Types Of Salads Research Articles

Expiration Date of Ready-to-Eat Salads: Effects on Microbial Load and Biochemical Attributes.

When minimally processed vegetables reach their expiration date, expose an increased microbial load. This includes mainly spoilage microorganisms but also foodborne pathogens, thus affecting the quality and safety of highly consumed ready-to-eat salads. A total of 144 ready-to-eat salads from the Cypriot market were analyzed in an attempt to determine the effects of the expiration date on the microbial load and plant metabolic variables of the salads. Possible correlations between them were also investigated for the first time. Furthermore, the impacts of the season (winter, summer), salad producing companies and type of salad and/or their interactions with the tested parameters were investigated. Results revealed that the microbial load (mainly spoilage microorganisms, such as Pseudomonas spp., yeasts and molds) increased towards the end of the shelf life. The microbial load was differentiated among the five salad producers and/or the salad types, highlighting the importance of a common and safe sanitation-processing chain in the preparation of ready-to-eat salads. Summer was the season in which Escherichia coli counts were found to be higher for plain lettuce, while Staphylococcus spp. was increased numbers for the lettuce+endive/radicchio, lettuce+rocket and lettuce+chives type of salads. Additionally, an increased Staphylococcus spp. was observed for plain rocket salads in winter. All samples examined were found negative for Salmonella enterica and Listeria monocytogenes. Moreover, carbon dioxide production and damage indexes (hydrogen peroxide and lipid peroxidation) increased on expiration date on both winter and summer seasons, indicating plant tissue stress at the end of shelf life. These findings indicate that the expiration date and relevant shelf life of processed vegetables are important parameters to be considered when postharvest management is applied to these products, ensuring safety and quality.

Detection of Cyclospora cayetanensis on bagged pre-cut salad mixes within their shelf-life and after sell by date by the U.S. food and drug administration validated method

Recently, outbreaks of Cyclospora cayetanensis in the U.S. were linked to the consumption of a variety of salads containing romaine and/or iceberg lettuce, carrots and/or red cabbage. The Bacteriological Analytical Manual (BAM) Chapter 19b method was validated for the detection of C. cayetanensis in carrots, cabbage and romaine lettuce, but has not been previously evaluated in ready-to-eat (RTE) salad mixes. In addition, the only samples available for traceback investigations are sometimes leftovers in bad conditions. This study evaluated the validated BAM method for detection of C. cayetanensis in two different RTE mixed salads (mix 1: romaine and iceberg lettuces, carrots, and red cabbage and mix 2: romaine and iceberg lettuces, carrots, red cabbage, radish, and pea pods) in good condition and after their sell by date. Individual samples (25 g) were seeded with five and 200 C. cayetanensis oocysts. Unseeded produce was used as negative control. The method included washing of the produce, concentration and extraction of C. cayetanensis DNA and molecular detection of C. cayetanensis 18 S rRNA gene. As few as five oocysts were detected in both fresh and after sell by date mix salads. All unseeded samples were negative, and all samples of both salad types seeded with 200 oocysts were positive. In samples seeded with 200 oocysts, average 18 S rRNA C. cayetanensis CT values were significantly higher in fresh salad mix 1 compared to fresh salad mix 2; CT values were significantly higher in the after sell by date salads compared to their respective fresh mixes (p < 0.05). In conclusion, the BAM method was able to detect as few as five oocysts even in after sell by date RTE mix salads. However, the differences in detection observed, highlight the importance of evaluating the performance of the validated C. cayetanensis detection method in different food matrices and conditions, in advance for future outbreak investigations.

Survival and growth of Listeria monocytogenes and Staphylococcus aureus in ready-to-eat Mediterranean vegetable salads: Impact of storage temperature and food matrix

This study aimed to evaluate the survival or growth behavior of L. monocytogenes and S. aureus in ready-to-eat vegetable salads including Arabic salad (tomato-cucumber salad) with or without 0.5% (w/w) salt and 1% (v/w) lemon juice, tahini salad, coleslaw salad, toum sauce salad (aioli) stored at 4, 10, and 24 °C for 5 d. L. monocytogenes showed greater growth or survival in all types of salads at all temperatures tested. L. monocytogenes grew in Arabic salad without additives at 10 °C and tahini salad at 4 and 10 °C. L. monocytogenes survived all preparation and storage conditions used in the current study and its numbers were detectable in all types of salads tested, and with a maximum reduction of 3.0 log CFU/g, except for toum sauce salad at 24 °C, the cells were not detected using enrichment broth. In addition, S. aureus survived in Arabic salad with or without additives and in tahini salad with a maximum reduction of 2.3 log CFU/g. However, S. aureus numbers sharply decreased in coleslaw and toum sauce salad and at 5 d they reached undetectable levels (≥2 log CFU/g) in coleslaw at 24 °C and in toum sauce at 10 and 24 °C. Addition of lemon juice and salt to Arabic salad significantly reduced the numbers of both pathogens.

Assessment of breeding hybrid potatoes in irrigated conditions of the steppe zone of the Southern Urals

The creation of varieties with a high potential productivity and adaptability applied to the environmental conditions of a particular climatic zone is the main goal for breeding programs. The purpose of this work is studying and identifying the most adaptable hybrid materials that are most adaptable to the conditions of the steppe zone of the Southern Urals for selection, combining high productivity, resistance to major diseases with the complex of economically valuable traits. The objects of research were breeding hybrids 10.76.32; 02.40.17; 01.2.50; 01.12.51; M07.48.19; 05.57.32 and 10.02.19 obtained in the potato breeding laboratory of the South Ural Scientific Research Institute of Horticulture and Potato. Assessment of the represented volume of samples was carried out according to the morphological characteristics of plants, productivity, marketability, starch content in potato tubers, culinary type, taste, resistance to pathogens (Erwinia carotovora atroseptica, Clavibacter michiganensis sepedonicus, Dickey pectobacterium atrosepticum, Phytophthora infestans, Streptomyces scabies, PVM, PVS, PVX, and PVY). The breeding hybrids under study significantly exceeded the variety - standard Nevsky - in terms of yield by 97-1182g per bush. The highest starch content was recorded in breeding hybrids: 02.40.17 (18.4%), M07.48.19 (18.2%), 0.1.2.50 (17.6%). In taste the highest tasting score received - M07.48.19, 02.40.17 (5 points), 05.57.32 (4.5 points), 10.02.19 (4.7 points). The culinary type assessment showed that to the salad type (preferably not fall apart) applies the selection hybrid 10.76.32. Over the years of research low susceptibility to the pathogens under consideration was possessed by the following hybrids: 01.12.51, M07.48.19 and 05.57.32.

Improving temperature management and retaining quality of fresh-cut leafy greens by retrofitting open refrigerated retail display cases with doors

Abstract Open refrigerated display cases in supermarkets are prevalent in the United States despite being prone to temperature fluctuations. We collaborated with a chain retailer in Florida to retrofit existing open vegetable display cases with doors, and monitored the display temperature profile over 5 months. Quality evaluations were performed on baby spinach, spring mix, and chopped romaine lettuce after storage under simulated open and closed case conditions. Doors improved spatial and temporal temperature uniformity in whole and fresh-cut vegetable cases. Optimal storage temperature for ready-to-eat produce (≤5 °C) was recorded over 98% of the time after door installation versus 49–88% before retrofitting. An overall temperature decrease in the fresh-cut produce case from 3.62 to 0.66 °C necessitated a thermostat setting adjustment of +1.1 °C to avoid freezing of salad product. Elevated headspace CO2 concentrations and higher populations of aerobic bacteria (6.6 log CFU g−1), yeasts and molds (4.6 log CFU g−1) were found under open display conditions for one or more salad products tested. Baby spinach leaves from the open case environment were lighter green and more yellowish in color. Electrolyte leakage and ascorbic acid content of the three salad types were similar between the open and closed door displays. Superior overall visual quality and stronger purchase intent were found for baby spinach and spring mix samples from the closed display case. These products had less severe off-odor and discoloration, and crispier texture than those held in the open case. The decreased overall temperature and improved temperature uniformity in closed display cases, along with better produce quality and potential energy savings, may encourage retailers to consider retrofitting open displays with doors or purchasing closed displays.

Characterization of spoilage‐related volatile organic compounds in packaged leaf salads

AbstractA study has been made of the volatile organic compounds (VOCs) released into the contained headspace of packaged lamb's lettuce (Valerianella locusta) plants, cut at the roots, and of separated rocket (Eruca sativa) and baby spinach (Spinacia oleracea) leaves. Direct real‐time analyses of the headspace were carried out on each of five consecutive days using selected‐ion flow‐tube mass spectrometry (SIFT‐MS) and secondary electrospray ionization mass spectrometry (SESI‐MS), together with concomitant off‐line analyses using solid‐phase microextraction (SPME) and gas chromatography mass spectrometry (GC‐MS). It was observed that the concentrations of organosulphur compounds, especially dimethyl sulphide (DMS) and dimethyl disulphide (DMDS) were relatively low in the headspace of fresh samples, but increased exponentially over the 5 days for rocket, increased to a lesser extent for spinach, and increased to an even lesser extent for lamb's lettuce. Methanol was detected in the headspace of even fresh samples of lamb's lettuce, and its concentration increased for the subsequent 2–3 days before decreasing. This trend was mirrored in the isoprenoids analysed, which are characteristic of plant tissues. These results show that direct real‐time VOC analyses by SIFT‐MS can be usefully exploited to monitor fresh leaf salad spoilage, and that SESI‐MS spectra show patterns that are characteristic of salad type and storage time.

SMALL RADISH FOR LIGHT CULTURE: CHALLENGES AND PROSPECTS

Intense light culture, the most impotent part of a regulated agroecosystem, makes it possible to produce high quality plant products all year round in any region of the world in close proximity to the consumer. It is most economically viable to use light culture for growing vegetables in the Far North, where there is an acute shortage of fresh vegetables and vitamins. Our studies of the range of different vegetable crops have shown that when using artificial lighting and low-volume cultivation technologies, many plant species and varieties have low productivity, low adaptability to the relevant conditions, and therefore unprofitable for mass production. To expand the range of vegetable products intended for cultivation in the light culture, it is necessary to do a massive screening of the varieties and hybrids of various crops available in the world assortment with the aim of selecting the best and also purposeful breeding of new forms and varieties maximally adapted to the appropriate cultivation technologies. The purpose of this work was to create new forms of small radish for light culture, having the necessary complex of economically valuable characters. The use of the previously developed methodology of predicting transgressions for economically valuable plant traits allowed us to obtain new promising forms of radish with using purposeful hybridization and subsequent stabilizing selection. Their characteristics are high productivity and early maturity (ripeness to harvesting for 21-25 days from seeding), the ability to produce marketable yield of roots in a small volume of root medium, resistance to bolting at higher temperatures. A number of the obtained forms also has a compact rosette of leaves and an almost glabrous leaf of the salad type. Marketable productivity of new forms of radish in intense light culture conditions reaches 5,5 kg/m2 (for hybrids F1) and 4 kg/m2 for stable lines, which is twice or more than the productivity of the parental cultivars and one and a half times more than the best in productivity cultivars that were tasted in light culture.

Tomato progenies selection in Rondônia, Brazil

ABSTRACT This study aimed to select endogamic progenies of tomato cv. Yoshimatsu and to conduct a progeny test in the state of Rondônia. The experiment was carried out in a randomized block design with four replicates and eight plants per plot, spacing 1x0.5 m, with one stem. A significant variation was observed among the fifteen progenies for productivity (2.0-5.5 kg plant-1), seed mass with placenta (18-31.5 g fruit-1), number of fruits per plant (18.8-38.7) and soluble solids (3.4-4.2°Brix). No significant variation was noticed for fruit size, pericarp thickness, number of locules, pH, number of flowers and fruit set, though. P6 progeny showed to be the most productive one (110 t ha-1): average fruit mass was 142.5 g, salad type tomato, 7.5 locules, 3.5°Brix, pH 4.2, 60.9 flowers per plant and 64.2% fruit set. Thus, these data show genetic variability of cultivar Yoshimatsu, being possible to obtain lines and/or cultivars with medium to large fruits adapted to the state of Rondônia.

Microbiological profile of different types of salads from hospital kitchens

ABSTRACT: The objective of this work was to verify the microbiological profile of different types of salads from hospital kitchens. During the period from 2010 to 2014, the Public Food Guidance Service (SOAP) received 641 samples of salads from two public hospitals in the Central West region of the São Paulo state, where they were submitted to microbiological analysis in order to determine the most probable number (MPN) of coliforms at 35 and 45ºC, carry out Salmonella spp. study and coagulase-positive staphylococci count. The results showed that in 30.56% of samples the coliform count at 35ºC was above 1,100 MPN/g and 12.17% of samples presented coliforms at 45ºC above 100 MPN/g, which is the maximum limit established by Brazilian law. The prevalence of contaminated samples among those without heat treatment was at 97.44%, and for samples with heat treatment the prevalence was at 2.56% for both cooked and braised foods. All samples were negative for Salmonella spp. presence and showed coagulase-positive staphylococci count at &lt; 1.0 × 102 UFC/g. Although no pathogenic agents were found, the high count for indicator microorganisms in a large number of samples suggests that the practices of obtaining and manipulating these foods are inadequate, facilitating the risk of contamination with pathogens, including other agents not included in this research. Thus, food and nutrition units must pay attention to food preparation procedures, especially since these meals are served to indoor patients.

Viability of murine norovirus in salads and dressings and its inactivation using heat-denatured lysozyme

In recent years, a number of food poisoning outbreaks due to the contamination of norovirus in ready-to-eat (RTE) foods such as salads have been reported, and this issue is regarded as a global problem. The risk of contamination of fresh vegetables with norovirus has been previously reported, but the survivability of norovirus that contaminates salads remains unknown. In addition, there have been limited reports on the control of norovirus in food products by using inactivating agents. In this study, the viability of norovirus in various types of salads and dressings was examined using murine norovirus strain 1 (MNV-1) as a surrogate for the closely related human norovirus. In addition, the inactivation of MNV-1 in salads was examined using heat-denatured lysozyme, which had been reported to inactivate norovirus. MNV-1 was inoculated in 4 types of salads (coleslaw, thousand island salad, vinaigrette salad, egg salad) and 3 types of dressings (mayonnaise, thousand island dressing, vinaigrette dressing), stored at 4°C for 5days. The results revealed that in the vinaigrette dressing, the infectivity of MNV-1 decreased by 2.6logPFU/mL in 5days, whereas in the other dressings and salads, the infectivity of MNV-1 did not show any significant decrease. Next, 1% heat-denatured lysozyme was added to the 4 types of salads, and subsequently it was found that in 2 types of salads (thousand island salad, vinaigrette salad), the infectivity of MNV-1 decreased by >4.0logPFU/g, whereas in coleslaw salad, a decrease of 3.0logPFU/g was shown. However, in egg salads, the infectivity of MNV-1 did not show such decrease. These results suggest that norovirus can survive for 5days in contaminated salads. Further, these findings also indicated that heat-denatured lysozyme had an inactivating effect on norovirus, even in salads. In the future, heat-denatured lysozyme can be used as a novel norovirus-inactivating agent, although it is essential to investigate the mechanism of inactivating effect of heat-denatured lysozyme against norovirus.

Evaluation of Microbiological Quality of Ready to Eat Salads in Alexandria City, Egypt

Microbial hazards continue to be one of the biggest threats to food safety. Ready to eat salads are one of the minimally processed foods that are widely served in restaurants, homes and hotels and should be evaluated to check there safety for human consumption. This study was carried out to evaluate the microbiological quality of ready to eat salad served in most restaurants in Alexandria city, Egypt. A total of 448 samples were collected from different restaurants at different districts of the city. Seven types of salads were analyzed for Total Viable Count Enterobacteriacea, Staphylococcus aurous, Molds and yeasts. The results revealed that most of the collected samples were highly contaminated with total aerobic bacteria. Different contamination levels of the salad with S. aurous, Enteobacteriaceae, Molds and yeasts were noticed to be dependent on the salad type and food hygiene level .Relevant recommendations are given.

Chlorophyll Fluorescence Imaging for Monitoring the Effects of Minimal Processing and Warm Water Treatments on Physiological Properties and Quality Attributes of Fresh-Cut Salads

In this study, chlorophyll fluorescence imaging (CFI) was used to monitor plant stress induced by cutting of mini romaine lettuce (Lactuca sativa L. var. longifolia) and by cutting and washing of endive (Cichorium endivia L.) during storage. Regarding the more detailed study of endive fresh-cut salads, we additionally monitored respiratory activity, phenylalanine ammonia lyase (PAL) activity, contents of plant pigments, and cut edge browning. Determination of maximum quantum efficiency Fv/Fm was feasible through sealed consumer-sized film bags, thus, enabling the non-invasive monitoring of both fresh-cut salad types in the corresponding modified atmosphere during storage. Cutting of romaine lettuce provoked a partially reversible drop of Fv/Fm during the first 24 h. Subsequently, Fv/Fm of cut romaine strongly decreased with elapsing shelf life, whereas intact leaves exhibited only a slight decline. Regarding minimally processed endive, warm water washing progressively reduced Fv/Fm with increasing heat exposure, while respiratory activities and the content of accessory pigments remained unaffected. The heat-dependent decrease of Fv/Fm was correlated to the inhibition of the PAL activity. Mildly warm washing (40 °C, 120 s; 45 °C, 60 s) reduced PAL activities, while Fv/Fm remained widely unaffected and visual quality was only partially improved. However, warm water washing at elevated temperatures (45 °C, 120 s; 50 °C, 30–60 s) enabled maximum visual quality retention, accompanied by a significant decrease of Fv/Fm. CFI may represent a useful tool to monitor the stress conditions due to cutting and warm water treatments, hence, allowing the systematic improvement of fresh-cut produce.

Multidrug-resistant diarrheagenic E. coli pathotypes are associated with ready-to-eat salad and vegetables in Pakistan

Diarrheagenic E. coli pathotypes are major foodborne pathogens causing gastrointestinal tract infections leading to hemolytic uremic syndrome and hemorrhagic colitis. Consumption of raw vegetables is encouraged due to its nutrient content and antioxidant properties, although their ingestion is linked to a series of foodborne disease outbreaks. The aim of this study was to evaluate the prevalence of Enterotoxigenic, Enteropathogenic, and Shiga toxin-producing E. coli pathotypes in raw vegetables and ready-to-eat salad for the development of better risk management. A total of 260 vegetable and salad mix (cucumber, lettuce, spinach, and carrot) samples were collected from commercial food markets in Southern districts of Khyber Pakhtunkhawa, Pakistan. About 34 % vegetable samples were contaminated with E. coli strains. 32.4 % E. coli strains from vegetable sample were identified as diarrheagenic E. coli pathotypes. Similarly, 26.7 % of salad samples were contaminated with E. coli pathotypes. 15 % [two Enterotoxigenic E. coli and one Enteropathogenic E. coli] were isolated from spinach salad samples. 25 % [three Enterotoxigenic E. coli, one Enteropathogenic E. coli and one Shiga toxin-producing E. coli] were isolated from mixed salad type A. 40 % [four Enterotoxigenic E. coli, two Enteropathogenic E. coli and two Shiga toxin-producing E. coli] were isolated from mixed salad type B. 92 % diarrheagenic E. coli pathotypes showed resistance against Tetracycline and 87 % to Ampicillin. This study showed that fresh vegetable and their products were contaminated with multidrug-resistant E. coli pathotypes.

Evaluation of Biological Value and Appraisal of Polyphenols and Glucosinolates from Organic Baby-Leaf Salads as Antioxidants and Antimicrobials against Important Human Pathogenic Bacteria

The present investigation has been carried out to investigate the biological role of four different types of baby-leaf salads and to study their potential as natural sources of antioxidants and antimicrobials against several isolates from important human pathogenic bacteria. Four single types of salads (green lettuce, red lettuce, rucola and watercress) and two mixtures [(1) red lettuce+green lettuce; (2) green lettuce + red lettuce + watercress + rucola] were assayed. The HPLC analysis revealed interesting levels of polyphenols and glucosinolates. The results showed a significant variation (p < 0.05) of polyphenols and glucosinolates with plant material. Nine different types of polyphenols grouped in three major classes were found: gallic acid, chlorogenic acid, caffeic acid and dicaffeoyltartaric acid (phenolic acids); quercitin-3-O-rutinoside, quercitin-3-O-rhamnoside, luteolin-7-O-glucoside and isorhamnetin (flavonoids); and cyanidin-3-glucoside (anthocyanins). Only three different glucosinolates were found: glucoraphanin; gluconasturtiin and 4-methoxy-glucobrassicin. A positive correlation was detected between polyphenol contents and antioxidant activity. Red lettuce and mixture 1 were the baby-leaf salads with the highest antioxidant potential. As for the antimicrobial activity, the results showed a selective effect of chemicals against Gram-positive and Gram-negative bacteria and Enterococcus faecalis and Staphylococcus aureus were the bacteria most affected by the phytochemicals. Based on the results achieved baby-leaf salads represent an important source of natural antioxidants and antimicrobial substances.

Caracterización morfológica de la diferenciación floral en tomate (Solanum lycopersicum L.)

In order to produce a document that identifies the morphological stages of floral differentiation in tomato, a microscopic study was conducted at Chapingo Autonomous University from October 2010 to October 2011. Two tomato varieties, Charleston and Barbarian, ball and salad types respectively, were planted to generate plant material. They were germinated in a special chamber and upon emitting cotyledons were taken to a glasshouse where they remained until having the second inflorescence. During this period, isolations, observations and photomicrographs were made of the meristems and floral organs. Based on these images and others reported by other authors, each of the morphological stages of the floral differentiation process were interpreted and described. It was observed in this species that vegetative to reproductive differentiation occurs in the apical meristem, and when the first inflorescence forms a vegetative axillary bud continues growth and retakes apical dominance. After forming three phytomers, the second inflorescence appears. The inflorescences form basipetally: i.e., when the meristem changes to reproductive it divides into two and two floral primordia appear, then on the base more primordia appear consecutively until the complete inflorescence is formed. The floral organs appear centripetally: first the calyx, then the corolla, later the androecium (filament and anthers) and finally the gynoecium (ovary, ovules, style and stigma).

Aspects of the microbiological quality and safety of ready-to-eat foods in Sharjah supermarkets in the United Arab Emirates.

Over the last few years, ready-to-eat (RTE) foods have become popular in grocery stores all over the world. This study was conducted to evaluate the microbiological safety and shelf life of some RTE salads sold in supermarkets in Sharjah Emirate, United Arab Emirates. Samples of four RTE salads, tabbouleh, hummus, Greek salad, and coleslaw, were obtained from supermarkets and examined for aerobic bacteria, Escherichia coli, Staphylococcus aureus, Salmonella, and Listeria monocytogenes. The results indicated significant differences (P < or = 0.05) for the aerobic bacteria count among the RTE salad types. In tabbouleh, hummus, Greek salad, and coleslaw, E. coli counts of 0.9, 0.50, 0.27, and 0.25 log most probable number (MPN)/g and total aerobic bacterial plate counts of 3.57, 2.71, 2.76, and 2.52 log CFU/g, respectively, were found after preparation (day 0). At day 0, all RTE salads tested except tabbouleh contained an acceptable count of total bacteria, but the aerobic bacteria count for all the RTE salads increased rapidly during storage from day 2 to day 6, regardless of the storage temperature (5, 25, and 40 degrees C). Twenty percent of all samples contained E. coli, although the numbers were as low as 1 log MPN/g. No S. aureus, L. monocytogenes, or Salmonella serotypes were detected in any of the RTE salads tested in this study.

Listeria monocytogenes isolated from vegetable salads sold at supermarkets in Santiago, Chile: Prevalence and strain characterization

Between 2000 and 2005, 717 samples of three types of salads were analysed for Listeria monocytogenes in Santiago, Chile in order to provide information to Chilean health authorities on the presence of the pathogen in vegetable salad samples and to ascertain the risk of these products for consumers. L. monocytogenes isolates were found in 88 out of 347 (25.4%) samples of frozen vegetable salads and in 22 out of 216 (10.2%) freshly supermarkets prepared, cooked or raw ready-to-eat vegetable salads; no Listeria was isolated from 154 samples of raw minimally processed salads industrially prepared. Enumeration of L. monocytogenes was done by plate count for 20 positive frozen samples, randomly chosen. Most of them (90%) had < 10 cfu/g. MPN technique was performed for 34 another positive samples; 12 had ≥ 1100/g, five ranged between 240 and 93, eight between 23 and three and nine had < 3.0. No L. monocytogenes was recovered after cooking 12 contaminated frozen samples. Isolation of strains was done using three selective agars. Sixty-two L. monocytogenes were isolated from lithium chloride phenylethanol moxalactam agar, 95 from Listeria selective agar Oxford formulation, and 103 from polymixin acriflavine lithium chloride ceftazidime aesculin mannitol agar. Fifty isolates (45.5%) belong to PCR group IIb (including strains serovar 1/2b), 41 (37.3%) to PCR group IVb (including strains serovar 4b), 17 (15.5%) to PCR group IIa (including strains serovar 1/2a), and 2 (1.8%) to PCR group IIc. With the use of DNA macrorestriction patterns analysis, 17 different clusters were detected among 71 isolates, with P10, the most frequent with 25 isolates (35.2%) of PCR group IIb.

Prepared salads and public health

In recent years the importance of prepared salads as potential vehicles of gastrointestinal infection has been highlighted by several large outbreaks both nationally and across international boundaries. Between 1992 and 2006, 2274 foodborne general outbreaks of infectious intestinal disease were reported in England and Wales, of which 4% were associated with the consumption of prepared salads. In total, 3434 people were affected, with 66 hospitalizations and one death reported. The attribution of prepared salad types and pathogens among prepared salad associated outbreaks are presented and discussed. Findings from UK studies on salad vegetables, fruit and mixed salads from 1995 to 2007 (21 247 samples) indicate that most bacteria of concern with regard to human health are relatively rare in these products (98.6% of satisfactory quality); however, outbreaks of salmonellosis were uncovered associated with bagged salad leaves and fresh herbs during two such studies. Although it is known that fresh salad vegetables, herbs or fruit may become contaminated from environmental sources, only in recent years has the association of foods of nonanimal origin, such as salad vegetables, with foodborne illness become evident and recurrent, demonstrating that major health problems can arise from consumption of contaminated prepared salads if hygiene practices breakdown.

SALADPLAN: a model of the decision-making process in lettuce and endive cropping

Market gardeners are facing new environmental, commercial and safety requirements and regulations that weigh heavily on their crop planting and management decisions. Producing high-quality products and simultaneously reducing the use of chemical products needs change in the multi-field planning of crops. In order to identify which cropping practice may be altered depending on each farm’s characteristics, we built a rule-based model that represents how market gardeners plan cropping cycles of lettuce and endive, here denoted as salad vegetables, on a farm scale. The model is adapted to the specificities of salad vegetable crops in the Mediterranean region, in particular the combination of several cycles per year and of open field and sheltered crops. The output variables are the developed areas allocated to the different salad types and the range of the harvest dates, which are two key factors for commercialisation. The model is based on identifying the successive decision steps of growers when building their farming systems; descriptive variables are the effective surface area and period for salad cultivation, the number of salad cycles per year, the developed surface area of each salad type and the dates of harvest. The decision-making rules leading to each descriptive variable are based on the agronomic characteristics of soil, climate and crops, farmers’ strategic objectives and organisation of farm resources. The cropping decisions were recorded in 38 farms in the large market-gardening region of Languedoc-Roussillon. In the sample, the number of salad types cultivated per farm varied from 1 to 8 and the harvesting period from 3 to 7 months. Our results demonstrate that the model can explain a substantial part of this variability, 26 and 28 farms among 38, respectively, being correctly classified by the model for the two variables. The original result of this work is to enhance the generality of a similar framework built earlier for arable cropping systems. From a practical point of view, this model can be used to determine the leeway available to the farmers for the introduction of technical change in salad cropping. It could therefore be used by agricultural advisors to plan salad crops either for individual farms or on the scale of a marketing structure.

Fate of Listeria monocytogenes on four types of minimally processed green salads

The fate of Listeria monocytogenes on green leafy vegetables: broad-leaved endive, curly-leaved endive (Cichorium endivia L.), butterhead lettuce (Lactuca sativa L.) and lamb's lettuce (Valerianella locusta L. Laterr.) was studied. Populations of L. monocytogenes increased by 1.5 log in 7 d at 10 o C on broad-leaved endives and butterhead lettuce, by 0.5 log on curly-leaved endives and decreased by 1 log on lamb's lettuce. Growth patterns of the epiphytic microflora were similar among the four salad types