a bake ry environment was examined via direct inoculation of slices of bread with bacterial culture. The three types of loaf examined were two soft grain varieties, one containing vinegar and the other containing calc ium propionate as the preservative agent, and a white variety containi ng calcium propionate. Differences in rope production caused by batch variation were studied by comparing seven leaves of each type of bread . Not all isolates were capable of causing extensive rope, but isolate s of Bacillus subtilis, B. licheniformis, B. megaterium and B. pumilus were able to produce such spoilage. Limited rope was also caused by p reexisting Bacillus species within the leaves. The amount of rope prod uction by an isolate was not constant on all loaf types or even betwee n different batches of the same variety, indicating that approaches th at rely on direct inoculation of leaves with culture are not applicabl e for assessing the rope-inducing potential of Bacillus isolates. Howe ver, it was clear from this study that vinegar in soft grain leaves wa s more effective than calcium propionate at inhibiting rope.