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alternative disinfection techniques to extend the shelf life of minimally processed iceberg lettuce.chlorination continues to be widely used by the fresh-cut industry for washing and disinfecting minimally processed fruits and vegetables. however, as chlorination has been reported to produce unhealthy by-products such as, chloramines and trihalomethanes, many alternative methods have been reported in the literature. this study examined the use of silver and hydrogen peroxide as possible alternative to chlorination. the results revealed an obvious bactericidal effect of hydrogen peroxide, silve ...201020141938
inactivation of escherichia coli o157:h7 on lettuce, using low-energy x-ray irradiation.low-energy x-ray irradiation was assessed as a means of eliminating escherichia coli o157:h7 on lettuce. round-cut iceberg lettuce samples (2.54-cm diameter) were dip or spot inoculated with a three-strain cocktail of e. coli o157:h7, stored for 24 h at 4 degrees c, and then irradiated at four dose levels up to 0.25 kgy using a prototype low-energy (70 kv) x-ray irradiator. e. coli o157:h7 survivors were quantified by plating on sorbitol macconkey agar containing cefixime and tellurite. dip inoc ...201020202343
development of a cost-effective method for nitrate and nitrite determination in leafy plants and nitrate and nitrite contents of some green leafy vegetables grown in the aegean region of turkey.an accurate, fast, easily applicable, and cost-effective method for the determination of nitrate and nitrite was developed. this method was much more reliable than the cadmium column reduction method, which is a tedious and time-consuming procedure and not easily applicable. the principle of the method was reduction of nitrate to nitrite with cadmium acetate solution and zinc powder and then treatment with griess reagent. recovery of the method changed from 92.9 to 102.8%, and detection limit wa ...201020384339
safety evaluation of an açai-fortified fruit and berry functional juice beverage (monavie active(®)).the safety of an açai (euterpe oleracea mart.) pulp enriched fruit and berry juice, monavie active®, fortified with the functional ingredient, glucosamine, was studied. the beverage was found not to be mutagenic, clastogenic, cytotoxic, or genotoxic, as determined by the bacterial reverse mutation assay, chromosomal aberration assay, mouse micronucleus assay, and mammalian cell gene mutation (l5178y) assay. the single dose ld50 based on a 14-day acute oral toxicity study is greater than 20,000 m ...201020452390
inactivation of murine norovirus 1, coliphage phix174, and bacillus fragilis phage b40-8 on surfaces and fresh-cut iceberg lettuce by hydrogen peroxide and uv light.in this study, the inactivating properties of liquid hydrogen peroxide (l-h(2)o(2)), vaporized hydrogen peroxide (v-h(2)o(2)), uv light, and a combination of v-h(2)o(2) and uv light were tested on murine norovirus 1 (mnv-1) and bacteriophages (φx174 and b40-8) as models for human noroviruses. disinfection of surfaces was examined on stainless steel discs based on european standard en 13697 (2001). for fresh-produce decontamination, a mixture of the viruses was inoculated onto shredded iceberg le ...201021183630
acids in combination with sodium dodecyl sulfate caused quality deterioration of fresh-cut iceberg lettuce during storage in modified atmosphere package.recent studies showed that sodium acid sulfate (sas) and levulinic acid (la) in combination with sodium dodecyl sulfate (sds) was effective in inactivating human pathogens on romaine lettuce. the present study investigated the effects of la and sas in combination with sds (as compared with citric acid and chlorine) on the inactivation of e. coli o157:h7 and sensory quality of fresh-cut iceberg lettuce in modified atmosphere packages during storage at 4 °c. results showed that la (0.5% to 3%) and ...201021535517
effect of storage temperature and duration on the behavior of escherichia coli o157:h7 on packaged fresh-cut salad containing romaine and iceberg lettuce.this study investigated the impact of storage temperature and duration on the fate of escherichia coli o157:h7 on commercially packaged lettuce salads, and on product quality. fresh-cut romaine and iceberg lettuce salads of different commercial brands were obtained from both retail and wholesale stores. the packages were cut open at one end, the lettuce salad inoculated with e. coli o157:h7 via a fine mist spray, and resealed with or without an initial n(2) flush to match the original package at ...201021535546
differences in attachment of salmonella enterica serovars to cabbage and lettuce leaves.this study investigated the ability of five salmonella enterica serovars to attach to and colonize intact and cut lettuce (iceberg, romaine) and cabbage surfaces. biofilm formation and attachment of salmonella serovars to intact and cut leaves were determined. populations of loosely and strongly attached salmonella were obtained to calculate the attachment strength (s(r)). biofilm formation, as determined by microtiter plate assay, varied with strain and growth medium used. salmonella tennessee ...201020226552
binding of virus-like particles of norwalk virus to romaine lettuce veins.noroviruses (nov) annually cause millions of cases of gastrointestinal disease in the united states. nov are associated with raw shellfish outbreaks, particularly oysters, which are thought to bioaccumulate nov particles during the filter-feeding process. nov outbreaks, however, have also been known to occur from other common-source food-borne vehicles, such as lettuce, frozen raspberries, and salad. in this study, we evaluated romaine lettuce as a potential vehicle for nov transmission by testi ...201021037300
effects of x-ray radiation on escherichia coli o157:h7, listeria monocytogenes, salmonella enterica and shigella flexneri inoculated on shredded iceberg lettuce.the main goal of this investigation was to study the efficacy of x-ray doses (0.1, 0.2, 0.3, 0.5, 0.75, 1.0, 1.5 and 2.0 kgy) on inoculated escherichia coli o157: h7, listeria monocytogenes, salmonella enterica and shigella flexneri on shredded iceberg lettuce. the second goal was to study the effect of x-ray on the inherent microflora counts and visual color of shredded iceberg lettuce during storage at 4 degrees c for 30 days. treatment with 1.0 kgy x-ray significantly reduced the population o ...201019913700
modeling logistic performance in quantitative microbial risk assessment.in quantitative microbial risk assessment (qmra), food safety in the food chain is modeled and simulated. in general, prevalences, concentrations, and numbers of microorganisms in media are investigated in the different steps from farm to fork. the underlying rates and conditions (such as storage times, temperatures, gas conditions, and their distributions) are determined. however, the logistic chain with its queues (storages, shelves) and mechanisms for ordering products is usually not taken in ...201020055976
shelf life and sensory characteristics of baby spinach subjected to electron beam irradiation.the use of ionizing radiation for the control of foodborne pathogens and extending the shelf life of fresh iceberg lettuce and fresh spinach has recently been approved by the u.s. food and drug administration. the efficacy of electron beam irradiation for controlling foodborne pathogens has been reported. for this experiment, the effectiveness of electron beam irradiation on the microbiological and sensory characteristics of fresh spinach was studied. total aerobic plate counts were reduced by 2 ...201020722955
water quality concerns and acceptance of irradiated food: a pilot study on mexican consumers.poor quality irrigation water is a major cause of disease transmission for urban inhabitants consuming fresh produce in many developing countries. irradiation of food is an alternative approach to reducing health risks for consumers, but its implementation depends heavily on consumer acceptance.201020648528
nitrate in leafy vegetables, culinary herbs, and cucumber grown under cover in estonia: content and intake.the content of nitrate in leafy vegetables, culinary herbs, and cucumber was determined during the years 2006-2008. all samples of estonian origin, except white cabbage, were grown under cover. seasonal differences in nitrate concentrations were observed in lettuce and spinach. nitrate concentrations in lettuce were 22% and those in spinach were 24% higher in winter crops compared with samples collected in summer. the mean nitrate level was 3023 mg kg(-1) for fresh lettuce and 2337 mg kg(-1) for ...201024785500
modeling the pulsed light inactivation of microorganisms naturally occurring on vegetable substrates.pulsed light (pl) is a fast non-thermal method for microbial inactivation. this research studied the kinetics of pl inactivation of microorganisms naturally occurring in some vegetables. iceberg lettuce, white cabbage and julienne-style cut carrots were subjected to increasing pl fluences up to 12j/cm(2) in order to study its effect on aerobic mesophilic bacteria determined by plate count. also, sample temperature increase was determined by infrared thermometry. survivors' curves were adjusted t ...201121645816
effect of modified atmosphere packaging on the persistence and expression of virulence factors of escherichia coli o157:h7 on shredded iceberg lettuce.fresh-cut leafy greens contaminated with escherichia coli o157:h7 have caused foodborne outbreaks. packaging conditions, coupled with abusive storage temperatures of contaminated lettuce, were evaluated for their effect on the potential virulence of e. coli o157:h7. shredded lettuce was inoculated with 5.58 and 3.98 log cfu e. coli o157:h7 per g and stored at 4 and 15°c, respectively, for up to 10 days. lettuce was packaged under treatment a (modified atmosphere packaging conditions used for com ...201121549041
role of o-antigen on the escherichia coli o157:h7 cells hydrophobicity, charge and ability to attach to lettuce.environmental factors encountered during growing and harvesting may contribute to escherichia coli o157:h7 contamination of lettuce. limited nutrients and extended exposure to water may cause e. coli o157:h7 to shed its o antigen. absence of the o157-polysaccharide antigen could affect the cell's physicochemical properties (hydrophobicity and cell charge) and ultimately influence its attachment to surfaces. the objectives of this study were to evaluate the effect of the e. coli o157:h7 o-antigen ...201121550681
salmonella typhimurium internalization is variable in leafy vegetables and fresh herbs.despite washing and decontamination, outbreaks linked to consumption of fresh or minimally-processed leafy greens have been increasingly reported in recent years. in order to assure the safety of produce it is necessary to gain knowledge regarding the exact routes of contamination. leaf internalization through stomata was previously reported as a potential route of contamination, which renders food-borne pathogens protected from washing and disinfection by sanitizers. in the present study we hav ...201121262550
assessment of escherichia coli o157:h7 transference from soil to iceberg lettuce via a contaminated field coring harvesting knife.the potential for lettuce field-coring harvesting knives to cross-contaminate lettuce heads with pathogens was evaluated. rings and blades of the harvest knives artificially contaminated with escherichia coli o157:h7 (ehec), were used to core three successive heads of iceberg lettuce. the coring rings and blades were inoculated by dipping into soils containing ehec at concentration ranges of 1-10(5) mpn/g soil. factors that influenced ehec transference from soil to iceberg lettuce via contaminat ...201122189025
quantitative microbial risk assessment for escherichia coli o157 on lettuce, based on survival data from controlled studies in a climate chamber.the aims of the study were to determine the survival of escherichia coli o157 on lettuce as a function of temperature and light intensity, and to use that information in a screening-level quantitative microbial risk assessment (qmra) in order to evaluate risk-reducing strategies including irrigation water quality guidelines, rinsing, and holding time between last irrigation and harvest. iceberg lettuce was grown in a climate chamber and inoculated with e. coli o157. bacterial numbers were deter ...201122186038
a survey of iceberg lettuce for the presence of salmonella, escherichia coli o157:h7, and listeria monocytogenes in japan.no information has been available on the prevalence of pathogens in fresh produce in japan. in the present study, information was collected on the occurrence of contamination by salmonella, escherichia coli o157:h7, and listeria monocytogenes in iceberg lettuce in a japanese retail store. a total of 419 samples of lettuce that had been harvested in different districts and/or by different producers from july 2008 to march 2009 were examined. a multiplex pcr method was used to simultaneously ident ...201121902925
Effect of wash treatments on reducing human norovirus on iceberg lettuce and perilla leaf.Human noroviruses (NoVs) are major causes of nonbacterial gastroenteritis; they are transmitted by food and water, as well as person-to-person. The consumption of contaminated raw or uncooked food such as vegetables and fruits has been identified as a common source of human NoV outbreaks. In an effort to understand the survival and persistence of human NoVs on fresh produce, the efficacy of washing treatments in the removal of human NoVs from vegetables was evaluated. This study used artificial ...201122054192
chlorine stabilizer t-128 enhances efficacy of chlorine against cross-contamination by e. coli o157:h7 and salmonella in fresh-cut lettuce processing.during fresh-cut produce processing, organic materials released from cut tissues can rapidly react with free chlorine in the wash solution, leading to the potential survival of foodborne bacterial pathogens, and cross-contamination when the free chlorine is depleted. a reported chlorine stabilizer, t-128, has been developed to address this problem. in this study, we evaluated the ability of t-128 to stabilize free chlorine in wash solutions in the presence of high organic loads generated by the ...201121535847
antimicrobial activity of apple, hibiscus, olive, and hydrogen peroxide formulations against salmonella enterica on organic leafy greens.salmonella enterica is one of the most common bacterial pathogens implicated in foodborne outbreaks involving fresh produce in the last decade. in an effort to discover natural antimicrobials for use on fresh produce, the objective of the present study was to evaluate the effectiveness of different antimicrobial plant extract-concentrate formulations on four types of organic leafy greens inoculated with s. enterica serovar newport. the leafy greens tested included organic romaine and iceberg le ...201122004815
iceberg lettuce as suggested source of a nationwide outbreak caused by two salmonella serotypes, newport and reading, in finland in 2008.a nationwide outbreak of salmonella enterica serotypes newport and reading occurred between 17 october and 28 november 2008 in finland. a total of 77 culture-confirmed salmonella newport and 30 salmonella reading cases, including one case with a double infection, were reported. all strains isolated from the patients were subtyped using serotyping, microbial resistance profiling, and pulsed-field gel electrophoresis (pfge). here, the pfge patterns of the studied salmonella newport strains were id ...201121669088
direct and sensitive detection of foodborne pathogens within fresh produce samples using a field-deployable handheld device.direct and sensitive detection of foodborne pathogens from fresh produce samples was accomplished using a handheld lab-on-a-chip device, requiring little to no sample processing and enrichment steps for a near-real-time detection and truly field-deployable device. the detection of escherichia coli k12 and o157:h7 in iceberg lettuce was achieved utilizing optimized mie light scatter parameters with a latex particle immunoagglutination assay. the system exhibited good sensitivity, with a limit of ...201121840701
multiple outbreaks of salmonella braenderup associated with consumption of iceberg lettuce.the aim of this study was to describe the findings from an outbreak investigation following several apparently unrelated community outbreaks of gastroenteritis. epidemiological, environmental, laboratory and traceback investigations were used to identify the source of the outbreak. we enrolled 23 (of 29) laboratory confirmed cases and 24 neighbourhood case-nominated controls in a case-control study which revealed that illness was associated with consumption of iceberg lettuce (matched odds ratio ...201121916661
effect of curli expression and hydrophobicity of escherichia coli o157:h7 on attachment to fresh produce surfaces.to investigate the effect of curli expression on cell hydrophobicity, biofilm formation and attachment to cut and intact fresh produce surfaces.201121205101
inactivation of a human norovirus surrogate, human norovirus virus-like particles, and vesicular stomatitis virus by gamma irradiation.gamma irradiation is a nonthermal processing technology that has been used for the preservation of a variety of food products. this technology has been shown to effectively inactivate bacterial pathogens. currently, the fda has approved doses of up to 4.0 kgy to control food-borne pathogens in fresh iceberg lettuce and spinach. however, whether this dose range effectively inactivates food-borne viruses is less understood. we have performed a systematic study on the inactivation of a human norovi ...201121441330
sensitivity of poliovirus type 1 chat strain and rotavirus sa-11 to e-beam irradiation on iceberg lettuce and spinach: quantifying the reduction in potential health risks.fresh produce such as lettuce and spinach serve as routes of foodborne illnesses. the u.s. fda has approved the use of ionizing irradiation upto 4 kgy as a pathogen kill step for fresh cut lettuce and spinach. the focus of this study was to determine the inactivation of poliovirus and rotavirus on lettuce and spinach when exposed to varying doses of high energy e-beam irradiation and to calculate the theoretical reduction in infection risks that can be achieved under different contamination scen ...201122179244
multistate outbreak of escherichia coli o157:h7 infections associated with a national fast-food chain, 2006: a study incorporating epidemiological and food source traceback results.a multistate outbreak of escherichia coli o157:h7 infections occurred in the usa in november-december 2006 in patrons of restaurant chain a. we identified 77 cases with chain a exposure in four states - delaware, new jersey, new york, and pennsylvania. fifty-one (66%) patients were hospitalized, and seven (9%) developed haemolytic uraemic syndrome; none died. in a matched analysis controlling for age in 31 cases and 55 controls, illness was associated with consumption of shredded iceberg lettuce ...201120429971
efficacy of slightly acidic electrolyzed water in killing or reducing escherichia coli o157:h7 on iceberg lettuce and tomatoes under simulated food service operation conditions.the objective of this study was to evaluate the efficacy of slightly acidic electrolyzed (saeo) water in killing or removing escherichia coli o157:h7 on iceberg lettuce and tomatoes by washing and chilling treatment simulating protocols used in food service kitchens. whole lettuce leaves and tomatoes were spot-inoculated with 100 μl of a mixture of 5 strains of e. coli o157:h7. washing lettuce with saeo water for 15 s reduced the pathogen by 1.4 to 1.6 log cfu/leaf, but the treatments did not co ...201122417508
comparison of sample preparation methods for the recovery of foodborne pathogens from fresh produce.sample preparation methods (pummeling, pulsifying, sonication, and shaking by hand) were compared for achieving maximum recovery of foodborne pathogens from iceberg lettuce, perilla leaves, cucumber, green pepper, and cherry tomato. antimicrobial and dehydration effects also were examined to investigate causes of poor recovery of pathogens. each produce type was inoculated with escherichia coli o157:h7, salmonella typhimurium, listeria monocytogenes, staphylococcus aureus, and bacillus cereus at ...201222980003
development of a risk-based methodology for estimating survival and growth of enteropathogenic escherichia coli on iceberg-lettuce exposed at short-term storage in foodservice centers.ready-to-eat lettuce is a food commodity prone to contamination by pathogenic microorganisms if processing and distribution conditions as well as handling practices are not effective. a challenge testing protocol was applied to ready-to-eat iceberg-lettuce samples by inoculating different initial contamination levels (4.5, 3.5 and 2.5 log cfu/g) of escherichia coli strain (serotype o158:h23) subsequently stored at 8, 12, 16, 20 and 24°c for 6h. a polynomial regression model for log difference (l ...201222677605
survival and growth of foodborne pathogens in minimally processed vegetables at 4 and 15 °c.we conducted this study to investigate the survival and growth of pathogens on fresh vegetables stored at 4 and 15 °c. vegetables (romaine lettuce, iceberg lettuce, perilla leaves, and sprouts) were inoculated with 4 pathogens (salmonella enterica serovar typhimurium, staphylococcus aureus, listeria monocytogenes, and escherichia coli o157:h7) and stored at 2 different temperatures for different periods of time (3, 6, 9, 12, and 15 d at 4 °c and 1, 2, 3, 5, and 7 d at 15 °c). populations of the ...201222260117
a pilot plant scale evaluation of a new process aid for enhancing chlorine efficacy against pathogen survival and cross-contamination during produce wash.developing food safety intervention technology that can be readily adopted by the industry often requires test conditions that match as closely as possible to those of commercial food processing operations; yet biosafety risks inherent in pathogen studies constrain most experiments to laboratory settings. in this study, we report the first semi-commercial pilot-scale evaluation of a new process aid, t128, for its impact on enhancing the antimicrobial efficacy of chlorinated wash water against pa ...201222857846
quantitative transfer of escherichia coli o157:h7 to equipment during small-scale production of fresh-cut leafy greens.postharvest contamination and subsequent spread of escherichia coli o157:h7 can occur during shredding, conveying, fluming, and dewatering of fresh-cut leafy greens. this study quantified e. coli o157:h7 transfer from leafy greens to equipment surfaces during simulated small-scale commercial processing. three to five batches (22.7 kg) of baby spinach, iceberg lettuce, and romaine lettuce were dip inoculated with a four-strain cocktail of avirulent, green fluorescent protein-labeled, ampicillinre ...201222980000
application of propidium monoazide quantitative pcr for selective detection of live escherichia coli o157:h7 in vegetables after inactivation by essential oils.the use of propidium monoazide (pma) is enjoying increased popularity among researchers in different fields of microbiology. its use in combination with real-time pcr (qpcr) represents one of the most successful approaches to detect viable cells. pma-qpcr has successfully been used to evaluate the efficacy of various disinfection technologies in different microorganisms. initially, in this study the effect of four essential oils (eos), cumin, clove, oregano and cinnamon, was evaluated on suspens ...201223072696
electrostatic spraying of food-grade organic and inorganic acids and plant extracts to decontaminate escherichia coli o157:h7 on spinach and iceberg lettuce.the prevalence of foodborne illnesses is continually on rise. in the u.s.a., escherichia coli o157:h7 (e. coli) has been associated with several outbreaks in minimally processed foods. spinach and lettuce pose higher food safety risks and recurring food recalls suggest the insufficiency of current disinfection strategies. we aimed at offering a natural antimicrobial alternative using organic acids (malic, tartaric, and lactic acids [ma, ta, and la, respectively]) and grape seed extract (gse) and ...201222757712
multi-residue determination of pharmaceutical and personal care products in vegetables.treated wastewater irrigation and biosolid amendment are increasingly practiced worldwide and contamination of plants, especially produces that may be consumed raw by humans, by pharmaceutical and personal care products (ppcps), is an emerging concern. a sensitive method was developed for the simultaneous measurement of 19 frequently-occurring ppcps in vegetables using high-performance liquid chromatography-electrospray ionization tandem mass spectrometry (hplc-esi-ms/ms) for detection, combined ...201222867843
antimicrobial activity of oregano oil against antibiotic-resistant salmonella enterica on organic leafy greens at varying exposure times and storage temperatures.the objective of this study was to evaluate the effectiveness of oregano oil on four organic leafy greens (iceberg and romaine lettuces and mature and baby spinaches) inoculated with salmonella newport as a function of treatment exposure times as well as storage temperatures. leaf samples were washed, dip inoculated with s. newport (6-log cfu/ml) and dried. oregano oil was prepared at 0.1, 0.3, and 0.5% concentrations in sterile phosphate buffered saline (pbs). inoculated leaves were immersed in ...201223498188
antimicrobial activity of oregano oil on iceberg lettuce with different attachment conditions.in this study, the antimicrobial activity of oregano oil was investigated under different attachment conditions of salmonella spp. to iceberg lettuce. inoculated lettuce was either not dried or dried for 30 min, 60 min, or 120 min, under either static air or moving air. washing iceberg lettuce with 500 ppm oregano oil for 1, 5, and 10 min reduced the population of salmonella spp. by (respectively) 1.3, 1.65, and 2.28 log cfu/g following the most challenging inoculation conditions, an inoculum dr ...201222757714
degradation of cyprodinil, fludioxonil, cyfluthrin and pymetrozine on lettuce after different application methods.degradation of two fungicides (cyprodinil and fludioxonil) and two insecticides (cyfluthrin and pymetrozine) applied on iceberg and romaine lettuce under field conditions with different methods (portable mistblower and chemigation) was studied field data showed that both distribution methods and lettuce cultivar affect the degradation trends of examined pesticides. in these trials the residues of all active ingredients after pre-harvest time were less than fifty's maximum residue levels; the val ...201217763031
isolation of phenolic compounds from iceberg lettuce and impact on enzymatic browning.enzymatic browning is generally reported as the reaction between phenolic substances and enzymes. the quality of iceberg lettuce is directly linked to this discoloration. in particular, the color change of lettuce stems considerably reduces consumer acceptance and thus decreases sales revenue of iceberg lettuce. ten phenolic compounds (caffeic acid, chlorogenic acid, phaseolic acid, chicoric acid, isochlorogenic acid, luteolin-7-o-glucuronide, quercetin-3-o-glucuronide, quercetin-3-o-galactoside ...201323473017
role of ascorbic acid in the inhibition of polyphenol oxidase and the prevention of browning in different browning-sensitive lactuca sativa var. capitata (l.) and eruca sativa (mill.) stored as fresh-cut produce.polyphenol oxidase (ppo) and, to a minor extent, peroxidase (pod) represent the key enzymes involved in enzymatic browning, a negative process induced by cutting fresh-cut produce such as lettuce (lactuca sativa) and rocket salad (eruca sativa). although ascorbic acid is frequently utilised as an anti-browning agent, its mechanism in the prevention of the browning phenomenon is not clearly understood.201323184255
dose-dependent effects of gamma radiation on lettuce (lactuca sativa var. capitata) seedlings.abstract purpose: the objectives of this study were to determine the effects of gamma radiation on lettuce growth and development, as well as on the content of photosynthetic pigments in 28 days lettuce leaf.201323020834
efficacy of commercial produce sanitizers against nontoxigenic escherichia coli o157:h7 during processing of iceberg lettuce in a pilot-scale leafy green processing line.chemical sanitizers are routinely used during commercial flume washing of fresh-cut leafy greens to minimize cross-contamination from the water. this study assessed the efficacy of five commercial sanitizer treatments against escherichia coli o157:h7 on iceberg lettuce, in wash water, and on equipment during simulated commercial production in a pilot-scale processing line. iceberg lettuce (5.4 kg) was inoculated to contain 10(6) cfu/g of a four-strain cocktail of nontoxigenic, green fluorescent ...201324215685
inactivation of internalized salmonella typhimurium in lettuce and green onion using ultraviolet c irradiation and chemical sanitizers.the internalized human pathogens in fresh produce are not effectively removed during conventional washing, and therefore, it may cause foodborne illness when the produce is consumed raw. thus, effective nonthermal processes are needed to prevent this risk.201323351161
modelling growth of escherichia coli o157:h7 in fresh-cut lettuce submitted to commercial process conditions: chlorine washing and modified atmosphere packaging.fresh-cut iceberg lettuce inoculated with escherichia coli o157:h7 was submitted to chlorine washing (150 mg/ml) and modified atmosphere packaging on laboratory scale. populations of e. coli o157:h7 were assessed in fresh-cut lettuce stored at 4, 8, 13 and 16 °c using 6-8 replicates in each analysis point in order to capture experimental variability. the pathogen was able to grow at temperatures ≥8 °c, although at low temperatures, growth data presented a high variability between replicates. ind ...201323200644
evaluation of models describing the growth of nalidixic acid-resistant e. coli o157:h7 in blanched spinach and iceberg lettuce as a function of temperature.the aim of this study was to model the growth of nalidixic acid-resistant e. coli o157:h7 (e. coli o157:h7nr) in blanched spinach and to evaluate model performance with an independent set of data for interpolation (8.5, 13, 15 and 27 °c) and for extrapolation (broth and fresh-cut iceberg lettuce) using the ratio method and the acceptable prediction zone method. the lag time (lt), specific growth rate (sgr) and maximum population density (mpd) obtained from each primary model were modeled as a fu ...201323839062
the antimicrobial effects of cinnamon leaf oil against multi-drug resistant salmonella newport on organic leafy greens.there is generally no kill-step when preparing salad vegetables, so there is a greater risk for foodborne illness from contaminated vegetables. some essential oils have antimicrobial activities and could provide a natural way to reduce pathogens on fresh produce. the objective of this study was to investigate the antimicrobial activity of cinnamon oil wash against salmonella enterica serotype newport on organic leafy greens. organic romaine and iceberg lettuce, and organic baby and mature spinac ...201323911760
antimicrobial activity of plant essential oils against escherichia coli o157:h7 and salmonella on lettuce.foodborne outbreaks associated with the consumption of fresh produce have increased. in an effort to identify natural antimicrobial agents as fresh produce-wash, the effect of essential oils in reducing enteric pathogens on iceberg and romaine lettuce was investigated. lettuce pieces were inoculated with a five-strain cocktail of escherichia coli o157:h7 or salmonella enterica (5 log cfu/g) and then immersed in a treatment solution containing 5 ppm free chlorine, cinnamaldehyde, or sporan(®) (80 ...201323256843
outbreaks of cyclosporiasis--united states, june-august 2013.during june-august 2013, cdc, state and local public health officials, and the food and drug administration (fda) investigated an unusually large number of reports of cyclosporiasis (compared with annual reports to the national notifiable disease surveillance system [e.g., 123 cases in 2012]), an intestinal infection caused by the parasite cyclospora cayetanensis. by september 20, cdc had been notified of 643 cases from 25 states, primarily texas (278 cases), iowa (153), and nebraska (86). inves ...201324172881
combined effects of ultrasound and surfactants to reduce bacillus cereus spores on lettuce and carrots.this study was performed to compare the effectiveness of ultrasound treatment singly and in combination with surfactants as an alternative method to conventional sanitizers containing chlorine for reducing numbers of bacillus cereus spores on fresh produce. a cocktail of three strains of b. cereus (10876, atcc 13061, and w-1) spores was inoculated onto iceberg lettuce and then treated with ultrasound for 0, 5, 10, 20 and 60 min. five minutes was found to be an adequate ultrasound (40 khz, 30 w/l ...201323290247
lead and cadmium in some berries and vegetables on the finnish market in 1991-1993.in order to determine the present contribution of vegetables and berries to the intake of lead and cadmium in finland major vegetable groups as well as strawberries and blackcurrants were collected from wholesale distribution centres, orchards and the food industry. pooled samples were mixed to represent wholesale distribution centres, exporting countries or geographical regions. lead and cadmium were determined after wet digestion in concentrated hno3 using etaas with zeeman effect background c ...20137781823
extended spectrum ß-lactamase- and constitutively ampc-producing enterobacteriaceae on fresh produce and in the agricultural environment.the attribution of fresh produce to the overall community-associated exposure of humans to esbl- or ampc-producing bacteria is currently unknown. to address this issue, the prevalence of esbl- and ampc-producing enterobacteriaceae on fresh produce produced in the netherlands was determined. seven vegetable types that are consumed raw were selected: blanched celery, bunched carrots, chicory, endive, iceberg lettuce, mushrooms, and radish. the vegetables were mostly obtained from supermarkets. to ...201424211774
clostridium difficile with moxifloxacin/clindamycin resistance in vegetables in ohio, usa, and prevalence meta-analysis.we (i) determined the prevalence of clostridium difficile and their antimicrobial resistance to six antimicrobial classes, in a variety of fresh vegetables sold in retail in ohio, usa, and (ii) conducted cumulative meta-analysis of reported prevalence in vegetables since the 1990s. six antimicrobial classes were tested for their relevance as risk factors for c. difficile infections (cdis) (clindamycin, moxifloxacin) or their clinical priority as exhaustive therapeutic options (metronidazole, van ...201425580297
impact of phytopathogen infection and extreme weather stress on internalization of salmonella typhimurium in lettuce.internalization of human pathogens, common in many types of fresh produce, is a threat to human health since the internalized pathogens cannot be fully inactivated/removed by washing with water or sanitizers. given that pathogen internalization can be affected by many environmental factors, this study was conducted to investigate the influence of two types of plant stress on the internalization of salmonella typhimurium in iceberg lettuce during pre-harvest. the stresses were: abiotic (water str ...201424220663
synergistic effects of ultrasound and sodium hypochlorite (naocl) on reducing listeria monocytogenes atcc19118 in broth, stainless steel, and iceberg lettuce.this study was performed in order to determine whether a combined treatment of ultrasound and sodium hypochlorite (naocl) is more effective than individual treatment on reducing listeria monocytogenes atcc19118 on stainless steel and iceberg lettuce. the bactericidal effect of ultrasound and naocl was investigated in tryptic soy broth (tsb), on stainless steel and iceberg lettuce. various concentrations of naocl (50, 100, 150, and 200 ppm) were tested along with various ultrasound treatment time ...201424927252
impact of organic load on escherichia coli o157:h7 survival during pilot-scale processing of iceberg lettuce with acidified sodium hypochlorite.chemical sanitizers are routinely used during commercial flume washing of fresh-cut leafy greens to minimize cross-contamination from the water. this study assessed the efficacy of three chlorine treatments against escherichia coli o157:h7 on iceberg lettuce, in wash water, and on surfaces of a pilot-scale processing line using flume water containing various organic loads. iceberg lettuce (5.4 kg) was inoculated to contain 10(6) cfu/g of a 4-strain cocktail of nontoxigenic, green fluorescent pro ...201425285483
tracking an escherichia coli o157:h7-contaminated batch of leafy greens through a pilot-scale fresh-cut processing line.cross-contamination of fresh-cut leafy greens with residual escherichia coli o157:h7-contaminated product during commercial processing was likely a contributing factor in several recent multistate outbreaks. consequently, radicchio was used as a visual marker to track the spread of the contaminated product to iceberg lettuce in a pilot-scale processing line that included a commercial shredder, step conveyor, flume tank, shaker table, and centrifugal dryer. uninoculated iceberg lettuce (45 kg) wa ...201425198839
prevalence and concentration of bacterial pathogens in raw produce and minimally processed packaged salads produced in and for the netherlands.recent outbreaks with vegetable or fruits as vehicles have raised interest in the characterization of the public health risk due to microbial contamination of these commodities. because qualitative and quantitative data regarding prevalence and concentration of various microbes are lacking, we conducted a survey to estimate the prevalence and contamination level of raw produce and the resulting minimally processed packaged salads as sold in the netherlands. a dedicated sampling plan accounted fo ...201424674429
arbuscular mycorrhizal symbiosis alleviates detrimental effects of saline reclaimed water in lettuce plants.the present study evaluated the effects of inoculation with arbuscular mycorrhizal fungi (amf; glomus iranicum var. tenuihypharum sp. nova) on the physiological performance and production of lettuce plants grown under greenhouse conditions and supplied with reclaimed water (rw; urban-treated wastewater with high electrical conductivity; 4.19 ds m(-1)). four treatments, fresh water, fresh water plus amf inoculation, rw and rw plus amf inoculation, were applied and their effects, over time, analyz ...201424287607
nitrates and nitrites in selected vegetables purchased at supermarkets in siedlce, poland.vegetables constitute a vital part of the human diet, being the main source of minerals, vitamins, dietary fibre and phytochemicals. they however, also contain nitrates and nitrites, which adversely affect human health.201424964574
comparison of the microbiological quality of environmentally friendly and conventionally grown vegetables sold at retail markets in korea.fresh produce is usually eaten raw without cooking or heating, which may increase the probability of foodborne infection. the microbiological quality of 11 types of fresh, raw vegetables (romaine lettuce, sesame leaves, crown daisy, garlic chives, iceberg lettuce, cabbage, broccoli, leek, chili pepper, capsicum, and zucchini) purchased at retail markets in iksan, korea as affected by cultivation method (environmentally friendly vegetables [organic, pesticide-free, and low-pesticide vegetables] a ...201425124136
whole-head washing, prior to cutting, provides sanitization advantages for fresh-cut iceberg lettuce (latuca sativa l.).the efficacy of two leafy produce wash methods, the traditional cutting-before-washing process and a new washing-before-cutting method, on reduction of escherichia coli o157:h7 inoculated on iceberg lettuce was compared. the washing tests were conducted in a pilot-scale washer using combinations of water, chlorine, peroxyacetic acid, and ultrasound. the washing-before-cutting process recorded an e. coli o157:h7 count reduction 0.79-0.80 log₁₀ cfu/g higher than that achieved with the cutting-befo ...201424704862
apple, carrot, and hibiscus edible films containing the plant antimicrobials carvacrol and cinnamaldehyde inactivate salmonella newport on organic leafy greens in sealed plastic bags.the objective of this study was to investigate the antimicrobial effects of carvacrol and cinnamaldehyde incorporated into apple, carrot, and hibiscus-based edible films against salmonella newport in bagged organic leafy greens. the leafy greens tested included organic romaine and iceberg lettuce, and mature and baby spinach. each leafy green sample was washed, dip inoculated with s. newport (10⁷ cfu/ml), and dried. each sample was put into a ziploc® bag. edible films pieces were put into the zi ...201424460771
development of an algorithm for feed-forward chlorine dosing of lettuce wash operations and correlation of chlorine profile with escherichia coli o157:h7 inactivation.the dynamic interactions of chlorine and organic matter during a simulated fresh-cut produce wash process and the consequences for escherichia coli o157:h7 inactivation were investigated. an algorithm for a chlorine feed-forward dosing scheme to maintain a stable chlorine level was further developed and validated. organic loads with chemical oxygen demand of 300 to 800 mg/liter were modeled using iceberg lettuce. sodium hypochlorite (naocl) was added to the simulated wash solution incrementally. ...201424680066
lettucenin sesquiterpenes contribute significantly to the browning of lettuce.wound-induced changes in the composition of secondary plant compounds cause the browning of processed lettuce. cut tissues near the lettuce butt end clearly exhibit increased formation of yellow-brown pigments. this browning reaction is typically been attributed to the oxidation of polyphenols by the enzyme polyphenol oxidase (ppo). however, in our previous study on iceberg lettuce, we showed that, besides the enzymatic polyphenol browning, other reactions must be involved in the formation of co ...201424818869
retention of iceberg lettuce quality by low temperature storage and postharvest application of 1-methylcyclopropene or gibberellic acid.this study was conducted to evaluate the changes in quality of iceberg lettuce during storage at different temperatures and the effects of postharvest treatments of 1-methylcyclopropene or gibberellic acid at high temperature. the results showed that quality of the lettuce was remarkably retained during storage at 0 °c, but significantly declined at 20 °c. however, quality of the vegetable at shelf-temperature (20 °c, 85 ~ 95% rh) was effectively delayed by the treatment with 1-methylcyclopropen ...201424803702
standard addition method based on four-way parafac decomposition to solve the matrix interferences in the determination of carbamate pesticides in lettuce using excitation-emission fluorescence data.the simultaneous determination of two carbamate pesticides (carbaryl and carbendazim) and of the degradation product of carbaryl (1-naphthol) in iceberg lettuce was achieved by means of parafac decomposition and excitation-emission fluorescence matrices. a standard addition method for a calibration based on four-way data was applied using different dilutions of the extract from iceberg lettuce as a fourth way that provided the enough variation of the matrix to carry out the four-way analysis. a ...201525863376
efficacy of neutral ph electrolyzed water in reducing escherichia coli o157:h7 and salmonella typhimurium dt 104 on fresh produce items using an automated washer at simulated food service conditions.the objective of this study was to determine the efficacy of neutral ph electrolyzed (neo) water (155 mg/l free chlorine, ph 7.5) in reducing escherichia coli o157:h7 and salmonella typhimurium dt 104 on romaine lettuce, iceberg lettuce, and tomatoes washed in an automated produce washer for different times and washing speeds. tomatoes and lettuce leaves were spot inoculated with 100 μl of a 5 strain cocktail mixture of either pathogen and washed with 10 or 8 l of neo water, respectively. washin ...201526155998
effectiveness of active packaging on control of escherichia coli o157:h7 and total aerobic bacteria on iceberg lettuce.contaminated leafy green vegetables have been linked to several outbreaks of human gastrointestinal infections. antimicrobial interventions that are adoptable by the fresh produce industry for control of pathogen contamination are in great demand. this study was undertaken to evaluate the efficacy of sustained active packaging on control of escherichia coli o157:h7 and total aerobic bacteria on lettuce. commercial iceberg lettuce was inoculated with a 3-strain mixture of e. coli o157:h7 at 10(2) ...201525974213
survival of salmonella and escherichia coli o157:h7 on strawberries, basil, and other leafy greens during storage.the survival of salmonella and escherichia coli o157:h7 on strawberries, basil leaves, and other leafy greens (spinach leaves, lamb and butterhead lettuce leaves, baby leaves, and fresh-cut iceberg lettuce) was assessed at cold (<7 °c) and ambient temperatures. all commodities were spot inoculated with e. coli o157:h7 or salmonella to obtain an initial inoculum of 5 to 6 log and 4 to 5 log cfu/g for strawberries and leafy greens, respectively. samples were air packed. strawberries were stored at ...201525836388
methodology for modeling the disinfection efficiency of fresh-cut leafy vegetables wash water applied on peracetic acid combined with lactic acid.a methodology to i) assess the feasibility of water disinfection in fresh-cut leafy greens wash water and ii) to compare the disinfectant efficiency of water disinfectants was defined and applied for a combination of peracetic acid (paa) and lactic acid (la) and comparison with free chlorine was made. standardized process water, a watery suspension of iceberg lettuce, was used for the experiments. first, the combination of paa+la was evaluated for water recycling. in this case disinfectant was a ...201526065727
prevalence and characterization of esbl- and ampc-producing enterobacteriaceae on retail vegetables.in total 1216 vegetables obtained from dutch stores during 2012 and 2013 were analysed to determine the prevalence of 3rd-generation cephalosporin (3gc) resistant bacteria on soil-grown fresh produce possibly consumed raw. vegetables grown conventionally and organically, from dutch as well as foreign origin were compared. included were the following vegetable types; blanched celery (n=192), bunched carrots (n=190), butterhead lettuce (n=137), chicory (n=96), endive (n=188), iceberg lettuce (n=19 ...201525828704
effects of oxygen-depleted atmospheres on survival and growth of listeria monocytogenes on fresh-cut iceberg lettuce stored at mild abuse commercial temperatures.the effects of oxygen-depleted atmospheres, 0.25% o2+12% co2 (balance n2) and 2% o2 + 6% co2 (balance n2), on growth of listeria monocytogenes on fresh-cut iceberg lettuce were determined. the study was carried out at mild abuse temperatures using controlled atmosphere chambers. during storage at a constant temperature of 7 °c, growth was enhanced at the lower oxygen level of 0.25% o2 by day 10. over 17 days of storage at temperatures designed to mimic mild abuse commercial conditions, there wer ...201525790986
salmonella surveillance on fresh produce in retail in turkey.although turkey is one of the major producers of fruits and vegetables in the world, there has been no information available on the prevalence of pathogens in fresh produce. to fill this gap, we collected 503 fresh produce samples including tomato, parsley, iceberg lettuce, green-leaf lettuce and five different fresh pepper varieties (i.e., green, kapya, bell, mazamort and charleston) from 3 major districts within 9 supermarkets and 3 bazaars in ankara, turkey to investigate the presence of salm ...201525643853
occurrence of multidrug resistant extended spectrum beta-lactamase-producing bacteria on iceberg lettuce retailed for human consumption.antibiotic resistance in bacteria is a global problem exacerbated by the dissemination of resistant bacteria via uncooked food, such as green leafy vegetables. new strains of bacteria are emerging on a daily basis with novel expanded antibiotic resistance profiles. in this pilot study, we examined the occurrence of antibiotic resistant bacteria against five classes of antibiotics on iceberg lettuce retailed in local convenience stores in rochester, michigan. in this study, 138 morphologically di ...201526064922
minimal processing of iceberg lettuce has no substantial influence on the survival, attachment and internalization of e. coli o157 and salmonella.the influence of a selection of minimal processing techniques (sanitizing wash prior to packaging, modified atmosphere, storage conditions under light or in the dark) was investigated in relation to the survival of, attachment to and internalization of enteric pathogens in fresh produce. cut iceberg lettuce was chosen as a model for fresh produce, escherichia coli o157:h7 (e. coli o157) and salmonella enterica were chosen as pathogen models. care was taken to simulate industrial post-harvest pro ...201627591385
assessing the growth of escherichia coli o157:h7 and salmonella in spinach, lettuce, parsley and chard extracts at different storage temperatures.the objective of this work was to study the growth potential of escherichia coli o157:h7 and salmonella spp. in leafy vegetable extracts at different temperature conditions.201626950043
structural and sensory characterization of novel sesquiterpene lactones from iceberg lettuce.lactuca sativa var. capitate (iceberg lettuce) is a delicious vegetable and popular for its mild taste. nevertheless, iceberg lettuce is a source of bitter substances, such as the sesquiterpene lactones. chemical investigations on the n-butanol extract led to the isolation of three novel sesquiterpene lactones. all compounds were isolated by multilayer countercurrent chromatography followed by preparative high-performance liquid chromatography. the structures were verified by means of spectrosco ...201626727458
efficacy of slightly acidic electrolyzed water and uv-ozonated water combination for inactivating escherichia coli o157:h7 on romaine and iceberg lettuce during spray washing process.spray washing is a common sanitizing method for the fresh produce industry. the purpose of this research was to investigate the antimicrobial effect of spraying slightly acidic electrolyzed water (saew) and a combination of ozonated water with ultraviolet (uv) in reducing escherichia coli o157:h7 on romaine and iceberg lettuces. both romaine and iceberg lettuces were spot inoculated with 100 μl of a 3 strain mixture of e. coli o157:h7 to achieve an inoculum of 6 log cfu/g on lettuce. a strong an ...201627305593
acinetobacter lactucae sp. nov., isolated from iceberg lettuce (asteraceae: lactuca sativa).strain nrrl b-41902t and three closely related strains were isolated from iceberg lettuce. the strain was found to consist of strictly aerobic, gram-stain-negative rods that formed cocci in late stationary phase. 16s rrna gene sequence analysis showed that strain nrrl b-41902t was most closely related to species within the genera acinetobacter, and that a grouping of it and the three other closely related strains was most closely related to the type strain of acinetobacter pittii, which was also ...201627339105
is there a relation between the microscopic leaf morphology and the association of salmonella and escherichia coli o157:h7 with iceberg lettuce leaves?to prevent contamination of fresh produce with enteric pathogens, more insight into mechanisms that may influence the association of these pathogens with fresh produce is needed. in this study, escherichia coli o157:h7 and salmonella were chosen as model pathogens, and fresh cut iceberg lettuce was chosen as a model fresh produce type. the morphological structure of iceberg lettuce leaves (stomatal density and length of cell margins per leaf area) was quantified by means of leaf peels and light ...201628221853
national outbreak of yersinia enterocolitica infections in military and civilian populations associated with consumption of mixed salad, norway, 2014.in may 2014, a cluster of yersinia enterocolitica (ye) o9 infections was reported from a military base in northern norway. concurrently, an increase in ye infections in civilians was observed in the norwegian surveillance system for communicable diseases. we investigated to ascertain the extent of the outbreak and identify the source in order to implement control measures. a case was defined as a person with laboratory-confirmed ye o9 infection with the outbreak multilocus variable-number tandem ...201627588690
3-chlorotyrosine formation in ready-to-eat vegetables due to hypochlorite treatment and its dietary exposure and risk assessment.washing of iceberg lettuce with hocl solutions in concentrations ranging from 1.41 to 141mg/l resulted in 0.69 to 2.05μg3-chlorotyrosine/g vegetable. as also six commercial ready-to-eat iceberg lettuces from different producers contained 3-chlorotyrosine from 1.00 to 2.24μg/g vegetable, a total of 122 ready-to-eat vegetable samples purchased in belgian supermarkets were further screened for their 3-chlorotyrosine content. 3-chlorotyrosine was detected above the detection limit (0.19μg/g sample) ...201629195871
improving light distribution by zoom lens for electricity savings in a plant factory with light-emitting diodes.the high energy consumption of a plant factory is the biggest issue in its rapid expansion, especially for lighting electricity, which has been solved to a large extent by light-emitting diodes (led). however, the remarkable potential for further energy savings remains to be further investigated. in this study, an optical system applied just below the led was designed. the effects of the system on the growth and photosynthesis of butterhead lettuce (lactuca sativa var. capitata) were examined, a ...201626904062
assessing the effect of sodium dichloroisocyanurate concentration on transfer of salmonella enterica serotype typhimurium in wash water for production of minimally processed iceberg lettuce (lactuca sativa l.).this study evaluated the impact of sodium dichloroisocyanurate (5, 10, 20, 30, 40, 50 and 250 mg l(-1) ) in wash water on transfer of salmonella typhimurium from contaminated lettuce to wash water and then to other noncontaminated lettuces washed sequentially in the same water. experiments were designed mimicking the conditions commonly seen in minimally processed vegetable (mpv) processing plants in brazil. the scenarios were as follows: (1) washing one inoculated lettuce portion in nonchlorina ...201627105015
deficit irrigation reduces postharvest rib pinking in wholehead iceberg lettuce, but at the expense of head fresh weight.postharvest pinking is a serious issue affecting lettuce quality. previous studies suggested the possibility of using deficit irrigation to control discolouration; however, this approach may also affect yield. this study investigated the effect of varying irrigation deficits on iceberg lettuce (lactuca sativa l.) to determine the relationship between irrigation deficit, pinking and fresh weight.201727404345
inactivation of human norovirus genogroups i and ii and surrogates by free chlorine in postharvest leafy green wash water.human noroviruses (hnovs) are a known public health concern associated with the consumption of leafy green vegetables. while a number of studies have investigated pathogen reduction on the surfaces of leafy greens during the postharvest washing process, there remains a paucity of data on the level of treatment needed to inactivate viruses in the wash water, which is critical for preventing cross-contamination. the objective of this study was to quantify the susceptibility of hnov genotype i (gi) ...201728887415
presence of trihalomethanes in ready-to-eat vegetables disinfected with chlorine.trihalomethanes (thms) - chcl3, chcl2br, chclbr2 and chbr3 - are drinking water disinfection by-products (dbps). these compounds can also be absorbed by different types of foods, including ready-to-eat (rte) fresh vegetables. the potential absorption of thms during washing of rte vegetables could pose a potential risk to consumers' health. the concentration of thms in the water used in the manufacturing process of these products shall not exceed the limit of 100 or 80 µgl-1 according to european ...201728934070
occupational rhinoconjunctivitis caused by the common indoor plant, hoya compacta.allergic reactions to the common house plant hoya compacta (hc) have not previously been described.201728898962
effect of different elicitors and preharvest day application on the content of phytochemicals and antioxidant activity of butterhead lettuce (lactuca sativa var. capitata) produced under hydroponic conditions.the effect of four elicitors on phytochemical content in two varieties of lettuce was evaluated. the best preharvest day for application of each elicitor was chosen. solutions of arachidonic acid (aa), salicylic acid (sa), methyl jasmonate (mj), and harpin protein (hp) were applied by foliar aspersion on lettuce leaves while cultivating under hydroponic conditions. application of elicitors was done at 15, 7, 5, 3, or 1 day before harvest. green lettuce showed the highest increase in phytochemica ...201728613869
persistence of escherichia coli o157:h7 during pilot-scale processing of iceberg lettuce using flume water containing peroxyacetic acid-based sanitizers and various organic loads.in order to minimize cross-contamination during leafy green processing, chemical sanitizers are routinely added to the wash water. this study assessed the efficacy of peroxyacetic acid and mixed peracid against e. coli o157:h7 on iceberg lettuce, in wash water, and on equipment during simulated commercial production in a pilot-scale processing line using flume water containing various organic loads. iceberg lettuce (5.4kg) inoculated to contain 10(6)cfu/g of a 4-strain cocktail of non-toxigenic, ...201728237883
manipulation of contents of nitrate, phenolic acids, chlorophylls, and carotenoids in lettuce (lactuca sativa l.) via contrasting responses to nitrogen fertilizer when grown in a controlled environment.this study aimed to use different nitrogen fertilizer regimes to produce butterhead lettuce with such large differences in nitrate content that they could be used as treatment and placebo to study the effect of inorganic nitrate on human health. plants were grown under controlled conditions at 27/23 °c day/night with a relatively low photosynthetically active radiation (par) of 150 μmol m-2 s-1 for 14 h day-1 and nitrogen supplies ranging from 26 to 154 ppm of n as ammonium nitrate in the fertig ...201729059519
inoculation density is affecting growth conditions of listeria monocytogenes on fresh cut lettuce.listeria monocytogenes is a particular risk for the ready-to-eat food sector because of its ability to grow in various environmental conditions. in the literature, growth and survival of l. monocytogenes on food is tested using inoculation densities ranging from less than 102 to over 105 cfu g-1. inoculation densities on food have been rarely tested as a factor for growth. in this study, inoculation densities from 102 to 105 of l. monocytogenes were tested on iceberg lettuce (lactuca sativa) in ...201729181800
matrix extension study: validation of the compact dry ec method for enumeration of escherichia coli and non-e. coli coliform bacteria in selected foods.the compact dry "nissui" ec method, originally certified by the aoac research institute performance test method(sm) program for enumeration of escherichia coli and non-e. coli coliforms in raw meat products (performance tested method(sm) 110402), has undergone an evaluation to extend the method's claim to cooked chicken, prewashed bagged shredded iceberg lettuce, frozen cod filets, instant nonfat dry milk powder, and pasteurized milk (2% fat). compact dry ec is a ready-to-use dry media sheet con ...201726965216
matrix extension study: validation of the compact dry cf method for enumeration of total coliform bacteria in selected foods.the compact dry "nissui" cf method, performance tested method(sm) 110401, was originally certified for enumeration of coliform bacteria by the aoac research institute performance tested methods(sm) program for raw meat products. compact dry cf is a ready-to-use dry media sheet, containing a cold-soluble gelling agent, a chromogenic medium, and selective agents, which are rehydrated by adding 1 ml of diluted sample. coliform bacteria produce blue/blue-green colonies on the compact dry cf, allowin ...201726965022
association between bacterial survival and free chlorine concentration during commercial fresh-cut produce wash operation.determining the minimal effective free chlorine (fc) concentration for preventing pathogen survival and cross-contamination during produce washing is critical for developing science- and risk-based food safety practices. the correlation between dynamic fc concentrations and bacterial survival was investigated during commercial washing of chopped romaine lettuce, shredded iceberg lettuce, and diced cabbage as pathogen inoculation study during commercial operation is not feasible. wash water was s ...201829173618
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