Eastern Regional Research Center, Agriculture Research Service, US Department of Agriculture, Wyndmoor, PA 19038, USA.
Int J Food Microbiol. 2010 Mar 31;138(1-2):91-9. doi: 10.1016/j.ijfoodmicro.2009.11.017. Epub 2009 Dec 3.
This study evaluated the efficacy of a supercritical carbon dioxide (SCCO(2)) system with a gas-liquid porous metal contactor for eliminating Escherichia coli K12 in apple cider. Pasteurized, preservative-free apple cider was inoculated with E. coli K12 and processed using the SCCO(2) system at CO(2) concentrations of 0-10% (wt.%, g CO(2)/100g product), outlet temperatures of 34, 38, and 42 degrees C, a system pressure of 7.6 MPa, and a flow rate of 1L/min. Increased CO(2) concentrations and temperatures significantly (P<0.05) enhanced the bactericidal effect, resulting in a maximum reduction of 7.31 log CFU/mL at 8% CO(2) and 42 degrees C. A response surface model indicated that minimum CO(2) concentrations of 9.9% at 34 degrees C, 7.4% at 38 degrees C, and 5.4% at 42 degrees C are needed to achieve a 5-log reduction of E. coli K12 in apple cider. SEM observations showed morphological changes in the cell envelope after SCCO(2) processing. At a processing condition of 8% and 38 degrees C, the reduction of E. coli was 6.03 log and the sublethal injury of the survivors was 84%. The regrowth or survival of E. coli in SCCO(2) processed apple cider was not observed during storage for 28 days at 4, 8, and 20 degrees C. Thus this study showed the potential of SCCO(2) processing with a gas-liquid porous metal contactor for the nonthermal pasteurization of apple cider.
本研究评估了超临界二氧化碳（SCCO₂）系统与气-液多孔金属接触器相结合，用于消除苹果 cider 中大肠杆菌 K12 的功效。巴氏杀菌、无防腐剂的苹果 cider 接种了大肠杆菌 K12，然后使用 SCCO₂ 系统在 CO₂浓度为 0-10%（wt.%，g CO₂/100g 产品）、出口温度为 34、38 和 42°C、系统压力为 7.6 MPa 和流速为 1L/min 的条件下进行处理。增加 CO₂浓度和温度显著（P<0.05）增强了杀菌效果，在 8% CO₂和 42°C 时最大减少了 7.31 log CFU/mL。响应面模型表明，在 34°C 时需要最小 CO₂浓度为 9.9%，在 38°C 时需要最小 CO₂浓度为 7.4%，在 42°C 时需要最小 CO₂浓度为 5.4%，才能使苹果 cider 中大肠杆菌 K12 减少 5-log。SEM 观察表明，SCCO₂ 处理后细胞包膜发生形态变化。在 8%和 38°C 的处理条件下，大肠杆菌的减少量为 6.03 log，幸存者的亚致死损伤为 84%。在 4、8 和 20°C 下储存 28 天时，未观察到 SCCO₂ 处理的苹果 cider 中大肠杆菌的再生长或存活。因此，本研究表明使用气-液多孔金属接触器的 SCCO₂ 处理具有用于苹果 cider 非热巴氏杀菌的潜力。
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