Antonio Martínez-López

Spanish National Research Council, Madrid, Madrid, Spain

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Publications (7)10.38 Total impact

  • Maria C Pina-Pérez, Dolores Rodrigo, Antonio Martínez-López
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    ABSTRACT: Abstract Natural ingredients-cinnamon, cocoa, vanilla, and anise-were assessed based on Bacillus cereus vegetative cell growth inhibition in a mixed liquid whole egg and skim milk beverage (LWE-SM), under different conditions: ingredient concentration (1, 2.5, and 5% [wt/vol]) and incubation temperature (5, 10, and 22°C). According to the results obtained, ingredients significantly (p<0.05) reduced bacterial growth when supplementing the LWE-SM beverage. B. cereus behavior was mathematically described for each substrate by means of a modified Gompertz equation. Kinetic parameters, lag time, and maximum specific growth rate were obtained. Cinnamon was the most bacteriostatic ingredient and cocoa the most bactericidal one when they were added at 5% (wt/vol) and beverages were incubated at 5°C. The bactericidal effect of cocoa 5% (wt/vol) reduced final B. cereus log10 counts (log Nf, log10 (colony-forming units/mL)) by 4.10±0.21 log10 cycles at 5°C.
    Foodborne Pathogens and Disease 08/2013; · 2.28 Impact Factor
  • M.C. Pina-Pérez, A. Martínez-López, D. Rodrigo
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    ABSTRACT: This work was carried out to study the potential effect of combining polyphenol-rich cocoa powder (CocoanOX 12%, CCX) with Pulsed Electric Field (PEF) technology to inactivate Cronobacter sakazakii cells inoculated into infant milk formula (IMF).This effect was studied for three different concentrations of cocoa powder, 1%, 2.5% and 5% (w/v), and for different addition times, 0, 2 and 4 h, before and after PEF treatment (15, 25 and 35 kV/cm), to determine the influence of both factors on inactivation and subsequent evolution of the treated cells under refrigerated conditions (8 °C, 12 h).The results indicated that combined PEF and CCX application, and the moment of CCX addition, pre-treatment/post-treatment, significantly affected the level of C. sakazakii inactivation achieved and subsequent evolution of the treated cells over 12 h at 8 °C (p ≤ 0.05). The maximum inactivation level, 4.41 log10 cycles, was achieved when CCX was added 4 h after PEF (15 kV/cm – 3000 μs) and the treated cells were kept under refrigerated (8 °C) storage for up to 12 h.
    Food Control. 07/2013; 32(1):87–92.
  • M.C. Pina-Pérez, A. Martínez-López, D. Rodrigo
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    ABSTRACT: This research studies a possible synergistic effect of hurdle technology using a combination of Pulsed Electric Fields (PEF) technology and a natural ingredient, cinnamon, on inactivation of Salmonella typhimurium in skim milk (SM). Firstly, different cinnamon concentrations (1, 2.5 and 5% (w/v)) were added to inoculated SM (107 CFU/mL) for quantitative study (Gompertz equation) of the effect of the natural ingredient on microbial growth behaviour (bactericidal/bacteriostatic) at different temperatures (8, 25, 36 °C). 5% (w/v) cinnamon supplementation of SM (SM-5% C) was bacteriostatic with regard to S. typhimurium growth according to μmax [0.016 ((CFU/mL)/h) (8 °C); 0.259 ((CFU/mL)/h) (25 °C); 0.603 ((CFU/mL)/h) (37 °C)] and λ [282.8 (h) (8 °C); 15.38 (h) (25 °C); 2.587 (h) (37 °C)] values. Secondly, PEF treatments of 10, 20 and 30 kV/cm were applied, at treatment times ranging between 60 and 3000 μs. All cinnamon supplementation levels (1, 2.5 and 5% (w/v)) had a synergistic effect within [0.171–0.989] log10 cycles (p < 0.05) due to non-thermal combination processing. The maximum synergistic effect was achieved by 10 kV/cm–3000 μs PEF treatment with 5% (w/v) cinnamon SM supplementation. The maximum inactivation level (1.97 log10 cycles) due to hurdle combination was achieved at 30 kV/cm–700 μs in SM-5% C.
    Food Research International. 10/2012; 48(2):777–783.
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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. · 2.28 Impact Factor
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    ABSTRACT: With a view to extending the shelf-life and enhancing the safety of liquid whole egg/skim milk (LWE-SM) mixed beverages, a study was conducted with Bacillus cereus vegetative cells inoculated in skim milk (SM) and LWE-SM beverages, with or without antimicrobial cocoa powder. The beverages were treated with Pulsed Electric Field (PEF) technology and then stored at 5 degrees C for 15 days. The kinetic results were modeled with the Bigelow model, Weibull distribution function, modified Gompertz equation, and Log-logistic models. Maximum inactivation registered a reduction of around 3 log cycles at 40 kV/cm, 360 micros, 20 degrees C in both the SM and LWE-SM beverages. By contrast, in the beverages supplemented with the aforementioned antimicrobial compound, higher inactivation levels were obtained under the same treatment conditions, reaching a 3.30 log(10) cycle reduction. The model affording the best fit for all four beverages was the four-parameter Log-logistic model. After 15 days of storage, the antimicrobial compound lowered Bacillus cereus survival rates in the samples supplemented with CocoanOX 12% by a 4 log cycle reduction, as compared to the untreated samples without CocoanOX 12%. This could indicate that the PEF-antimicrobial combination has a synergistic effect on the bacterial cells under study, increasing their sensitivity to subsequent refrigerated storage.
    International journal of food microbiology 02/2009; 130(3):196-204. · 3.01 Impact Factor
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    ABSTRACT: High Hydrostatic Pressure (HHP) inactivation (325–400 MPa; 0–20 min; maximum temperature 30 °C) of cells of Listeria innocua CECT 910 was studied in two different growth phases (exponential and stationary), and the corresponding survival curves were obtained for each case. The curves were fitted to two nonlinear models, the modified Gompertz equation and the Baranyi model. The kinetic constants calculated for both models, µmax and kmax, indicated that cells in exponential growth phase were more sensitive to pressure than those in stationary phase. Both mathematical models were suitable for describing L. innocua HHP survival curves, rendering kinetic constants that increased with increasing pressure. When considering the experimental models validation, both Gompertz and Baranyi predicted in a similar way, however Baranyi had slightly lower Af (Accuracy factor) and Bf (Bias factor) values, which indicated better prediction values. In summary, both mathematical models were perfectly valid for describing L. innocua inactivation kinetics under HHP treatment.Industrial relevanceThe mathematical models for inactivation and growth of microorganisms are the foundation of predictive microbiology and are used in risk assessments procedures as part of the food safety management system. Besides, these models together with those applied to inactivation of enzymes and destruction of quality factors are essential to optimize processes and thus to lay the foundations for industrial processing. It is therefore necessary to identify generally applicable kinetic models that will produce primary and secondary kinetic parameters and are statistically reliable as a key tool to predict the behaviour of microorganisms, enzymes and quality factors after processing.
    Innovative Food Science & Emerging Technologies. 01/2009;
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    ABSTRACT: In general, food engineers are trained to solve engineering problems in the food industry. More specifically, the food engineer must specify the functional requirements, design, and testing of food products, and finally, the evaluation of products to check for overall efficiency, cost, reliability, and most importantly, safety. Food safety must be considered foremost as the overall engineering problem encountered in the food supply chain, and it must be solved from a food safety engineering perspective. This article will show that the food safety engineering perspective is needed in order to produce high quality food products (minimally processed) that are both safe and secure. This multi-disciplinary approach will involve certain engineering components: (i) predictive microbiology as a tool to evaluate and improve food safety in traditional and new processing technologies, (ii) advanced food contaminants detection methods, (iii) advanced processing technologies, (iv) advanced systems for re-contamination control, (v) advanced systems for active and intelligent packaging.
    Food Engineering Reviews 1(1):84-104. · 2.81 Impact Factor