本研究目的在建立枯草桿菌(Bacillus subtilis)於蘿蔔糕中溫度波動下的生長預測模式，以作為冷藏米製糕點衛生安全管理的依據。首先測定枯草桿菌在蘿蔔糕中，於13、15、20、25、30℃下的生長數據，並將數據套入高柏茲模式（Gompertz model）作非線性迴歸，由迴歸參數決定比生長速率(μ)，遲滯時間(λ)，及最大生長菌數 (N max) 等生長參數，並建立生長參數的預測模式。結果得知平方根模式（square-root model）適用於描述比生長速率與溫度的關係（ ）；生長遲滯時間的預測模式，則以遲滯時間與比生長速率倒數之線性關係模式（ ）較為適用；最大生長菌數與溫度關係，則以線性模式為佳（ ）。利用所建立的生長參數預測模式，預測枯草桿菌於恆溫（18℃）與可生長溫度下菌體之生長，結果預測值與觀測值接近，顯示模式的適用性。將模式用於預測枯草桿菌在低溫波動下的生長時，當溫度低於10℃以下會造成菌體的死亡，故不致於滋生造成危害；但形成的孢子，在食品工業上具有潛在的危險性。 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.
