Vurma Mustafa, Pandit Ram B, Sastry Sudhir K, Yousef Ahmed E
Department of Food Science and Technology, The Ohio State University, 2015 Fyffe Court, Columbus, Ohio 43210, USA.
J Food Prot. 2009 Jul;72(7):1538-46. doi: 10.4315/0362-028x-72.7.1538.
The aim of this study was to integrate an ozone-based sanitization step into existing processing practices for fresh produce and to evaluate the efficacy of this step against Escherichia coli O157:H7. Baby spinach inoculated with E. coli O157:H7 (approximately 10(7) CFU/g) was treated in a pilot-scale system with combinations of vacuum cooling and sanitizing levels of ozone gas (SanVac). The contribution of process variables (ozone concentration, pressure, and treatment time) to lethality was investigated using response-surface methodology. SanVac processes decreased E. coli O157:H7 populations by up to 2.4 log CFU/g. An optimized SanVac process that inactivated 1.8 log CFU/g with no apparent damage to the quality of the spinach had the following parameters: O3 at 1.5 g/kg gas-mix (935 ppm, vol/vol), 10 psig of holding pressure, and 30 min of holding time. In a separate set of experiments, refrigerated spinach was treated with low ozone levels (8 to 16 mg/kg; 5 to 10 ppm, vol/vol) for up to 3 days in a system that simulated sanitization during transportation (SanTrans). The treatment decreased E. coli populations by up to 1.4 log CFU/g, and the optimum process resulted in a 1.0-log inactivation with minimal effect on product quality. In a third group of experiments, freshly harvested unprocessed spinach was inoculated with E. coli O157:H7 and sequentially subjected to optimized SanVac and SanTrans processes. This double treatment inactivated 4.1 to > or = 5.0 log CFU/g, depending on the treatment time. These novel sanitization approaches were effective in considerably reducing the E. coli O157: H7 populations on spinach and should be relatively easy to integrate into existing fresh produce processes and practices.
本研究的目的是将基于臭氧的消毒步骤整合到新鲜农产品现有的加工流程中，并评估该步骤对大肠杆菌O157:H7的消毒效果。接种了大肠杆菌O157:H7（约10(7) CFU/g）的嫩菠菜在中试规模系统中采用真空冷却和臭氧气体消毒水平（SanVac）相结合的方式进行处理。使用响应面方法研究了工艺变量（臭氧浓度、压力和处理时间）对致死率的影响。SanVac工艺可使大肠杆菌O157:H7数量减少多达2.4 log CFU/g。一种优化的SanVac工艺在对菠菜品质无明显损害的情况下使1.8 log CFU/g失活，其参数如下：气体混合物中臭氧含量为1.5 g/kg（935 ppm，体积/体积）、保持压力为10 psig、保持时间为30分钟。在另一组实验中，冷藏菠菜在模拟运输过程中消毒的系统（SanTrans）中用低臭氧水平（8至16 mg/kg；5至10 ppm，体积/体积）处理长达3天。该处理可使大肠杆菌数量减少多达1.4 log CFU/g，最佳工艺可实现1.0对数级失活，对产品品质影响最小。在第三组实验中，对接种了大肠杆菌O157:H7的新鲜收获未加工菠菜依次进行优化的SanVac和SanTrans工艺处理。根据处理时间不同，这种双重处理可使4.1至≥5.0 log CFU/g失活。这些新型消毒方法在大幅减少菠菜上的大肠杆菌O157:H7数量方面有效，并且应该相对容易整合到现有的新鲜农产品加工流程和实践中。
