Heat resistance of Bacillus cereus, Salmonella typhimurium and Lactobacillus delbrueckii in relation to pH and ethanol
Heat resistance of Bacillus cereus, Salmonella typhimurium and Lactobacillus delbrueckii in relation to pH and ethanol
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DOI：
10.1016/s0168-1605(00)00465-7
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发表时间：
2001-01-22
影响因子：
5.4
通讯作者：
Gaze, JE
中科院分区：
文献类型：
--
作者：
Casadei, MA;Ingram, R;Gaze, JE
本工作的目的是研究单独使用乙醇以及与低 pH 值结合使用对特定细菌耐热性的影响。所选择的细菌代表耐热和热敏感病原体（蜡状芽孢杆菌和鼠伤寒沙门氏菌）和相对耐热的腐败微生物（德氏乳杆菌）。所选细菌在不同温度（蜡状芽孢杆菌为 70 至 97 摄氏度、鼠伤寒沙门氏菌为 48 至 54 摄氏度、德氏乳杆菌为 44 至 60 摄氏度）、不同 pH（3、5 和 7）和乙醇含量（0、2.5、5、7.5 和 10%）的培养基中进行处理。事实证明，这两个因素对于降低本研究中检查的细菌的耐热性非常有效。在 pH 7 时，乙醇含量增加最多 10% 会导致 D 值下降最多 100 倍（鼠伤寒沙门氏菌）。 pH 从 7 降至 3 也会导致 D 值降低 100 倍（鼠伤寒沙门氏菌）。对于蜡样芽孢杆菌，使用 D 值的 log(10) 与温度、pH 和乙醇含量相关的回归分析来产生二阶多项式方程。 z 值随 pH 值降低而增加，并且细胞在较低 pH 值下对乙醇更敏感。对于鼠伤寒沙门氏菌，用于描述 D 值的 log,, 与温度和乙醇含量之间关系的多项式方程也是二阶方程，表明 z 值和乙醇之间的关系是非线性的。对于德氏乳杆菌，z 值与加热介质的乙醇含量无关。还测试了 25 和 37 摄氏度的耐酸能力（德氏乳杆菌和鼠伤寒沙门氏菌）和酸适应能力（鼠伤寒沙门氏菌）。在热处理温度下，德氏乳杆菌比鼠伤寒沙门氏菌具有更强的乙醇和 pH 耐受性，而在培养温度（25 和 37 摄氏度）下，鼠伤寒沙门氏菌比德氏乳杆菌更耐受酸。酸适应提高了鼠伤寒沙门氏菌在25℃下对低pH值的耐受性，但未能提高其在48℃下的耐热性。在所有使用的细菌中，pH 值和乙醇的影响在较低处理温度下更为明显，因此考虑到热处理的减少和/或产品配方的变化，它们的重要性变得更大。 (C) 2001 Elsevier Science B.V. 保留所有权利。
The aim of the present work was to investigate the effect of ethanol alone and in combination with low pH on the heat resistance of specific bacteria. The bacteria chosen are representative of heat resistant and heat sensitive pathogens (Bacillus cereus and Salmonella typhimurium) and of relatively heat resistant spoilage microorganisms (Lactobacillus delbrueckii). The chosen bacteria were treated at different temperatures ranging between 70 and 97 degreesC for B. cereus, 48 and 54 degreesC for S. typhimurium and 44 and 60 degreesC for L. delbrueckii, in media of different pH (3, 5 and 7) and ethanol content (0, 2.5, 5, 7.5 and 10%). Both factors proved to be very effective in reducing the heat resistance of the bacteria examined in this work. At pH 7, an increase in ethanol content up to 10% caused D values to decrease by up to 100-fold (S. typhimurium). A drop from pH 7 to pH 3 also caused up to a 100-fold reduction in the D values (S. typhimurium). For B. cereus the regression analysis of the log(10) of the D value in relation to temperature, pH and ethanol content was used to produce a second order polynomial equation. The z values increased at decreasing pH and cells were more sensitive to ethanol at lower pH. For S. typhimurium the polynomial equation produced to describe the relationship between log,, of the D values and temperature and ethanol content was also a second order equation indicating that the relationship between z values and ethanol was non-linear. For L. delbrueckii, z values were independent of the ethanol content of the heating medium. Acid tolerance at 25 and 37 degreesC (L. delbrueckii and S. typhimurium) and acid adaptation (S. typhimurium) were also tested. L. delbrueckii was more ethanol and pH tolerant than S. typhimurium at heat treatment temperatures whilst S. typhimurium was more acid tolerant than L. delbrueckii at incubation temperatures (25 and 37 degreesC). Acid adaptation increased the tolerance of S. typhimurium to low pH at 25 degreesC but failed to improve its thermal resistance at 48 degreesC. In all bacteria used, the effects of pH and ethanol were more evident at lower treatment temperatures and therefore their significance becomes greater in view of reduced thermal processing and/or changes in product formulation. (C) 2001 Elsevier Science B.V. All rights reserved.