Consumption Of Lettuce Research Articles

Agronomic and physio-biochemical responses of lettuce to exogenous sodium nitroprusside (SNP) applied under different irrigation regimes

Drought adversely affects crop production in areas with water shortages. In such areas, various methods need to be implemented to alleviate the effect of water stress on plants. Nitric oxide (NO) is an important plant growth regulator that affects various physiological processes. In this study, we determined ways to increase water-stress tolerance of lettuce by applying exogenous sodium nitroprusside (SNP, a donor of NO). In total, 12 treatments were administered, including three SNP doses (0, 50, and 100 µM) and four levels of irrigation (I100, I80, I60, and I40). An increase in the doses of NO partially increased the water consumption of lettuce under full and deficit irrigation conditions. The highest water consumption (125.1 mm) and the highest yield (39.1 t/ha) were recorded for lettuce plants that were administered the I100 treatment with 100 µM SNP. SNP significantly increased the lettuce yield and irrigation water productivity (IWP) under deficit irrigation and full irrigation. SNP promoted chlorophyll synthesis by increasing photosynthesis. The application of 100 µM SNP increased catalase (CAT) activity approximately three times compared to CAT activity in the control group, and it also significantly increased peroxidase (POD) activity. Additionally, high doses of SNP reduced membrane damage in lettuce leaves. These results indicated that under water stress, exogenous NO improves photosynthesis by increasing chlorophyll synthesis, activates antioxidant enzymes, such as CAT and POD, protects lettuce against oxidative damage, and increases irrigation water productivity, thus increasing the yield.

Essential and non-essential elements in lettuce produced on a rooftop urban garden in São Paulo metropolitan region (Brazil) and assessment of human health risks

This study evaluated the essential and non-essential elements in lettuce cultivated on a rooftop urban garden in the metropolitan region of São Paulo. In addition, the human health risks associated with the potentially toxic metals based on the estimated daily intake (EDI), the target hazard quotient (THQ), and the possible sources of heavy metal contamination by multivariate statistical were analyzed. The lettuces contain essential macronutrients such as K, Ca, and Mg. The Cd, Cu, and Pb concentrations did not exceed the Brazilian legislation limit. Ba, Ni, Cr, Co, and Pb presented low levels compared to oral reference dose and they may be associated to vehicles emissions. Both EDI and THQ values suggested minimal risk upon consumption of lettuce.

Quantitative Risk Assessment for Salmonella in Lettuce (Lactuca sativa) Consumed in Benin, West Africa

The present study aims at quantitatively assessing the risk associated with Salmonella in lettuce (Lactuca sativa) consumed in Benin (West Africa). To that end, a survey was conducted involving 550 respondents to determine the conditions under which the product is handled along the supply chain and its consumption pattern. The prevalence and concentration of Salmonella in lettuce were collected from the literature. The consumption data and the data on Salmonella concentrations in lettuce were combined to estimate the exposure to Salmonella using a probabilistic risk assessment method. The @Risk software package (Palisade USA) was used to run Monte Carlo simulations with 10,000 iterations. Three dose-response models were used to assess the risk of salmonellosis. Different scenarios were tested to identify factors that could influence the risk of salmonellosis. The results showed that lettuce is exposed to temperature abuse under inappropriate hygienic conditions. In 90% of the cases, the exposure to Salmonella was between 3 and 7 log CFU/serving. The risk of salmonellosis per serving varied from 7.7% to 95% depending on the dose-response used with the scenario taking into account the current handling conditions of the lettuce. In contrast, when considering the scenario where the cold chain is respected along the supply chain, the risk of salmonellosis varied from 0% to 3.3% depending on the dose response used. The study highlights the importance of the cold chain, good agricultural practices and good hygienic practices to reduce exposure to Salmonella through the consumption of lettuce and thus the risk of salmonellosis.

Manure and biochar have limited effect on lettuce leaf endophyte resistome

Soil amendment with manure compost and biochar is widely adopted to improve soil fertility and promote plant growth, and their effects on soil microbial communities and resistome have been well documented. However, there is sparse information regarding their effects on vegetable endophytes, which represent a major source of human exposure to pathogens and antibiotic resistance genes (ARGs) when eaten raw. Here, we investigated the impacts of manure compost or biochar addition on the bacterial community compositions and ARGs in the soil-lettuce continuum including soil, seed, leaf, and root samples. A total of 137 ARGs and 31 mobile genetic elements (MGEs) were detected in all the samples after 60 days of cultivation. The relative abundance of ARGs and the diversity of bacteria communities presented a consistent decreasing trend from soil to root endophytes, then leaf endophytes. Manure compost addition increased the diversity and abundance of ARGs in soil, while significant changes in the ARG profiles and bacterial communities were not observed in leaf endophytes after manure compost or biochar addition, or both. Bipartite networks analysis suggested that seed microbiome was one of the major sources of plant endophytes and ARGs. Twenty potential human pathogens were isolated from lettuce, indicating potential exposure risk to pathogens via the consumption of raw lettuce. These results suggest limited impacts of manure compost and biochar addition on lettuce endophytes and highlight the contribution of seed microbiome to endophyte ARG profiles.

A New Potential Dietary Approach to Supply Micronutrients to Physically Active People through Consumption of Biofortified Vegetables.

Micronutrients are required in many reactions involved in physical activity and exercise. Most physically active people do not meet the body’s needs in terms of micronutrients through diet. The novelty of the present manuscript is the use of an innovative dietary approach to supply micronutrients to physically active people through biofortified food. Therefore, the key point of this study was to verify whether supplementation with biofortified vegetables—and specifically molybdenum (Mo)-enriched lettuce—in healthy volunteers affects essential regulators of body homeostasis and, specifically, hematological parameters, iron and lipid metabolism, and hepatic function. Twenty-four healthy volunteers were allocated in a double-blinded manner to either a control group that consumed lettuce, or the intervention group, which consumed Mo-enriched lettuce, for 12 days. Blood samples were collected at baseline (T0) and after 12 days (T1). We found that supplementation with Mo-enriched lettuce did not affect hematological parameters, liver function, or lipid metabolism, but significantly improved iron homeostasis by increasing non-binding hemoglobin iron by about 37% and transferrin saturation by about 42%, while proteins of iron metabolism (e.g., transferrin, ferritin, ceruloplasmin) were not affected. The serum molybdenum concentration increased by about 42%. In conclusion, this study shows that consumption of Mo-biofortified lettuce ameliorates iron homeostasis in healthy subjects, and suggests that it could be used as a new nutritional supplementation strategy to avoid iron deficiency in physically active people.

Phytochemicals, Nutrition, Metabolism, Bioavailability, and Health Benefits in Lettuce-A Comprehensive Review.

Lettuce is one of the most famous leafy vegetables worldwide with lots of applications from food to other specific uses. There are different types in the lettuce group for consumers to choose from. Additionally, lettuce is an excellent source of bioactive compounds such as polyphenols, carotenoids, and chlorophyll with related health benefits. At the same time, nutrient composition and antioxidant compounds are different between lettuce varieties, especially for green and red lettuce types. The benefit of lettuce consumption depends on its composition, particularly antioxidants, which can function as nutrients. The health benefits rely on their biochemical effect when reaching the bloodstream. Some components can be released from the food matrix and altered in the digestive system. Indeed, the bioaccessibility of lettuce is measuring the quantity of these compounds released from the food matrix during digestion, which is important for health-promoting features. Extraction of bioactive compounds is one of the new trends observed in lettuce and is necessarily used for several application fields. Therefore, this review aims to demonstrate the nutritional value of lettuce and its pharmacological properties. Due to their bioaccessibility and bioavailability, the consumer will be able to comprehensively understand choosing a healthier lettuce diet. The common utilization pattern of lettuce extracted nutrients will also be summarized for further direction.

Detection of pesticide residues and risk assessment from the local fruits and vegetables in Incheon, Korea

This study was conducted to investigate the pesticide residue concentrations and assess potential human health risks from fruit and vegetable consumption in Incheon. A total of 1,146 samples of 20 different types of fruits and vegetables were collected from the Incheon area in 2020. The pesticide residues were analyzed by the multi-residue method of the Korean Food Code for 400 different pesticides. Among the fruit and vegetable samples, 1,055 samples (92.1%) were free from detectable residues, while 91 samples (7.9%) contained residues and 11 samples (1.0%) had residues exceeding the Korean maximum residue limit. A total of 32 different pesticide residues were found and 8 residues exceeded MRLs. The most frequently detected pesticide residues were chlorfenapyr, procymidone, etofenprox, pendimethalin, fluopyram and azoxystrobin. The highest values of short term and long term exposure were obtained in the case of consumption of lettuce(leaves) with chlorfenpyr. For chronic dietary exposure, the cumulative hazard index (cHI) were below 100%. The results of this study showed that the detected pesticides were not exposed to potential health risks through the consumption of fruits and vegetables.

Detoxification Role of Metabolic Glutathione S-Transferase (GST) Genes in Blood Lead Concentrations of Jamaican Children with and without Autism Spectrum Disorder.

Glutathione S-transferases (GST) are involved in the detoxification of exogenous chemicals including lead (Pb). Using data from 344 pairs of autism spectrum disorder (ASD) cases and age- and sex-matched typically developing (TD) controls (2–8 years old) from Jamaica, we investigated the interaction between three GST genes and ASD status as determinants of blood Pb concentrations (BPbCs). We found that ASD cases had lower geometric mean BPbCs than TD children (1.74 vs. 2.27 µg/dL, p < 0.01). Using a co-dominant genetic model, ASD cases with the Ile/Val genotype for the GSTP1 Ile105Val polymorphism had lower GM BPbCs than TD controls, after adjusting for a known interaction between GSTP1 and GSTT1, child’s parish, socioeconomic status, consumption of lettuce, fried plantains, and canned fish (Ile/Val: 1.78 vs. 2.13 µg/dL, p = 0.03). Similarly, among carriers of the I/I or I/D (I*) genotype for GSTT1 and GSTM1, ASD cases had lower adjusted GM BPbCs than TD controls (GSTT1 I*: 1.61 vs. 1.91 µg/dL, p = 0.01; GSTM1 I*: 1.71 vs. 2.04 µg/dL, p = 0.01). Our findings suggest that genetic polymorphisms in GST genes may influence detoxification of Pb by the enzymes they encode in Jamaican children with and without ASD.

Cryptosporidium’s burden of disease attributable to consumption of wastewater-irrigated raw vegetables

Conventional wastewater treatment plants do not effectively remove parasitic protozoa resulting in their presence in wastewater effluent. Therefore, agricultural reuse of wastewater effluent could be a route of Cryptosporidium transmission into the food chain. Samples of secondary wastewater, wastewater-irrigated soil and vegetable samples were collected from an experimental field and analyzed using real-time PCR for quantification of Cryptosporidium oocysts. Quantitative microbial risk analysis (QMRA) was performed to determine the annual disease burden from Cryptosporidium associated with consumption of wastewater-irrigated vegetables. Detection of Clostridium perfringens spores as a potential indicator for the presence of Cryptosporidium was also performed. Cryptosporidium was observed in 64% of the effluent samples ranging from 16 to 162 oocysts L−1, whereas no oocysts were detected in wastewater-irrigated soil and the vegetable samples. The mean annual disease burden for consumption of lettuce (6.6 × 10−5 DALY per person per year (pppy)) was higher than spring onion (3.4 × 10−6 DALY pppy) which both exceeding the WHO guideline of 10−6 DALYs pppy. However, the disease burden was within the acceptable range considering the less stringent level of 10−4 DALY pppy. Clostridium spores were detected in 92% of the effluent samples with no relationship with the presence of Cryptosporidium. The results of this study suggest that agricultural reuse of treated wastewater may not be a major health concern of cryptosporidiosis in a semi-arid region. However, because of the higher risk from lettuce, the choice of an appropriate crop would be needed to completely meet the WHO recommendations for safe reuse of wastewater. The accuracy of the QMRA model could be improved by further investigating the decay rate of oocysts in the same region.

Impact on Glucose Homeostasis: Is Food Biofortified with Molybdenum a Workable Solution? A Two-Arm Study.

Diabetes is expected to increase up to 700 million people worldwide with type 2 diabetes being the most frequent. The use of nutritional interventions is one of the most natural approaches for managing the disease. Minerals are of paramount importance in order to preserve and obtain good health and among them molybdenum is an essential component. There are no studies about the consumption of biofortified food with molybdenum on glucose homeostasis but recent studies in humans suggest that molybdenum could exert hypoglycemic effects. The present study aims to assess if consumption of lettuce biofortified with molybdenum influences glucose homeostasis and whether the effects would be due to changes in gastrointestinal hormone levels and specifically Peptide YY (PYY), Glucagon-Like Peptide 1 (GLP-1), Glucagon-Like Peptide 2 (GLP-2), and Gastric Inhibitory Polypeptide (GIP). A cohort of 24 people was supplemented with biofortified lettuce for 12 days. Blood and urine samples were obtained at baseline (T0) and after 12 days (T2) of supplementation. Blood was analyzed for glucose, insulin, insulin resistance, β-cell function, and insulin sensitivity, PYY, GLP-1, GLP-2 and GIP. Urine samples were tested for molybdenum concentration. The results showed that consumption of lettuce biofortified with molybdenum for 12 days did not affect beta cell function but significantly reduced fasting glucose, insulin, insulin resistance and increased insulin sensitivity in healthy people. Consumption of biofortified lettuce did not show any modification in urine concentration of molybdenum among the groups. These data suggest that consumption of lettuce biofortified with molybdenum improves glucose homeostasis and PYY and GIP are involved in the action mechanism.

Prevalence and antibioresistance of Escherichia coli and Salmonella isolated from lettuce and irrigation water in Ouagadougou, Burkina Faso

Introduction. The use of partially or untreated wastewater in the irrigation of vegetable crops constitutes a risk of microbiological contamination that can cause diarrhea in the consumer. Aim. This study mainly aimed to assess the level of contamination of irrigation water and lettuce as well as to determine the antibiotic resistance profile of isolated bacteria. Methods. A total of eighty samples of lettuce and ten irrigation waters were collected from the market gardening sites of Boulmiougou, Bissigin, the National School of Public Health and Tanghin. The research of thermotolerant coliforms, Escherichia coli and Salmonella was done following ISO standard methods. Isolated Escherichia coli and Salmonella strains were tested for their resistance profile by using the Kirby-Bauer method with a panel of twenty different antibiotics. Results. Out of the eighty lettuce samples, 68.75% (55) contained thermotolerant coliforms with an average load of 8.75 ×105 CFU g-1. The prevalence of Escherichia coli was 57.5% (46) and Salmonella prevalence was 11.25% (9) including eight strains of Salmonella enterica spp. and one strain of Salmonella enterica arizonea. All irrigation waters were contaminated by thermotolerant coliforms at an average concentration of 3.11×104 CFU/100mL. The prevalence of Escherichia coli in the irrigation waters was 40% (4/10) while Salmonella enterica spp. was 20% (2/10). The highest antibiotic resistance was found in Escherichia coli strains with ampicillin 28.26%, amoxicillin + clavulanic acid 26.09% and tetracycline 19.57%. Conclusion. The water used to irrigate vegetable crops in Ouagadougou could be a major source of contamination of vegetables by microorganisms. In addition, the consumption of lettuce would constitute a risk of propagation of salmonellosis among the population.

Assessment of the food-water-energy nexus suitability of rooftops. A methodological remote sensing approach in an urban Mediterranean area

• A framework to identify roofs for food, water, and energy production is proposed. • Agriculture can be implemented on 8% of roofs to produce tomatoes and lettuce. • A total of 87% of roofs are suitable for integrating rainwater harvesting systems. • A total of 50% of roofs are suitable for integrating photovoltaic panels. • Service buildings and residential housing are more suitable for agriculture. This work established a framework to identify and analyze the technical feasibility of roofs for integrating urban agriculture, rainwater harvesting, and photovoltaic systems using various remote sensing. The framework was applied to a region north of Barcelona. Three levels of solar access requirements for tomatoes, leafy crops, strawberries, and microgreens were established. The case study included compact and disperse urban forms, residential and nonresidential building uses and various building typologies. It was identified that 8% of the roof area is feasible for tomato and lettuce production, and production could satisfy the 210% of average intake of tomatoes and the 21% average yearly consumption of lettuce. Rainwater harvesting systems could supply 94.26% of the water requirements for lettuce growing in an open-air system; in contrast, 53% of irrigation could be satisfied for tomato production in rooftop greenhouse systems. The results showed a potential for 80% of roof area to be used for rainwater harvesting systems, representing the average yearly water consumption of 44% of citizens for laundry, showering, toilet flushing, cleaning and irrigation uses. Finally, 50% of the roofs are suitable for photovoltaic panels, representing an average energy consumption of 18% of citizens.

Anxiety Status and Coping Strategies in Association with Sociodemographic Factors, Dietary and Lifestyle Habits in Greece.

Aim:The aim of this study was to investigate the relationship between nutritional habits, lifestyle, anxiety, and coping strategies.Background:Anxiety is an underestimated and often undiagnosed subclinical disorder that burdens the general public of modern societies and increases illness suscentibility.Methods:The study group consisted of 693 individuals living in Peloponnese, Greece. A standardized questionnaire that consists of the dietary habits and lifestyle questionnaire, the trait Anxiety STAI-X-2 questionnaire and the brief-COPE questionnaire, was used. Principal components analysis identified the factors from the questionnaires, and stepwise multivariate regression analysis investigated their relationships.Results:Weekly consumption of fruits, tomatoes, salads and lettuce, together with Εmotional/Ιnstrumental support, Denial/Behavioural disengagement, substance use and self-blame, was the most important predictors of anxiety scores. Positive reframing/Humour and Acceptance/Planning are also associated with the Positive STAI factor and decreased anxiety scores.Conclusion:Healthy nutritional habits, comprised of consumption of salads and fruits, together with adaptive coping strategies, such as Positive reframing/Humour and Active problem solving, may provide the most profound improvement in the anxiety levels of a healthy population in Peloponnese, Greece.

Evaluation of consumer domestic habits on the environmental impact of ready-to-eat and minimally processed fresh-cut lamb's lettuce

Food consumption is associated with various environmental impacts and therefore consumer choices represent an important driver for environmental decisions. This study evaluates the environmental impact of fresh-cut salad lamb's lettuce (Valerianella Locusta L.) consumption consumer habits on the whole life cycle. Minimally processed lamb's lettuce and ready to eat lamb's lettuce were analysed following the life cycle assessment method. The functional unit was defined as a commercial unit of fresh-cut salad lamb's lettuce (130 g packaged salad). Representative data related to the consumption stages were obtained using questionnaires and results were compared to the whole life cycle of fresh-cut salad. The minimally processed salad required an average of 14 dm3 of water to be washed while the ready to eat salad needs 8.8 dm3 (36% less). Regarding the whole life cycle, the higher impact was identified in the agricultural phase for both products (46% average amongst impact categories). The consumers’ behaviour was quantified as significant in the whole life cycle: the consumption stages have an average impact of 18% and 15% amongst impact categories for the minimally processed salad and for the ready to eat, respectively. The environmental impact of consumers’ habits can be easily reduced with responsible and virtuous behaviour. The proposed ideal habits scenario showed a potential reduction of environmental impact ranged from 1% for minimally processed salad to 97% for ready to eat salad.

LED versus HPS Lighting: Effects on Water and Energy Consumption and Yield Quality in Lettuce Greenhouse Production

High-pressure sodium (HPS) lighting is increasingly replaced by LED lighting in lettuce greenhouse cultivation. In contrast to HPS lighting, LEDs do not heat radiation. Therefore, the leaf temperature is significantly lower under LEDs. This raises the question of whether LED lighting has a positive impact on the reduction in water consumption during lettuce production. In this paper, we investigated this question and found that the water consumption of lettuce produced under LEDs was significantly lower (−15%) than under HPS without loss of yield. We also found that supplementary lighting increases the concentrations of caffeoylquinic acid, dicaffeoyltartaric acid, dicaffeoylquinic acid and that of the total phenolic compounds in lettuce leaves by 61%, 39%, 163% and 38%, respectively. Only the LED fixture was also efficient enough to increase the concentration of caffeoyltartaric acid (+24%). Most of the phenolic compounds showed a very strong positive correlation with the chlorophyll concentration in lettuce, which predominated in the leaves exposed to the LED lighting. Based on these facts, we conclude that by optimizing the light composition, more sustainable plant production, higher concentrations of chlorophyll and some phenolic compounds are possible.

An Overview of Traceback Investigations and Three Case Studies of Recent Outbreaks of Escherichia coli O157:H7 Infections Linked to Romaine Lettuce

Leafy greens contaminated with Shiga toxin-producing Escherichia coli have continued to cause foodborne illness outbreaks in recent years and present a threat to public health. An important component of foodborne illness outbreak investigations is determining the source of the outbreak vehicle through traceback investigations. The U.S. Food and Drug Administration is home to traceback investigation experts who use a standardized process to initiate, execute, and interpret the results of traceback investigations in collaboration with the Centers for Disease Control and Prevention and state and local partners. Traceback investigations of three outbreaks of Shiga toxin-producing E. coli infections linked to romaine lettuce in 2018 and 2019 were examined to demonstrate challenges, limitations, and opportunities for improvement. The three outbreaks resulted in a total of 474 illnesses, 215 hospitalizations, and 5 deaths. These illnesses were linked to the consumption of romaine lettuce from three distinct growing regions in Arizona and California. Some of the challenges encountered included the time it took to initiate a traceback, limited product-identifying information throughout the supply chain, lack of interoperability in record-keeping systems, and comingling of product from multiple suppliers. These challenges led to time delays in the identification of the farm source of the leafy greens and the inability to identify the root cause of contamination. Implementation of technology-enabled traceability systems, testing of these systems, and future regulations to incentivize adoption of traceability systems are some of the initiatives that will help address these challenges by improving traceback investigations and ultimately preventing foodborne illnesses and future outbreaks from occurring.

The acute effect of incorporating lettuce or watercress into a moderately high-fat meal on postprandial lipid, glycemic response, and plasma inflammatory cytokines in healthy young men: a randomized crossover trial

BackgroundPostprandial responses to food mostly depend on the composition of the meal and the consumption of vegetables may modulate this postprandial state. In this study, the effects of lettuce or watercress consumption with a moderately high-fat meal (40% kcal from fat) on postprandial lipemia, glycemia, and inflammatory cytokines were determined in healthy men.MethodsThis randomized, 3-arm, crossover study was conducted in sixteen healthy young men with a mean ± SEM age and body mass index (in kg/m2) of 22.8 ± 0.5 years old and 23.7 ± 1.16, respectively. Lettuce and watercress were added to the test meal in portions of 100 g and cellulose was added to the control meal. Thereafter, blood samples were collected by passing 0, 1, 2, 3, and 4 h for analysis. The postprandial response was measured in plasma glucose, triglycerides (TG), total cholesterol, high-density-lipoproteins cholesterol (HDL-C), and low-density-lipoproteins cholesterol (LDL-C), as the area under the postprandial curve (AUC). Moreover, plasma tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) were determined once before and once 4 h after the meal’s consumption.ResultsThe 0–4-h AUCs for glucose (385.7, 361.9, and 382.3 mg/dL for the control, lettuce, and watercress meals, respectively) were calculated to be lower when meal was consumed with lettuce compared to the control (P < 0.05) and watercress (P < 0.01) meals. The maximum values of insulin were obtained as 43.8 ± 18.8, 33.5 ± 19.5, and 42.8 ± 17.7 μIU/mL for the control, lettuce, and watercress meals, respectively. As well, the lettuce-containing meal more reduced the AUC for insulin compared with the control (P < 0.05), but not watercress. Notably, plasma TG, total cholesterol, HDL-C, and LDL-C had no significant differences among the meals. Moreover, the levels of plasma IL-6 and TNF-α did not differ among the meals.ConclusionIn this study on healthy men, the addition of lettuce to a moderately high-fat meal delayed the postprandial glycemic response. However, the effect of the consumption of these vegetables on postprandial responses in subjects with cardiometabolic risk factors remains to be elucidated yet.This clinical trial was registered at the Iran Clinical Trials Registration Office (IRCT) on March 3, 2018, with an ID of IRCT20160702028742N4 (https://www.irct.ir/user/trial/23233/view).

Effects of water and salinity stresses on growth, yield, and water use of iceberg lettuce.

Salinity and drought stresses have become widespread in many regions of the world. Although there are several studies, their findings about the response of lettuce to water and salinity stresses are contradictory. This paper therefore aims to evaluate the effects of water deficit and irrigation water salinity on growth, yield, and water consumption of iceberg lettuce. For these purposes, two experiments were carried out under Mediterranean conditions. The water yield response factors (Ky ) determined for the lettuce plant grown under stress conditions caused by water (Ky =1.69) and irrigation water salinity (Ky =2.62) were quite different from each other. The classical salinity tolerance model did not reflect the results accurately because the fresh yield and plant water consumption of lettuce increased sharply with increasing soil salinity up to 2.17 dS m-1 and then decreased slightly after this value. Thus, a new model was created to reflect both the increase and decrease in fresh yield. The actual salt tolerance model for iceberg lettuce plant showed that the optimum salinity is 1.84 dS m-1 with relative yield decreases of 8.26 and 22.7% per unit salinity increase above and below the optimum salinity level, respectively. Lettuce fresh yield at soil salinity below the optimum salinity experienced greater reduction than at soil salinity above the optimum value. The results reveal that the use of low-salinity irrigation water should be preferred to increase fresh yield in iceberg lettuce cultivation. © 2021 Society of Chemical Industry.

LED Enhances Plant Performance and Both Carotenoids and Nitrates Profiles in Lettuce.

Recent studies show that vegetables at early stage of development contain higher amounts of phytonutrients and minerals, and lower amounts of nitrates than at fully developed stage. Nevertheless, the effects of some spectrum light on the carotenoid content of lettuce microgreens are unknown. Three different LED lamps were checked: (i) artificial white light (T0); (ii) continuous light-emitting diodes with longer blue-wavelength (T1), and (iii) continuous light-emitting diodes with longer red-wavelength (T2). Different lettuce cvs. were grown under the above described lamps. Plants were collected after 10, 15, 35 and 50 days from planting to produce sprouts, microgreens, initial baby leaf, and baby leaf, respectively. Response to different continuous spectrum lights related to productivity and nitrate content was variable for the different plants. Accumulation of nitrates at initial stages in plant tissues was clearly lower than at final stages of crop development, ranging from 50.2 to 73.4mg 100 g1 fresh weight for T2. Lettuce consumption is preferable at microgreen stage in comparison with baby leaf stage. Nitrate amounts at microgreen stage were lower than in baby leaf stage, and this content was inversely correlated with carotenoid content, which in tissues was higher at microgreens stage influenced by LED.

Risk of infection withSalmonella andEscherichiacoli O157:H7 due to consumption of lettuce in southern Brazil

This study was carried out to estimate the risks of infection due to consumption of lettuce contaminated with these pathogens in Southern Brazil. The quantitative microbial risk assessment (QMRA) model comprised nine modules from storage of lettuce in producer farms until consumption. Scenarios were simulated using prevalence, concentration, and exposure levels lower than found in Brazil. Different procedures of washing and disinfection as well as cold chain (≤5ºC) in all distribution steps were also tested. Models built in Excel spreadsheet were simulated using @Risk® software. The QMRA simulations show that overall risks of foodborne disease due to consumption of lettuce are higher for Salmonella than for E. coli O157:H7. All alternative scenarios to clean lettuce, increase the risk (the best procedure was washing leaves with potable water followed by immersion in 200 ppm of sodium hypochlorite sanitizer for 15 minutes and rinsing with potable water). The major risk reduction was due to cold chain scenario. Sensitivity analyses indicated that in addition to the maintenance of the cold chain and the washing and disinfection procedures, it is important to reduce the prevalence and concentration of pathogens on lettuce in fields, in order to decrease the risk of infection by these bacteria.