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1.
《Food Control》2007,18(5):441-447
Pasteurized milk was inoculated with two strains of Staphylococcus aureus (CECT4013 or ATCC13565) and used to elaborate soft-curd cheeses with approximately 7.5-log CFU/g of S. aureus. Cheeses were submitted to 10 min high hydrostatic pressure (HHP) treatments of 300, 400 or 500 MPa at 5 °C or 20 °C. Staphylococcus enterotoxin (SE) was evaluated in cheeses containing ATCC13565. Counts of S. aureus were measured after HHP treatment (day 1) and after 2, 15 and 30 days ripening at 8 °C. Inactivation increased with pressure and storage time, but was similar for both treatment temperatures. Maximum S. aureus reductions were achieved after 30 days ripening for samples treated at 500 MPa and 5 °C: 6.0 ± 0.1 and 4.7 ± 0.5-log CFU/g for CECT4013 and ATCC13565, respectively. However, SE was detected in all cheese samples containing ATCC13565 before and after HHP and after 30 days ripening.  相似文献   

2.
《Food Control》2007,18(11):1383-1390
Shredded carrots were inoculated with Escherichia coli O157:H7, Salmonella or Listeria monocytogenes and washed for 1 or 2 min with chlorine (Cl; 200 ppm), peroxyacetic acid (PA; 40 ppm) or acidified sodium chlorite (ASC; 100, 200, 500 ppm) under simulated commercial processing conditions. After washed, the carrots were spin dried, packaged and stored at 5 °C for up to 10 days. Bacterial enumeration was significantly (P  0.05) reduced by 1, 1.5 and 2.5 log CFU/g after washing with ASC 100, 250 and 500 ppm, respectively. All sanitizers reduced pathogen load below that of tap water wash and unwashed controls. During storage at 5 °C the bacterial load of all treatments increased gradually, but to different extent in different treatments. ASC inhibited bacterial growth more effectively than the other sanitizers and also maintained the lowest pathogen counts (<1 log CFU/g) during storage. Organic matter in the process water significantly (P  0.05) reduced the antibacterial efficacy of Cl, but not that of PA or ASC. Therefore, ASC shows the potential to be used as a commercial sanitizer for washing shredded carrots.  相似文献   

3.
《Food Control》2007,18(7):878-884
Nisin, a bacteriocin, was immobilized into palmitoylated alginate-based films or in activated alginate beads. Sterile beef muscle slices or ground beef were inoculated with Staphylococcus aureus at a level of 104 CFU/g. Sliced beef was then coated with palmitoylated alginate-based films containing 0, 500 or 1000 IU/mL of nisin. Also, ground beef was mixed with 0, 500 or 1000 IU/mL of nisin covalently linked to activated alginate beads in order to evaluate the effect of nisin concentration on S. aureus level. The content of S. aureus in beef was determined during storage at 4 °C. Results demonstrated that after 7 days of storage, a reduction of 0.91 and 1.86 log CFU/cm2 was observed on sliced beef covered with film containing 500 or 1000 IU/mL of nisin, respectively. After 14 days of storage, when nisin solution (500 or 1000 IU/g) was mixed with ground beef, 2.2 and 2.81 log CFU/g reductions of S. aureus counts were respectively observed. However, when nisin (500 or 1000 IU/g) was linked into activated alginate beads, 1.77 and 1.93 log CFU/g reductions of S. aureus counts were respectively observed (P  0.05). These results suggest that sterile, hydrophobic and biodegradable films or beads incorporating various amounts of nisin could be used efficiently to control the growth of pathogens or microorganisms responsible of spoilage at the surface of round beef or other meat products.  相似文献   

4.
《Food Control》2007,18(9):1121-1125
The effects of polylactic acid (PLA) based biodegradable film packaging on the microbial and physicochemical quality of green peppers (Capsicum annuum L.) were compared to the effects of low-density polyethylene (LDPE) film packaging, and perforated LDPE film packaging. Each package containing green peppers was heat-sealed and stored for 7 days at 10 °C. The microbial levels (aerobic bacteria, coliform bacteria, and yeast and moulds) and physicochemical properties such as colour, weight loss, hardness, ascorbic acid concentration, O2 and CO2 concentrations, were monitored during storage. Results indicated that the physicochemical properties of colour, hardness, ascorbic acid concentration, and microbial levels (total aerobic bacteria, and moulds and yeasts) did not show remarkable changes during storage period. The microbial levels in coliform bacteria were increased by less than 1 log CFU/g (0.2 log CFU/g) in the biodegradable film packaging, 2.3 log CFU/g in LDPE film package, and less than 1 log CFU/g (0.9 log CFU/g) in the perforated LDPE film package, after 7 days storage period. The results suggest that the biodegradable film with higher water vapor permeability can be used to maintain the quality and sanitary conditions (protection from microbial and insect contamination) of freshly harvested green peppers in modified atmosphere packaging.  相似文献   

5.
《Food Control》2006,17(2):102-107
The ability of Listeria monocytogenes to survive and grow at refrigeration temperature in some ready to eat (RTE) poultry products is a public health concern. The inhibitory effect of clove oil (1% and 2%, v/w) applied to the surface of RTE chicken frankfurters was determined on seven strains of L. monocytogenes inoculated at low (102–103 cfu/g) or high cell numbers (104–106 cfu/g), and stored at 5 °C for 2 weeks or at 15 °C for 1 week. All strains of L. monocytogenes survived and grew on control frankfurters at 5 °C and 15 °C but growth was inhibited under both storage conditions in the presence of either 1% or 2% clove oil. Depending on the sensory considerations, the addition of clove oil to frankfurters may be an effective strategy to control L. monocytogenes in chicken frankfurters.  相似文献   

6.
《Food Control》2010,21(8):1081-1086
The effects of isothiocyanates (ITCs) on microbiological, physicochemical, and sensory properties were investigated in tofu on days 0, 2, 4, 6, 8, and 10 of storage at 10 °C. When compared to the control (8.14 log CFU/g), the 200 ppm of ITCs (4.40 log CFU/g) effectively retarded the growth of microflora in tofu after 10 days of storage. The initial pH slightly declined after 10 days of storage, ranging between 5.81 and 6.14. The control showed significantly higher acid values over storage. Compared to the control, the preference to sensory attributes (color, taste, odor, chewiness, and over acceptance) of ITC-treated samples was highly rated after 10 days of storage. The ITCs can be used as an alternative for extending the shelf life and improving the safety of tofu.  相似文献   

7.
《Food Control》2007,18(2):108-112
The effect of gamma irradiation for inactivating the pathogens inoculated into the ready-to-eat Kimbab, steamed rice rolled by dried laver, was investigated. The pathogens used were Salmonella Typhimurium, Escherichia coli, Staphylococcus aureus and Listeria ivanovii which are important for public health. The growth of four test organisms inoculated (about 106–107 CFU/g) into the Kimbab were sustained by an irradiation treatment during 24 h of storage regardless of the temperature at 10, 20 and 30 °C. Four pathogen inoculated into Kimbab decreased 2–3 log CFU/g by 1 kGy treatment and was not detected after 3 kGy. The D10 value of pathogens inoculated into the Kimbab were 0.31–0.44 kGy among the four organisms. This study indicated that a low dose irradiation can maintain microbial safety for ready-to-eat Kimbab, steamed rice rolled by dried laver.  相似文献   

8.
Antimicrobial packaging with lactic acid bacteria incorporated into the film matrix is a novel approach for controlling the growth of food-borne pathogens in ready-to-eat food. The overall objective of this study was to assess the effect of two strains of lactic acid bacteria (LAB) and nisin trapped in an alginate matrix, on Listeria monocytogenes growth on vacuum packed cold-smoked salmon. A film was formulated containing two LAB strains and nisin (100 IU/mL). LAB viability and bacteriocin like substance production (BLS) were assessed using the plate antagonism technique. To check the film antagonistic activity, pieces of salmon (4.0 × 4.0 cm2), inoculated with L. monocytogenes at a final concentration of 104 CFU/cm2, were covered with film containing both LAB strains plus nisin and stored at 4 °C. L. monocytogenes colonies on OXA agar were counted after 0, 7, 14, 21 and 28 days to evaluate pathogen inhibition. All treatments led to effective diffusion of the BLS that inhibited L. monocytogenes for 20 days after film preparation, with inhibition zones of 5.7 cm2 for film coupons of 8 mm in diameter. After 28 days, salmon pieces covered with the film without inhibitors showed an increase of 2.4 log cycles in L. monocytogenes growth. In contrast, films with either LAB strain or a combination of both strains and nisin had a bacteriostatic effect on the pathogen over a period of 28 days, which exceeds the industrial standard shelf life for smoked salmon. The results demonstrate that these films inhibit L. monocytogenes growth on salmon during refrigerated storage.  相似文献   

9.
The effect of storage temperature abuse on the growth and physiology of Bacillus cereus in cooked rice was examined using plate counting and flow cytometry (FCM). Concurrently, toxigenic potential was measured through recording phosphatidylcholine-specific phospholipase C (PC-PLC) activity. Rice spiked with endospores was incubated at 4 °C, 10 °C or 18 °C for 6 days. Growth was not recorded at 4 °C, whereas >1.0 × 106 CFU g?1 were detected at 10 °C and 18 °C. PC-PLC activity was temperature dependent and was not destroyed by microwaving. FCM population profiling complemented plate count data, providing novel physiological data e.g. on the membrane integrity, redox or intracellular activities of cells over time during low temperature incubation.  相似文献   

10.
《Food Control》2007,18(9):1043-1049
The effects of different concentrations of Zataria multiflora Boiss. essential oil (EO, 0.0%, 0.005%, 0.015%, 0.03% and 0.045%) and nisin (N, 0.0, 0.25, 0.5, 1.5 and 2.5 μg ml−1), pH values (7.4, 6.5 and 6.0), temperatures (Ts, 10, 20 and 30 °C) and storage times (Ds, up to 43 days) on log10 probability percentage of growth initiation (log P%) of one vegetative cell of Bacillus cereus in brain heart infusion broth were evaluated in a factorial design study. The log P% of the organism was significantly affected (P < 0.01) by the values of EO, N, pH, T and D.The combinations of T  20 °C, EO  0.03% and pH values (7.4, 6.5 and 6.0) could not obviously affect the growth of the organism in this study. Whereas, the strong inhibitory action was observed by increasing EO concentration to 0.045 at T  20 °C and selected pH values (7.4, 6.5 and 6.0) and by decreasing temperature to 10 °C at EO  0.015% and pH values used in this study. The inhibitory effect of N also was enhanced by decreasing storage temperature to 10 °C at the selected pH values (7.4, 6.5 and 6.0) in this study.The growth of the organisms was strongly affected by increasing EO concentration to 0.03% in combination with N concentrations used at the selected temperatures in this study. The growth of the organism was completely inhibited at combinations EO  0.015%, N  1.5 μg ml−1, T  30 °C and pH  7.4 during 43 days of storage in this study. This synergistic effect of EO and N was enhanced in lower pH values (6.5 and 6.0) in the present study. The growth of organism was completely inhibited at combinations of EO  0.005 and N  1.5 μg ml−1 at pH = 6.0, and EO  0.03 and N  0.5 μg ml−1 at pH  6.5 during the study at the selected Ts (30, 20 and 10 °C).  相似文献   

11.
《Food Control》2006,17(8):609-616
This study was conducted to evaluate the efficacy of gaseous ozone exposure on Listeria innocua 2030c growth during cold-smoke processing of Oncorhynchus mykiss (salmon-trout). Three sets of experiments were performed: inoculation with L. innocua 2030c followed by a 20 min ozone exposure were applied to (a) fresh salmon-trout after filleting, (b) to fresh whole fish, and (c) to fresh whole fish after removal of the fish slime. In sets (a) and (b) fillets were subsequently cold-smoked but not in set (c). The ozone concentration inside the exposure chamber after 20 min reached 0.1 × 10−3 g/l.Counts of L. innocua 2030c were performed after treatment for sets (a), (b) and (c), after smoking and weekly during 21 days in vacuum packs at 5 °C, for sets (a) and (b). Sampling for total Aerobic Plate Counts (APC) of non-inoculated samples was also performed in set (a). The percentage of salt in the water phase, peroxide values and the effect of treatment on sensory properties of cold-smoked salmon-trout fillets were also determined in the first and second set. In the first set, a decrease of less than 1 log10 in L. innocua numbers occurred on ozone treated samples in all sampling occasions. APC was slightly lower on fresh fillets after treatment and on smoked fillets at 3 weeks of storage at 5 °C (less than 1 log10 CFU/g). In the second set, a reduction greater than 1 log10 L. innocua/g occurred on smoked fillets at the end of the storage period. In the third set, the slime removal resulted in a 1 log10 L. innocua/g reduction on fresh treated samples.Ozone treatment had no significant (p > 0.05) effect on L. innocua counts on samples compared to those on untreated fish. In both sets, no significant differences among ozone treated/untreated samples were noticeable by sensory evaluation (p > 0.05).  相似文献   

12.
《Food Control》2010,21(4):478-486
Enterocin AS-48 was tested alone or in combination with chemical preservatives and/or heat against Listeria monocytogenes and Staphylococcus aureus in a cooked ham model system. AS-48 (20, 40 and 60 μg g−1) alone was active against L. monocytogenes at 5 and 15 °C, but it was not sufficient to avoid regrowth of Listeria during the 60 days storage. Combination of AS-48 (40 μg g−1) with nitrite/nitrate, pentasodium tripolyphosphate, sodium benzoate or potassium sorbate improved the anti-listeria effect during storage at 5 °C. The most effective combination was AS-48-nitrite/nitrate (0.007%) that reduced listeria below detection level from the beginning to end of storage. Although much more resistant, S. aureus was also inhibited by AS-48 alone at 5 °C, and especially in combinations with nitrite/nitrate, pentasodium tripolyphosphate, sodium lactate and sodium acetate. Best results against both pathogens were obtained when sodium pyrophosphate was applied in combination with 60 μg g−1 AS-48. Sub-lethal heat (60 °C, 2 min) clearly increased AS-48 activity against both Listeria and Staphylococcus.  相似文献   

13.
《Food Control》2007,18(10):1282-1288
The objective of this work was to evaluate the inactivation induced by ultra high pressure homogenisation (UHPH) of Staphylococcus aureus ATCC 13565 and Staphylococcus carnosus CECT 4491 inoculated into milk and orange juice considering the effect of inlet temperature of the sample (6 and 20 °C) on the lethality values and on the production of sublethal injuries. Samples of UHT whole milk and UHT orange juice were inoculated at a concentration of approximately 7.0 log (CFU/ml) and pressurized with a dual valve UHPH machine at 300 MPa at the primary homogenising valve and at 30 MPa on the secondary valve. Viable and injured bacterial counts were measured 2 h after UHPH treatment and after 3, 6, and 9 days of storage at 4 °C for milk, and after 3, 6, 9, 12, and 15 days of storage at 4 °C for orange juice. The inlet temperature, the food matrix and the kind of strain influenced significantly (P < 0.05) the lethality level, which was higher for S. aureus in whole milk at an inlet temperature of 20 °C. No sublethal injuries were detected after treatments. The change over time of viable counts for both strains showed a very strong decreasing tendency during the storage at 4 °C for orange juice, while the strain S. carnosus showed a low decreasing tendency and greater resistance when inoculated in milk and pressurized at 6 °C.  相似文献   

14.
Since the 1980s, an increase in outbreaks of human listeriosis linked to contaminated food has been a concern of health authorities. Intensively manipulated foods, such as Brazilian fresh sausage, are frequently responsible for food-borne diseases. In this work the occurrence of Listeria monocytogenes and the efficacy of bacteriophage P100 (LISTEX?) to control the microorganism was evaluated in Brazilian fresh sausage. Eighty samples were analyzed, 40 each of swine and chicken Brazilian fresh sausage. Listeria spp. were isolated from 12 samples (15%), of which three (3.75%) were positive for L. monocytogenes. L. monocytogenes strains isolated belonged to serotype 1/2a. L. monocytogenes 1/2a was inoculated in Brazilian fresh sausage (2.1 × 104 cfu/g) with the bacteriophage added thereafter (3.0 × 107 pfu/g). Samples were analysed immediately (day zero) and then stored at 4 °C for 10 days. The bacteriophage P100 reduced L. monocytogenes counts by 2.5 log units at both 0 and 10 days compared to controls without bacteriophage. In spite of this, the populations of L. moncytogenes increased over the 10 day storage. Our data demonstrate that in one of the samples the use of the bacteriophage dropped the bacteria count below the level of direct detection. This study demonstrates a new alternative for pathogen control in the food industry, especially in the processes used to produce Brazilian fresh sausage.  相似文献   

15.
《Food Control》2007,18(4):287-291
Cryptococcus laurentii was evaluated for its activity in reducing postharvest gray mold decay, blue mold decay and Rhizopus decay of peach caused by Botrytis cinerea, Penicillium expansum and Rhizopus stolonifer respectively, and in reducing natural decay development of peach fruits. The concentrations of antagonist had significant effects on biocontrol effectiveness: the higher the concentrations of the antagonist, the lower the disease incidence. At concentrations of C. laurentii at 1 × 109 CFU ml−1, the gray mold decay was completely inhibited after 4 days incubation at 25 °C, while the control fruit had 50% decay, when inoculated with B. cinerea spores suspension of 1 × 105 spores ml−1; no complete control of the blue mold or Rhizopus mold was observed, when peach fruits were stored at 25 °C for 4 days (challenged with P. expansum) or 5 days (challenged with R. stolonifer) respectively, but the decay was distinctly prevented, the incidence of blue mold or Rhizopus mold was reduced by 78.6% or 80% respectively, compared with control, at challenged with P. expansum or R. stolonifer spores suspension of 5 × 104 spores ml−1, respectively. C. laurentii significantly reduced the natural development of decay and did not impair quality parameters of fruit following storage at 2 °C for 30 days followed by 20 °C for 7 days.  相似文献   

16.
《Food Control》2007,18(1):5-10
The radiation pasteurization process was performed to improve the microbiological quality of fresh vegetable juice. Carrot and kale juice were irradiated and their microbiological, nutritional, and sensory properties were evaluated. The contaminating bacteria in the juices before irradiation ranged from 106 to 107 CFU/ml. All the aerobic and coliform bacteria in the carrot juice were eliminated by irradiation at a dose of 3 kGy, whereas about 102 CFU/ml of the bacteria survived in the kale juice irradiated at up to 5 kGy. However, the cells that survived from irradiation in the kale juice did not grow, whereas those of the non-irradiated samples reached 109 CFU/ml after 3 days of storage at 10 °C. Amino acids were stable at up to 5 kGy of an irradiation. Radiation resulted in a dose-dependent reduction of the ascorbic acid content. However, the contents of the total ascorbic acid, including dehydroascorbic acid, were stable at up to 3 kGy of an irradiation. The sensory evaluation results immediately after irradiation were not different in any of the samples. At a 3-day storage, the sensory quality of the irradiated juice was adequate, while the quality of the non-irradiated control was deteriorated.  相似文献   

17.
This study evaluated the effectiveness of a supercritical carbon dioxide (SCCO2) system, with a gas–liquid porous metal contactor, for reducing Escherichia coli K12 in diluted buffered peptone water. 0.1% (w/v) buffered peptone water inoculated with E. coli K12 was processed using the SCCO2 system at CO2 concentrations of 3.1–9.5 wt%, outlet temperatures of 34, 38, and 42 °C, a system pressure of 7.6 MPa, and a flow rate of 1 L/min. Increased CO2 concentrations and temperatures significantly (P < 0.05) enhanced microbial reduction. A maximum reduction of 5.8-log was obtained at 8.2% CO2 and 42 °C. To achieve a 5-log reduction of E. coli K12 in 0.1% buffered peptone water, minimum CO2 concentrations of 9.5%, 5.5%, and 5.3% were needed at 34, 38, and 42 °C, respectively. Further reductions of cells were observed after storage for 7 days at 4 °C. But storage at 25 °C increased the number of viable cells to 8-log cfu/mL after 7 days. This study showed the potential of the pilot scale SCCO2 system with a gas–liquid porous metal contactor for microbial inactivation in liquid food.  相似文献   

18.
《Food Control》2006,17(2):127-131
Safe and shelf-stable natural casing were prepared using a combination of hurdles viz. reduced water activity, packaging and gamma irradiation. Washed lamb intestines were treated with common salt to reduce water activity to 0.80 ± 0.02, packed in polyethylene bags and subjected to gamma-irradiation (5 and 10 kGy). Control non-irradiated samples had high total viable counts (106 CFU/g), aerobic spores (103 CFU/g), spores of sulphite reducing clostridia (103 CFU/g), potentially pathogenic bacteria such as staphylococci (104 CFU/g) and coliforms (102 CFU/g). Treatment with gamma radiation resulted in a dose dependent reduction in counts of these microbes. A dose of 5 kGy was sufficient to reduce total viable counts by three log cycles; spore counts by two log cycles and completely eliminate staphylococci and coliforms. Samples subjected to a 10 kGy dose were devoid of any viable microbes. The reduced water activity of the product prevented growth of the microbes in natural casings during storage at room temperature. Sausages prepared using hurdle processed natural casing were examined for sensory and textural properties. It was observed that product acceptability and mechanical strength was not affected by radiation processing. Our studies indicated that shelf-stable and safe natural casing could be prepared using a combination of hurdles.  相似文献   

19.
《Food Control》2007,18(5):548-553
This study evaluated the effects of ozonated water (1, 3, and 5 ppm) alone with different exposure times (0.5, 1, 3, or 5 min), and combinations of 3 ppm ozone with 1% organic acids (acetic, citric, or lactic acids) during 5-min exposure for control of Escherichia coli O157:H7 and Listeria monocytogenes on enoki mushroom and to observe the regrowth of these pathogenic bacteria on treated enoki mushroom during storage for 10 days at 15 °C. Results showed that ozone treatment gave less than 1.0- and 0.5-log count reductions on E. coli O157:H7 and L. monocytogenes, respectively. Efficacy was improved with combined 3 ppm ozone and 1% citric acid treatment, resulting in 2.26- and 1.32-log count reductions, respectively. During storage at 15 °C (10 days) after combined treatment and packaging, populations of E. coli O157:H7 and L. monocytogenes increased to more than 8.0 log cfu/g, indicating that the combined treatment did not have a residual antimicrobial effect during storage. Although the storage study did not show control of these pathogens, the combined ozone–organic acid treatment was more effective than individual treatments in reducing initial population levels of these pathogens on enoki mushroom.  相似文献   

20.
《Food Control》2010,21(5):679-685
The inhibitory effects of the pediocin PA-1 in frankfurters and the Pediococcus acidilactici MCH14 pediocin-producing strain itself in Spanish dry-fermented sausages were evaluated. The experiments were carried out by in situ assays using Listeria monocytogenes and Clostridium perfringens as target bacteria strains. The inhibition of L. monocytogenes by the P. acidilactici MCH14 pediocin-producing strain was effective in Spanish dry-fermented sausages, being the counts of this pathogen reduced by 2 log cycles compared to the control. In frankfurters, the counts of L. monocytogenes, using 5000 bacteriocin units/ml (BU/ml) of the pediocin PA-1 produced by P. acidilactici MCH14, decreased by 2 and 0.6 log cycles after storage at 4 °C for 60 days and at 15 °C for 30 days, respectively, with respect to the control. Similar results were obtained for C. perfringens, with 5000 BU/ml the counts of this strain were reduced by 2 and 0.8 log cycles after storage at 10 °C for 60 days and at 15 °C for 30 days, respectively, with respect to the control. Both the pediocin PA-1 and the P. acidilactici MCH14 pediocin-producing strain could be a useful alternative for protection against these food-borne pathogens in meat products.  相似文献   

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