以反應曲面模式探討於乳酸鏈球菌素存在下大腸桿菌O157:H7於絞牛肉系統中受螯合劑、有機酸及貯存溫度之影響   全文下載

Effect of Chelators, Organic Acid and Storage Temperature on Growth of Escherichia coli O157: H7 in Ground Beef Treated with Nisin, Using Response Surface Methodology

本研究係利用反應曲面法探討螯合劑、有機酸及貯存溫度等抑菌因子對E. coli O157:H7 於乳酸鏈球菌素存在下之絞牛肉系統中生長之影響。實驗因子及層階分別為貯存溫度（10°C 、15°C 、20°C）、乙二酸四乙酸（Ethylenediaminetetra-acetic acid, EDTA）（5 mM 、25 mM 、45 mM）及醋酸（0.25%、0.75%、1.25%），乳酸鏈球菌素濃度為103 IU／g。生長參數如對數生長速率、繼代時間、遲滯時間及最大菌數等乃利用生長曲線套用Gompertz 方程式後所得。結果顯示溫度、EDTA 濃度及醋酸濃度對繼代時間與遲滯時間均有顯著性影響，且以溫度之影響最為顯著（p<0.01）；而最大菌數模式中，僅有醋酸對其具顯著性影響。選用等性狀圖形中較大或較小反應性狀值之組合進行驗證，結果顯示與預測結果相符，顯示本研究所得繼代時間模式可適當描述E. coli O157: H7於15°C，15 mM EDTA及1.25%醋酸中之生長；遲滯時間模式可適當描述該菌於10°C，25 mM EDTA及1.25%醋酸中之生長；而最大菌數模式則可描述E. coli O157: H7於10°C ， 25 mM EDTA及1%醋酸環境下之生長。"

This study was performed to determine the effects of antimicrobial factors on the growth of Escherichia coli O157: H7 in ground beef. Response surface methodology design was used to determine the effects of temperature (10°C, 15°C, 20°C), EDTA (5 mM, 25 mM, 45 mM) and acetic acid concentration (0.25%, 0.75%, 1.25%)on the growth of E. coli O157: H7 in ground beef treated with nisin (103 IU/g). A growth curve was fitted by using nonlinear regression of the Gompertz equation, and growth parameters such as exponential growth rate (EGR), lag phase duration (LPD), generation time (GT), and maximum population density (MPD) were obtained. The results indicated that the effects of temperature, EDTA and acetic acid were significant to the responses of GT and LPD, with the effects of temperature being the most significant (p<0.01). However, a significant difference was found only on the effect of acetic acid on the MPD model (p<0.05). The verified experiments were chosen from the larger or smaller values of responses on the contour plots. The experimental values were confirmed to the predicted conditions, indicating that the model could be used for predicting the response of GT, LPD and MPD in the conditions of 15°C,15 mM EDTA, 1.25 % HAc; 10°C, 25 mM EDTA, 1.25 % HAc; 10°C, 25 mM EDTA and 1 % HAc, respectively. 本研究係利用反應曲面法探討螯合劑、有機酸及貯存溫度等抑菌因子對E. coli O157:H7 於乳酸鏈球菌素存在下之絞牛肉系統中生長之影響。實驗因子及層階分別為貯存溫度（10°C 、15°C 、20°C）、乙二酸四乙酸（Ethylenediaminetetra-acetic acid, EDTA）（5 mM 、25 mM 、45 mM）及醋酸（0.25%、0.75%、1.25%），乳酸鏈球菌素濃度為103 IU／g。生長參數如對數生長速率、繼代時間、遲滯時間及最大菌數等乃利用生長曲線套用Gompertz 方程式後所得。結果顯示溫度、EDTA 濃度及醋酸濃度對繼代時間與遲滯時間均有顯著性影響，且以溫度之影響最為顯著（p<0.01）；而最大菌數模式中，僅有醋酸對其具顯著性影響。選用等性狀圖形中較大或較小反應性狀值之組合進行驗證，結果顯示與預測結果相符，顯示本研究所得繼代時間模式可適當描述E. coli O157: H7於15°C，15 mM EDTA及1.25%醋酸中之生長；遲滯時間模式可適當描述該菌於10°C，25 mM EDTA及1.25%醋酸中之生長；而最大菌數模式則可描述E. coli O157: H7於10°C ， 25 mM EDTA及1%醋酸環境下之生長。