Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 130
Filtrar
1.
J Food Prot ; 73(4): 747-51, 2010 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-20377966

RESUMEN

Each carcass in groups of 25 pig, cattle, or bison carcasses was sampled by five people: two or three people experienced with carcass sampling and two or three without previous experience. Each person sampled a different randomly selected site on a dressed carcass side by swabbing an undelimited area of approximately 100 cm(2) with a moistened synthetic sponge. The numbers of aerobic bacteria, coliform bacteria, and Escherichia coli recovered from each sample were determined. The mean log and log mean values were calculated for each set of 25 counts for each group of bacteria from pig carcasses and each set of 25 aerobic counts from cattle and bison carcasses from the samples obtained by each person. Values for the log of the total number recovered were calculated for all the sets of counts from samples obtained by each person. Most of the corresponding statistics for each set of counts of the same type for samples obtained by five people from the same group of carcasses differed by less than 0.5 log unit. These findings indicate that the numbers of bacteria recovered from carcasses by swabbing with sponges are unlikely to differ substantially as a result of samples being collected by different people using the same procedure.


Asunto(s)
Mataderos , Recuento de Colonia Microbiana/normas , Contaminación de Alimentos/análisis , Microbiología de Alimentos , Competencia Mental/psicología , Mataderos/instrumentación , Mataderos/normas , Animales , Bacterias Aerobias/aislamiento & purificación , Técnicas Bacteriológicas/métodos , Técnicas Bacteriológicas/normas , Bison/microbiología , Búfalos/microbiología , Bovinos/microbiología , Recuento de Colonia Microbiana/métodos , Seguridad de Productos para el Consumidor , Enterobacteriaceae/aislamiento & purificación , Escherichia coli/aislamiento & purificación , Manipulación de Alimentos/métodos , Humanos , Especificidad de la Especie , Porcinos/microbiología , Recursos Humanos
2.
J Food Prot ; 72(8): 1790-801, 2009 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-19722420

RESUMEN

Reports on the microbiological effects of decontaminating treatments routinely applied to carcasses at beef packing plants indicate that washing before skinning may reduce the numbers of enteric bacteria transferred from the hide to meat. Washing skinned carcasses and/or dressed sides can reduce the numbers of aerobes and Escherichia coli by about 1 log unit, and pasteurizing sides with steam or hot water can reduce their numbers by > 1 or > 2 log units, respectively. Spraying with 2% lactic acid, 2% acetic acid, or 200 ppm of peroxyacetic acid can reduce the numbers of aerobes and E. coli by about 1 log, but such treatments can be ineffective if solutions are applied in inadequate quantities or to meat surfaces that are wet after washing. Trimming and vacuum cleaning with or without spraying with hot water may be largely ineffective for improving the microbiological conditions of carcasses. When contamination of meat during carcass dressing is well controlled and carcasses are subjected to effective decontaminating treatments, the numbers of E. coli on dressed carcasses can be < 1 CFU/ 1,000 cm2. However, meat can be recontaminated during carcass breaking with E. coli from detritus that persists in fixed and personal equipment. The adoption at all packing plants of the carcass-dressing procedures and decontaminating treatments used at some plants to obtain carcasses that meet a very high microbiological standard should be encouraged, and means for limiting recontamination of product during carcass breaking and for decontaminating trimmings and other beef products should be considered.


Asunto(s)
Desinfectantes/farmacología , Desinfección/métodos , Contaminación de Alimentos/prevención & control , Manipulación de Alimentos/métodos , Industria para Empaquetado de Carne/métodos , Animales , Bacterias/crecimiento & desarrollo , Bovinos , Recuento de Colonia Microbiana , Contaminación de Alimentos/análisis , Manipulación de Alimentos/normas , Microbiología de Alimentos , Humanos , Higiene , Carne/microbiología , Industria para Empaquetado de Carne/normas
3.
Int J Food Microbiol ; 124(3): 299-302, 2008 Jun 10.
Artículo en Inglés | MEDLINE | ID: mdl-18466991

RESUMEN

For better understanding of the complex behaviour of Escherichia coli at chiller temperatures, log phase E. coli grown at 15 degrees C were incubated at 8, 6, or 2 degrees C for 4 days, and were then incubated at 15 degrees C for 12 h. Cultures were sampled after incubation at the lower temperatures, and during subsequent incubation at 15 degrees C. Proteins extracted from the samples were separated by two-dimensional polyacrylamide gel electrophoresis (2D-PAGE). Spots of 45 previously identified proteins that were differentially expressed at 15 or < or =8 degrees C were quantified by image analysis. After incubation at 8 or 6 degrees C for 4 days cells were growing with or without formation of elongated cells (filaments), respectively, but growth did not occur at 2 degrees C. In cells incubated at 8 or 6 degrees C proteins associated with the stress response and energy generation were upregulated and proteins associated with protein synthesis were downregulated, while protein levels in cells incubated at 2 degrees C were little changed. When cells were then incubated at 15 degrees C, the levels of differentially expressed proteins in cells that had been incubated at 8 or 6 degrees C decreased or increased towards the levels found in cells growing at 15 degrees C, but some proteins were still under or over expressed after 12 h. In cells incubated at 15 degrees C after incubation at 2 degrees C, the levels of many of the proteins declined but the levels of proteins associated with protein synthesis increased. The findings indicate that the physiological states of log phase E. coli incubated at < or =2 degrees C or at higher chiller temperature are different, but that for both states incubation at an above chiller temperature for >3 generations is required before protein levels adjusted to those usual for the higher temperature. Cells in these different physiological states may respond differently to other stresses encountered during warming of chilled foods.


Asunto(s)
Proteínas de Escherichia coli/metabolismo , Escherichia coli/crecimiento & desarrollo , Escherichia coli/metabolismo , Contaminación de Alimentos/prevención & control , Conservación de Alimentos/métodos , Recuento de Colonia Microbiana , Seguridad de Productos para el Consumidor , Manipulación de Alimentos/métodos , Microbiología de Alimentos , Humanos , Temperatura , Factores de Tiempo
4.
Int J Food Microbiol ; 124(3): 291-4, 2008 Jun 10.
Artículo en Inglés | MEDLINE | ID: mdl-18450311

RESUMEN

Fifty samples were collected from each of skinned and dressed carcasses, from each of culled beef breeding cows and fed beef cattle <18 months old at two beef packing plants A and B, and from culled dairy cows at a packing plant C. The 450 samples were collected by swabbing an area of about 1000 cm2 in the anal region of each carcass. DNA extracted from each swab was tested for the IS900 and F57 sequences of the Mycobacterium avium subsp. paratuberculosis (MAP) genome by two stage, nested polymerase chain reaction (PCR) procedures. An internal amplification control (IAC) was detected in 45 or more of each group of 50 DNA preparations. IS900 and F57 were detected in some IAC-positive preparations from all and all but one of the groups of carcasses, respectively. Of the IAC-positive preparations in each group, between 6 and 54% were positive for IS900, and between 4 and 20% were positive for F57. When preparations were tested by single stage, quantitative PCR procedures, IS900 was detected in two samples but F57 was detected in none. The MAP DNA on carcasses was probably derived from small numbers of MAP from the environment that contaminated the animals' hides.


Asunto(s)
Bovinos/microbiología , ADN Bacteriano/química , Contaminación de Alimentos/análisis , Mycobacterium avium subsp. paratuberculosis/aislamiento & purificación , Animales , Secuencia de Bases , ADN Bacteriano/genética , Microbiología de Alimentos , Amplificación de Genes , Reacción en Cadena de la Polimerasa , Prevalencia , Reproducibilidad de los Resultados , Sensibilidad y Especificidad , Análisis de Secuencia de ADN , Especificidad de la Especie
5.
Meat Sci ; 79(1): 181-7, 2008 May.
Artículo en Inglés | MEDLINE | ID: mdl-22062611

RESUMEN

Eye of round primal cuts of beef were injected with brines containing a dye and Listeria innocua. The amounts of brine in portions of meat were determined from the concentrations of dye in the tissues, and the numbers of L. innocua in the tissues were determined from the numbers of colonies recovered on hydrophobic grid membrane filters incubated on a selective agar. Portions of meat from primals injected with brine after extensive mechanical tenderizing yielded L. innocua at numbers that would be expected from the amounts of brine in the meat. However, portions of meat from primals injected with brine without or before mechanical tenderizing yielded only about 10% of the expected numbers of L. innocua. The numbers of L. innocua recovered from injected meat that was not tenderized, relative to the amount of brine retained by the meat, declined with decreasing brine pressure and increasing strokes per minute of the needle head. When brine was injected at about 5% with low brine pressure and high head speed, the numbers of L. innocua retained in the meat were <1% of the expected numbers. When injected meat was examined microscopically, L. innocua were observed only between the muscle fibres in meat that was not tenderized before injection, but between fibres and in lacunae in tissue damaged by mechanical tenderizing before injection. The distributions of brine and bacteria in injected primals apparently did not alter substantially during storage in vacuum packs, at 2°C, for 2 weeks.

6.
Int J Food Microbiol ; 119(3): 200-6, 2007 Nov 01.
Artículo en Inglés | MEDLINE | ID: mdl-17719669

RESUMEN

The behaviours of cold-adapted, log-phase cultures of eight strains of Escherichia coli incubated at 2, 6, 8 and 10 degrees C for 10 days were examined by determining absorbance at 600 nm (A(600)), viable counts and cell size distribution as indicated by forward angle light scattering (FALS) values, obtained for samples collected each day from each culture. Cell lengths were determined from photomicrographs of samples for which the flow cytometry data indicated the mean cell lengths were maximal or minimal for each culture. At 2 degrees C, A(600) values for all strains and viable counts for some changed little, while viable counts for other strains declined progressively by >1 log unit. At 6 degrees C, A(600) values for most strains increased at progressively declining rates and then remained constant while viable counts increased to reach maximum values before maximum A(600) values were attained, and then declined. At 8 degrees C, the behaviours of most strains were similar to the behaviour at 6 degrees C. At 10 degrees C, seven of the strains grew exponentially, but for most of these the growth rate determined from A(600) values differed from that determined from viable count data. Mean FALS values for cultures incubated at 6, 8, or 10 degrees C showed various patterns of increase and decrease, indicating fluctuations in cell lengths. For all strains, the minimum cell length was <3 microm, but the maximum cell lengths ranged from <20 to >140 microm. The findings suggest that the formation of elongated cells or filaments is usual behaviour for E. coli growing at temperatures approaching or below the minimum for sustained growth.


Asunto(s)
Escherichia coli/citología , Escherichia coli/crecimiento & desarrollo , Modelos Biológicos , Recuento de Colonia Microbiana , Citometría de Flujo , Cinética , Viabilidad Microbiana , Temperatura
7.
Meat Sci ; 77(2): 149-60, 2007 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-22061585

RESUMEN

Large game animals and birds used for the commercial production of meat include deer of various species, wild boar and feral pigs, ostriches, emus and rheas, crocodiles and alligators, bison, and kangaroos. Meat from feral pigs and kangaroos is obtained from wild animals only, but much or most meat from the other game animals or birds is obtained from farmed animals. The microbiological conditions of meats from hunted animals can be compromised by poor placement of shots, the usual evisceration and sometimes further dressing of carcass in the field, and ageing of carcasses at ambient temperatures. However, the general microbiological conditions of carcasses from farmed game animals or birds slaughtered and dressed at suitable abattoirs can be comparable with or better than the microbiological conditions of carcasses from domestic animals or birds. The incidences of enteric pathogens on meat from wild or farmed game animals or birds can be less than those for meat from intensively reared domestic animals, but infection of some game meats with Trichinella or other foodborne parasites may occur.

8.
Int J Food Microbiol ; 110(2): 187-93, 2006 Jul 15.
Artículo en Inglés | MEDLINE | ID: mdl-16793158

RESUMEN

The log mean numbers of aerobes, coliforms, Escherichia coli and presumptive staphylococci plus listerias on chicken carcasses and carcass portions at various stages of processing at a poultry packing plant were estimated from the numbers of those bacteria recovered from groups of 25 randomly selected product units. The fractions of listerias in the presumptive staphylococci plus listerias groups of organisms were also estimated. Samples were obtained from carcasses by excising a strip of skin measuring approximately 5 x 2 cm(2) from a randomly selected site on each selected carcass, or by rinsing each selected carcass portion. The log mean numbers of aerobes, coliforms, E. coli and presumptive staphylococci plus listerias on carcasses after scalding at 58 degrees C and plucking were about 4.4, 2.5, 2.2 and 1.4 log cfu/cm(2), respectively. The numbers of bacteria on eviscerated carcasses were similar. After the series of operations for removing the crop, lungs, kidneys and neck, the numbers of aerobes were about 1 log unit less than on eviscerated carcasses, but the numbers of the other bacteria were not substantially reduced. After cooling in water, the numbers of coliforms and E. coli were about 1 log unit less and the numbers of presumptive staphylococci plus listerias were about 0.5 log unit less than the numbers on dressed carcasses, but the numbers of aerobes were not reduced. The numbers of aerobes were 1 log unit more on boneless breasts, and 0.5 log units more on skin-on thighs and breasts that had been tumbled with brine than on cooled carcasses; and presumptive staphylococci plus listerias were 0.5 log unit more on thighs than on cooled carcasses. Otherwise the numbers of bacteria on the product were not substantially affected by processing. Listerias were <20% of the presumptive staphylococci plus listerias group of organisms recovered from product at each point in the process except after breasts were tumbled with brine, when >40% of the organisms were listerias.


Asunto(s)
Contaminación de Alimentos/análisis , Manipulación de Alimentos/métodos , Microbiología de Alimentos , Industria de Procesamiento de Alimentos/métodos , Carne/microbiología , Animales , Bacterias Aerobias/aislamiento & purificación , Pollos , Recuento de Colonia Microbiana , Seguridad de Productos para el Consumidor , Enterobacteriaceae/aislamiento & purificación , Escherichia coli/aislamiento & purificación , Embalaje de Alimentos/métodos , Embalaje de Alimentos/normas , Industria de Procesamiento de Alimentos/normas , Humanos , Listeria/aislamiento & purificación , Staphylococcus/aislamiento & purificación , Temperatura
9.
Int J Food Microbiol ; 107(1): 12-9, 2006 Mar 01.
Artículo en Inglés | MEDLINE | ID: mdl-16256234

RESUMEN

Temperature is used to control the growth of microorganisms in foods. The minimum temperature for sustained growth of Escherichia coli is 7 degrees C. E. coli cells in the logarithmic phase of growth at 15 degrees C were incubated at 8, 6 or 2 degrees C. The cells grew with the formation of filaments at the two higher temperatures, but did not grow at 2 degrees C. In order to investigate more thoroughly the nature of filament formation in E. coli at temperatures near the minimum temperature for sustained growth, cells were harvested after 1 day at 2 degrees C or at times up to 4 or 8 days at 8 or 6 degrees C, respectively. Proteins extracted from the cells were separated by two-dimensional polyacrylamide gel electrophoresis (2D-PAGE), and spots containing differentially expressed proteins were identified by quadropole time-of-flight tandem (Q-ToF-2) mass spectrometry. For most of the identified proteins, the amounts were not substantially different in cells grown at 15 degrees C or incubated at 2 degrees C. In cells incubated at 8 or 6 degrees C, proteins associated with stress responses, the tricarboxylic acid cycle and electron transport were present in substantially greater amounts, and proteins associated with protein synthesis were present in substantially smaller amounts than in cells grown at 15 degrees C. These findings suggest that the stringent response is induced in E. coli incubated at temperatures near the minimum for growth, so the formation of filaments at those temperatures may be a result of the stringent response.


Asunto(s)
Frío , Proteínas de Escherichia coli/metabolismo , Escherichia coli/crecimiento & desarrollo , Escherichia coli/metabolismo , Microbiología de Alimentos , Electroforesis en Gel Bidimensional , Citometría de Flujo , Conservación de Alimentos/métodos , Espectrometría de Masas , Factores de Tiempo
10.
J Food Prot ; 69(12): 2837-42, 2006 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-17186647

RESUMEN

Records of Escherichia coli counts in samples routinely collected from carcasses were obtained from one pork and three beef packing plants. The data obtained from each plant were divided into sets from consecutive 6-month periods. For each set of counts, log total counts were calculated for subsets of various sizes. For each set of log total counts, the mean (x), the standard deviation (SD), and an action limit of x + 3 SD were calculated, and the set was tested for a normal distribution. With the data from samples collected at the pork packing plant during 6 years, the proportion of samples with counts of zero in the 12 sets ranged from 15 to 45%. For that plant, appropriate action limits could be derived from log total counts for subsets of nine unit values. With the data from samples collected during 8 years at one beef packing plant, the proportion of samples with counts of zero in the 16 sets ranged from 88 to 99%. For that plant, appropriate action limits could be derived from log total counts for subsets of 15 unit values. With the data from samples collected during 2 or 2.5 years at each of the other beef packing plants, the proportion of samples with counts of zero in all sets was > 99%. For those data, action limits could not be derived from values for subsets of log total counts.


Asunto(s)
Bovinos/microbiología , Escherichia coli/aislamiento & purificación , Contaminación de Alimentos/análisis , Embalaje de Alimentos/normas , Porcinos/microbiología , Animales , Recuento de Colonia Microbiana , Microbiología de Alimentos
11.
J Food Prot ; 79(2): 205-12, 2016 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-26818980

RESUMEN

Inactivation of Escherichia coli O157:H7 in beef roasts cooked under selected cooking conditions was evaluated. Eye of round roasts were each inoculated at five sites in the central plane with a five-strain cocktail of E. coli O157:H7 at ca. 6.3 log CFU per site and cooked to center temperatures of 56 to 71°C in a convection oven set at 120, 140, 180, or 200°C, in a conventional oven set at 120 or 210°C, and in a slow cooker set on high or low. Prime rib roasts were each inoculated at 10 sites throughout the roast with the same E. coli O157:H7 cocktail at ca. 6.6 log CFU per site and cooked in the conventional oven set at 140 or 180°C to center temperatures of 58 to 71°C. The number of sites yielding E. coli O157:H7 after cooking decreased with increasing roast center temperature for the eye of round roasts cooked in the convection oven or in the slow cooker at a given setting, but this trend was not apparent for roasts of either type cooked in the conventional oven. Reductions of E. coli O157 in both types of roasts were generally less at the center than at other locations, particularly locations closer to the surface of the meat. When eye of round roasts were cooked to the same center temperature in the convection oven, the reduction of E. coli O157:H7 increased with increasing oven temperature up to 180°C and decreased after that. The reduction of E. coli O157:H7 in replicate roasts cooked under conditions in which the organism was not eliminated during cooking mostly differed by >1 log CFU per site. However, E. coli O157:H7 was not recovered from any of the inoculation sites when eye of round roasts were cooked to 65, 60, 60, or 63°C in the convection oven set at 120, 140, 180, and 200°C, respectively; cooked to 63 or 71°C in the conventional oven set at 120 and 210°C, respectively; or cooked to 63°C in the slow cooker set at high or low. For prime rib roasts, E. coli O157:H7 was not recovered from any of the inoculation sites in roasts cooked to 71 or 58°C in the conventional oven set at 140 and 180°C, respectively.


Asunto(s)
Culinaria/métodos , Escherichia coli O157/aislamiento & purificación , Carne/microbiología , Animales , Bovinos , Recuento de Colonia Microbiana , Culinaria/instrumentación , Escherichia coli O157/clasificación , Escherichia coli O157/genética , Escherichia coli O157/crecimiento & desarrollo , Calor , Carne/análisis , Temperatura , Factores de Tiempo
12.
J Food Prot ; 68(4): 796-800, 2005 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-15830673

RESUMEN

Whole or halved top butt prime beef cuts were treated in two types of mechanical tenderizing machines that both pierced the meat with thin blades but that used blades of different forms. Aerobes on meat surfaces and in the deep tissues of cuts after treatments were counted. When cuts were treated at a laboratory using a Lumar machine, the contamination of deep tissues increased significantly (P < 0.01) with increasing numbers of aerobic bacteria on meat surfaces and decreased significantly (P < 0.001) with increasing distance from the incised surface. However, contamination did not increase significantly (P > 0.1) with repeated incising of the meat. When halved cuts were incised one or eight times using a commercially cleaned Ross machine at a retail store, the numbers of aerobes recovered from deep tissues were similar with both treatments. When halved cuts were treated in one or other machine, deep tissue contamination was greater with the Lumar machine than with the Ross machine. Contamination of deep tissues as a result of tenderizing by piercing with thin blades can be minimized if the blades are designed to limit the number of bacteria carried into the meat and the microbiological condition of incised surface is well controlled.


Asunto(s)
Bacterias Aerobias/aislamiento & purificación , Contaminación de Equipos , Contaminación de Alimentos/análisis , Manipulación de Alimentos/métodos , Carne/microbiología , Animales , Bacterias Aerobias/crecimiento & desarrollo , Bovinos , Recuento de Colonia Microbiana , Seguridad de Productos para el Consumidor , Microbiología de Alimentos , Industria de Procesamiento de Alimentos/normas , Higiene
13.
J Food Prot ; 68(12): 2718-20, 2005 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-16355849

RESUMEN

Groups of 25 skin-on thighs or skin-on, skinned, or tumbled breast portions of broiler chicken carcasses were sampled by excision of skin or muscle tissue, rinsing, or swabbing. Counts of total aerobic bacteria, coliforms, and Escherichia coli were recorded for each sample. For all types of carcass portions, the mean log counts and the total log counts obtained for each group of bacteria by excision or rinsing mostly differed by <0.5 log unit. However, the counts obtained by swabbing were generally >0.5 log unit lower than the smaller of the values obtained by the other two sampling methods.


Asunto(s)
Bacterias Aerobias/aislamiento & purificación , Pollos/microbiología , Enterobacteriaceae/aislamiento & purificación , Escherichia coli/aislamiento & purificación , Contaminación de Alimentos/análisis , Animales , Recuento de Colonia Microbiana , Seguridad de Productos para el Consumidor , Microbiología de Alimentos , Humanos
14.
Meat Sci ; 71(3): 506-13, 2005 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-22060926

RESUMEN

Most horse meat is consumed by humans and/or animals in the region where it is produced. However, horse meat for human consumption is exported in large quantities from the Americas and in lesser quantities from Eastern Europe, to Western Europe and Japan where it is often eaten raw. Horse meat prepared to a good hygienic condition should not be prone to early microbial spoilage, but contamination of the meat with Salmonella and Yersinia enterocolitica may be relatively common, and infection of the meat with Trichinella may occur occasionally. Those organisms from horse meat could cause disease when the raw meat is eaten. Moreover, accumulation of cadmium in horse liver and kidney may render those tissues unsafe for human consumption.

15.
Meat Sci ; 69(3): 501-7, 2005 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-22062989

RESUMEN

To obtain information about the microbiological quality of horse meat exported from North America, the microbiological conditions of hot or cold boned primal cuts and carcass quarters from horse carcasses processed at a North American packing plant were examined. In addition, temperature histories were obtained from boxes of hot boned meat during cooling, and from horse carcass quarters air freighted to Europe. The log mean numbers of aerobes recovered from horse carcasses after dressing were >2 logcfu/cm(2). Log total numbers of coliforms and Escherichia coli recovered from 25 samples from such carcasses were >2 log and <2 logcfu/2500 cm(2), respectively. Numbers of bacteria generally similar to those were recovered from cooled carcasses or hot or cold boned cuts. The cooling process for hot boned meat met with standards for hot boned beef cooling processes based on calculated growth of E. coli at box centres. The deep tissues of carcass quarters cooled and the temperatures of their surfaces rose during air freighting, but surface temperatures mostly remained below 7 °C. The microbiological condition of horse carcass quarters delivered to plants in Europe would likely be comparable with the microbiological conditions of hanging beef delivered from packing plants to distant customers within North America.

16.
Meat Sci ; 69(4): 811-6, 2005 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-22063161

RESUMEN

When striploins were mechanically tenderized at a beef packing plant, the log total numbers of aerobes, coliforms, staphylococci/listerias and Escherichia coli recovered from surfaces before or after tenderizing were about 2.8, 2.0, 0.6 and 0.3 log cfu 25 cm(-2), respectively. The numbers of those organisms recovered from the deep tissues of the tenderized meat were about 2.0, 1.5 and 1.2 log cfu 25 g(-1) and none, respectively. The aerobes recovered from the deep tissues were unexpectedly numerous in view of the small numbers of bacteria on meat surfaces. That suggests deep tissue contamination was affected by factors other than the numbers on meat surfaces. After cooking tenderized beef to medium rare or well done conditions, with maximum temperatures at steak centres of ⩽65.4 or ⩽73.4 °C, respectively, aerobes were recovered from only 2 of 25 samples cooked to each condition, at numbers of one or two per sample. This indicates that such cooking can ensure the microbiological safety of mechanically tenderized beef prepared under controlled conditions.

17.
Int J Food Microbiol ; 16(1): 51-62, 1992 May.
Artículo en Inglés | MEDLINE | ID: mdl-1389994

RESUMEN

Swab samples from the surfaces of carcasses and cuts were obtained at various stages of the dressing, chilling and cutting operations in three pig processing plants. The aerobic microflora obtained from those swabs were enumerated and characterized. The flora on the skins of carcasses exiting the scalding tanks were dominated by Gram-positive organisms, with numbers about 10(3)/cm2. After dehairing, numbers were about 10(4)/cm2 with major fractions of Gram-negative organisms. Flora numbers and compositions were largely unaltered after the singeing operations, but lesser numbers were recovered after the carcasses were polished. Carcass dressing did not change the numbers on the skin. During the chilling of carcasses, the flora at two large plants altered little, but drying of the carcass surfaces at a smaller plant reduced the Gram-negative fraction of the flora. Numbers on serous and fat surfaces exposed during the dressing and cutting of carcasses were initially about 10(2)/cm2. That number was approximately maintained on finished skinned cuts produced at the smaller plant, but further contamination with lactobacilli and Brochothrix thermosphacta occurred during cutting. At the larger plants, the flora on skinned cuts were similar to those on skins, although further contamination with B. thermosphacta occurred at one plant.


Asunto(s)
Bacterias/aislamiento & purificación , Contaminación de Alimentos , Manipulación de Alimentos/métodos , Carne/microbiología , Mataderos/normas , Animales , Bacterias/crecimiento & desarrollo , Manipulación de Alimentos/normas , Porcinos
18.
Int J Food Microbiol ; 51(2-3): 123-32, 1999 Oct 15.
Artículo en Inglés | MEDLINE | ID: mdl-10574088

RESUMEN

The hindquarters skinning operations in a commercial beef carcasses dressing process were modified, and for short trial periods reorganized for the purpose of reducing the numbers of bacteria deposited on the carcasses. During performance of modified or reorganized operations, samples were obtained from randomly selected carcasses, by swabbing specified sites related to opening cuts, rump skinning or flank skinning operations, randomly selected sites along the lines of the opening cuts, randomly selected sites on the skinned hindquarters of carcasses, or randomly selected sites on carcass sides leaving the dressing process. For each form of the hindquarters skinning operations, a set of 25 samples of each type was collected, with a single sample being obtained from each selected carcass or side. Aerobic counts, coliforms and Escherichia coli were enumerated in each sample, and a log mean value was estimated for each set of 25 counts on the assumption of a log normal distribution of the counts. The data indicated that the log numbers of total aerobes, coliforms and E. coli that were deposited on carcasses during the modified hindquarters skinning operations were generally about 0.5, 1.0 and 1.0 log unit less, respectively, than the log numbers that had been deposited on the carcasses during the unmodified operations. Reorganization of the modified operations gave further small but consistent reductions in the numbers of bacteria. It, therefore, appears that changes to dressing procedures which are guided by appropriate microbiological data can produce consistent reductions in the microbiological contamination of carcasses.


Asunto(s)
Manipulación de Alimentos/métodos , Microbiología de Alimentos , Productos de la Carne/microbiología , Animales , Bovinos , Recuento de Colonia Microbiana
19.
Int J Food Microbiol ; 74(1-2): 111-8, 2002 Mar 25.
Artículo en Inglés | MEDLINE | ID: mdl-11929165

RESUMEN

Manufacturing beef was pasteurized by immersion in water of 85 degrees C for 60 s, or was not pasteurized before being coarsely ground. The coarsely ground beef was vacuum-packaged and stored at 2 degrees C for up to 6 weeks. Before storage and at weekly intervals, three packs of pasteurized and three of unpasteurized beef were opened. The meat from each pack was finely ground and displayed in two overwrapped packs at 4 degrees C for 3 days after storage for up to 3 weeks, or for 2 days after longer storage times. Samples for microbiological analysis were obtained at the times of preparation of display packs and at the end of display. Displayed meat was assessed daily for colour, discolouration and retail acceptability, and for odour intensity and acceptability at the end of display. Before storage, the numbers of total aerobic bacteria, presumptive pseudomonads and presumptive Brochothrix thermosphacta recovered from pasteurized meat were >1 log unit less than the corresponding numbers recovered from unpasteurized meat, but the numbers of presumptive lactic acid bacteria and presumptive enterobacteria were <1 log unit less from pasteurized than from unpasteurized meat. After all periods of storage and display, the numbers of bacteria recovered from pasteurized and unpasteurized meat at each time were mostly similar. The colour of pasteurized meat was perceived as being paler than that of unpasteurized meat, but discolouration and retail acceptability of pasteurized and unpasteurized meat were perceived as similar at most times. The odours of displayed, pasteurized and unpasteurized meat were perceived to be similar at all times that odours were assessed. The findings indicate that pasteurizing of manufacturing beef to improve the microbiological safety of ground beef would not unacceptability degrade the appearance of the ground product, but that the storage life of ground beef would not be greatly extended by the treatment.


Asunto(s)
Bacterias/crecimiento & desarrollo , Manipulación de Alimentos/métodos , Embalaje de Alimentos/métodos , Productos de la Carne/microbiología , Animales , Bovinos , Color , Comportamiento del Consumidor , Seguridad de Productos para el Consumidor , Microbiología de Alimentos , Productos de la Carne/normas , Refrigeración , Gusto , Temperatura , Factores de Tiempo , Resultado del Tratamiento , Vacio
20.
Int J Food Microbiol ; 97(2): 171-8, 2004 Dec 15.
Artículo en Inglés | MEDLINE | ID: mdl-15541803

RESUMEN

Microbiological samples were obtained by swabbing detained and routinely processed pig carcasses before and after cooling, and sides, loin portions and loin cuts at various stages of the carcass breaking process. Aerobes, coliforms and Escherichia coli were enumerated in each sample. All three groups of bacteria were more numerous on detained than on routinely processed carcasses. Both trimming and cooling reduced the numbers of E. coli but not the numbers of aerobes on detained carcasses. After cooling, the log mean number of aerobes and E. coli on detained carcasses were each about 0.5 log unit more than the log mean numbers on routinely processed carcasses, but numbers of coliforms on the two types of carcass were similar. There were small increases in the numbers of coliforms and E. coli on carcasses during their movement from the cooler to the breaking facility. The numbers of bacteria on the meat apparently did not increase during the carcass-breaking process, although bacteria were redistributed on the product. Despite that, substantial numbers of bacteria were recovered from parts that do not contact food in cleaned conveying equipment used for carcass breaking. However, those bacteria included few coliforms and no E. coli. These findings suggest that the contamination of meat with E. coli from persistent detritus in carcass breaking equipment, such as has been found to occur at beef packing plants, may be prevented when carcass-breaking equipment and facilities are dried after cleaning, and wetting of equipment during processing is avoided.


Asunto(s)
Contaminación de Equipos , Manipulación de Alimentos/métodos , Industria de Procesamiento de Alimentos/normas , Carne/microbiología , Animales , Bacterias Aerobias/crecimiento & desarrollo , Bacterias Aerobias/aislamiento & purificación , Recuento de Colonia Microbiana , Enterobacteriaceae/crecimiento & desarrollo , Enterobacteriaceae/aislamiento & purificación , Contaminación de Equipos/prevención & control , Escherichia coli/crecimiento & desarrollo , Escherichia coli/aislamiento & purificación , Embalaje de Alimentos/métodos , Industria de Procesamiento de Alimentos/métodos , Porcinos
SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA