Abstract This study aimed to investigate the effect of acid adaptation on the resistance of Escherichia coli O157:H7 and Salmonella Typhimurium to X-ray irradiation. The non-acid-adapted and acid-adapted E. coli O157:H7 cell counts decreased 8.02 and 5.48 log CFU/mL in apple juice, respectively, whereas the S. Typhimurium cell counts reduced by 3.87 and 3.98 log CFU/mL, respectively, after treatment with 1.0 kGy X-ray. In apple juice, the D5d (dose required for 5-log reduction in cell count) values for non-acid-adapted and acid-adapted E. coli O157:H7 cells were 0.66 and 0.92 kGy, respectively, whereas those for non-acid-adapted and acid-adapted S. Typhimurium cells were 1.40 and 1.30 kGy, respectively. The acid-adapted E. coli O157:H7 cells exhibited higher X-ray resistance than the non-acid-adapted cells in apple juice. However, the acid-adapted and non-acid-adapted S. Typhimurium cells exhibited similar resistance to X-ray irradiation in apple juice. Additionally, the effect of X-ray irradiation on apple juice quality attributes was evaluated. The color, pH, and total phenolic contents of apple juice were not significantly affected (P > 0.05) at all treatment doses of X-ray. The results of this study suggest that the inactivation of acid-adapted cells of E. coli O157:H7, which is the predominant pathogen implicated in apple juice-related disease outbreaks, must be considered for the application of X-ray irradiation in apple juice sterilization process.

中文翻译：

---

酸适应对苹果汁中大肠杆菌O157:H7和鼠伤寒沙门氏菌对X射线辐照抗性的影响

摘要 本研究旨在研究酸适应对大肠杆菌O157:H7 和鼠伤寒沙门氏菌对X 射线辐照抗性的影响。苹果汁中未适应酸和适应酸的大肠杆菌 O157:H7 细胞计数分别减少了 8.02 和 5.48 log CFU/mL，而鼠伤寒沙门氏菌细胞计数分别减少了 3.87 和 3.98 log CFU/mL , 用 1.0 kGy X 射线处理后。在苹果汁中，非酸适应和酸适应大肠杆菌 O157:H7 细胞的 D5d（细胞计数减少 5 个对数所需的剂量）值分别为 0.66 和 0.92 kGy，而非酸适应的 D5d（细胞计数减少 5 个对数所需的剂量）值分别为 0.66 和 0.92 kGy适应和酸适应的鼠伤寒沙门氏菌细胞分别为 1.40 和 1.30 kGy。在苹果汁中，酸适应的大肠杆菌 O157:H7 细胞比非酸适应的细胞表现出更高的 X 射线耐受性。然而，酸适应和非酸适应的鼠伤寒沙门氏菌细胞对苹果汁中的 X 射线辐射表现出相似的抵抗力。此外，还评估了 X 射线辐射对苹果汁品质属性的影响。在所有 X 射线处理剂量下，苹果汁的颜色、pH 值和总酚含量均未受到显着影响（P > 0.05）。这项研究的结果表明，在苹果汁中应用 X 射线辐照时，必须考虑灭活大肠杆菌 O157:H7 的酸适应细胞，这是与苹果汁相关疾病爆发的主要病原体。灭菌过程。在所有 X 射线处理剂量下，苹果汁的总酚含量和总酚含量均无显着影响（P > 0.05）。这项研究的结果表明，在苹果汁中应用 X 射线辐照时，必须考虑灭活大肠杆菌 O157:H7 的酸适应细胞，这是与苹果汁相关疾病爆发的主要病原体。灭菌过程。在所有 X 射线处理剂量下，苹果汁的总酚含量和总酚含量均无显着影响（P > 0.05）。这项研究的结果表明，在苹果汁中应用 X 射线辐照时，必须考虑灭活大肠杆菌 O157:H7 的酸适应细胞，这是与苹果汁相关疾病爆发的主要病原体。灭菌过程。