[Inhibition of bacterial growth in thawed cake and rapid evaluation methods for microbiological quality]

The inhibition of bacterial growth in thawed cake kept under refrigeration and rapid evaluation methods for microbiological quality of the cake were investigated. The effects of the freezing temperature and the addition of ethanol or emulsifier on bacterial numbers in a cake model after storage for 72 hr at 10 degrees C following the thawing process were also studied. Bacterial growth in the cake model was inhibited by the additives under various freezing conditions. In addition, rapid evaluation methods for estimating bacterial numbers in the cake model after incubation for 72 hr at 10 degrees C were studied. High correlations were found between bacterial numbers in the cake model incubated for 24 hr at 20 degrees C and for 6 hr at 35 degrees C with tryptic soy broth and that of the cake model incubated for 72 hr at 10 degrees C. This result indicated that rapid evaluation by incubation for 24 hr at 20 degrees C or for 6 hr at 35 degrees C with tryptic soy broth can be used to predict the bacterial numbers in a cake model after incubation for 72 hr at 10 degrees C. Furthermore, the ATP-bioluminescence method was applied to shorten the testing time, because culture on an agar medium was not necessary.