摘要:

ABSTRACTPrecooked homogenized crawfish tail meat was inoculated withListeria monocytogenes,treated with lactic acid, and packaged in various atmospheres for D value determinations at 60C. D60values using 0.0, 0.5, 0.75, and 1.0% lactic acid (LA) treated meat were 4.68, 4.41, 3.46, and 2.49 min, respectively. LA increased sensitivity ofL. monocytogenesto heat but this was not solely due to a reduction of pH. Sensory analyses of odor, color, taste, and texture of uninoculated whole crawfish tail meat demonstrated no significant differences (P>0.05) between LA treated samples and controls. D60values for the bacterium in crawfish tail meat homogenate packed in air, O2, CO2, or N2were 10.58, 9.22, 11.68, or 12.97 min, respectively, which were not significantly different (P>0.05). When 1% LA was added, significant decreases (P0.05) D60values for crawfish tail meat treated with 1% LA and packed in air, O2, CO2, or N2were 3.44, 3.88, 3.48, or 3.08, respectively. These results show that heat treatments of 60C were lethal toL. monocytogenesin packaged crawfish tail meat homogenate regardless of package atmosphere. Additionally, LA increased the lethality of heat to the bacterium in all tested package atmospheres.

ISSN:0149-6085    

DOI:10.1111/j.1745-4565.1995.tb00116.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

ABSTRACTThe use of DNA probes for rapid identification of foodborne pathogens is an emerging field. We have standardized a method for the detection ofSalmonellain food samples by using a specific insertion sequence (IS‐200) ofSalmonellachromosomal DNA as the probe. The procedure for colony hybridization, and washing conditions for the stringency were established. All the tenSalmonellastrains, belonging to various serotypes tested were positive while 18 other bacterial cultures, mainly belonging to the family Enterobacteriaceae such as E. coliShigella, Proteusetc., were negative in colony hybridization. The sensitivity of the detection was found to be 105cfu using32P‐labeled probe. We surveyed 16 chicken and 6 fish samples from local market using IS‐200 probe after preenrichment and selective enrichment. All the samples tested were found positive with DNA probe. The major strains ofSalmonellaisolated from these samples wereS. gallinarum, S. typhimurium, S. enteritidis, S. choleraesuisandS. paratyphiA. These results were confirmed by standardSalmonellaidentification m

ISSN:0149-6085    

DOI:10.1111/j.1745-4565.1995.tb00117.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

ABSTRACTClostridium perfringensgrowth from a spore inoculum was investigated in vacuum‐packaged, cook‐in‐bag ground beef that included 0.3% (w/w) sodium pyrophosphate, pH 5.5 or 7.0, and salt (sodium chloride) at 0 or 3% (w/w). The packages were processed to an internal temperature of 71.1C, ice chilled and stored at various temperatures. The total C. perfringens population was determined by plating diluted samples on tryptose‐sulfite‐cycloserine agar followed by anaerobic incubation for 48 h at 37C. At 28C, a combination of 3% salt and pH 5.5 was effective in delaying growth for 24 h. At 15C, growth occurred within 6 days in samples with pH 7.0, but was delayed until day 8 in the presence of 3% salt at pH 7.0. Vegetative cells were not observed even after 21 days 21 of storage at 15C in the presence 3% salt at pH 5.5. C. perfringensgrowth was not observed at 4C regardless of pH or salt levels. The D‐values ranged from 23.33 min (3% salt, pH 7.0) to 13.99 min (3% salt, pH 5.5). Cyclic and static temperature abuse of refrigerated products for 12–15 h did not permitC. perfringensgrowth. However, temperature abuse of cook‐in‐bag beef products for periods longer than 15 h in the absence of salt led to growth ofC. perfringensfrom

ISSN:0149-6085    

DOI:10.1111/j.1745-4565.1995.tb00118.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

ABSTRACTThe effect of modified atmosphere packaging (MAP) (70% CO2/30% N2; 30% CO2/70% N2) on the shelf‐life of fresh chicken carcasses stored at 2, 4, 7 and 9C was investigated. The shelf‐lives of MAP carcasses (70% CO2/30%N2) stored at 2, 4, 7 and 9C were 25, 21, 12 and 8 days, respectively compared with 7 days for air‐packaged ones stored at 4C; the shelf‐life of MAP carcasses (30% CO2/70%N2) stored at the same temperatures were 20, 15, 8 and 8 days, respectively. The inhibitory effect of MAP on the growth of Enterobacteriaceae and on the production of spoilage metabolites, such as free fatty acids and extract release volume, was negligible at higher temperatures (7 and 9C) and more pronounced at lower temperatures (2 and 4C), especially at higher concentrations of CO2(70% CO2/30% N2). The occurrence and growth of organisms such asEscherichia coli,coliforms, Staphylococcus aureus, SalmonellaandCampylobacterin carcasses stored at different temperatures were also doc

ISSN:0149-6085    

DOI:10.1111/j.1745-4565.1995.tb00119.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

ABSTRACTSeveral organic acids or salts approved as food additives enhance the inactivation of foodborne pathogens such asListeria monocytogenes.Although there has been research on the effects of individual organic acids on the inactivation kinetics ofL. monocytogenes,little information exists on their activity when used in combination with other food additives. We undertook to characterize the effects of combinations of 90% sodium acetate or sodium propionate, two salts that inhibitL. monocytogenes,with 8% EDTA (disodium salt) and 2% ascorbic acid on the nonthermal inactivation of a three‐strain mixture ofL. monocytogenes.Activity was assessed in Brain Heart Infusion broth (BHI) at various concentrations (0.0–2.0% w/v), pH values (3.0–4.5) and temperatures (4–28C). Samples were removed periodically for up to 175 days and viable counts determined. Survivor curves were generated using a logistics‐based inactivation model and used to calculate “time to a 4‐D (99.99%) inactivation”(t4‐D).The rate of inactivation was directly related to concentration of the acid mixture and temperature of incubation and inversely related to pH. The primary factor effecting inactivation rates was pH, followed by the concentration of the undissociated form of the primary organic acid (acetic or propionic). Evaluation of the mixture components individually and in combination indicated the components acted largely in an additive manner. The results indicate that combinations of primary and secondary organic acids and EDTA may have advantages for enhancing the inactivation ofL. monocytogenesin refrigerated, mildly acidic foods, while avoiding organoleptic effects associated with excessive level

ISSN:0149-6085    

DOI:10.1111/j.1745-4565.1995.tb00120.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

ABSTRACTThe effects of chlorine against 2 strains ofE. coliattached to the surface of beef carcass tissue (BCT) were examined using a model carcass washer. Lean and adipose BCT with approximately 5 log10CFU/cm2E. colibacteria were spray‐treated with water and sodium hypochlorite (NaOCl) to give chlorine concentrations of 50, 100, 250, 500, or 800ppm, incubated for 24 h, 4C, andE. colipopulations enumerated. Spray treatments with water did significantly (P<0.05) reduce the bacterial populations of either organism attached to lean or adipose BCT, as compared to populations of controls; however, reductions were less than 0.60 log10CFU/cm2.Treatments with 500 and 800 ppm chlorine againstE. coliATCC 25922 attached to BCT resulted in the greatest reductions of 1.22 and 1.28 log10CFU/cm2,respectively. At 800 ppm chlorine, E. coliO157:H7 ATCC 43895 attached to BCT was reduced by 1.04 log10CFU/cm2,whereas spray treatments with 50, 100, 250, and 500 ppm chlorine resulted in reductions of<1 log10CFU/cm2.Spray treatments with chlorine from sodium hypochlorite solutions reduced populations ofE. coli,however, these reductions were not sufficient to completely inactivate the bacteria attached to red mea

ISSN:0149-6085    

DOI:10.1111/j.1745-4565.1995.tb00121.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

ABSTRACTPolyphosphates are multifunctional ingredients added to many foods, particularly meat products. In addition to their moisture‐binding properties, polyphosphates have been reported to inhibit various bacteria. In the current study, four food‐grade polyphosphates were evaluated for their effects on the growth ofAeromonas hydrophilaK144 in both a model system and a food system. Since polyphosphates can interact with other food factors, effect of these compounds were studied at different NaCl levels and temperatures. The model system was BHI Broth modified by the addition of polyphosphates (sodium pyrophosphate, sodium tripolyphosphate, Hexaphos, or Sodaphos) and NaCl; incubation was aerobic at 5 or 28C. The food system was ground pork with NaCl and polyphosphate added and inoculated withA. hydrophila.Individually, the polyphosphates were relatively noninhibitory in both BHI broth and ground pork, but NaCl and temperature interacted with the polyphosphates in the model system to increase generation and lag times ofA. hydrophila.In BHI broth, a combination of 2% of any of the polyphosphates tested and 3.5% NaCl inactivated the bacterium; this inactivation was temperature‐dependent. By both a plating system and electron microscopy, the polyphosphate‐NaCl combination was shown to injure the bacterium. In the ground pork, the polyphosphate‐NaCl combination limited growth of the bacterium during refrigerated storage. These results suggest that polyphosphates could be useful to control the presence ofA. hydrophilain cert

ISSN:0149-6085    

DOI:10.1111/j.1745-4565.1995.tb00122.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

ISSN:0149-6085    

DOI:10.1111/j.1745-4565.1995.tb00123.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY