Tecnologia de los Alimentos

Zaragoza, Spain

Tecnologia de los Alimentos

Zaragoza, Spain

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Arroyo C.,Tecnologia de los Alimentos | Cebrian G.,Tecnologia de los Alimentos | Condon S.,Tecnologia de los Alimentos | Pagan Tomas R.,Tecnologia de los Alimentos
Journal of Applied Microbiology | Year: 2012

Aims: The objective was to study the response of Cronobacter sakazakii ATCC 29544 cells to heat, pulsed electric fields (PEF), ultrasound under pressure (Manosonication, MS) and ultraviolet light (UV-C) treatments after exposure to different sublethal stresses that may be encountered in food-processing environments. Methods and Results: Cronobacter sakazakii stationary growth-phase cells (30°C, 24h) were exposed to acid (pH 4·5, 1h), alkaline (pH 9·0, 1h), osmotic (5% NaCl, 1h), oxidative (0·5mmoll -1 H 2O 2, 1h), heat (47·5°C, 1h) and cold (4°C, 4h) stress conditions and subjected to the subsequent challenges: heat (60°C), PEF (25kVcm -1, 35°C), MS (117μm, 200kPa, 35°C) and UV-C light (88·55mWcm -2, 25°C) treatments. The inactivation kinetics of C. sakazakii by the different technologies did not change after exposure to any of the stresses. The combinations of sublethal stress and lethal treatment that were protective were: heat shock-heat, heat shock-PEF and acid pH-PEF. Conversely, the alkaline shock sensitized the cells to heat and UV-C treatments, the osmotic shock to heat treatments and the oxidative shock to UV-C treatments. The maximum adaptive response was observed when heat-shocked cells were subjected to a heat treatment, increasing the time to inactivate 99·9% of the population by 1·6 times. Conclusions: Cronobacter sakazakii resistance to thermal and nonthermal preservation technologies can increase or decrease as a consequence of previous exposure to stressing conditions. Significance and Impact of the Study: The results help in understanding the physiology of the resistance of this emerging pathogen to traditional and novel preservation technologies. © 2011 The Authors. Journal of Applied Microbiology © 2011 The Society for Applied Microbiology.


Conesa C.,Tecnologia de los Alimentos | Rota C.,University of Zaragoza | Castillo E.,Tecnologia de los Alimentos | Perez M.D.,Tecnologia de los Alimentos | And 2 more authors.
International Journal of Dairy Technology | Year: 2010

The effect of different heat treatments on the antimicrobial activity of bovine lactoferrin against Escherichia coli O157:H7, Salmonella enteritidis and Listeria monocytogenes has been studied. We have observed that the heat treatments lower than 85°C for 10 min did not affect the antibacterial activity of the protein. Hydrolysates of bovine lactoferrin were found to be more active than the native protein against the three pathogens. Moreover, the antibacterial effect of bovine lactoferrin was also assayed in milk and whey, and although we found a reduction in the number of viable cells, this reduction was lower than in culture media. © 2010 Society of Dairy Technology.


Somolinos M.,Tecnologia de los Alimentos | Garcia D.,Tecnologia de los Alimentos | Manas P.,Tecnologia de los Alimentos | Condon S.,Tecnologia de los Alimentos | Pagan R.,Tecnologia de los Alimentos
International Journal of Food Microbiology | Year: 2010

Stationary growth phase cells of Escherichia coli were more pulsed electric fields (PEF) resistant in citrate-phosphate McIlvaine buffer at pH 4.0 than at pH 7.0. The greater PEF resistance was also confirmed in fruit juices of similar acid pH. In this work we studied whether the higher PEF resistance of E. coli at acid pH was due to the low pH itself or to the interaction of the components of the treatment medium with the cells. The protective effect on E. coli cells was due to the presence of organic acids such as citric, acetic, lactic or malic at pH 4.0. The protective effect of citric acid at pH 4.0 depended on its concentration. A linear relationship was observed between the Log10 of the citric acid concentration and the degree of inactivation. Organic acids contained in laboratory treatment media (citrate-phosphate buffer) or in fruit juices did not sensitize E. coli cells to PEF but, on the contrary, they induced a protective effect that made E. coli cells more resistant at pH 4.0 than at neutral pH. This work could be useful for improving food preservation by PEF technology and it contributes to the knowledge of the mechanism of microbial inactivation by PEF. © 2009 Elsevier B.V. All rights reserved.


PubMed | Tecnologia de los Alimentos
Type: Journal Article | Journal: Meat science | Year: 2011

On the basis of considering foods with water activity from 0600 to 0910 to be intermediate-moisture foods (IMF), we determined the water activity, pH, and some chemical parameters for 70 samples from 17 different selected types of Spanish intermediate-moisture meat products. Even though the salt content is the main water-activity depressor, the sodium chloride molality in the overall amount of water of the product cannot be used to calculate the a(w) value of these types of meat products of intermediate moisture.


PubMed | Tecnologia de los Alimentos
Type: Journal Article | Journal: Journal of applied microbiology | Year: 2012

The objective was to study the response of Cronobacter sakazakii ATCC 29544 cells to heat, pulsed electric fields (PEF), ultrasound under pressure (Manosonication, MS) and ultraviolet light (UV-C) treatments after exposure to different sublethal stresses that may be encountered in food-processing environments.Cronobacter sakazakii stationary growth-phase cells (30C, 24h) were exposed to acid (pH 45, 1h), alkaline (pH 90, 1h), osmotic (5% NaCl, 1h), oxidative (05mmoll(-1) H(2) O(2), 1h), heat (475C, 1h) and cold (4C, 4h) stress conditions and subjected to the subsequent challenges: heat (60C), PEF (25kVcm(-1) , 35C), MS (117m, 200kPa, 35C) and UV-C light (8855mWcm(-2), 25C) treatments. The inactivation kinetics of C. sakazakii by the different technologies did not change after exposure to any of the stresses. The combinations of sublethal stress and lethal treatment that were protective were: heat shock-heat, heat shock-PEF and acid pH-PEF. Conversely, the alkaline shock sensitized the cells to heat and UV-C treatments, the osmotic shock to heat treatments and the oxidative shock to UV-C treatments. The maximum adaptive response was observed when heat-shocked cells were subjected to a heat treatment, increasing the time to inactivate 999% of the population by 16 times.Cronobacter sakazakii resistance to thermal and nonthermal preservation technologies can increase or decrease as a consequence of previous exposure to stressing conditions.The results help in understanding the physiology of the resistance of this emerging pathogen to traditional and novel preservation technologies.


PubMed | University of Vigo, Tecnologia de los Alimentos, University of Concepción and University of Salamanca
Type: Journal Article | Journal: Sensors (Basel, Switzerland) | Year: 2015

The potential of near infrared spectroscopy (NIR) with remote reflectance fiber-optic probes for determining the mineral composition of propolis was evaluated. This technology allows direct measurements without prior sample treatment. Ninety one samples of propolis were collected in Chile (Bio-Bio region) and Spain (Castilla-Len and Galicia regions). The minerals measured were aluminum, calcium, iron, potassium, magnesium, phosphorus, and some potentially toxic trace elements such as zinc, chromium, nickel, copper and lead. The modified partial least squares (MPLS) regression method was used to develop the NIR calibration model. The determination coefficient (R2) and root mean square error of prediction (RMSEP) obtained for aluminum (0.79, 53), calcium (0.83, 94), iron (0.69, 134) potassium (0.95, 117), magnesium (0.70, 99), phosphorus (0.94, 24) zinc (0.87, 10) chromium (0.48, 0.6) nickel (0.52, 0.7) copper (0.64, 0.9) and lead (0.70, 2) in ppm. The results demonstrated that the capacity for prediction can be considered good for wide ranges of potassium, phosphorus and zinc concentrations, and acceptable for aluminum, calcium, magnesium, iron and lead. This indicated that the NIR method is comparable to chemical methods. The method is of interest in the rapid prediction of potentially toxic elements in propolis before consumption.


PubMed | Tecnologia de los Alimentos
Type: Journal Article | Journal: International journal of food microbiology | Year: 2010

Stationary growth phase cells of Escherichiacoli were more pulsed electric fields (PEF) resistant in citrate-phosphate McIlvaine buffer at pH 4.0 than at pH 7.0. The greater PEF resistance was also confirmed in fruit juices of similar acid pH. In this work we studied whether the higher PEF resistance of E. coli at acid pH was due to the low pH itself or to the interaction of the components of the treatment medium with the cells. The protective effect on E. coli cells was due to the presence of organic acids such as citric, acetic, lactic or malic at pH 4.0. The protective effect of citric acid at pH 4.0 depended on its concentration. A linear relationship was observed between the Log(10) of the citric acid concentration and the degree of inactivation. Organic acids contained in laboratory treatment media (citrate-phosphate buffer) or in fruit juices did not sensitize E. coli cells to PEF but, on the contrary, they induced a protective effect that made E. coli cells more resistant at pH 4.0 than at neutral pH. This work could be useful for improving food preservation by PEF technology and it contributes to the knowledge of the mechanism of microbial inactivation by PEF.

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