Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 39
Filtrar
Más filtros

Tipo del documento
Intervalo de año de publicación
1.
Aging Clin Exp Res ; 28(6): 1061-1065, 2016 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-27380506

RESUMEN

Scaling up and replication of successful innovative integrated care models for chronic diseases is one of the targets of the European Innovation Partnership on Active and Healthy Ageing (EIP on AHA). MACVIA-LR® (MAladies Chroniques pour un VIeillissement Actif en Languedoc-Roussillon) is a Reference Site of the EIP on AHA. The main objective of MACVIA-LR® is to develop innovative solutions in order to (1) improve the care of patients affected by chronic diseases, (2) reduce avoidable hospitalization and (3) scale up the innovation to regions of Europe. The MACVIA-LR® project also aims to assess all possible aspects of medicine-including non-pharmacologic approaches-in order to maintain health and prevent chronic diseases. These approaches include hydrotherapy and balneotherapy which can be of great importance if health promotion strategies are considered. Balneotherapy at Balaruc-les-Bains focusses on musculoskeletal diseases and chronic venous insufficiency of the lower limbs. Each year, over 46,000 people attend an 18-day course related to a new falls prevention initiative combining balneotherapy and education. On arrival, each person receives a flyer providing information on the risk of fall and, depending on this risk, a course is proposed combining education and physical activity. A pilot study assesses the impact of the course 6 and 12 months later. This health promotion strategy for active and healthy ageing follows the FEMTEC (World Federation of Hydrotherapy and Climatotherapy) concept.


Asunto(s)
Accidentes por Caídas/prevención & control , Envejecimiento/fisiología , Balneología/métodos , Enfermedad Crónica , Promoción de la Salud , Enfermedades Musculoesqueléticas , Enfermedad Crónica/epidemiología , Enfermedad Crónica/rehabilitación , Europa (Continente)/epidemiología , Ejercicio Físico/fisiología , Promoción de la Salud/métodos , Promoción de la Salud/estadística & datos numéricos , Humanos , Enfermedades Musculoesqueléticas/epidemiología , Enfermedades Musculoesqueléticas/rehabilitación , Educación del Paciente como Asunto
2.
J Dairy Sci ; 95(11): 6204-14, 2012 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-22939794

RESUMEN

Nanoparticles of bovine α-lactalbumin (α-LA) prepared by desolvation and glutaraldehyde crosslinking are promising carriers for bioactive compounds in foods. The objective of this work was to study the effect of changes in hydrophobic interactions by using different desolvating agents (acetone, ethanol, or isopropanol) and the use of a heat or high-pressure treatment step before the desolvation process on the size, structure, and properties of α-LA nanoparticles. In all cases, a high average particle yield of 99.63% was obtained. Smaller sizes (152.3 nm) can be obtained with the use of acetone as the desolvating agent and without any pretreatment. This is the first time that α-LA nanoparticles in the size range of 100 to 200 nm have been obtained. These nanoparticles, with an isoelectric point of 3.61, are very stable at pH values >4.8, based on their ζ-potential, although their antioxidant activity is weak. The use of the desolvating agent with the smallest polarity index (isopropanol) produced the largest particles (293.4 to 324.9 nm) in all cases. These results support the idea that controlling hydrophobic interactions is a means to control the size of α-LA nanoparticles. No effect of pretreatment on nanoparticle size could be detected. All types of nanoparticles were easily degraded by the proteolytic enzymes assayed.


Asunto(s)
Lactalbúmina/química , Nanopartículas/química , 2-Propanol/farmacología , Acetona/farmacología , Animales , Bovinos , Etanol/farmacología , Concentración de Iones de Hidrógeno , Interacciones Hidrofóbicas e Hidrofílicas/efectos de los fármacos , Punto Isoeléctrico , Lactalbúmina/efectos de los fármacos , Microscopía Electrónica de Transmisión
3.
Int J Surg ; 97: 106168, 2022 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-34785344

RESUMEN

BACKGROUND AND AIMS: Emergency General Surgery (EGS) conditions account for millions of deaths worldwide, yet it is practiced without benchmarking-based quality improvement programs. The aim of this observational, prospective, multicenter, nationwide study was to determine the best benchmark cutoff points in EGS, as a reference to guide improvement measures. METHODS: Over a 6-month period, 38 centers (5% of all public hospitals) attending EGS patients on a 24-h, 7-days a week basis, enrolled consecutive patients requiring an emergent/urgent surgical procedure. Patients were stratified into cohorts of low (i.e., expected morbidity risk <33%), middle and high risk using the novel m-LUCENTUM calculator. RESULTS: A total of 7258 patients were included; age (mean ± SD) was 51.1 ± 21.5 years, 43.2% were female. Benchmark cutoffs in the low-risk cohort (5639 patients, 77.7% of total) were: use of laparoscopy ≥40.9%, length of hospital stays ≤3 days, any complication within 30 days ≤ 17.7%, and 30-day mortality ≤1.1%. The variables with the greatest impact were septicemia on length of hospital stay (21 days; adjusted beta coefficient 16.8; 95% CI: 15.3 to 18.3; P < .001), and respiratory failure on mortality (risk-adjusted population attributable fraction 44.6%, 95% CI 29.6 to 59.6, P < .001). Use of laparoscopy (odds ratio 0.764, 95% CI 0.678 to 0.861; P < .001), and intraoperative blood loss (101-500 mL: odds ratio 2.699, 95% CI 2.152 to 3.380; P < .001; and 500-1000 mL: odds ratio 2.875, 95% CI 1.403 to 5.858; P = .013) were associated with increased morbidity. CONCLUSIONS: This study offers, for the first time, clinically-based benchmark values in EGS and identifies measures for improvement.


Asunto(s)
Cirugía General , Procedimientos Quirúrgicos Operativos , Adulto , Anciano , Benchmarking , Estudios de Cohortes , Urgencias Médicas , Femenino , Mortalidad Hospitalaria , Humanos , Persona de Mediana Edad , Complicaciones Posoperatorias , Estudios Prospectivos , Mejoramiento de la Calidad , Estudios Retrospectivos
4.
Food Sci Technol Int ; 17(6): 541-7, 2011 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-22049160

RESUMEN

High hydrostatic pressure (HHP) was applied to fresh mango nectar (FMN) and sterilized mango nectar (SMN) to inactivate Escherichia coli and pectin methylesterase (PME). Pressure was applied at 275, 345 and 414 MPa. The come-up time (CUT) as well as 1, 2 and 4 min of treatment times were applied at the selected pressure to evaluate the inactivation effect on E. coli and PME. Total plate counts (TPC) were also evaluated in FMN. Results showed that mesophiles are inactivated in FMN to an important degree (up to 4 log) only with the CUT; the highest inactivation for mesophiles (7 log) was reported at 414 MPa after 4 min. Meanwhile, for E. coli 345 and 414 MPa after 2 and 1 min, respectively, were able to inactivate all viable cells in FMN. However, in SMN after 4 min at 275 MPa all cells of E. coli were also inactivated, showing the protective effect of the media between FMN and SMN. The PME showed its resistance to be inactivated with high pressure, showing the highest decrease in enzymatic activity (45%) after 4 min at 345 MPa but with an important activation at the highest pressure (414 MPa).


Asunto(s)
Bebidas/microbiología , Hidrolasas de Éster Carboxílico/metabolismo , Escherichia coli/aislamiento & purificación , Conservación de Alimentos , Frutas/microbiología , Mangifera/microbiología , Proteínas de Plantas/metabolismo , Recuento de Colonia Microbiana , Activación Enzimática , Escherichia coli/crecimiento & desarrollo , Enfermedades Transmitidas por los Alimentos/prevención & control , Frutas/enzimología , Calor , Presión Hidrostática , Cinética , Mangifera/enzimología , Viabilidad Microbiana , Desnaturalización Proteica , Esterilización , Factores de Tiempo
5.
J Dairy Sci ; 93(4): 1420-8, 2010 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-20338419

RESUMEN

The effects of high hydrostatic pressure (HHP) processing (at 200 to 600 MPa, 25 to 55 degrees C, and from 5 to 15 min) on some structural properties of alpha-lactalbumin was studied in a pH range of 3.0 to 9.0. The range of HHP processes produced a variety of molten globules with differences in their surface hydrophobicity and secondary and tertiary structures. At pH values of 3 and 5, there was a decrease in the alpha-helix content concomitant with an increase in beta-strand content as the pressure increased. No changes in molecular size due to HHP-induced aggregation were detected by sodium dodecyl sulfate-PAGE. All samples showed higher thermostability as the severity of the treatment increased, indicating the formation of a less labile structure related to the HHP treatment.


Asunto(s)
Presión Hidrostática , Lactalbúmina/química , Animales , Bovinos , Electroforesis en Gel de Poliacrilamida , Fluorescencia , Concentración de Iones de Hidrógeno , Interacciones Hidrofóbicas e Hidrofílicas , Presión Hidrostática/efectos adversos , Conformación Proteica , Temperatura , Factores de Tiempo
6.
J Frailty Aging ; 5(4): 233-241, 2016.
Artículo en Inglés | MEDLINE | ID: mdl-27883170

RESUMEN

The Région Languedoc Roussillon is the umbrella organisation for an interconnected and integrated project on active and healthy ageing (AHA). It covers the 3 pillars of the European Innovation Partnership on Active and Healthy Ageing (EIP on AHA): (A) Prevention and health promotion, (B) Care and cure, (C) and (D) Active and independent living of elderly people. All sub-activities (poly-pharmacy, falls prevention initiative, prevention of frailty, chronic respiratory diseases, chronic diseases with multimorbidities, chronic infectious diseases, active and independent living and disability) have been included in MACVIA-LR which has a strong political commitment and involves all stakeholders (public, private, patients, policy makers) including CARSAT-LR and the Eurobiomed cluster. It is a Reference Site of the EIP on AHA. The framework of MACVIA-LR has the vision that the prevention and management of chronic diseases is essential for the promotion of AHA and for the reduction of handicap. The main objectives of MACVIA-LR are: (i) to develop innovative solutions for a network of Living labs in order to reduce avoidable hospitalisations and loss of autonomy while improving quality of life, (ii) to disseminate the innovation. The three years of MACVIA-LR activities are reported in this paper.


Asunto(s)
Envejecimiento , Política de Salud , Promoción de la Salud , Vida Independiente , Medicina Preventiva , Accidentes por Caídas/prevención & control , Anciano , Anciano de 80 o más Años , Enfermedad Crónica , Comorbilidad , Unión Europea , Francia , Hospitalización , Humanos , Afecciones Crónicas Múltiples , Salud Bucal , Autonomía Personal , Polifarmacia , Calidad de Vida , Enfermedades Respiratorias
7.
Biomaterials ; 14(7): 491-6, 1993 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-8329520

RESUMEN

The degradation of poly[bis(glycine ethyl ester)phosphazene] in aqueous media was studied by following the appearance of some of its expected by-products in solution. Disc-shaped polymer slabs of 12 mm diameter and 1.2 mm thickness were prepared by compression moulding, followed by incubation in aqueous media under carefully controlled conditions of pH and temperature. Low molecular weight by-products (phosphate and glycine) were assayed for up to 60 d using ultraviolet and visible spectroscopy. Slabs placed in pH 12.0 media at 20 degrees C took 16 d to disappear completely (no longer visible), while at 37 and 47 degrees C this occurred in 12 d. Also, slabs placed in pH 7.0 and 4.0 media took 60 and 24 d, respectively, to disappear at 47 degrees C. However, at 20 and 37 degrees C only some of the material disappeared at pH 7.0 after 60 d. In all cases, the cumulative fractional loss of by-products from the slabs was < 1, indicating the presence in solution of other species which were unaccounted for. This study showed that poly[bis(glycine ethyl ester)phosphazene] slabs have a lifetime in physiological media which makes them an acceptable support for short-term controlled drug release, and complements others, in which polyphosphazenes were used for a similar application.


Asunto(s)
Compuestos Organofosforados/química , Polímeros/química , Biodegradación Ambiental , Química Farmacéutica , Preparaciones de Acción Retardada , Compuestos Organofosforados/síntesis química , Polímeros/síntesis química , Temperatura , Agua
8.
Biotechnol Prog ; 1(2): 140-6, 1985 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-20568151

RESUMEN

Segregation tendency in food powder mixtures can be monitored by simple vibration or flow tests. It is shown that segregation can occur not only in free flowing powders but also in cohesive powders. The intensity of the phenomenon depends not only on the composition, size and mechanical history of the powder but also on whether the mixture is "ordered" or not.

9.
Int J Food Microbiol ; 51(1): 7-17, 1999 Oct 01.
Artículo en Inglés | MEDLINE | ID: mdl-10563459

RESUMEN

Consumer demand for fresh-like products with little or no degradation of nutritional and organoleptic properties has led to the study of new technologies in food preservation. Pulsed electric fields (PEF) is a nonthermal preservation method used to inactivate microorganisms mainly in liquid foods. Microorganisms in the presence of PEF suffer cell membrane damage. Nisin is a natural antimicrobial known to disrupt cell membrane integrity. Thus the combination of PEF and nisin represents a hurdle for the survival of Listeria innocua in liquid whole egg (LWE). L. innocua suspended in LWE was subjected to two different treatments: PEF and PEF followed by exposure to nisin. The selected frequency and pulse duration for PEF was 3.5 Hz and 2 micros, respectively. Electric field intensities of 30, 40 and 50 kV/cm were used. The number of pulses applied to the LWE was 10.6, 21.3 and 32. The highest extent of microbial inactivation with PEF was 3.5 log cycles (U) for an electric field intensity of 50 kV/cm and 32 pulses. Treatment of LWE by PEF was conducted at low temperatures, 36 degrees C being the highest. Exposure of L. innocua to nisin following the PEF treatment exhibited an additive effect on the inactivation of the microorganism. Moreover, a synergistic effect was observed as the electric field intensity, number of pulses and nisin concentration increased. L. innocua exposed to 10 IU nisin/ml after PEF exhibited a decrease in population of 4.1 U for an electric field intensity of 50 kV/cm and 32 pulses. Exposure of L. innocua to 100 IU nisin/ml following PEF resulted in 5.5 U for an electric field intensity of 50 kV/cm and 32 pulses. The model developed for the inactivation of L. innocua by PEF and followed by exposure to nisin proved to be accurate (p = 0.05) when used to model the inactivation of the microorganism by PEF in LWE with 1.2 or 37 IU nisin/ml. The presence of 37 IU nisin/ml in LWE during the PEF treatment for an electric field intensity of 50 kV/cm and 32 pulses resulted in a decrease in the population of L. innocua of 4.4 U.


Asunto(s)
Antibacterianos/farmacología , Huevos/microbiología , Estimulación Eléctrica/métodos , Conservación de Alimentos/métodos , Listeria/crecimiento & desarrollo , Nisina/farmacología , Recuento de Colonia Microbiana , Industria de Procesamiento de Alimentos , Listeria/efectos de los fármacos , Listeriosis/prevención & control
10.
Int J Food Microbiol ; 51(1): 19-30, 1999 Oct 01.
Artículo en Inglés | MEDLINE | ID: mdl-10563460

RESUMEN

Pulsed electric fields (PEF) is an emerging nonthermal processing technology used to inactivate microorganisms in liquid foods such as milk. PEF results in loss of cell membrane functionality that leads to inactivation of the microorganism. There are many processes that aid in the stability and safety of foods. The combination of different preservation factors, such as nisin and PEF, to control microorganisms should be explored. The objective of this research was to study the inactivation of Listeria innocua suspended in skim milk by PEF as well as the sensitization of PEF treated L. innocua to nisin. The selected electric field intensity was 30, 40 and 50 kV/cm and the number of pulses applied was 10.6, 21.3 and 32. The sensitization exhibited by PEF treated L. innocua to nisin was assessed for 10 or 100 IU nisin/ml. A progressive decrease in the population of L. innocua was observed for the selected field intensities, with the greatest reduction being 2 1/2 log cycles (U). The exposure of L. innocua to nisin after PEF had an additive effect on the inactivation of the microorganism as that exhibited by the PEF alone. As the electric field, number of pulses and nisin concentration increased, synergism was observed in the inactivation of L. innocua as a result of exposure to nisin after PEF. The reduction of L. innocua accomplished by exposure to 10 IU nisin/ml after 32 pulsed electric fields was 2, 2.7, and 3.4 U for an electric field intensity of 30, 40, and 50 kV/cm, respectively. Population of L. innocua subjected to 100 IU nisin/ml after PEF was 2.8-3.8 U for the selected electric field intensities and 32 pulses. The designed model for the inactivation of L. innocua as a result of the PEF followed by exposure to nisin proved to be accurate in the prediction of the inactivation of L. innocua in skim milk containing 1.2 or 37 IU nisin/ml. Inactivation of L. innocua in skim milk containing 37 IU nisin/ml resulted in a decrease in population of 3.7 U.


Asunto(s)
Antibacterianos/farmacología , Estimulación Eléctrica/métodos , Conservación de Alimentos/métodos , Listeria/crecimiento & desarrollo , Leche/microbiología , Nisina/farmacología , Animales , Recuento de Colonia Microbiana , Listeria/efectos de los fármacos , Listeriosis/prevención & control
11.
Int J Food Microbiol ; 51(1): 31-8, 1999 Oct 01.
Artículo en Inglés | MEDLINE | ID: mdl-10563461

RESUMEN

Pulsed electric fields (PEF) is a nonthermal food preservation process where organoleptic and nutritional properties of the food are maintained. PEF is known to inactivate microorganisms by causing dielectric breakdown of the cell membrane, thus altering the functionality of the membrane as a semipermeable barrier. The extent of damage of the cell membrane, whether visible in the form of a pore or as loss of membrane functionality leads to the inactivation of the microorganism. The objective of this study was to investigate under transmission electron microscopy (TEM) the morphological changes on Listerit innocua as a result of PEF treatment in skimmed milk containing nisin. L. innocua was subjected to PEF at selected electric field intensities of 30, 40, and 50 kV/cm. L. innocua was treated by PEF in both skimmed milk with and without 37 IU nisin/ml. L. innocua treated by PEF in skimmed milk exhibited an increase in the cell wall roughness. cytoplasmic clumping, leakage of cellular material, and rupture of the cell walls and cell membranes. L. innocua subjected to PEF in skimmed milk containing 37 IU nisin/ml exhibited an increased cell wall width. At the highest electric field intensity, 50 kV/cm, elongation of the cell length was observed. There were no morphological differences between cells treated by PEF in skimmed milk with or without nisin. The combination of PEF and nisin exhibit an additive effect in the morphological damage observed on L. innocua. Pore formation was observed on L. innocua for an electric field intensity of 40 kV/cm. The inactivation of L. innocua was a consequence of rupture of the cell membrane and loss of cell membrane functionality.


Asunto(s)
Antibacterianos/farmacología , Estimulación Eléctrica/métodos , Conservación de Alimentos/métodos , Listeria/ultraestructura , Leche/microbiología , Nisina/farmacología , Animales , Listeria/efectos de los fármacos , Listeriosis/prevención & control , Microscopía Electrónica
12.
Int J Food Microbiol ; 60(2-3): 147-52, 2000 Sep 25.
Artículo en Inglés | MEDLINE | ID: mdl-11016604

RESUMEN

Death and injury following exposure of Micrococcus luteus to nisin and pulsed electric field (PEF) treatment were investigated in phosphate buffer (pH 6.8, sigma = 4.8 ms/cm at 20 degrees C). Four types of experiment were carried out, a single treatment with nisin (100 IU/ml at 20 degrees C for 2 h), a single PEF treatment, a PEF treatment followed by incubation with nisin (as before) and addition of nisin to the bacterial suspension prior to the PEF treatment. The application of nisin clearly enhanced the lethal effect of PEF treatment. The bactericidal effect of nisin reduced viable counts by 1.4 log10 units. Treatment with PEF (50 pulses at 33 kV/cm) resulted in a reduction of 2.4 log10 units. PEF treatment followed by nisin caused a reduction of 5.2 log10 units in comparison with a 4.9 log10 units reduction obtained with nisin followed by PEF. Injury of surviving cells was investigated using media with different concentrations of salt. Sublethally damaged cells of M. luteus could not be detected by this means, following PEF treatment.


Asunto(s)
Antibacterianos/farmacología , Campos Electromagnéticos , Conservación de Alimentos/métodos , Micrococcus luteus/crecimiento & desarrollo , Nisina/farmacología , Recuento de Colonia Microbiana , Micrococcus luteus/efectos de los fármacos
13.
Int J Food Microbiol ; 44(1-2): 125-32, 1998 Oct 20.
Artículo en Inglés | MEDLINE | ID: mdl-9849790

RESUMEN

The influence of pH, aw, L-alanine, and fat concentration of milk on the initiation of germination and inactivation by high hydrostatic pressure (HHP) (250 mPa at 25 degrees C for 15 min and 690 mPa at 40 degrees C for 2 min) of Bacillus cereus sporulated at 20, 30 and 37 degrees C was investigated. B. cereus sporulated at the lowest temperature was found to be the most resistant to the initiation of germination and inactivation by HHP. At ambient pressure, the rate and extension of germination induced by L-alanine were also lower in B. cereus sporulated at 20 than 30 or 37 degrees C. The optimum pH for the germination and inactivation of B. cereus depended on the sporulation temperature. At 250 mPa the extent of germination for the three suspensions increased with higher pH. At 690 mPa, the pH barely affected the germination of B. cereus sporulated at 20 degrees C (3 log cycles), but the inactivation increased as the pH of the medium was lowered. After the same treatment, pressure optimally initiated the germination of B. cereus sporulated at 30 and 37 degrees C (6-7 log cycles) around neutral pH. Higher inactivation was obtained at pH 6. High concentrations of sucrose protected the spores from the germinating and inactivating effect of HHP. At aw 0.92, no germination was detected when the spores were pressurized at 250 mPa, and only 1 log cycle of B. cereus sporulated at 20 and 30 degrees C and 2 log cycles of B. cereus sporulated at 37 degrees C were germinated at 690 mPa. In addition, no inactivation was observed at aW 0.92 even at 690 mPa. The presence of L-alanine in the medium of pressurization increased the germination initiated by HHP at 250 mPa, but not at 690 mPa. A combination of 250 mPa at 25 degrees C with L-alanine (100 mM) was found to give an additive response. The initiation of germination and inactivation by HHP were not affected by the fat concentration of the milk.


Asunto(s)
Bacillus cereus/fisiología , Alanina/farmacología , Concentración de Iones de Hidrógeno , Presión Hidrostática , Esporas Bacterianas/fisiología , Temperatura
14.
Int J Food Microbiol ; 81(3): 223-9, 2003 Mar 25.
Artículo en Inglés | MEDLINE | ID: mdl-12485748

RESUMEN

The kinetics of Lactobacillus plantarum inactivation by pulsed electric fields (PEF) was studied in two different growth stages (exponential and stationary), but in the same reference medium (0.6% peptone water). Electric field intensity and treatment time varied from 20 to 28 kV/cm and 30 to 240 micros, respectively. The experimental data showed that cells in the exponential growth stage were more sensitive to PEF treatment than those in the stationary stage. The inactivation data were adjusted to the Bigelow and Hülsheger models and the Weibull frequency distribution function, and constants were calculated for both growth stages in each model. The models were tested and their accuracy was assessed by using the Accuracy Factor. According to this parameter, the Weibull frequency distribution function gave better fittings for the inactivation by PEF than Bigelow or Hülsheger models. On the other hand, the Bigelow model gave a good accuracy factor and is simpler.


Asunto(s)
Electricidad , Conservación de Alimentos/métodos , Lactobacillus/crecimiento & desarrollo , Estimulación Eléctrica , Microbiología de Alimentos , Cinética , Modelos Biológicos , Flujo Pulsátil , Reproducibilidad de los Resultados , Sensibilidad y Especificidad , Distribuciones Estadísticas
15.
Int J Food Microbiol ; 54(1-2): 91-8, 2000 Mar 10.
Artículo en Inglés | MEDLINE | ID: mdl-10746578

RESUMEN

The use of pulsed electric fields (PEF) is considered as a mild process in the inactivation of microorganisms present in liquid food products. PEF treatments of Escherichia coli and Listeria innocua suspended in milk and phosphate buffer, with same pH and same conductivities, yielded to similar inactivation. Reduction rates obtained in distilled water indicated that conductivity of the food product is a main parameter in bacterial inactivation. Bacteria attached to polystyrene beads were inactivated by PEF at a greater (E. coli) or equal rate (L. innocua) than free-living bacteria. Base on the use of selective and non-selective enumeration media, no clear indications were obtained for sublethal damage of microorganisms surviving the PEF treatment. E. coli cells subjected to 60 pulses at 41 kV/cm were examined by transmission and scanning electron microscopy. Changes in the cytoplasm were observed and the cell surface appeared rough. The cells outer membranes were partially destroyed allowing leaking of cell cytoplasm.


Asunto(s)
Escherichia coli , Microbiología de Alimentos , Listeria , Electricidad , Escherichia coli/ultraestructura , Listeria/ultraestructura , Microscopía Electrónica , Flujo Pulsátil
16.
J Food Prot ; 66(6): 1007-12, 2003 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-12801001

RESUMEN

The pulsed electric field inactivation kinetics of Escherichia coli suspended in orange juices with three different concentrations of carrot juice (0, 20, and 60%) was studied. Electric field strengths ranged from 25 to 40 kV/cm, and treatment times ranged from 40 to 340 micros. Experimental data were fitted to Bigelow, Hülsheger, and Weibull distribution functions, and the Weibull function provided the best fit (with the lowest mean square error). The dependency of each model's kinetic constant on electric field strength and carrot juice concentration was studied. A secondary model was developed to describe the relationship of Weibull parameters a and n to electric field strength and carrot juice concentration. An empirical mathematical model based on the Weibull distribution function, relating the natural logarithm of the survival fraction to treatment time, electric field strength, and carrot juice concentration, was developed. Parameters were estimated by a nonlinear regression. The results of this study indicate that the error rate for the model's predictions was 6.5% and that the model was suitable for describing E. coli inactivation.


Asunto(s)
Bebidas/microbiología , Citrus/microbiología , Daucus carota/microbiología , Electricidad , Escherichia coli/crecimiento & desarrollo , Estimulación Eléctrica , Microbiología de Alimentos , Cinética , Modelos Teóricos , Valor Predictivo de las Pruebas , Flujo Pulsátil , Distribuciones Estadísticas
17.
J Food Prot ; 66(12): 2336-42, 2003 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-14672234

RESUMEN

The effects of pulsed electric fields (PEFs) on pectin methyl esterase (PME), molds and yeast, and total flora in fresh (nonpasteurized) mixed orange and carrot juice were studied. The PEF effect was more extensive when juices with high levels of initial PME activity were subjected to treatment and when PEF treatment (at 25 kV/cm for 340 micros) was combined with a moderate temperature (63 degrees C), with the maximum level of PME inactivation being 81.4%. These conditions produced 3.7 decimal reductions in molds and yeast and 2.4 decimal reductions in total flora. Experimental inactivation data for PME, molds and yeast, and total flora were fitted to Bigelow, Hülsheger, and Weibull inactivation models by nonlinear regression. The best fit (lowest mean square error) was obtained with the Weibull model.


Asunto(s)
Bebidas/microbiología , Hidrolasas de Éster Carboxílico/metabolismo , Citrus sinensis/microbiología , Daucus carota/microbiología , Electricidad , Hongos/crecimiento & desarrollo , Estimulación Eléctrica , Manipulación de Alimentos/métodos , Microbiología de Alimentos , Cinética , Modelos Teóricos , Flujo Pulsátil , Distribuciones Estadísticas , Temperatura , Levaduras/crecimiento & desarrollo
18.
J Food Prot ; 61(9): 1213-5, 1998 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-9766081

RESUMEN

Zygosaccharomyces bailii inactivation was evaluated in oscillatory high hydrostatic pressure (HHP) treatments at sublethal pressures (207, 241, or 276 MPa) and compared with continuous HHP treatments in laboratory model systems with a water activity (aw) of 0.98 and pH 3.5. The yeast was inoculated into laboratory model systems and subjected to HHP in sterile bags. Two HHP treatments were conducted: continuous (holding times of 5, 10, 15, 20, 30, 60, or 90 min) and oscillatory (two, three, or four cycles with holding times of 5 min and two cycles with holding times of 10 min). Oscillatory pressure treatments increased the effectiveness of HHP processing. For equal holding times, Z. bailii counts decreased as the number of cycles increased. Holding times of 20 min in HHP oscillatory treatments at 276 MPa assured inactivation (< 10 CFU/ml) of Z. bailii initial inoculum. Oscillatory pressurization could be useful to decrease Z. bailii inactivation time.


Asunto(s)
Presión Hidrostática , Zygosaccharomyces/crecimiento & desarrollo , Medios de Cultivo , Técnicas Microbiológicas , Análisis de Supervivencia , Factores de Tiempo
19.
J Food Prot ; 64(2): 259-63, 2001 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-11271778

RESUMEN

The inactivation kinetics of Lactobacillus plantarum was studied in orange-carrot juice using high intensity pulsed electric fields. The results indicated that under the treatment conditions applied, 28.6, 32.0, and 35.8 kV/cm and treatment times ranging from 10.2 to 46.3 micros, the inactivation of L. plantarum obtained was up to 2.5 decimal reductions. Experimental and literature data were fitted to Bigelow, Hülsheger et al. and Peleg models and to Weibull frequency distribution function. Weibull was the one that best interpreted the data with accuracy factor values closer to 1.


Asunto(s)
Bebidas/microbiología , Citrus/microbiología , Daucus carota/microbiología , Electricidad , Lactobacillus/crecimiento & desarrollo , Citrus/química , Daucus carota/química , Estimulación Eléctrica , Cinética , Lactobacillus/fisiología , Flujo Pulsátil
20.
J Food Prot ; 61(12): 1657-60, 1998 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-9874344

RESUMEN

The effects of the come-up time at selected pressures (50 to 689 MPa) on Saccharomyces cerevisiae and Zygosaccharomyces bailii viability were evaluated at 21 degrees C. For Z. bailii the effects of the water activity (a(w)) of the suspension media and the stage of the growth cycle were also investigated. Pressure come-up times exerted an important effect on the yeast survival fraction, decreasing counts as pressure increased. An increased sensitivity to pressure treatments was observed with yeast cells from the exponential growth phase. Lethality increased as a(w) of the suspension media increased. For an a(w) of 0.98 and cells from the stationary growth phase, pressure treatments at less than 200 MPa had no effect on Z. bailii viability; however, no survivors (< 10 CFU/ml) were observed in treatments applied only for the time needed to reach pressures greater than 517 MPa. Yeast survivor curves showed an excellent fit (r > 0.996) when described by a phenomenological model based on the Fermi equation, S(P) = 1/¿1 + exp[(P - Pc)/k]¿, where S(P) is the survival fraction, P is the pressure, Pc is a critical pressure corresponding to 50% survival, and k is a constant representing the steepness of the curve.


Asunto(s)
Presión Hidrostática , Saccharomyces cerevisiae/crecimiento & desarrollo , Esterilización/métodos , Zygosaccharomyces/crecimiento & desarrollo , Recuento de Colonia Microbiana , Frutas/microbiología , Factores de Tiempo
SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA