| Summary: | 碩士 === 東海大學 === 食品科學系 === 87 === The objective of this study is to develop predictive methods for estimating the number of Bacillus subtilis in steamed daikon cake at temperature fluctuation. Growth rates of B. subtilis in daikon rice cakes at 13,15,20,25 and 30℃were measured. The experimental growth data were fitted in modified-Gompertz model, and derived a non-linear regression equation. The growth parameters, lag time (λ), specific growth rate (μ), and maximum bacterial numbers (N max) were calculated with the parameters of the regression equation. A square-root model （ ）is adequate to describe the relationship of specific growth rate and temperature. For predicting lag time, the linear equation of lag time versus the reciprocal of specific growth rate is suitable（ ）. The relationship of maximum bacterial numbers and temperature was fitted in square-root model very well. （ ）.
The growth parameter models were used to predict the growth of B. subtilis under a condition of constant temperature at 18℃ and a condition of the growth temperature. The results of the prediction were closed to experimental data. The models were also applied to predict the proliferation of B.subtilis in daikon cakes under a condition of temperature fluctuation. The result showed that the storage temperature lower than 10℃ will cause decresing of the cell counts and formation of endospores. The spores might be a potent risk in this kind of food products.
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