Person: García De Fernando Minguillón, Gonzalo Doroteo
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First Name
Gonzalo Doroteo
Last Name
García De Fernando Minguillón
Affiliation
Universidad Complutense de Madrid
Faculty / Institute
Veterinaria
Department
Farmacia Galénica y Tecnología Alimentaria
Area
Tecnología de los Alimentos
Identifiers
2 results
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Item Analysis and validation of a predictive model for growth and death of Aeromonas hydrophila under modified atmospheres at refrigeration temperatures(Applied and Environmental Microbiology, 2004) George, Susan; Baranyi, József; García De Fernando Minguillón, Gonzalo Doroteo; Velasco De Diego, Raquel; Pin Arias, CarmenSpecific growth and death rates of Aeromonas hydrophila were measured in laboratory media under various combinations of temperature, pH, and percent CO2 and O2 in the atmosphere. Predictive models were developed from the data and validated by means of observations obtained from (i) seafood experiments set up for this purpose and (ii) the ComBase database (http://www.combase.cc; http://wyndmoor.arserrc.gov/combase/). Two main reasons were identified for the differences between the predicted and observed growth in food: they were the variability of the growth rates in food and the bias of the model predictions when applied to food environments. A statistical method is presented to quantitatively analyze these differences. The method was also used to extend the interpolation region of the model. In this extension, the concept of generalized Z values (C. Pin, G. García de Fernando, J. A. Ordo´n˜ez, and J. Baranyi, Food Microbiol. 18:539-545, 2001) played an important role. The extension depended partly on the density of the model-generating observations and partly on the accuracy of extrapolated predictions close to the boundary of the interpolation region. The boundary of the growth region of the organism was also estimated by means of experimental results for growth and death rates.Item Indirect measurement of the lag time distribution of single cells of Listeria innocua in food(Applied and Environmental Microbiology, 2006) D'Arrigo, Matilde; George, Susan M.; Pin Arias, Carmen; Ordóñez Pereda, Juan Antonio; Velasco De Diego, Raquel; García De Fernando Minguillón, Gonzalo DoroteoThe distribution of log counts at a given time during the exponential growth phase of Listeria innocua measured in food samples inoculated with one cell each was applied to estimate the distribution of the single-cell lag times. Three replicate experiments in broth showed that the distribution of the log counts is a linear mapping of the distribution of the detection times measured by optical density. The detection time distribution reflects the lag time distribution but is shifted in time. The log count distribution was applied to estimate the distributions of the lag times in a liquid dairy product and in liver pate´ after different heat treatments. Two batches of ca. 100 samples of the dairy product were inoculated and heated at 55°C for 45 min or at 62°C for 2 min, and an unheated batch was incubated at 4°C. The final concentration of surviving bacteria was ca. 1 cell per sample. The unheated cells showed the shortest lag times with the smallest variance. The mean and the variance of the lag times of the surviving cells at 62°C were greater than those of the cells treated at 55°C. Three batches of pate´ samples were heated at 55°C for 25 min, 62°C for 81 s, or 65°C for 20 s. A control batch was inoculated but not heated. All pate´ samples were incubated at 15°C. The distribution of the lag times of the cells heated at 55°C was not significantly different from that of the unheated cells. However, at the higher temperatures, 62°C and 65°C, the lag duration was longer and its variance greater