Publications
| Title | Abstract | Year(sorted ascending) Filter | PMID Filter |
|---|
| plant hormone interaction and phenolic metabolism in the regulation of russet spotting in iceberg lettuce. | russet spotting (rs) is a physiological disorder induced in iceberg lettuce (lactuca sativa l.) by exposure to parts per million levels of ethylene at 5 +/- 2 degrees c. ethylene induced phenylalanine ammonia-lyase and ionically bound peroxidase activities that correlated with development of rs symptoms. the ethylene-treated tissue had significantly higher lignin content than air control tissue with lignification localized in walls of rs-affected cells. ethylene also caused the accumulation of t ... | 1988 | 16666434 |
| microflora of partially processed lettuce. | bacteria, yeasts, and molds isolated from partially processed iceberg lettuce were taxonomically classified. the majority of bacterial isolates were gram-negative rods. pseudomonas, erwinia, and serratia species were commonly found. yeasts most frequently isolated from lettuce included members of the genera candida, cryptococcus, pichia, torulaspora, and trichosporon. comparatively few molds were isolated; members of the genera rhizopus, cladosporium, phoma, aspergillus, and penicillium were ide ... | 1990 | 2082830 |
| determination of biogenic amines in leafy vegetables by amino acid analyser. | an automated ion-exchange chromatographic method is described for determination of biogenic amines in leafy vegetables using a cation-exchange resin column in potassium form and a three-buffer system. the following amines were separated and quantified for chinese cabbage, endive, iceberg lettuce and radiocchio: putrescine, histamine, cadaverine, spermidine, agmatine, spermine, tyramine. amines from vegetable samples were extracted with 10% trichloroacetic acid. the total concentration of these a ... | 1994 | 8178576 |
| outbreak of shigella sonnei infection traced to imported iceberg lettuce. | in the period from may through june 1994, an increase in the number of domestic cases of shigella sonnei infection was detected in several european countries, including norway, sweden, and the united kingdom. in all three countries epidemiological evidence incriminated imported iceberg lettuce of spanish origin as the vehicle of transmission. the outbreaks shared a number of common features: a predominance of adults among the case patients, the presence of double infections with other enteropath ... | 1995 | 7751364 |
| an outbreak of shigella sonnei infection associated with consumption of iceberg lettuce. | 1995 | 8903151 | |
| kinetic study of the suicide inactivation of latent polyphenoloxidase from iceberg lettuce (lactuca sativa) induced by 4-tert-butylcatechol in the presence of sds. | in plants, polyphenoloxidase undergoes an irreversible inactivation during the oxidation of o-diphenol to o-quinones. in the present paper, using latent polyphenoloxidase from iceberg lettuce (lactuca sativa), in the presence of an activating agent, sds, the kinetic parameters that characterize the enzyme during its action on the suicide substrate 4-tert-butylcatechol have been determined. the effect of ph has also been considered. it was seen that the presence of sds in the reaction medium chan ... | 1997 | 9187250 |
| characterization of monophenolase activity of polyphenol oxidase from iceberg lettuce. | polyphenol oxidase (ec 1.14.18.1), a thylakoid membrane-bound enzyme, was isolated by sonication of osmotically shocked chloroplasts from iceberg lettuce (lactuca sativa). the enzyme showed monophenolase activity when assayed on (p-hydroxyphenyl)propionic acid with 3-methyl-2-benzothiazolinone hydrazone in a reliable continuous spectrophotometric method, with high sensitivity, accuracy, and precision. the monophenolase activity showed a lag period before the steady-state rate (v(ss)) was reached ... | 1999 | 10563992 |
| the storage life of packed shredded iceberg lettuce dipped in glycine betaine solutions. | the effects of glycine betaine dip, packaging method, and storage time on the sensory quality of shredded iceberg lettuce were first modeled using a statistical experimental design, followed by a second storage test verifying the effect of the glycine betaine treatment. shredded lettuce was dipped in 0 to 100 mg/liter active chlorine solution and then in 0 to 1.0 mol/liter glycine betaine solution, packed in 25 microm oriented polypropylene film, 250 g per package, and stored at 5 degrees c for ... | 1999 | 10419209 |
| behavior of listeria monocytogenes and aeromonas spp. on fresh-cut produce packaged under equilibrium-modified atmosphere. | storage experiments were conducted to follow the behavior of pathogens on fresh-cut vegetables (trimmed brussels sprouts, grated carrots, shredded iceberg lettuce, and shredded chicory endives) packaged under an equilibrium-modified atmosphere (ema) (2 to 3% o2, 2 to 3% co2, and 94 to 96% n2) and stored at 7 degrees c. as a comparison, fresh-cut vegetables were also packaged in a perforated high-barrier film (air conditions) and stored at 7 degrees c. in a first step, the shelf life of the veget ... | 1999 | 10528715 |
| survival of enterohemorrhagic escherichia coli o157:h7 in bovine feces applied to lettuce and the effectiveness of chlorinated water as a disinfectant. | bovine feces are a potential vehicle for transmitting enterohemorrhagic escherichia coli o157:h7 to humans. a study was undertaken to determine survival characteristics of e. coli o157:h7 on iceberg lettuce using 0.1% peptone water and bovine feces as carriers for inocula. four levels of inoculum, ranging from 10(0) to 10(5) cfu of e. coli o157:h7 per g of lettuce, were applied. populations surviving on lettuce stored at 4 degrees c were monitored for up to 15 days. regardless of the type of car ... | 1999 | 10456734 |
| comparison of the attachment of escherichia coli o157:h7, listeria monocytogenes, salmonella typhimurium, and pseudomonas fluorescens to lettuce leaves. | attachment of escherichia coli o157:h7, listeria monocytogenes, salmonella typhimurium, and pseudomonas fluorescens on iceberg lettuce was evaluated by plate count and confocal scanning laser microscopy (cslm). attachment of each microorganism (approximately 10(8) cfu/ml) on the surface and the cut edge of lettuce leaves was determined. e. coli o157:h7 and l. monocytogenes attached preferentially to cut edges, while p. fluorescens attached preferentially to the intact surfaces. differences in at ... | 2000 | 11041147 |
| penetration of escherichia coli o157:h7 into lettuce tissues as affected by inoculum size and temperature and the effect of chlorine treatment on cell viability. | penetration of escherichia coli o157:h7 into iceberg lettuce tissues and the effect of chlorine treatment on cell viability were evaluated. attachment of different inoculum levels (10(9), 10(8), and 10(7) cfu/ml) was examined by determining the number of cells at the surface and the cut edge of lettuce leaves (2 by 2 cm). e. coli o157:h7 attached preferentially to cut edges at all inoculum levels, with greater attachment per cm2 of lettuce at higher inoculum levels. a longer attachment time allo ... | 2000 | 10772206 |
| bactericidal activity of isothiocyanate against pathogens on fresh produce. | the bactericidal activity of allyl and methyl isothiocyanate (aitc and mitc) was tested with a rifampicin-resistant strain of salmonella montevideo and streptomycin-resistant strains of escherichia coil o157:h7 and listeria monocytogenes scott a. iceberg lettuce inoculated with high (10(7) to 10(8) cfu/g) and low (10(3) to 10(4) cfu/g) concentrations of bacterial pathogens was treated with aitc and mitc in sealed containers at 4 degrees c for 4 days. aitc showed stronger bactericidal activity th ... | 2000 | 10643765 |
| more americans are eating "5 a day" but intakes of dark green and cruciferous vegetables remain low. | epidemiological investigations repeatedly show that the regular consumption of dark green and cruciferous vegetables, tomatoes and citrus fruits in particular is related to reduced cancer risk. we used the 1994-1996 continuing survey of food intakes by individuals to examine the types of fruits and vegetables consumed by americans. the analytic sample population, which consisted of 4806 men and women (25-75 y old) who completed two nonconsecutive 24-h recalls, consumed 3.6 +/- 2.3 servings of ve ... | 2000 | 11110870 |
| volatile aldehydes are promising broad-spectrum postharvest insecticides. | a variety of naturally occurring aldehydes common in plants have been evaluated for their insecticidal activity and for phytotoxicity to postharvest fruits, vegetables, and grains. twenty-nine compounds were initially screened for their activity against aphids on fava bean leaf disks. application under reduced pressure (partial vacuum) for the first quarter of fumigation increased insecticidal activity severalfold. the 11 best aldehydes were assayed against aphids placed under the third leaf of ... | 2000 | 10995371 |
| how healthy is iceberg lettuce? | 2000 | 10815561 | |
| evidence for a tetrameric form of iceberg lettuce (lactuca sativa l.) polyphenol oxidase: purification and characterization. | polyphenol oxidase from iceberg lettuce (lactuca sativa l.) chloroplasts was released from the thylakoid-membrane by sonication, and it was extensively purified to homogeneity as judged by sds-page. purification was achieved by ammonium sulfate fractionation, gel-filtration chromatography, and ion-exchange chromatography. two molecular forms were separated by gel-filtration chromatography with apparent molecular masses of 188 and 49 kda. both forms were characterized by sedimentation analysis wi ... | 2001 | 11600037 |
| hysteresis and positive cooperativity of iceberg lettuce polyphenol oxidase. | a kinetic study of the diphenolase activity of latent polyphenol oxidase (ppo), purified from iceberg lettuce (lactuca sativa l), revealed a sigmoid relationship between the reaction rate and the substrate concentration with a high hill coefficient (n(h) = 3.8). this positive cooperativity had not been previously described for any ppo. furthermore, the enzyme showed a lag phase in the expression of this activity, suggesting a hysteretic nature of the enzyme. the kinetic behavior, the latency and ... | 2001 | 11726215 |
| reveal 8-hour test system for detection of escherichia coli o157:h7 in raw ground beef, raw beef cubes, and iceberg lettuce rinse: collaborative study. | five different food types were analyzed by the reveal for e. coli o157:h7 8-hour test system (reveal 8) and either the u.s. food and drug administration's bacteriological analytical manual (bam) culture method or the u.s. department of agriculture food safety inspection service (fsis) culture method for the presence of e. coli o157:h7. a total of 27 laboratories representing academia and private industry in the united states and canada participated. food types were inoculated with e. coli o157:h ... | 2001 | 11417637 |
| penetration of escherichia coli o157:h7 into lettuce as influenced by modified atmosphere and temperature. | the effects of temperature and atmospheric oxygen concentration on the respiration rate of iceberg lettuce and escherichia coli o157:h7 cells attachment to and penetration into damaged lettuce tissues were evaluated. respiration rate of lettuce decreased as the temperature was reduced from 37 to 10 degrees c. reducing the temperature further to 4 degrees c did not affect the respiration rate of lettuce. respiration rate was also reduced by lowering the atmospheric oxygen concentration. lettuce w ... | 2001 | 11726166 |
| survival and growth of escherichia coli o157:h7 inoculated onto cut lettuce before or after heating in chlorinated water, followed by storage at 5 or 15 degrees c. | this study determined the effects of mild heat and chlorine treatment followed by storage for up to 18 days at 5 degrees c or 7 days at 15 degrees c on the survival and growth of escherichia coli o157:h7 inoculated onto fresh-cut iceberg lettuce. the efficacy of treatment with 20 ppm chlorine in killing the pathogen on lettuce at 50 degrees c was determined. treatment of lettuce with 20 ppm chlorine at either 20 or 50 degrees c did not result in significantly greater reductions in populations of ... | 2001 | 11252471 |
| evaluation of household sanitizers for reducing levels of escherichia coli on iceberg lettuce. | diluted solutions of various household sanitizers (apple cider vinegar, white vinegar, bleach, and a reconstituted lemon juice product) were tested for their effectiveness in reducing counts of inoculated escherichia coli and naturally present aerobic, mesophilic bacteria on lettuce. sanitization treatments were carried out at 4 degrees c and at room temperature (ca. 21 degrees c) with and without agitation and at different exposure times (0, 1, 5, and 10 min). of the sanitizers tested, 35% whit ... | 2002 | 12380754 |
| inactivation of escherichia coli o157:h7, salmonella enterica serotype enteritidis, and listeria monocytogenes on lettuce by hydrogen peroxide and lactic acid and by hydrogen peroxide with mild heat. | iceberg lettuce is a major component in vegetable salad and has been associated with many outbreaks of foodborne illnesses. in this study, several combinations of lactic acid and hydrogen peroxide were tested to obtain effective antibacterial activity without adverse effects on sensory characteristics. a five-strain mixture of escherichia coli o157:h7, salmonella enterica serotype enteritidis, and listeria monocytogenes was inoculated separately onto fresh-cut lettuce leaves, which were later tr ... | 2002 | 12182470 |
| cross-contamination of lettuce with escherichia coli o157:h7. | contamination of produce by bacterial pathogens is an increasingly recognized problem. in march 1999, 72 patrons of a nebraska restaurant were infected with enterohemorrhagic escherichia coli (ehec) o157:h7, and shredded iceberg lettuce was implicated as the food source. we simulated the restaurant's lettuce preparation procedure to determine the extent of possible ehec cross-contamination and growth during handling. ehec inoculation experiments were conducted to simulate the restaurant's cuttin ... | 2002 | 11899044 |
| survival and growth of listeria monocytogenes and escherichia coli o157:h7 in ready-to-eat iceberg lettuce washed in warm chlorinated water. | cut iceberg lettuce inoculated with escherichia coli o157:h7 and listeria monocytogenes before and after washing for 3 min in cold (4 degrees c) and warm (47 degrees c) water containing 100 mg/liter total chlorine was stored at i and 10 degrees c in oxygen-permeable film packages (6,000 to 8,000 cc/m2/24 h). cold chlorinated water was detrimental to the survival of e. coli o157: h7 and l. monocytogenes at both storage temperatures. in contrast, washing in warm chlorinated water favored the growt ... | 2002 | 11899043 |
| mild heat treatment of lettuce enhances growth of listeria monocytogenes during subsequent storage at 5 degrees c or 15 degrees c. | the objective of this study was to determine the influence of mild heat treatment, storage temperature and storage time on the survival and growth of listeria monocytogenes inoculated onto cut iceberg lettuce leaves. | 2002 | 11849355 |
| suspending lettuce type influences recoverability and radiation sensitivity of escherichia coli o157:h7. | an outbreak strain of escherichia coli o157:h7 was inoculated onto closely related but structurally distinct types of lettuce (lactuca sativa): boston (butterhead lettuce), iceberg (crisphead lettuce), and green leaf and red leaf (colored variants of looseleaf lettuce). the e. coli o157:h7 was inoculated either onto the surface of cut leaf pieces or into a homogenized leaf suspension. samples were gamma irradiated, and the radiation sensitivity of the inoculated bacteria was expressed as a d-val ... | 2002 | 12233847 |
| effect of wash water temperature and chlorination on phenolic metabolism and browning of stored iceberg lettuce photosynthetic and vascular tissues. | cut tissues from distinct anatomical locations in iceberg lettuce (lactuca sativa l.) were subjected to washing in cold (4 degrees c) and warm (47 degrees c) water with or without chlorine to assess their propensity to discoloration during storage. total protein (bradford method) and phenolic (tph; folin-ciocalteu method) contents and polyphenol oxidase (ppo; spectrophotometric method using catechol as a substrate), peroxidase (pod; guaiacol substrate), and phenylalanine ammonia-lyase (pal; phen ... | 2002 | 12137468 |
| sensorial and chemical quality of gamma-irradiated fresh-cut iceberg lettuce in modified atmosphere packages. | a study was conducted to investigate the effects of various doses of irradiation on the quality of fresh-cut iceberg lettuce and to determine a suitable maximum dose. fresh-cut iceberg lettuce packaged in film bags was exposed to 0, 1, 2, 3, and 4 kgy of gamma radiation and stored at 3 degrees c for 14 days. co2 levels were higher and o2 levels were lower in packages containing irradiated lettuce than in those containing nonirradiated lettuce for most of the storage period. comparison with nonir ... | 2002 | 12430699 |
| consumer acceptance of fresh-cut iceberg lettuce treated with 2% hydrogen peroxide and mild heat. | an antibacterial treatment consisting of 2% hydrogen peroxide at 50 degrees c for 60 s was evaluated for its effects on the sensory quality of fresh-cut iceberg lettuce. treated lettuce was packaged in polyethylene film by a protocol used in the fresh-cut produce industry and then stored along with untreated controls for 3, 10, and 15 days at 5 degrees c. gas chromatographic analysis confirmed that the desired initial volume (approximately 6 liters) and oxygen gas content (approximately 10%) wer ... | 2002 | 12182471 |
| effects of vacuum and controlled atmosphere treatments on insect mortality and lettuce quality. | laboratory studies were conducted to determine the effects of vacuum and controlled atmosphere on mortality of aphids, nasonovia ribisnigri (mosley) and macrosiphum euphorbiae (thomas), and leafminer, liriomyza langei frick, and on the visual quality of iceberg lettuce at three different temperatures. vacuum at 50 mbar and controlled atmosphere with 6% co2 were effective in controlling aphids and leafminer larvae. complete control of n. ribisnigri and m. euphorbiae was achieved with vacuum treat ... | 2003 | 14503580 |
| warm water treatment in combination with modified atmosphere packaging reduces undesirable effects of irradiation on the quality of fresh-cut iceberg lettuce. | fresh-cut iceberg lettuce dipped in either 5 or 47 degrees c water for 2 min was packaged in modified atmosphere film bags and then exposed to 0, 0.5, 1, or 2 kgy gamma-radiation. dipping cut lettuce in 47 degrees c water for 2 min prior to irradiation reduced antioxidant and phenolic accumulations induced by irradiation. irradiation at 2 kgy increased cellular leakage and sogginess of cut lettuce dipped in both temperatures. samples irradiated at 0.5 and 1 kgy had similar firmness and vitamin c ... | 2003 | 12590460 |
| detection of organophosphate and carbamate pesticides in vegetable samples by a photothermal biosensor. | previously developed photothermal biosensor was optimised by determining the most suitable enzyme substrate (acetylthiocholine iodide) and the optimal carrier buffer (0.05 m phosphate buffer, ph 8.0). excitation laser operating at 488 nm and 120 mw power provided the highest biosensor sensitivity. the biosensor was tested for detection of toxic organophosphate and carbamate compounds present in samples of salad, iceberg lettuce, and onion. sufficient sensitivities to different pesticides (carbof ... | 2003 | 12445439 |
| the nitrogen and nitrate economy of butterhead lettuce (lactuca sativa var capitata l). | quantifying and simulating the relationships between crop growth, total-nitrogen (total-n) and nitrate-n (no3--n) concentration can improve crop nutritional husbandry. in this study, the relationship between shoot relative growth rate (rgr) and shoot total-n, organic-n and no3--n concentration of hydroponically-grown lettuce (lactuca sativa var. capitata l. cv. kennedy) was described and simulated. plants were grown hydroponically for up to 74 d. nitrogen was supplied throughout (control; t1), o ... | 2003 | 12885858 |
| occurrence of yersinia pseudotuberculosis in iceberg lettuce and environment. | 2003 | 12756795 | |
| assessment of control measures to achieve a food safety objective of less than 100 cfu of listeria monocytogenes per gram at the point of consumption for fresh precut iceberg lettuce. | the important new concept of the food safety objective (fso) offers a strategy to translate public health risk into a definable goal such as a specified maximum frequency or concentration of a hazardous agent in a food at the time of consumption that is deemed to provide an appropriate level of health protection. for the foodborne pathogen listeria monocytogenes, there is a proposed fso of < 100 cfu/g in ready-to-eat (rte) products at the time of consumption. fresh precut iceberg lettuce is one ... | 2003 | 12597486 |
| influence of variations in methodology on populations of listeria monocytogenes recovered from lettuce treated with sanitizers. | the elimination of listeria monocytogenes inoculated onto a piece of cut iceberg lettuce (3.8 by 3.8 cm) by treatment with chlorinated water (200 micrograms/ml free chlorine) and a 0.5% (wt/vol) solution of fit professional line antibacterial cleaner (fit) was investigated. the efficacy of the two sanitizers was not influenced by the composition of the medium used to culture the l. monocytogenes used in the inocula, the number of strains in the inoculum, or the recovery medium used to enumerate ... | 2004 | 15083726 |
| influence of bovine manure as fertilizer on the bacteriological quality of organic iceberg lettuce. | to investigate the bacteriological quality, and the occurrence of selected pathogenic bacteria from organically grown iceberg lettuce fertilized with bovine manure in the form of compost, firm manure and slurry in a 2-year field trial. | 2004 | 15012817 |
| survival of campylobacter jejuni on various fresh produce. | the survival of seven human and two chicken campylobacter jejuni strains, with known penner heat-stable (hs) serotypes and pulsed-field gel electrophoresis (pfge) genotypes, was investigated on fresh-cut iceberg lettuce. in addition, the survival of four selected c. jejuni strains was assessed on cantaloupe pieces, cucumber slices, grated carrot and strawberries. fresh produce was inoculated with 10(5) to 10(7) colony-forming units (cfu) of c. jejuni per gram, and the bacterium was enumerated us ... | 2004 | 15541805 |
| efficacy of chlorine and a peroxyacetic acid sanitizer in killing listeria monocytogenes on iceberg and romaine lettuce using simulated commercial processing conditions. | the efficacy of chlorine (100 microg/ml) and a peroxyacetic acid sanitizer (80 microg/ml; tsunami 100) in killing listeria monocytogenes inoculated at populations of 1 to 2, 2 to 3, and 4 to 5 log cfu/g of iceberg lettuce pieces, shredded iceberg lettuce, and romaine lettuce pieces was determined by treatment conditions simulating those used by a commercial fresh-cut lettuce processor. the lettuce/treatment solution ratio was 1:100 (wt/vol), treatment temperature was 4 degrees c, and total treat ... | 2004 | 15222557 |
| survival and recovery of escherichia coli o157:h7, salmonella, and listeria monocytogenes on lettuce and parsley as affected by method of inoculation, time between inoculation and analysis, and treatment with chlorinated water. | the effects of method for applying inoculum and of drying time after inoculation on survival and recovery of foodborne pathogens on iceberg lettuce and parsley were studied. five-strain mixtures of escherichia coli o157:h7, salmonella, or listeria monocytogenes were applied to lettuce and parsley by dip, spot, or spray inoculation methods. inocula were dried for 2 h at 22 degrees c or for 2 h at 22 degrees c and then 22 h at 4 degrees c before being treated with water (control) or chlorine (200 ... | 2004 | 15222533 |
| a widespread outbreak of yersinia pseudotuberculosis o:3 infection from iceberg lettuce. | the vehicles and sources of yersinia pseudotuberculosis infection are unknown. in finland, clinical microbiology laboratories routinely report y. pseudotuberculosis isolations and submit isolates for serotype analysis. in october 1998, the number of serotype o:3 infections increased markedly. | 2004 | 14976592 |
| lettuce and chicory byproducts as a source of antioxidant phenolic extracts. | a process to obtain enriched antioxidant phenolic extracts from lettuce (baby, romaine, and iceberg cultivars) and chichory byproducts as a way to valorize these byproducts was developed. two extraction protocols using water and methanol as solvent were used. amberlite xad-2 nonionic polymeric resin was used to purify the extracts. the extraction yield, phenolic content, and phenolic yield were evaluated as well as the antioxidant capacity of the extracts (dpph, abts, and frap assays). baby and ... | 2004 | 15291483 |
| effect of different washing procedures on phenolic metabolism of shredded, packaged iceberg lettuce during storage. | different washing treatments applying chlorinated, ozonated, and tap water were examined for their effect on the phenolic metabolism of minimally processed iceberg lettuce (lactuca sativa l.) during storage in consumer-sized bags at 4 degrees c for up to 9 days. to eliminate problems associated with raw material inhomogeneity, processing was conducted on a pilot-plant scale under operating conditions of industrial practice. inherent product heterogeneity caused by diverse lettuce leaf tissues wa ... | 2004 | 15537312 |
| distribution and population development of nasonovia ribisnigri (homoptera: aphididae) in iceberg lettuce. | a field study was conducted to determine the distribution and development of aphid nasonovia ribisnigri (mosley) (homoptera: aphididae) populations in iceberg lettuce, lactuca sativa l. 'salinas'. lettuce plants were transplanted and caged individually in the field and inoculated with apterous n. ribisnigri at 0, 1, 2, 3, and 4 wk after transplanting in spring and fall 2002. plants were harvested 15-50 d after inoculations; numbers of alates and apterous n. ribisnigri were counted or estimated o ... | 2004 | 15279267 |
| lettuce and carrot allergy: are they related? | lettuce is commonly included in many elimination diets of subjects with either food allergy or atopic dermatitis since ige-mediated allergic reactions have not been reported. we have observed a positive carrot skin test and/or rast in two clinically lettuce sensitive, ragweed allergic subjects and positive lettuce skin test and/or rast in two ragweed allergic patients with oral allergy syndrome to carrot. in this study lettuce allergy and the allergenic relationship between iceberg lettuce (lact ... | 2004 | 8005454 |
| ozonated water extends the shelf life of fresh-cut lettuce. | the use of ozonated water as a sanitizer to extend the shelf life of fresh-cut lettuce and the effect on the antioxidant constituents (polyphenols and vitamin c) were investigated. fresh-cut iceberg lettuce (lactuca sativa l.) was washed at 4 degrees c using three different ozonated water dips [10, 20, and 10 activated by ultraviolet c (uv-c) light mg l(-1) min total ozone dose], and the dips were compared with water and chlorine rinses. treated lettuce was packaged in air or active modified atm ... | 2005 | 15998129 |
| ultralow oxygen treatment for postharvest control of nasonovia ribisnigri (homoptera: aphididae) on iceberg lettuce. | the aphid nasonovia ribisnigri (mosley) is a common pest of lettuce in the united states. it hinders export of u.s. lettuce to the overseas market such as japan where it is a quarantined pest. ultralow oxygen treatments were studied for control of the insect on iceberg lettuce. small-scale ultralow oxygen treatments in plastic jars were conducted at 1, 5, and 10 degrees c for different durations to determine effective treatment against nymphs and alates of n. ribisnigri. at oxygen levels of 0.01 ... | 2005 | 16539111 |
| effect of heat shock on browning-related enzymes in minimally processed iceberg lettuce and crude extracts. | the effects of heat shock on ppo and pod activity in minimally processed iceberg lettuce was examined during storage (10 days). the results were compared with the effect of temperature on crude extracts of these enzymes (in vitro analysis). fresh-cut lettuce washed at 50 degrees c showed significantly lower ppo and pod activity throughout storage than lettuce washed at 4 degrees c and 25 degrees c. these results were consistent with a sensory analysis in which the panellists found the lowest bro ... | 2005 | 16195584 |
| efficacy of aerosolized peroxyacetic acid as a sanitizer of lettuce leaves. | aerosolized sanitizer was investigated as a potential alternative to aqueous and gaseous sanitizers for produce. peroxyacetic acid was aerosolized (5.42 to 11.42 microm particle diameter) by a commercially available nebulizer into a model cabinet. iceberg lettuce leaves were inoculated with three strains each of escherichia coli o157:h7, listeria monocytogenes, and salmonella typhimurium and then treated with aerosolized peroxyacetic acid for 10, 30, or 60 min in a model aerosol cabinet at room ... | 2005 | 21132990 |
| effects of cattle feeding regimen and soil management type on the fate of escherichia coli o157:h7 and salmonella enterica serovar typhimurium in manure, manure-amended soil, and lettuce. | survival of the green fluorescent protein-transformed human pathogens escherichia coli o157:h7 and salmonella enterica serovar typhimurium was studied in a laboratory-simulated lettuce production chain. dairy cows were fed three different roughage types: high-digestible grass silage plus maize silage (6:4), low-digestible grass silage, and straw. each was adjusted with supplemental concentrates to high and low crude protein levels. the pathogens were added to manure, which was subsequently mixed ... | 2005 | 16204535 |
| application of microbial risk assessment to the development of standards for enteric pathogens in water used to irrigate fresh produce. | microbial contamination of the surfaces of cantaloupe, iceberg lettuce, and bell peppers via contact with irrigation water was investigated to aid in the development of irrigation water quality standards for enteric bacteria and viruses. furrow and subsurface drip irrigation methods were evaluated with the use of nonpathogenic surrogates, coliphage prd1, and escherichia coli atcc 25922. the concentrations of hepatitis a virus (hav) and salmonella in irrigation water necessary to achieve a 1:10,0 ... | 2005 | 15895721 |
| growth of listeria monocytogenes on iceberg lettuce and solid media. | the growth of pathogenic bacterium listeria monocytogenes on fresh-cut iceberg lettuce under constant temperatures was modelled in order to investigate microbial safety during distribution of this vegetable. we examined the effects of several incubation temperatures, ranging from 5 to 25 degrees c, on bacterial growth. these data were fitted to the baranyi model and the curves showed a high correlation coefficient at all temperature (r2 > 0.95). in addition, the native bacterial flora of the let ... | 2005 | 15862883 |
| accumulation and perchlorate exposure potential of lettuce produced in the lower colorado river region. | the colorado river is contaminated with perchlorate concentrations of 1.5-8 microg/l, an anion linked to thyroid dysfunction. over 90% of the lettuce (lactuca sativa l.) consumed during the winter months in the united states is produced in the lower colorado river region. studies were conducted in this region to survey the potential for lettuce perchlorate accumulation and estimate potential human exposure to perchlorate from lettuce. total uptake of perchlorate in the above-ground plant of iceb ... | 2005 | 15969537 |
| prediction of pathogen growth on iceberg lettuce under real temperature history during distribution from farm to table. | the growth of pathogenic bacteria escherichia coli o157:h7, salmonella spp., and listeria monocytogenes on iceberg lettuce under constant and fluctuating temperatures was modelled in order to estimate the microbial safety of this vegetable during distribution from the farm to the table. firstly, we examined pathogen growth on lettuce at constant temperatures, ranging from 5 to 25 degrees c, and then we obtained the growth kinetic parameters (lag time, maximum growth rate (micro(max)), and maximu ... | 2005 | 15979180 |
| efficiency of sodium hypochlorite, fumaric acid, and mild heat in killing native microflora and escherichia coli o157:h7, salmonella typhimurium dt104, and staphylococcus aureus attached to fresh-cut lettuce. | the effect of the disinfectant sodium hypochlorite (naclo), with or without mild heat (50 degrees c) and fumaric acid, on native bacteria and the foodborne pathogens staphylococcus aureus, escherichia coli o157:h7, and salmonella typhimurium dt104 attached to iceberg lettuce leaves was examined. the retail lettuce examined consistently harbored 6 to 7 log cfu/g of native bacteria throughout the study period. inner leaves supported 1 to 2 log cfu/g fewer bacteria than outer leaves. about 70% of t ... | 2006 | 16496572 |
| determination of total aerobic and indicator bacteria on some raw eaten vegetables from wholesalers in ankara, turkey. | the aim of this study was to investigate the bacteriological quality of some raw eaten salad vegetables obtained from wholesalers in ankara, turkey. a total of 180 samples including lettuces, cos lettuce, iceberg lettuce, parsley, dill and carrots were analyzed for total aerobic bacteria, total coliform bacteria and e. coli between january 2004 and april 2004. compact dry media (nissui pharmaceutical co. ltd., japan) were used for bacteriological analysis. outer leaves of lettuce, cos lettuce an ... | 2006 | 16503303 |
| differential killing activity of cetylpyridinium chloride with or without bacto neutralizing buffer quench against firmly adhered salmonella gaminara and shigella sonnei on cut lettuce stored at 4 degrees c. | cetylpyridinium chloride (cpc) activity was quenched with bacto neutralizing buffer on inoculated cut iceberg lettuce. this protocol permitted comparison of the numbers of salmonella gaminara- or shigella sonnei-inoculated cells on lettuce that survived 1 min of cpc treatment. cut lettuce was inoculated with about 6 log of salmonella or 9 log of shigella and stored in whirl-pak bags at 4 degrees c for up to 4 days. loosely adhered pathogen cells were washed off before cpc treatment. firmly adher ... | 2006 | 16786847 |
| efficacy of disinfectants to reduce listeria monocytogenes on precut iceberg lettuce. | the efficacy of water, chlorinated water (100 ppm), peracetic acid solution (0.05%), and commercial citric acid-based produce wash (0.25%) to reduce the population of listeria monocytogenes on precut lettuce was tested. samples were inoculated with a mixture of equal amounts of five l. monocytogenes strains at a level of 4.7 log cfu/g, and analyzed on the day of washing and after 3 and 6 days of storage at 6 degrees c. sanitizer reduced the number of l. monocytogenes at maximum 1.7 log cfu/g and ... | 2006 | 16865887 |
| lettuce for human consumption collected in costa rica contains complex communities of culturable oxytetracycline- and gentamicin-resistant bacteria. | the present widespread use of antimicrobials in crop farming is based upon their successful application in human medicine. however, recent evidence suggests that the massive anthropogenic release of antimicrobials into the biosphere has selected for resistant bacteria and facilitated the transfer of resistance genes among them. this work deals with the examination of iceberg lettuce collected at 10 farms from two regions in costa rica. farmers from nine sampling sites regularly apply commercial ... | 2006 | 16957206 |
| comparison of virulence between clinical and environmental pseudomonas aeruginosa isolates. | new strains of pseudomonas aeruginosa were isolated from clinical and environmental settings in order to characterize the virulence properties of this opportunistic pathogen. p. aeruginosa was frequently recovered from oil-contaminated samples but not from non-oil-contaminated soils. the virulence of five environmental and five clinical strains of p. aeruginosa was tested using two different models, drosophila melanogaster and lactuca sativa var. capitata l. there was no difference in the virule ... | 2006 | 17236157 |
| intra-laboratory validation of a concentration method adapted for the enumeration of infectious f-specific rna coliphage, enterovirus, and hepatitis a virus from inoculated leaves of salad vegetables. | salad vegetables exposed to fecal contamination may cause outbreaks of hepatitis or gastro-enteritis if they are eaten raw. a procedure, based on elution with phosphate-buffered saline and concentration by filtration through membrane filters, was developed for the recovery of enteric viruses from salad leaves. the method was evaluated using lettuce leaves inoculated with hepatitis a virus (hav), poliovirus, and ms2 bacteriophage. in addition, this method was validated by an intra-laboratory stud ... | 2006 | 16387377 |
| evidence of an antilisterial factor induced by wounding of iceberg lettuce tissues. | to examine the influence of wound-associated reactions in cut iceberg lettuce (lactuca sativa l.) tissues on the fate of listeria monocytogenes. | 2006 | 16478519 |
| leaf mechanical properties modulate feeding movements and ingestive success of the pond snail, lymnaea stagnalis. | we examined the mechanical properties of butterhead and iceberg lettuce leaves, and the rate at which they were eaten by the pond snail lymnaea stagnalis. the outer part of butterhead leaves were less robust than either the inner butterhead or outer iceberg leaves (young's modulus 2.8, 5.2, 7.7 mpa respectively; ultimate tensile stress 0.18, 0.34 0.51 mpa) which were also thicker. snails ingested inner butterhead and iceberg strips more slowly (36 and 32%) than outer butterhead. this was not due ... | 2006 | 16810503 |
| effect of ozonated water treatment on microbial control and on browning of iceberg lettuce (lactuca sativa l.). | we examined the effect of ozonated water treatment on microbial control and quality of cut iceberg lettuce (lactuca sativa l.). fresh-cut lettuce was washed in ozonated water (3, 5, and 10 ppm) for 5 min at ambient temperature. the native bacterial population on the lettuce declined in response to a rise in ozone concentration. however, there was no further bacterial reduction (1.4 log cfu/g) above 5 ppm ozone. although ozonated water treatment increased the phenylalanine ammonia lyase (pal) act ... | 2006 | 16416913 |
| effectiveness of organic acid, ozonated water and chlorine dippings on microbial reduction and storage quality of fresh-cut iceberg lettuce. | the comparative effects of organic (citric and lactic) acids, ozone and chlorine on the microbiological population and quality parameters of fresh-cut lettuce during storage were evaluated. | 2007 | 20836169 |
| inactivation of escherichia coli and listeria monocytogenes on iceberg lettuce by dip wash treatments with organic acids. | to study and compare the efficacy of organic acids and chlorine dipping in inactivation of escherichia coli and listeria monocytogenes on fresh-cut iceberg lettuce. | 2007 | 17576223 |
| detection and quantification by real-time rt-pcr of hepatitis a virus from inoculated tap waters, salad vegetables, and soft fruits: characterization of the method performances. | water, salad vegetables and fruits exposed to fecal contamination may cause outbreaks of hepatitis a. a protocol of viral concentration by filtration on electronegative membrane filter and a protocol based on a viral elution in tris-glycine buffer, ph 9.5 with concentration by polyethylene glycol precipitation were associated with real-time, reverse transcriptase-pcr to detect hepatitis a virus (hav) artificially inoculated in 2 l of tap water, or on 25 g of fruits or salad vegetables. these met ... | 2007 | 17490771 |
| influence of curli expression by escherichia coli 0157:h7 on the cell's overall hydrophobicity, charge, and ability to attach to lettuce. | curli fibers are produced by some escherichia coli cells in response to environmental stimuli. these extracellular proteins enhance the cell's ability to form biofilms on various abiotic surfaces. e. coli 0157:h7 cells readily attach to a variety of fruit and vegetable surfaces. it is not known whether the expression of curli influences the cell's ability to attach to produce surfaces. in this study, the effect of curli expression on the cell's overall hydrophobicity, charge, and ability to atta ... | 2007 | 17612061 |
| shelf-life extension of fresh-cut iceberg lettuce (lactuca sativa l) by different antimicrobial films. | this study was conducted to investigate the antibacterial activity and shelf-life extension effect of iceberg lettuce packed in bn/pe film. the bn/pe film has a strong microbial suppression effect on pathogenic bacteria such as escherichia coli, salmonella enteritidis, and s. typhimurium. the number of psychrophiles and mesophiles during 5 days of cold storage of fresh-cut iceberg lettuce at 10 degrees c packaged in bn/pe film was strictly suppressed in comparison with other tested films (opp, p ... | 2007 | 18051596 |
| growth and bacteriocin production by lactic acid bacteria in vegetable broth and their effectiveness at reducing listeria monocytogenes in vitro and in fresh-cut lettuce. | the fresh-cut fruit and vegetable industry is searching for alternatives to replace chemical treatments with biopreservative approaches that ensure the safety of the product and fulfil consumer preferences for minimally processed foods. in this study, the use of bacteriocins produced by lactic acid bacteria has been tested as a substitute for chemical disinfection of fresh-cut iceberg lettuce. first, the ability of several non-plant origin bacteriocinogenic strains (nisin z(+), plantaricin c(+), ... | 2007 | 17613374 |
| survival of escherichia coli o157:h7 and salmonella enterica serovars typhimurium in iceberg lettuce and the antimicrobial effect of rice vinegar against e. coli o157:h7. | the microbiological safety of fresh produce is a significant concern of consumers and industry. after applying at an inoculated level (about 10(6) cfug(-1)) of e. coli o157:h7 and salmonella enterica serovars typhimurium on shredded iceberg lettuce and water samples individually, they were stored at 4 degrees c for 14 days and 22 degrees c for 7 days to monitor the growth and survival of pathogens. the results showed that at the end of 4 degrees c storage, populations of two pathogens in lettuce ... | 2007 | 17613372 |
| inactivation of escherichia coli o157:h7, salmonella typhimurium, and listeria monocytogenes on stored iceberg lettuce by aqueous chlorine dioxide treatment. | inactivation of escherichia coli o157:h7, salmonella typhimurium, and listeria monocytogenes in iceberg lettuce by aqueous chlorine dioxide (clo(2)) treatment was evaluated. iceberg lettuce samples were inoculated with approximately 7 log cfu/g of e. coli o157:h7, s. typhimurium, and l. monocytogenes. iceberg lettuce samples were then treated with 0, 5, 10, or 50 ppm clo(2) solution and stored at 4 degrees c. aqueous clo(2) treatment significantly decreased the populations of pathogenic bacteria ... | 2008 | 19021812 |
| bioprotection of golden delicious apples and iceberg lettuce against foodborne bacterial pathogens by lactic acid bacteria. | lactic acid bacteria were isolated from fresh vegetables and fruit and its ability to inhibit the growth of foodborne human pathogens (escherichia coli, listeria monocytogenes, pseudomonas aeruginosa, salmonella typhimurium, and staphylococcus aureus) was tested using the agar spot assay. eighteen isolates showed a strong antagonistic capacity and were further characterised and identified using 16s rdna sequencing and api 50ch. most of them pertained to leuconostoc spp. and lactobacillus plantar ... | 2008 | 18191266 |
| bioprotective leuconostoc strains against listeria monocytogenes in fresh fruits and vegetables. | ten leuconostoc mesenteroides and one ln. citreum strains isolated from fresh fruit and vegetables were tested for their antagonistic capacity against listeria monocytogenes. genetic differences among strains were analyzed by random amplified polymorphic dna (rapd). all the isolates clustered together and differed from the type strain ln. mesenteroides atcc 8293 as well as from ln. fallax and ln. citreum. organic acids, hydrogen peroxide and bacteriocins were detected as main inhibition mechanis ... | 2008 | 18625532 |
| irradiation in the production, processing and handling of food. final rule. | the food and drug administration (fda) is amending the food additive regulations to provide for the safe use of ionizing radiation for control of food-borne pathogens, and extension of shelf-life, in fresh iceberg lettuce and fresh spinach (hereinafter referred to in this document as "iceberg lettuce and spinach") at a dose up to 4.0 kilo gray (kgy). this action is in partial response to a petition filed by the national food processors association on behalf of the food irradiation coalition. | 2008 | 18958941 |
| efficacy of neutral electrolyzed water (new) for reducing microbial contamination on minimally-processed vegetables. | consumption of minimally-processed, or fresh-cut, fruit and vegetables has rapidly increased in recent years, but there have also been several reported outbreaks associated with the consumption of these products. sodium hypochlorite is currently the most widespread disinfectant used by fresh-cut industries. neutral electrolyzed water (new) is a novel disinfection system that could represent an alternative to sodium hypochlorite. the aim of the study was to determine whether new could replace sod ... | 2008 | 18237810 |
| irradiation compared with chlorination for elimination of escherichia coli o157:h7 internalized in lettuce leaves: influence of lettuce variety. | pathogenic bacteria internalized in leaf tissues are not effectively removed by surface treatments. irradiation has been shown to inactivate leaf-internalized bacteria, but many aspects of targeting these protected pathogens remain unknown. bacterial cells of a cocktail mixture of 3 isolates of escherichia coli o157:h7 were drawn into the leaves of iceberg, boston, green leaf, and red leaf lettuce using vacuum perfusion. the inoculated leaves were treated with a 3-min wash with sodium hypochlori ... | 2008 | 18577002 |
| contaminants and microorganisms in dutch organic food products: a comparison with conventional products. | organic products were analysed for the presence of contaminants, microorganisms and antibiotic resistance and compared with those from conventional products. no differences were observed in the fusarium toxins deoxynivalenol and zearalenone in organic and conventional wheat, during both a dry period and a very wet period which promoted the production of these toxins. nitrate levels in head lettuce produced organically in the open field were much lower than those in conventional products. in iceb ... | 2008 | 18608495 |
| inactivation of murine norovirus 1 and bacteroides fragilis infecting phage b40-8 by the use of sodium hypochlorite and peroxyacetic acid as decontaminating agents for shredded iceberg lettuce. | 2008 | 18831252 | |
| inactivation of ms2 f(+) coliphage on lettuce by a combination of uv light and hydrogen peroxide. | the efficacy of a produce decontamination method based on a combination of uv light (254 nm) and hydrogen peroxide (h2o2) to inactivate the ms2 f(+) coliphage inoculated onto iceberg lettuce was evaluated. lettuce inoculated with 6.57 log pfu of ms2 was reduced by 0.5 to 1.0 log unit when illuminated with uv light alone for 20 to 60 s (12.64 to 18.96 mj/cm2). in contrast, a 3-log reduction in ms2 was achieved with 2% (vol/vol) h2o2 spray delivered at 50 degrees c. no significant increase in log ... | 2008 | 18522021 |
| antimicrobial (bn/pe) film combined with modified atmosphere packaging extends the shelf life of minimally processed fresh-cut iceberg lettuce. | this study was conducted to investigate the effect of modified atmosphere packaging (map) in combination with bn/pe film on the shelf life and quality of fresh-cut iceberg lettuce during cold storage. the total mesophilic population in the sample packed in bn/pe film under map conditions was dramatically reduced in comparison with that of pe film, pe film under map conditions, and bn/pe film. the o2 concentration in the bn/pe film under map conditions decreased slightly as the storage period pro ... | 2008 | 18388478 |
| looking for meaning: eye movements are sensitive to overlapping semantic features, not association. | theories of semantic memory differ in the extent to which relationships among concepts are captured via associative or via semantic relatedness. we examined the contributions of these two factors, using a visual world paradigm in which participants selected the named object from a four-picture display. we controlled for semantic relatedness while manipulating associative strength by using the visual world paradigm's analogue to presenting asymmetrically associated pairs in either their forward o ... | 2009 | 19815791 |
| moderate and high doses of sodium hypochlorite, neutral electrolyzed oxidizing water, peroxyacetic acid, and gaseous chlorine dioxide did not affect the nutritional and sensory qualities of fresh-cut iceberg lettuce (lactuca sativa var. capitata l.) after washing. | besides the traditionally used sodium hypochlorite (20 and 200 mg l(-1)), alternative sanitizers such as peroxyacetic acid (80 and 250 mg l(-1)) and neutral electrolyzed oxidizing water (4.5 and 30 mg l(-1) free chlorine) as well as chlorine dioxide gas (1.54 mg l(-1)) were evaluated for their efficiency in reducing the microbial load of fresh-cut iceberg lettuce. an additional rinsing step with tap water and cooling of the sanitizing solutions, which are obvious for the fresh-cut industry, were ... | 2009 | 19371140 |
| transfer of escherichia coli o157:h7 to iceberg lettuce via simulated field coring. | the field-core (cut and core) harvesting technique used for iceberg lettuce was evaluated as a potential means of cross-contamination with escherichia coli o157:h7. chlorinated water treatment was evaluated for its efficacy in removing or inactivating the pathogen on the blade portion of the field coring device and on cored lettuce. field coring devices inoculated by immersing blades in soil containing e. coli o157:h7 at 3.74 or 6.57 log cfu/g contained 3.13 and 4.97 log cfu per blade, respectiv ... | 2009 | 19343932 |
| potential of escherichia coli o157:h7 to grow on field-cored lettuce as impacted by postharvest storage time and temperature. | a recent development in iceberg lettuce harvesting is field coring, the technique of removing the outer leaves and the cores of the lettuce heads at the time of harvesting in order to reduce shipping waste and maximize production yield. however, this method may increase the potential for contamination during field procedures and therefore, it is important to evaluate the survival and growth of escherichia coli o157:h7 on pre-cored lettuce under simulated field conditions. using a coring knife ar ... | 2009 | 19019473 |
| microbial antagonists of escherichia coli o157:h7 on fresh-cut lettuce and spinach. | fresh-cut lettuce and spinach can become contaminated with pathogens at numerous points from the field to the retail market. natural microflora present on fresh produce may help reduce the pathogen load. the objective of this study was to isolate natural microflora from fresh-cut iceberg lettuce and baby spinach and to determine whether these bacteria were antagonistic toward escherichia coli o157:h7. samples were collected under conditions that mimicked actual practices between production and r ... | 2009 | 19681287 |
| efficacy of chlorine, acidic electrolyzed water and aqueous chlorine dioxide solutions to decontaminate escherichia coli o157:h7 from lettuce leaves. | this study compared the efficacy of chlorine (20-200 ppm), acidic electrolyzed water (50 ppm chlorine, ph 2.6), acidified sodium chlorite (20-200 ppm chlorite ion concentration, sanova), and aqueous chlorine dioxide (20-200 ppm chlorite ion concentration, trinova) washes in reducing populations of escherichia coli o157:h7 on artificially inoculated lettuce. fresh-cut leaves of romaine or iceberg lettuce were inoculated by immersion in water containing e. coli o157:h7 (8 log cfu/ml) for 5 min and ... | 2009 | 19428137 |
| efficacy of sodium hypochlorite and peroxyacetic acid to reduce murine norovirus 1, b40-8, listeria monocytogenes, and escherichia coli o157:h7 on shredded iceberg lettuce and in residual wash water. | the efficiency of sodium hypochlorite (naocl) and peroxyacetic acid (paa) to reduce murine norovirus 1 (mnv-1), a surrogate for human norovirus, and bacteroides fragilis hsp40-infecting phage b40-8 on shredded iceberg lettuce was investigated. the levels of removal of viruses mnv-1 and b40-8 were compared with the reductions observed for bacterial pathogens listeria monocytogenes and escherichia coli o157:h7. two inoculation levels, one with a high organic load and the other containing a 10-fold ... | 2009 | 19517733 |
| internalization of salmonella enterica in leaves is induced by light and involves chemotaxis and penetration through open stomata. | outbreaks of salmonellosis related to consumption of fresh produce have raised interest in salmonella-plant interactions leading to plant colonization. incubation of gfp-tagged salmonella enterica with iceberg lettuce leaves in the light resulted in aggregation of bacteria near open stomata and invasion into the inner leaf tissue. in contrast, incubation in the dark resulted in a scattered attachment pattern and very poor stomatal internalization. forcing stomatal opening in the dark by fusicocc ... | 2009 | 19648358 |
| effectiveness of bacteriophages in reducing escherichia coli o157:h7 on fresh-cut cantaloupes and lettucet. | consumption of produce contaminated with escherichia coli o157:h7 has resulted in cases of foodborne illness. we determined the efficacy of a mixture of three e. coli o157:h7-specific bacteriophages (ecp-100) in reducing the number of viable e. coli o157:h7 on contaminated fresh-cut iceberg lettuce and cantaloupe. e. coli o157:h7 was spot inoculated on lettuce pieces (9 cm2) with a population of 3.76 log cfu/cm2, allowed to dry, and then sprayed with a control (phosphate-buffered saline) or ecp- ... | 2009 | 19681274 |
| use of the systems approach to determine the fate of escherichia coli o157:h7 on fresh lettuce and spinach. | lettuce and spinach inoculated with escherichia coli o157:h7 were processed and handled in ways that might occur in commercial situations, including variations in holding times before and after product cooling, transportation conditions and temperatures, wash treatments, and product storage temperatures and times. populations of background microflora and e. coli o157:h7 were enumerated after each step in the system. data analysis was done to predict response variables with a combination of indep ... | 2009 | 19681286 |
| reduction of escherichia coli o157:h7 on produce by use of electrolyzed water under simulated food service operation conditions. | treatment of fresh fruits and vegetables with electrolyzed water (ew) has been shown to kill or reduce foodborne pathogens. we evaluated the efficacy of ew in killing escherichia coli o157:h7 on iceberg lettuce, cabbage, lemons, and tomatoes by using washing and/or chilling treatments simulating those followed in some food service kitchens. greatest reduction levels on lettuce were achieved by sequentially washing with 14-a (amperage) acidic ew (acew) for 15 or 30 s followed by chilling in 16-a ... | 2009 | 19777886 |
| disinfection of iceberg lettuce by titanium dioxide-uv photocatalytic reaction. | securing the physical quality and microbial safety of fresh foods has been a major focus in the food industry. to improve quality and increase the shelf life of fresh produce, disinfection methods have been developed. titanium dioxide (tio2) photocatalytic reactions under uv radiation produce hydroxyl radicals that can be used for disinfection of foodborne pathogenic bacteria. we investigated the effects of tio2-uv photocatalytic disinfection on the shelf life of iceberg lettuce. counts of natur ... | 2009 | 19777894 |
| evaluation of treatments for elimination of foodborne pathogens on the surface of leaves and roots of lettuce (lactuca sativa l.). | several outbreaks of salmonella and escherichia coli o157:h7 infections have been associated with consumption of leafy greens. questions remain concerning the ability of these pathogens to become internalized within lettuce and spinach tissues. an effective validated surface disinfection method for lettuce is needed before factors affecting internalization of pathogens can be studied. the objective of this study was to develop a surface disinfection method for lettuce leaves and roots. iceberg l ... | 2009 | 19350966 |
| efficacy of myrtle oil against salmonella typhimurium on fresh produce. | the antimicrobial activity of myrtle leaves (myrtus communis) oil was tested against the nalidixic acid resistant strain of salmonella typhimurium atcc 13311. an inoculum (100 microl, ca.10(8) cfu/ml) was deposited on the skin of whole tomatoes and 10 g of shredded iceberg lettuce, dried for 2 h at 22 degrees c and held for 22 h at 4 degrees c before treatments. inoculated iceberg lettuce (3.51-3.99 log cfu/g) and tomatoes (3.47-4.86 log cfu/tomato) were treated with three different washing proc ... | 2009 | 19217679 |
| persistence of escherichia coli on injured iceberg lettuce in the field, overhead irrigated with contaminated water. | fresh produce is increasingly implicated in food-related illnesses. escherichia coli can survive in soil and water and can be transferred onto plant surfaces through farm management practices such as irrigation. a trial was conducted to evaluate the impact of field conditions on e. coli persistence on iceberg lettuce irrigated with contaminated water, and the impact of plant injury on the persistence of e. coli. lettuce heads were injured at 14, 7, 3, 2, 1, and 0 days before inoculation, with un ... | 2009 | 19343931 |
| development of a hierarchical bayesian model to estimate the growth parameters of listeria monocytogenes in minimally processed fresh leafy salads. | the optimal growth rate mu(opt) of listeria monocytogenes in minimally processed (mp) fresh leafy salads was estimated with a hierarchical bayesian model at (mean+/-standard deviation) 0.33+/-0.16 h(-1). this mu(opt) value was much lower on average than that in nutrient broth, liquid dairy, meat and seafood products (0.7-1.3 h(-1)), and of the same order of magnitude as in cheese. cardinal temperatures t(min), t(opt) and t(max) were determined at -4.5+/-1.3 degrees c, 37.1+/-1.3 degrees c and 45 ... | 2009 | 19239977 |
| dry deposition of gaseous radioiodine and particulate radiocaesium onto leafy vegetables. | radionuclides released to the atmosphere during dry weather (e.g. after a nuclear accident) may contaminate vegetable foods and cause exposure to humans via the food chain. to obtain experimental data for an appropriate assessment of this exposure path, dry deposition of radionuclides to leafy vegetables was studied under homogeneous and controlled greenhouse conditions. gaseous (131)i-tracer in predominant elemental form and particulate (134)cs-tracer at about 1 mum diameter were used to identi ... | 2009 | 19640563 |
| optimization and evaluation of a decontamination step with peroxyacetic acid for fresh-cut produce. | since several disadvantages are associated with the use of sodium hypochlorite as a decontamination agent, the attention for alternative agents such as peroxyacetic acid (paa) is increasing. in this study the effectiveness of paa to remove the native microflora was tested in four types of fresh-cut vegetables: grated carrots, fresh-cut white cabbage, iceberg lettuce and leek. furthermore, the influence of varying paa concentrations (0, 25, 80, 150 and 250 ppm) and varying contact times (1, 5 and ... | 2009 | 19835776 |