| 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 ... | 2015 | 25828704 |
| 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 ... | 2014 | 24211774 |
| 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 ... | 2014 | 25580297 |
| 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 ... | 2013 | 24172881 |
| 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 ... | 2017 | 26965216 |
| 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 ... | 2015 | 26065727 |
| 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 ... | 2014 | 24674429 |
| 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 ... | 2014 | 24287607 |
| 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 ... | 2013 | 23839062 |
| 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 ... | 2012 | 22677605 |
| 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 ... | 2014 | 24220663 |
| 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 ... | 2015 | 25790986 |
| 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 ... | 2014 | 24927252 |
| 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 ... | 2014 | 25285483 |
| 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 ... | 2014 | 25198839 |
| 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 ... | 2012 | 22980000 |
| 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 ... | 2016 | 27591385 |
| 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. | 2016 | 26950043 |
| 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 ... | 2015 | 25643853 |
| 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 ... | 2013 | 23911760 |
| 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 ... | 2013 | 23256843 |
| 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 ... | 2016 | 27588690 |
| 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 ... | 2014 | 25124136 |
| 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 |
| 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 ... | 2013 | 7781823 |
| 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 |
| 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 |
| 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. | 2014 | 24964574 |
| 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 ... | 2017 | 26965022 |
| 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 ... | 2016 | 27339105 |
| 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, ... | 2017 | 28237883 |
| 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 ... | 2016 | 28221853 |
| 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 ... | 2016 | 27305593 |
| 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 ... | 2015 | 26155998 |
| 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) ... | 2015 | 25974213 |
| 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 ... | 2015 | 25836388 |
| 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 ... | 2014 | 24704862 |
| 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. ... | 2014 | 24680066 |
| 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 ... | 2013 | 24215685 |
| 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 ... | 2013 | 23200644 |
| 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 ... | 2012 | 23072696 |
| 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 ... | 2012 | 22857846 |
| 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 ... | 2012 | 22757712 |
| 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 ... | 2016 | 27105015 |
| 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 ... | 2014 | 24460771 |
| 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. | 2013 | 23351161 |
| 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 ... | 2012 | 22867843 |
| 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 ... | 2011 | 21645816 |
| 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 ... | 2010 | 24785500 |
| 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 |
| the role of smell, taste, flavour and texture cues in the identification of vegetables. | it has been shown that the identification of many foods including vegetables based on flavour cues is often difficult. the effect of providing texture cues in addition to flavour cues on the identification of foods and the effect of providing taste cues only on the identification of foods have not been studied. the aim of this study was to assess the role of smell, taste, flavour and texture cues in the identification of ten vegetables commonly consumed in the netherlands (broccoli, cauliflower, ... | 2018 | 29108741 |
| 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 ... | 2017 | 29181800 |
| 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 ... | 2017 | 29059519 |
| 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 ... | 2017 | 28613869 |
| 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. | 2017 | 27404345 |
| 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 ... | 2016 | 26904062 |
| 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 ... | 2016 | 26727458 |
| 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 ... | 2014 | 24803702 |
| 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 ... | 2013 | 23473017 |
| 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. | 2013 | 23184255 |
| 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. | 2013 | 23020834 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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) ... | 2016 | 29195871 |
| 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 ... | 2018 | 29173618 |
| 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 ... | 2017 | 28934070 |
| 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. | 2017 | 28898962 |
| 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) ... | 2017 | 28887415 |
| 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 ... | 2015 | 25863376 |
| 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 ... | 2014 | 24818869 |
| 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 ... | 2012 | 22757714 |
| 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 ... | 2010 | 20722955 |
| 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. | 2010 | 20648528 |
| 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 |
| 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 |
| 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 |
| 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 ... | 2012 | 17763031 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |