Publications (2)4.52 Total impact
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Article: Monte Carlo simulation as a method to determine the critical factors affecting two strains of Escherichia coli inactivation kinetics by high hydrostatic pressure.
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ABSTRACT: The survival curves of two strains of Escherichia coli (ATCC 4157 and ATCC 23716) were obtained by high hydrostatic pressure (HHP) at four pressure levels (100, 200, 300, and 400 MPa) in an orange juice-skim milk (OJ-SM) mixed beverage. The effect of suspension medium pH on HHP inactivation was studied at three pH levels: 4, 4.5, and 5. The Weibull model provided an accurate fit to the data according to adjusted-regression coefficients (adjusted-R(2)) [0.860-0.996], root mean square error values [0.001-0.150], and accuracy factor [1.001-1.125] values. For sensitivity analysis, Monte Carlo simulation was run to determine the most influential factors affecting HHP inactivation of E. coli strains. According to these results, the most influential factor for E. coli (ATCC 4157) HHP inactivation was the pH of the OJ-SM beverage at low HHP intensity, whereas pressure was more influential under strong HHP treatment conditions. Concerning E. coli K-12 (ATCC 23716), pressure (P) was the most influential parameter independently of the pH of OJ-SM beverage. The higher the P, the higher the inactivation achieved. The sensitivity analysis indicated greater E. coli K-12 (ATCC 23716) resistance to the HHP processing, possibly because of greater acidity tolerance.Foodborne Pathogens and Disease 12/2009; 7(4):459-66. · 2.26 Impact Factor -
Article: Synergistic effect of high hydrostatic pressure and natural antimicrobials on inactivation kinetics of Bacillus cereus in a liquid whole egg and skim milk mixed beverage.
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ABSTRACT: An in-depth study was conducted in order to extend the storage life of a liquid whole egg-skim milk (LWE-SM) mixed beverage to enhance its safety and the safety of related beverages. Bacillus cereus vegetative cells (1 x 10(8) colony-forming units [CFU]/mL) were inoculated in LWE-SM beverages with or without natural antimicrobial supplements: flavonol rich-cocoa powder (cocoanOX 12%, CCX) (700 ppm), vanillin (700 ppm), anise (700 ppm), and cinnamon (700 ppm). B. cereus cells were maintained at 10 degrees C for 10 days in the different beverages to test the bacteriostatic or inhibitory effect of the aforementioned ingredients. Beverages were treated with high hydrostatic pressure (HHP) technology and stored at 10 degrees C for 15 days after treatment. All natural antimicrobials reduced the micro(max) values and increased the lag phase time of B. cereus, and Gompertz growth curves showed different inhibitory effects depending on the substance. The maximum inhibitory effect (1.330 log cycle reduction) was achieved in LWE-SM-cinnamon-supplemented beverage. The maximum inactivation achieved by HHP in LWE-SM beverage was a reduction of around 3.89 +/- 0.25 log cycles at 300 MPa for 12 minutes. When supplemented beverages were treated under the same conditions, enhanced inactivation levels were achieved. This increased inactivation can be attributed to a synergistic effect when the LWE-SM was supplemented with flavonol-rich cocoa powder, cinnamon, and vanillin. The maximum synergistic effect was observed in LWE-SM-CCX-supplemented beverage. During the refrigerated storage of B. cereus HHP-treated cells in beverages to which antimicrobials had been added, the inhibitory effect was dependent on the previously applied pressure level.Foodborne Pathogens and Disease 6(6):649-56. · 2.26 Impact Factor
