Lettuce Types Research Articles

The influence of cultivation method on nitrate content in some lettuce samples

The use of nitrogen fertilizers is one of the main effects for the accumulation of nitrates in plants. Conventional agriculture, in comparison to integrated and organic farming, causes greater environmental pollution and poorer quality of crops. Within the framework of the research, we studied the influence of the method of cultivation on the content of nitrates in the samples of lettuce (Lactuca sativa L.). The samples were received directly from growing areas from different parts of Slovenia and analysed in the laboratory for the nitrate content (NO3-) according to the accredited method. The samples from conventional cultivation showed the highest sample representation (51 %), with values in the highest concentration range (1000 - 2500 mg of NO3- kg-1, one sample exceeded 2500 mg kg-1 fresh mass). Within the framework of integrated cultivation, there were less such samples (34 %), and among the samples from organic cultivation no sample exceeded 1000 mg of NO3- kg-1. Of 88 analysed samples, one sample exceeded the statutory limit value applicable to lettuce of the type Iceberg ('Ljubljanska ledenka'). On average, the Iceberg samples contained more nitrates than other types of lettuce.

Inactivation mechanism of Salmonella Typhimurium on the surface of lettuce and physicochemical quality assessment of samples treated by micro-plasma discharged water

Abstract The potential of micro-plasma discharged water (m-PDW) treatment on reduction of Salmonella Typhimurium ATCC 14028 from the surface of lettuce leaves was evaluated. The surface of iceberg lettuce and red leaf lettuce pieces (3 cm × 3 cm) was inoculated with a S. Typhimurium suspension. The measured S. Typhimurium reductions were 3.0-log CFU/piece and 2.6-log CFU/piece for iceberg lettuce and red leaf lettuce, respectively for a 3-min treatment. The overall reductions measured for the levels of kaempferol and quercetin in both types of lettuce were within the experimental error for a 3-min plasma treatment. There was no significant change in color (p > 0.05) for plasma operations of the same duration. Leaching of water contributed to a greater extent towards physiochemical changes such as color constraints, kaempferol and quercetin content occurred for the treated lettuce samples, although the overall physicochemical quality changes measured in this study remains in the satisfactory level.

A novel integrated non-targeted metabolomic analysis reveals significant metabolite variations between different lettuce (Lactuca sativa. L) varieties

Lettuce is an important leafy vegetable that represents a significant dietary source of antioxidants and bioactive compounds. However, the levels of metabolites in different lettuce cultivars are poorly characterized. In this study, we used combined GC × GC-TOF/MS and UPLC-IMS-QTOF/MS to detect and relatively quantify metabolites in 30 lettuce cultivars representing large genetic diversity. Comparison with online databases, the published literature, standards as well using collision cross-section values enabled putative identification of 171 metabolites. Sixteen of these 171 metabolites (including phenolic acid derivatives, glycosylated flavonoids, and one iridoid) were present at significantly different levels in leaf and head type lettuces, which suggested the significant metabolomic variations between the leaf and head types of lettuce are related to secondary metabolism. A combination of the results and metabolic network analysis techniques suggested that leaf and head type lettuces contain not only different levels of metabolites but also have significant variations in the corresponding associated metabolic networks. The novel lettuce metabolite library and novel non-targeted metabolomics strategy devised in this study could be used to further characterize metabolic variations between lettuce cultivars or other plants. Moreover, the findings of this study provide important insight into metabolic adaptations due to natural and human selection, which could stimulate further research to potentially improve lettuce quality, yield, and nutritional value.

Purple lettuce (Lactuca sativa L.) attenuates metabolic disorders in diet induced obesity

Purple lettuce (Lactuca sativa L.) is a type of low caloric vegetable often consumed freshly, whereas its function in metabolic control has been little studied. To investigate the protective effect of a type of purple lettuce against metabolic risk factors, we treated the C57BL/6J DIO mice with or without purple lettuces for 8 weeks. Results showed that purple lettuce effectively attenuated many metabolic risk factors in DIO mice. Typically, purple lettuce prevented the body weight gain by reducing fat mass accumulation and increasing energy expenditure. Additionally, consumption of purple lettuces enhanced glucose homeostasis, increased insulin sensitivity and improved the lipid profile in the DIO mice. This was, at least partly, attributable to its abundance of bioactive molecules like esculin and chlorogenic acid. High intake of purple lettuces modulated the intestinal microbiota composition like decreased Lachnospiraceae. We conclude that purple lettuce has great potential as functional foods in prevention of metabolic disorders.

Consumer preferences for aquaponic produce: Implications from an experimental auction

AbstractAquaponics is the integration of aquaculture and hydroponics to grow fish and plants together in one system. Many producers in the northern United States are attracted to aquaponics for its potential to produce indoors year‐round. However, little is known about consumer preferences for products grown in aquaponic systems. To address this knowledge gap, we conducted an experimental auction to measure the impact of information about production method on consumers’ willingness‐to‐pay (WTP) for lettuce. For most participants, WTP was similar for both aquaponic and soil grown lettuce with overall average bids of $1.47 per 8 ounces and $1.48 per 8 ounces, respectively. Learning how samples were grown (either aquaponic or soil‐grown) rarely changed bids significantly, although on average, participants with environmental group membership lowered their bids for aquaponic lettuce samples. In general, higher frequency shoppers expressed higher average WTP for all types of lettuce. [Q100 Agriculture: General, Q220 Renewable Resources and Conservation: Fishery; Aquaculture]

UJI ZPT HANTU TERHADAP PERTUMBUHAN DAN PRODUKSI SELADA MERAH (Lactuca sativa)

Lettuce plants is one of the vegetables that have commercial value and goodprospects for development, because demand for lettuce plants continues to increasein line with population growth and awareness of nutritional needs and thedevelopment of such culinary business. Red lettuce new red fire red to black curlyleaves, the red if given full sun. This type of lettuce is not widely grown in Riau,when environmental conditions allow, the problem is the type of Ultisol, then toovercome it is to the development of good farming such as the provision of plantgrowth regulator (PGR) Hantu. Hantu PGR containing gibberellic acid, IndolAcetic Acid, Kinetin and Zeatin. The research objective was to determine the effectand get the best Hantu PGR concentration on the growth and production of redlettuce. Research conducted experiments with completely randomized design with 5 level of treatment that is without giving PGR Hantu (H0), the provision of 1 ml / l of water (H1), administration of 2 ml / l of water (H2), giving 3 ml / l water (H3) and the provision of 4 ml / l of water (H4) to four (4) replicates. Data were analyzed by analysis of variance followed by a further test DMRT level of 5%. The results showed that the Hantu PGR can promote the growth and production of red lettuce plants, with the best concentration was 2 ml / l of water.

Relationship between chlorophyll fluorescence parameters and quality of the fresh and stored lettuce ( Lactuca sativa L.)

Abstract Quality of lettuce relates to growing conditions, cultivar and storage conditions. There is a need to introduce in the plant production a forecast system for abiotic stresses to enable recognizing early changes of the plant quality before visual changes occur, based on non-destructive measurement methods. The objective of this study was to evaluate the relationship between photochemical processes dynamics and quality parameters of the lettuce. The results will be useful to assess the quality and storage ability of the lettuce and to determine chlorophyll fluorescence parameters, which could well characterize early changes of quality during plant production and storage. Two cultivars of lettuce were investigated 'Omega' F1 - butterhead lettuce type, and 'Aficion' F1 - 'Batavia' type, which were grown in three hydroponic systems: in mineral wool slabs, coconut fibre, and NFT (nutrient film technique). The harvested plants were tested after 3 d and after 6 d of storage. The results of this study showed that lettuce of 'Aficion' F1 and 'Omega' F1 cvs. differ significantly in yield, quality and different ChlF parameters. 'Aficion' F1 of 'Batavia' type was characterized by higher dry mass, soluble solids, Chl a, Chl b and carotenoid contents than the 'Omega' F1 plants. Only 'Omega' cultivar showed reaction to the growing medium used. The influence of storage period on both cultivars was similar. Storage for 3 d period particularly affected decreasing of SPAD index, and the chlorophyll fluorescence parameters such as PI total, Area, Fo, Fm, Fv, Reo / CSo and increasing of ABS / RC, kP / ABS × kF and kN / ABS × kF. In general, 'Aficion' plants photosynthetic apparatus was significantly less modified during the storage. The level of degradation of the plant tissues during storage has a different effect on structure and reactions in photosynthetic light phase parameters in leaves. The analysis of the photoinduced chlorophyll fluorescence rise allows to monitor the damage dynamics in thylakoid membranes and connect them with the quality parameters of plant tissue.

First report on Pseudomonas viridiflava causing bacterial leaf spot of curly lettuce in Turkey

During the winter growing season of 2016, bacterial leaf spot disease, characterized as water-soaked,dark-brown and irregular spots 2-8 mm in diameter, was observed on curly type lettuce (Lactuca sativa var. crispa) in greenhouses of Samsun province (Carsamba town) in the Black Sea Region of Turkey. Fluorescent colonies were further purified on KB to perform further tests with the reference isolate. Pathogenicity of isolates was confirmed on 30-day-old curly type lettuce plants, and they were identified as Pseudomonas viridiflava based on biochemical test results confirmed using PCR-amplification of the 16S rDNA gene and sequencing. This is the first report of P. viridiflava, the causal agent of curly type lettuce in Turkey.

Development and validation of an analytical method for multiresidue determination of pesticides in lettuce using QuEChERS-UHPLC-MS/MS.

A new analytical method for multiresidue determination of 16 multiclass pesticides in lettuce was developed using ultra-high performance liquid chromatography with tandem mass spectrometry with a triple quadrupole mass analyzer and positive mode electrospray ionization, using a previously optimized quick, easy, cheap, effective, rugged, and safe method for sample preparation. Validation studies, according to document SANTE/11945/2015, demonstrated that the developed method is selective, accurate, and precise, providing recoveries of 70-120%, relative standard deviations≤20% and quantification limits from 3μg/kg. The method was compared with one based on high-performance liquid chromatography with tandem mass spectrometry, in terms of chromatographic performance, detectability and matrix effect for five varieties of lettuce. The new method provided a reduction in the time for the chromatographic analysis of 50%, from 30 to 15min, using a lower mobile phase flow rate (0.147mL/min), which reduced the consumption of mobile phase by 25%, and injection of smaller amounts of sample (1.7μL). Lower limits of quantification were obtained for almost all pesticides studied for green-leaf lettuce. However, in relation to the matrix effect, four of the five types of lettuce studied presented higher matrix effects.

Productivity of Lettuce Varieties in Conveyor Cultivation in the Open and Protected Soil of the Southeast of Kazakhstan

In the framework of diversification of vegetable production in Kazakhstan, special attention is paid to minor vegetable crops. Conveyor cultivation of green vegetables plays an important role in providing fresh vegetables to consumers year-round. In this regard, two types of lettuce have been studied: Leaf lettuce and heading lettuce. The studies were performed in 2014-2016 at the Kazakh Research Institute of Potato and Vegetables Growing and at the Kazakh National Agrarian University. It has been established that the conveyor cultivation of leaf and heading lettuce with the use of protected and open soil is an efficient method of uninterrupted supply of local green products to the population in the off-season period. In protected soil, lettuce should be cultivated in four periods with the use of rootstock, by sowing seeds from the first third of January until the second third of February. The age of rootstock is 23 to 26 days for leaf lettuce and 28-32 days for heading lettuce. For obtaining early lettuce in the open ground, it should be sown in four periods, starting from the first third of April until second third of May. During the first period, rootstock is to be used (18 days old) and in the other three periods, the method without rootstock is to be used. Varieties of Odessian Kucheryavets lettuce (leaf lettuce) and Krupnokochanny (heading lettuce) are recommended for vegetable farms.

Evaluation of lettuce genotypes for mineral content

Lettuce is considered as a high value vegetable due to its richness in phytonutrients. Nowadays, it is produced all the year round and consumed fresh so that all the ingredients stay intact. Estimation of different elements in different types of lettuce is essential in developing nutritionally rich, good quality varieties for cultivation. Sixty two genotypes comprising both heading and non-heading types were analyzed for six mineral content such as Calcium, Sulphur, Zinc, Copper, Manganese and Iron. The genotypes studied belonged to six lettuce types, namely Latin (three), Stem (five), Crisphead (thirteen) Butterhead (Eight), Leaf (twenty three) and Cos (ten). Overall, latin types were rich in sulphur, while crisphead types were rich in calcium and copper and butterhead in zinc, manganese and iron. The stem types, however, were found to be lesser in most of the minerals compared to other types. The Pennlake Crisphead lettuce genotype had highest calcium content (390.07 ppm), New chicken stem type had highest sulphur content (7.80 ppm), L-S-2 leaf type had highest zinc content (29.91 ppm), Balmoral crisphead type had highest copper content (10.98 ppm), Great takes Katrain crisphead type had highest magnesium content (44.94 ppm) followed by Sheetal crisphead type (44.11 ppm) and All source butterhead type had highest iron content (605.52 ppm). The comprehensive analysis helped by providing detailed information about the composition of minerals of different types as well as genotypes. The information so obtained will go a long way in developing mineral content dense lettuce varieties.

RNA sequencing provides insights into the evolution of lettuce and the regulation of flavonoid biosynthesis

Different horticultural types of lettuce exhibit tremendous morphological variation. However, the molecular basis for domestication and divergence among the different horticultural types of lettuce remains unknown. Here, we report the RNA sequencing of 240 lettuce accessions sampled from the major horticultural types and wild relatives, generating 1.1 million single-nucleotide polymorphisms (SNPs). Demographic modeling indicates that there was a single domestication event for lettuce. We identify a list of regions as putative selective sweeps that occurred during domestication and divergence, respectively. Genome-wide association studies (GWAS) identify 5311 expression quantitative trait loci (eQTL) regulating the expression of 4105 genes, including nine eQTLs regulating genes associated with flavonoid biosynthesis. GWAS for leaf color detects six candidate loci responsible for the variation of anthocyanins in lettuce leaves. Our study provides a comprehensive understanding of the domestication and the accumulation of anthocyanins in lettuce, and will facilitate the breeding of cultivars with improved nutritional value.

HOW TO SUSTAINE ECOLOGICAL FOOD PRODUCTION UNDER URBAN CONDITIONS

Sustainable horticulture production, recycling organic wastes, mitigate climate change impacts and greenhouse gas emission and save natural resources under urban and rural areas are a serious issues need to create new strategies. Rooftop garden and vermicomposting technologies performed an integrated strategy to share in achieving resilience city. The study was conducted out during two successive winter seasons (2015 and 2016) under urban conditions at Central Laboratory for Agricultural Climate (CLAC), Giza, Egypt. The study investigated the use and the effect of vermicompost as an amendable substrate in different proportions (10 and 20% V/V) with sand: peat moss (1:1 V/V) and sand combined with two nutrient solution sources (chemical nutrient solution and vermi-liquid) with two EC levels (1 and 1.5 dS m-1) on lettuce yield under urban condition. Iceberg lettuce type cv. Robinson F1 hybrid was cultivated in split split plot design with three replicates. The study aimed to alternate or minimize the use of peat moss by vermicompost and chemical fertilizers by organic source via vermi-liquid to provide more sustainable production and mitigate climate change impacts via converting urban organic wastes through vermicomposting technology into vermicompost and vermi-liquid. Results revealed that using vermicompost as a substrate amendment combined with different substrates had a significant effect on lettuce yield through enhancing the physical and chemical properties of substrate and support plant nutrition. The use of chemical nutrient solution + EC level 1.5 dS m-1 + substrate sand: peat moss: vermicompost ((40: 40: 20% V/V) for producing the highest yield of lettuce under the investigation conditions. While for environmentally and safety, vermi-liquid + Ec level 1.5 dSm-1 + substrate sand: peat moss: vermicompost (40: 40: 20% V/V) was recommended. The study supported the micro and small scale urban farm to match the food security and safety needs via using vermicomposting outputs and simple substrate culture in top roof garden technique. Recycling urban organic wastes and mitigating greenhouse gases (GHG's) emission as well as sustainable food production need more efficient efforts and real contribution. Ecology food could be sustained under urban condition.

Evaluation of Lettuce Between Spring Water, Hydroponic, and Flow-through Aquaponic Systems

ABSTRACTLettuce (Lactuca sativa L.) is an important vegetable crop that can be grown in hydroponic and aquaponic systems. A comparative study to evaluate the efficacy of a cold water flow-through aquaponic system (FTS) to a hydroponic system is lacking. Twenty-seven lettuce cultivars with green or red leaves, in seven subtypes, belonging to four popular types in the Western diet, were grown in spring water or aquaponic or hydroponic treatments. Spring and aquaponic water flowed directly from a spring and a raceway growing rainbow trout, respectively. The hydroponic treatment had nutrients added to a recirculated system. Stand establishment, average yield, and productivity (yield/week) were determined for each subtype or cultivar and compared among water treatments. No comparison among lettuce types, subtypes, or cultivars was made due to inherent differences among genotypes. Total yield and productivity (402.5 g·m−2 and 4.9 kg/tray/week, respectively) in the FTS were lower than those in the hydroponic system (468.9 g·m−2 and 6.7 kg/tray/week, respectively). Average yields of butterhead and bibb subtypes in aquaponics were higher than in the hydroponic treatment. Bibb subtype lettuces performed better in the aquaponic treatment, and average yields of butterhead and romaine, one of the most popular and nutritious lettuce types, were similar to those in the hydroponic treatment. The cvs. Outredgeous in romaine, Winter Density in bibb, Red Sails in leaf, and Red Saladbowl in oakleaf subtypes were recommended for an FTS. Average yields of green lettuces were higher than red lettuces in the bibb subtype in all treatments. Lettuce yield, depending on cultivar, could be comparable to hydroponic or field production based upon yield per area.

EFECTOS DEL USO DE MANTA TÉRMICA SOBRE VARIABLES AMBIENTALES Y RENDIMIENTO DE UN CULTIVO DE LECHUGA

El presente trabajo tuvo como objetivo evaluar el efecto de la protección de la manta térmica sobre el comportamiento de variables ambientales y el rendimiento de un cultivo de lechuga. Para ello, se sembró durante dos temporadas otoño-invernales un cultivar de lechuga tipo mantecosa (Lactuca sativa var. capitata) en bandejas de germinación de 128 celdas, con posterior trasplante en campo, realizado a los 37 días (ciclo 1) y 49 días (ciclo 2) después de la siembra. Los tratamientos fueron: 1) Cultivo protegido con manta térmica (MT); 2) Testigo no protegido (T) en un diseño experimental en parcelas divididas con tres repeticiones. El marco de plantación utilizado fue de 0,35 m entre hileras y 0,25 m entre plantas. El riego se efectuó mediante un sistema de goteo. Se evaluó el efecto de la manta térmica sobre la trasmisividad de la radiación fotosintéticamente activa (RFA), temperatura y humedad relativa del aire, rendimiento del cultivo, suma térmica en grados.día-1 desde el trasplante hasta la cosecha (ºC.ddt-1). Los resultados mostraron en el tratamiento MT una trasmisividad promedio de la RFA de 0,69 (ciclo 1) y 0,73 Mj.m-2.día-1 (ciclo 2), incremento de la temperatura del aire mínima, media y máxima en 1,1; 2,0 y 3,1 ºC, respectivamente, y de la humedad relativa. El rendimiento en peso fresco (t ha-1) presentó diferencias estadísticas significativas entre los tratamientos, siendo de: 37,7 (MT); 15,5 (T) para el ciclo 1 y 33,8 (MT) y 14,7 (T) para el ciclo 2. La suma térmica fue mayor en el tratamiento con manta térmica. La protección del cultivo permitió una mayor precocidad con mejoras significativas en el rendimiento.

Soil disinfestation with dimethyl disulfide for management of Fusarium wilt on lettuce in Italy

The efficacy of dimethyl disulfide (DMDS) applied in pre-planting treatment by shank injection was investigated on the lettuce Fusarium oxysporum f.sp. lactucae (FOL) pathosystem in Northern Italy (Piedmont), in three experimental trials. DMDS was tested alone or in combination with metham sodium at 35.9 g/m2, on lettuce cultivars showing different levels of susceptibility to the pathogen. DMDS, at 60 g/m2, reduced FOL symptoms on the highly susceptible butterhead type of 70, 97 and 99%, and of 87, 97 and 100% on the moderately susceptible cultivar, respectively. DMDS at 30 and 40 g/m2 showed a only partial efficacy on both lettuce types used in naturally infested soil, with a disease reduction from 30.3 to 64.5%, significantly comparable with dazomet. The results provided by DMDS at 40 g/m2 plus metham sodium at 35.9 g/m2 were statistically similar to those obtained with DMDS alone at 60 g/m2, and better than those provided by dazomet alone. A positive effect on lettuce yield and weed control by DMDS, at the highest dosage tested and by DMDS plus metham sodium, was also observed.

Plant Growth and Photosynthesis Response to Low Potassium Conditions in Three Lettuce (<i>Lactuca sativa</i>) Types

Chronic kidney disease has become a major public health problem worldwide. The aim of this study was to investigate the differences in plant growth and photosynthesis among three lettuce (Lactuca sativa) types with different morphological characteristics under low potassium conditions, providing information for improving the method of low-potassium lettuce culture. Lettuce was hydroponically grown in half-strength Enshi formula nutrient solution containing 4, 2, or 1 me·L−1 K+. The plant yield and relative growth rates (RGR) of all three lettuce types were lowest under a treatment with 1 me·L−1 K+. In green leaf lettuce, reductions in both the net assimilate rate (NAR) and leaf area ratio (LAR) led to a decline in RGR. In Boston lettuce and romaine lettuce, the reduction of RGR was mainly due to a reduction in LAR, and to a lesser extent caused by NAR. Reduced potassium in the nutrient solution had a greater effect on mature leaves than on newly expanded leaves for all three lettuce types. In green leaf lettuce and Boston lettuce, photosynthetic rates of mature leaves significantly decreased under reduced potassium treatments, with a steady or gradually increased intercellular CO2 concentration; this indicated that non-stomatal factors suppressed photosynthesis. In romaine lettuce, the photosynthetic rate was less influenced by reduced potassium levels in the nutrient solution, and the significant increase observed in leaf mass per area might contribute to maintaining photosynthesis in the leaf. The decrease in photosynthesis in mature leaves exhibited a similar trend to the decreased potassium content in the leaves within the three lettuce types, but the factor related to the reduction of photosynthesis was different.

Calcium Cyanamide Effects on Nitrogen Use Efficiency, Yield, Nitrates, and Dry Matter Content of Lettuce

Core Ideas Calcium cyanamide may be a good N fertilizer source for lettuce crops. Calcium cyanamide can reduce nitrate accumulation in lettuce crops. Calcium cyanamide did not improve lettuce crop N use efficiency. Lettuce genotypes influence the crop N uptake and N utilization efficiency. A 2‐yr field study was conducted to evaluate the effects of calcium cyanamide as an alternative nitrogen (N) fertilizer source on N use efficiency (NUE), yield, and quality of two types of lettuce (Lactuca sativa L.), romaine (var. longifolia, cv. Manavert) and red oak‐leaf (var. crispa, cv. Aruba), grown on clay soil under a Mediterranean environment. Pretransplanting application of 120 kg ha−1 of N as calcium cyanamide (120CC) was compared with a traditional split application of 120 kg ha−1 of soluble N (120SN) consisting of 50% ammonium sulfate applied before transplanting and 50% as ammonium nitrate applied after transplanting. An unfertilized control (0‐N) was included to calculate NUE indices. At harvest leaf area index, dry weight, fresh yield, dry matter concentration, and NUE indices were not affected by the N source. Leaf nitrate (NO3−) content was on average 55 and 41% higher in Aruba than in Manavert in the first (Exp‐1) and second (Exp‐2) season, respectively. Plants fertilized with 120CC had lower leaf NO3− content (41 and 18% in Aruba and 70 and 21% in Manavert in Exp‐1 and Exp‐2, respectively) compared with those fertilized with 120SN. These results suggest calcium cyanamide may be used as an effective tool to reduce leaf NO3− accumulation and to produce high‐quality lettuce in compliance with European Regulation No. 1258/2011 while assuring competitive yields.

Revisiting quick, easy, cheap, effective, rugged, and safe parameters for sample preparation in pesticide residue analysis of lettuce by liquid chromatography–tandem mass spectrometry

A new analytical method using a quick, easy, cheap, effective, rugged, and safe (QuEChERS) procedure for multi-residue determination of 16 multiclass pesticides in five different types of lettuce was developed using high-performance liquid chromatography coupled to electrospray ionization tandem mass spectrometry. The QuEChERS procedure was optimized in terms of extractor solvent, partitioning salts and clean-up salts, through recovery, gravimetric analysis and matrix-effect studies. Microwave extraction and the use of disposable pipette extraction in the clean-up step were also tested, providing interesting alternatives to the traditional QuEChERS method, depending on the pesticides properties. The use of a laboratory-made phenyl-type sorbent, based on silica and poly(2-phenylpropyl)methylsiloxane, was studied in the clean-up step, presenting promising results as a substitute for primary secondary amine (PSA). The optimized QuEChERS method was defined employing acetonitrile, citrate buffer and clean-up with PSA, MgSO4 and graphitized carbon black. The method developed was validated according to Document SANTE/11945/2015 and proved to be selective, accurate and precise, obtaining limits of quantification from 5μgkg−1 and recoveries in the range of 70–120% with relative standard deviation≤20%. The method was applied on 14 real samples from commercial markets in Brazil and 21% of the samples analyzed presented irregularities, according to local pesticides regulations.

Nutritional Value of Crisphead ‘Iceberg’ and Romaine Lettuces (Lactuca sativa L.)

<p>Lettuce (<em>Lactuca sativa</em> L.) is one of the most popular vegetables worldwide, but is often viewed as low in nutritional value. However, lettuce contains health-promoting nutrients and biosynthesis of such phytochemicals varies depending on cultivar, leaf color and growing conditions. Studies of such parameters on the nutritional value have not been conclusive because the lettuce samples were collected from heterogeneous growing conditions and/or various developmental stages. In our study nutritional composition was evaluated in the two most popular lettuce types in Western diets, romaine and crisphead ‘Iceberg’, with red or green leaves grown under uniform cultivating conditions and harvested at the same developmental stage. In the investigated lettuce cultivars, insoluble fiber content was higher (<em>P </em>≤ 0.05) in romaine than crisphead lettuces. Alpha-linolenic acid (omega-3 polyunsaturated fatty acid) was the predominant fatty acid and was higher in romaine than crisphead. Iron and bone health-promoting minerals (Ca, Mg and Mn) were significantly higher (<em>P</em> ≤ 0.001) in romaine. The content of Beta-carotene and lutein in romaine (668.3 ug g<sup>-1</sup> dry weight) was ~45% higher than in crisphead (457.3 ug g<sup>-1</sup>dry weight). For leaf color comparison, red cultivars provided higher amount of minerals (Ca, P, Mn and K), total carotenoids, total anthocyanins and phenolics than green cultivars. Based on our study results, romaine was generally higher in nutrients analyzed, especially red romaine contained significantly higher amount of total carotenoids, total anthocyanins and phenolics. Therefore, romaine type lettuces with red rather than green leaves may offer a better nutritional choice.</p>