Thermal inactivation of Pediococcus sp. in simulated apple cider during high-temperature short-time pasteurization

Prompted by concerns regarding outbreaks of food-borne illness which have occurred due to the consumption of commercial, nonpasteurized fruit juices contaminated with Escherichia coli O157:H7, the US Food and Drug Administration and Canadian Food Inspection Agency are considering several new safety standards to apply to fresh juices, including mandatory pasteurization of all apple cider. In support of these initiatives, a study was conducted to evaluate the pasteurization of simulated cider using a heat-resistant nonpathogenic test bacterium, Pediococcus sp. NRRL B-2354. Thermal inactivation of the Pediococcus sp. was determined using a pilot scale high-temperature short-time (HTST) pasteurizer with a plate heat exchanger. The cumulative lethal effect, or pasteurization effect (PE), was obtained by converting times at different temperatures in the various sections of the pasteurizer to the equivalent time at the reference temperature (72 °C). PE was then related by a simple linear function to the log10 of the percentage of viable counts with a power transformation of the PE values to improve linear fit. r2 values for the four Pediococcus sp. trials varied from 0.921 to 0.981. Intertrial variation was incorporated into the model using @RISK™ simulation software. Output from simulations confirmed that treatment at 71 °C for 16 s can ensure a 5-log reduction of Pediococcus sp.