Effects of high pressure and mild heat on endogenous microflora and on the inactivation and sublethal injury of Escherichia coli inoculated into fruit juices and vegetable soup
Effects of high pressure and mild heat on endogenous microflora and on the inactivation and sublethal injury of Escherichia coli inoculated into fruit juices and vegetable soup
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DOI：
10.4315/0362-028x-70.7.1587
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发表时间：
2007-07-01
影响因子：
2
通讯作者：
Pilar Cano, M.
中科院分区：
文献类型：
--
作者：
Munoz, Marina;de Ancos, Begona;Pilar Cano, M.
研究了高压处理和温和温度对人工接种于橙汁、苹果汁和蔬菜汤中的内源菌群和大肠杆菌CECT 515的影响。一般情况下，好氧菌的生存能力随着压力和温度的升高而显著降低。虽然在350 MPa和60℃的温度下，嗜氧中温营养细胞的浓度下降幅度最大，但在350 MPa和20℃的温度下，果汁中的酵母和霉菌浓度低于检测水平（1 log CFU/ml），而蔬菜汤的酵母和霉菌浓度不超过2 log CFU/ml。根据响应面法的数学模型，对接种大肠杆菌的食品进行多次处理，以最少的实验次数获得最多的信息。在压力（150 ~ 350mpa）和温度（20 ~ 60℃）范围内的测试次数限制在11次。由于R-2值令人满意，这些模型被认为是足够的。在橙汁248.25 MPa和59.91℃，苹果汁203.50 MPa和57.18℃，蔬菜汤269.8 MPa和59.9℃的条件下，得到了大肠杆菌减少6对数的最佳工艺参数（压力和温度）。随着压力和温度的升高，大肠杆菌发生亚致死性损伤。在果汁和蔬菜汤中，在350 MPa和20℃的温度下，几乎所有的大肠杆菌细胞都受到损伤。
The objective of this study was to determine the effects of high-pressure treatments and mild temperatures on endogenous microflora and Escherichia coli CECT 515 artificially inoculated into orange and apple juices and vegetable soup. In general, the viability of aerobic bacteria was significantly reduced as pressure and temperature increased. Although the greatest reduction in the concentration of aerobic mesophilic vegetative cells was reached at 350 MPa and 60 degrees C, the same reduction occurred in fruit juices at 350 MPa and 20 degrees C. Yeasts and molds were below the level of detection (1 log CFU/mI) for the fruit juices and did not exceed 2 log CFU/ml for vegetable soup. Foods inoculated with E. coli were subjected to several treatments as indicated by the mathematical model applied in response surface methodology to obtain the maximum information with the minimum number of experiments. The number of tests for a range of pressures (150 to 350 MPa) and temperatures (20 to 60 degrees C) was limited to 11. The models were considered adequate because of satisfactory R-2 values. The optimum process parameters (pressure and temperature) for a 6-log reduction of E. coli were obtained at 248.25 MPa and 59.91 degrees C in orange juice, 203.50 MPa and 57.18 degrees C in apple juice, and 269.8 MPa and 59.9 degrees C in vegetable soup. Sublethal injury of E. coli occurred as pressure and temperature increased. Nearly all of the E. coli cells were injured at 350 MPa and 20 degrees C in fruit juices and after all treatments in vegetable soup.