Pear Samples Research Articles

Z-sep+ based QuEChERS technique for the pre-concentration of malathion pesticide in fruits followed by analysis using UV-Vis spectroscopy

ABSTRACT In this work, the concentrations of malathion in fruits were determined using UV-Vis spectrophotometry prior to pre-concentration using QuEChERS. The Z-sep+/PSA sorbent combination was used for the d-SPE clean-up and extraction was done using acetonitrile during QuEChERS. The absorbance of malathion was measured using a UV-Vis spectrophotometer at a wavelength of 415 nm. The QuEChERS parameters, which included type and volume of extraction solvent, type and mass of sorbents, and centrifugation rate, were optimised prior to application of the developed method to real fruit samples. The linear range was from 0.1 to 0.9 mg kg−1 while the coefficient of determination (R2) was 0.9999. The limit of detection (LOD) for malathion was found to be 0.017 mg kg−1 and the limit of quantification was 0.05 mg kg−1. Orange samples were found to have no malathion residues when the developed method was applied to them while the concentrations of malathion in apple and pear samples were 0.07 mg kg−1 and 0.09 mg kg−1 respectively.

Identification and Characterization of a Pear Chlorotic Leaf Spot-Associated Virus, a Novel Emaravirus Associated with a Severe Disease of Pear Trees in China.

Pear chlorotic leaf spot (PCLS) is a recently emerged disease of commercially cultivated sandy pear (Pyrus pyrifolia) trees in central and southern China. By integrating high-throughput sequencing and conventional Sanger sequencing of reverse-transcription (RT)-PCR products, a novel emaravirus infecting pear trees was identified and molecularly characterized. The virus was provisionally named pear chlorotic leaf spot-associated virus (PCLSaV). PCLSaV shows the typical molecular features of members of the genus Emaravirus in the family Fimoviridae. It has a genome composed of at least five negative-sense RNA segments, with each containing a single open reading frame and two complementary 13-nucleotide stretches at the 5' and 3' termini. PCLSaV shows a close phylogenetic relationship with recognized emaraviruses but forms a separate clade. Moreover, double-membrane-bound bodies were observed in PCLSaV-infected tissues and in extracts of PCLSaV-infected leaves. For the first time, our study revealed the profile distribution of viral RNA reads from the RNA-seq libraries of three samples along the RNA1 to RNA5 of an emaravirus. Field surveys combined with specific RT-PCR assays revealed the presence of PCLSaV in almost all PCLS-diseased pear samples, strongly supporting the association of the virus with the PCLS disease. This study revealed the first emaravirus infecting pear trees and its association with a severe pear chlorotic leaf disease.

Does bruising influence the volatile profile of pears?

PurposeVolatile flavor plays a main role in defining the fruit quality by consumers. Bruising leads often to dark spots on fruits and its amount could highly affect product quality. This paper aims to study the effect of bruising on the volatilome released by pears by using proton transfer reaction – mass spectrometry (PTR-MS).Design/methodology/approachFingerprints of non-bruised and bruised pear samples were collected through PTR-MS for 28 days, and discriminant analysis was used to discriminate the fruit products. The CIELAB color changes were also measured during the entire ripening period.FindingsBruised pears released a higher intensity of volatile organic compounds (VOCs) compared to non-bruised pears (p16days = 0.049, p22days = 0.012, p28days = 0.006). In particular, the release of m/z 45 and m/z 47 were significantly (pm/z 45 = 0.076, pm/z 47 = 0.095.) higher in bruised samples, suggesting that the bruising event accelerated the natural ripening process. CIELAB color coordinates were also recorded. The coordinate a* showed a linear increase during the whole 28 days because of the loss of the green component. The CIELAB ΔE* was higher in the bruised pears than the non-bruised pears (p = 0.022).Originality/valueBruising can affect food quality and taste. Bruise susceptibility has been largely studied on apples, tomatoes and peaches, but rarely on pears. Very little is known about the effect of bruising on the volatilome of pears. Moreover, bruising research usually involved the study of physical properties; on the contrary, PTR-MS, applied to bruising research, has never been used before. Besides the analysis of volatilome, the changes in color were also recorded for the whole 28 days of analysis. The proposed method could be applied for the monitoring of pears quality in the food industry.

Occurrence of perchlorate, chlorate and polar herbicides in different baby food commodities.

The incidence of endocrine disruptors, both possible (glyphosate and glufosinate), and demonstrated (perchlorate and chlorate), was estimated in baby food commodities (meat, fish, cheese, vegetable and fruit). Ion-chromatography coupled to high resolution mass spectrometry analysis of the 105 samples did not show traces of glyphosate, glufosinate or their metabolites, while in 10.5% of the samples a quantifiable amount of perchlorate was found. Some samples based on fruit and vegetables revealed a substantial amount of chlorate, especially the preparations that contained carrots and potatoes: five samples were in a concentration range of 40-120μgkg-1, while one homogenized pear sample reached 372.2μgkg-1. The pure meat samples revealed occasional chlorate appearance, with less than 10μgkg-1. This is the first report of chlorate evaluated in various types of baby food and may serve as symptomatic data regarding its occurrence in infant/toddler diets. Therefore, effective monitoring programs and subsequent strict regulations are strongly required.

Inside black pearls

The quality of natural and cultured pearls depends on the size, shape and properties of the surface. The inner structure of the pearl is not known, and not taken into account. Indeed, it is assumed that the cultured pearl is a nucleus covered by a thin organic layer, a thin prismatic layer and a thick nacreous layer. The examination of spherical and pear shape samples resulting from the grafting of the black lip pearl oyster (Pinctada margaritifera) shows that this assumption is, in most cases, erroneous. Optical, electron and atomic force microscopic observations, infrared and Raman analyses, as well as micro X-ray fluorescence and micro X-ray absorption near-edge spectroscopy data show that the inner structure of a pearl does not depend on its shape. Both circle or pear shape and spherical pearls show a large variability of the inner structures and composition. There are no two identical samples. Moreover, the arrangement is irregular within a single pearl, and some structures (aragonitic pseudo-prisms) do not exist in the shell.

Comparative transcriptome analyses of fruit development among pears, peaches, and strawberries provide new insights into single sigmoid patterns

BackgroundPear fruit exhibit a single sigmoid pattern during development, while peach and strawberry fruits exhibit a double sigmoid pattern. However, little is known about the differences between these two patterns.ResultsIn this study, fruit weights were measured and paraffin sections were made from fruitlet to maturated pear, peach, and strawberry samples. Results revealed that both single and double sigmoid patterns resulted from cell expansion, but not cell division. Comparative transcriptome analyses were conducted among pear, peach, and strawberry fruits at five fruit enlargement stages. Comparing the genes involved in these intervals among peaches and strawberries, 836 genes were found to be associated with all three fruit enlargement stages in pears (Model I). Of these genes, 25 were located within the quantitative trait locus (QTL) regions related to fruit weight and 90 were involved in cell development. Moreover, 649 genes were associated with the middle enlargement stage, but not early or late enlargement in pears (Model II). Additionally, 22 genes were located within the QTL regions related to fruit weight and 63 were involved in cell development. Lastly, dual-luciferase assays revealed that the screened bHLH transcription factors induced the expression of cell expansion-related genes, suggesting that the two models explain the single sigmoid pattern.ConclusionsSingle sigmoid patterns are coordinately mediated by Models I and II, thus, a potential gene regulation network for the single sigmoid pattern was proposed. These results enhance our understanding of the molecular regulation of fruit size in Rosaceae.

Highly Sensitive Detection of Thiabendazole Residues in Food Samples Based on Multiwall Carbon Nanotubes Decorated Two-Dimensional Layered Molybdenum Disulfide

Thiabendazole (TBZ), a widely used agricultural antifungal, has been evidenced to pose serious threat to human health. However, highly sensitive detection of it in food samples is difficult owing to the complexity of food matrix. Herein, an electrochemical sensor, based on multiwall carbon nanotubes (MWCNTs) decorated two-dimensional layered molybdenum disulfide (MoS2), was firstly developed for rapid detection of TBZ using square wave voltammetry method. It is demonstrated that the modification of MoS2 with MWCNTs enhances the catalytic performance to TBZ oxidation. Under optimized conditions, the electrochemical sensor shows admirable linearity range, high selectivity and low detection limit. In pear, water spinach and tap water sample analyses, satisfactory recoveries from 92.83 to 101.92% with coefficients of variation less than 5% were obtained, showing high consistence with the HPLC results. This work puts forward a rapid and reliable method for the highly sensitive screening of the residues of TBZ in food resource.

Some approaches to mathematics modeling of pome crops yielding ability

The analysis of methods of mathematical modeling of pome crops on the example of studying 5 varietal samples of pears, taking into account the factors affecting the yielding ability. 15 main factors were considered, such as: maximum, minimum and average temperatures, relative humidity, incidence of chlorosis, drought resistance, morphological characteristics. Mathematical analysis with the construction of mathematical models was carried out using the software package Matlab. As a result, mathematical models characterizing the influence of both individual and multiple factors on the yielding ability of pear cultivars were obtained.

Aqueous two-phase extraction technique based on magnetic ionic liquid-nonionicsurfactant for phenolic acids in grape, apple, pear, and banana

An aqueous two-phase extraction system was constituted using magnetic ionic liquid-nonionic surfactant for phenolic acids and the developed method was applied to apple, grape, pear, and banana samples. Ionic liquids based on imidazolium containing butyl, allyl, and benzyl groups were used for extraction. The parameters influencing the extraction efficiency such as volume of ionic liquids, type and amount of surfactant and salt, ultrasound extraction time, temperature, and sample pH were optimized. The extraction efficiencies of ionic liquids were compared for phenolic acids under optimized conditions. Limits of detection and limits of quantification were in the range of 1.34-1.56 μg L$^{-1\, }$and 4.33-4.68 μg L$^{-1}$, respectively. The interday and intraday precision (RSD%) for the phenolic acids at 5 and 25 μg L$^{-1\, }$were in the range of 4.48%-5.69% and 3.02%-4.51%, respectively. The spiked recoveries of phenolic acids were between 70.78% and 99.97% in real samples.

Self-reduction bimetallic nanoparticles on ultrathin MXene nanosheets as functional platform for pesticide sensing

Two-dimensional (2D) transition metal carbides and nitrides, named MXene, appear promising application prospects in sensor filed. Metal nanoparticles, especially bimetallic nanoparticles, are the superior nanocatalyst, which process excellent features due to the high specific surface area and synergistic catalytic capacity. Using ultrathin MXene nanosheets as the natural reducing agent and support, we prepare the shape-controlled Au-Pd bimetallic nanoparticles via a self-reduction process at room temperature in a short time, which can well enhance the catalytic performance and are benefit for the acetylcholinesterase immobilization. Based on their desired properties, we propose a disposable electrochemical biosensor for the detection of organophosphorus pesticide using the multi-dimensional nanocomposites (MXene/Au-Pd) as the functional platform. Under the optimized conditions, our fabricated biosensor exhibits a favorable linear relationship with the concentration of paraoxon from 0.1 to 1000 μg L−1, with a low detection limit of 1.75 ng L−1. Furthermore, the biosensor can be applied for paraoxon detection in pear and cucumber samples, providing an effective and useful avenue for the applicability of novel 2D nanomaterials in biosensing field.

A disposable electrochemical sensor based on electrospinning of molecularly imprinted nanohybrid films for highly sensitive determination of the organotin acaricide cyhexatin.

Nanofibrous polyporous membranes imprinted with cyhexatin (CYT) were formed via the ordered distribution of the imprints in electrospun nanofibers. The MIPs have a high mass transfer rate and enhanced adsorption capacity. In addition, a printed carbon electrode with enhanced sensitivity was developed via electrochemical fabrication of reduced graphene oxide (rGO) and gold nanoparticles (AuNPs). The molecularly imprinted sensor exhibits excellent selectivity and sensitivity for CYT. The structure and morphology of the nanohybrid films were characterized by using scanning electron microscopy, atomic force microscopy and chronoamperometry. The sensing performances were evaluated by cyclic voltammetry, differential pulse voltammetry and electrochemical impedance spectroscopy by using hexacyanoferrate(IV) as an electrochemical probe. The electrode, best operated at a working potential of around 0.16V (vs. Ag/AgCl), has a linear response in the1-800ngmL-1 CYT concentration range and a detection limit of 0.17ngmL-1 (at S/N = 3). The sensor demonstrated satisfactory recoveries when applied to the determination of CYT in spiked pear samples. Graphical abstract Schematic presentation of the electrochemical sensor for detection of CYT.

Rapid Quantification of Radioactive Strontium-90 in Fresh Foods via Online Solid-Phase Extraction-Inductively Coupled Plasma-Dynamic Reaction Cell-Mass Spectrometry and Its Comparative Evaluation with Conventional Radiometry.

This paper describes a rapid quantification method for radioactive strontium (90Sr) in fresh foods (perishable foods) and has been comparatively evaluated with the common classical radiometric quantification method. Inductively coupled plasma–dynamic reaction cell-mass spectrometry with online solid-phase extraction (cascade-ICP–MS) rapidly determines 90Sr in a pure water-based sample. Despite its advantages, its application to fresh foods (perishable foods) has not yet been reported; however, the analytical potential of this method for fresh foods must be evaluated. In this study, 90Sr was determined in 12 fresh foods via improved cascade-ICP–MS (Icas-ICP–MS). Addition and recovery tests were demonstrated using real samples of grape, apple, peach, Japanese pear, rice, buckwheat, soybean, spinach, shiitake mushroom, grass, sea squirt, and flounder. With a decomposed solution of Japanese pear, the measurement value coincided with the amount of spiked 90Sr. The reproducibility of the measurements was represented by relative standard deviations of 14.2 and 5.0% for spiked amounts of 20 and 200 Bq/kg, respectively (n = 10), and the recovery rates were 93.7 ± 7.1%. In this case, the limit of detection (LOD) was 2.2 Bq/kg (=0.43 pg/kg). These results were compared with the data obtained using a common classical radiometric quantification method (nitrate precipitation-low background gas flow counter (LBC) method) in the same samples. Both the methods showed equivalent performances with regard to reproducibility, precision, and LODs but different analysis times. Icas-ICP–MS required ∼22 min for analysis, whereas the nitrate precipitation-LBC method required 20 days, confirming that Icas-ICP–MS is the suitable method for analyzing 90Sr in fresh foods.

Исследование компонентов, формирующих органолептические характеристики плодов и ягод

The research featured consumer properties of 18 varieties of apples, 12 varieties of pears, and 6 varieties of strawberries grown in the Republic of Belarus. The research objective was to study the sensory component composition of apples, pears, and strawberries to select varieties with the best consumer properties. Hexylacetate was detected in Charovnitsa, Zaslavskoye, Belarusian Sinap, and Pamyat Sikory apples. As for the pear varieties, Alesya, Belan, and Krasavita were found to contain butylbutanoate and hexylbutanoate. In all the samples of fresh pears, aroma-forming esters were mainly represented by hexylacetate and butyl acetate. Pears that reached full ripeness contained esters of unsaturated acids that are responsible for a characteristic pear flavor: methyl 2.4-decadienoate and two isomers of (cis-, trans-) ethyl-2.4-decadienoate. All the samples of strawberry contained linalool, which gives a floral flavor. Its quantity differed according to the variety: from 0.4% (Rusish variety) to 4.53% (Alpha variety). The apple varieties of Pamyat Kovalenko, Krasavita, and Dyayment had a high content of sugars (≥ 10%). Charovnitsa, Belana, and Zorka had a low acidity and can be recommended for the production of juice products for children. All the studied varieties of pears had a low sugar content (about 7%) and organic acids (≤ 0.3%), which also makes them suitable for children. The average acid content for strawberry was 9.1 g/kg, while the predominant acid was citric. However, Belarusian strawberries contained less sugar than stated in the databases, an average of 52.5 g/kg. Belana, Dyayment, Zorka, and Charovnitsa apples and Pamyat Yakovleva pears demonstrated a high sugar-acid index and the most harmonious taste. Garden strawberries had a low sugar-acid index value, not more than 6.2. The samples revealed various amounts of catechins, phenolic acids, flavonols, and anthocyanins. The obtained data on the component composition of 18 varieties of apples, 12 varieties of pears, and 6 varieties of garden strawberries of the B elarusian selection can serve as a marker of the authenticity of products by comparing with the existing database of basic quality indicators and the composition of raw materials.

Organic-inorganic manganese (II) halide hybrids based paper sensor for the fluorometric determination of pesticide ferbam

Organic–inorganic metal halide hybrids, which consist of metal halide anions and organic cations, have been widely applied in the sensor design. Instead of general lead (high toxicity) and copper (I) (weak stability) halide hybrids, the low toxic and highly luminescent manganese (II) halide hybrids may be more promising for optical sensors. In this work, a paper sensor based on the organic-inorganic manganese (II) halide hybrids is fabricated as the first attempt. Three new highly luminescent and soluble manganese (II) halide hybrids MnBr4(TPA)2, MnBr4(TEA)2 and MnCl4(btmdme)2 are prepared, and their quantum yields are 89.23%, 78.86% and 71.28%, respectively. The hybrids are dispersed uniformly and immoblized on the wax-based paper. The as-fabricated sensor is used for the fluorometric determination of pesticide ferbam, and the limit of detection is calculated to be 0.06 ppm, which is even lower than the maximum permissible concentration in EU pesticides database. Moreover, the practical application of ferbam assay for apple and pear samples is described with satisfactory recoveries (91.88–101.32%). The mechanism of ferbam detection is investigated in detail, and tentatively explained by the interaction between the manganese in MnBr4(TPA)2 and the sulfur in ferbam together with the inner filter effect (IFE).

Colorimetric bio-barcode immunoassay for parathion based on amplification by using platinum nanoparticles acting as a nanozyme.

A competitive bio-barcode immunoassay is described for the trace detection of parathion in water, pear, cabbage, and rice samples. It is based on amplification by platinum nanoparticle acting as a nanozyme. Gold nanoparticles (AuNPs) were modified with (a) monoclonal antibodies (mAbs) against parathion, and (b) thiolated single-stranded DNA (ssDNA) oligonucleotides. Magnetic nanoparticles (MNPs) were functionalized with ovalbumin coupled with parathion hapten. Parathion and its hapten compete with mAbs on the surface of the AuNPs. Subsequently, the platinum nanoparticles (PtNPs) probe, which was functionalized with the complementary thiolated ssDNA (C-ssDNA), was added to the reaction mixture for the detection of parathion. The signal was catalytically amplified by coupling with platinum nanozyme using teramethylbenzidine and H2O2 as the chromogenic system. The immunoassay has a linear range that extends from 0.01-50μg·L-1, and the limit of detection is 2.0 × 10-3μg·L-1. The recoveries and relative standard deviations (RSDs) ranged from 91.1-114.4% and 3.6-15.8%, respectively. The method correlates well with data obtained by gas chromatography-tandem mass spectrometry (GC-MS/MS). Graphical abstract The parathion and the magnetic nanoparticles (MNPs) labelled with hapten-OVA competitively reacted to AuNPs modified with mAbs and thiolated DNA for thedetection of parathion. The signal was catalyzed by platinum nanozyme. The limit of detection for parathion is 2.0 ng·L-1.

Valorization of Prickly Pear Juice Geographical Origin Based on Mineral and Volatile Compound Contents Using LDA.

In the present work the mineral content and volatile profile of prickly pear juice prepared from wild cultivars was investigated. Fruits used in the study originated from three areas of the Peloponnese Peninsula. Twenty-five macro- and micro-minerals (K, Na, P, Ca, Mg, Al, B, Ba, Be, Co, Cr, Cu, Fe, Li, Mn, Mo, Ni, Sb, Se, Si, Sn, Ti, Tl, V, Zn) were determined using inductively coupled plasma atomic emission spectroscopy (ICP-OES). Furthermore, analysis of the mineral content of soil samples with ICP-OES showed a perfect correlation with those of fruit juices. Volatile compounds (alcohols, aldehydes, hydrocarbons, terpenoids, and others) were identified using an optimized headspace solid phase microextraction coupled to gas chromatography mass spectrometry (HS-SPME/GC-MS) method. Multivariate analysis showed significant differences (p < 0.05) among the investigated parameters with respect to juice geographical origin. Prickly pear juice samples were classified according to geographical origin by 85.7% and 88.9% using 7 minerals and 21 volatile compounds, respectively.

Opuntia ficus-indica (L.) Mill. and Annona cherimola Mill. by-products: a potential to be exploited

Introduction: Fruits have become increasingly important in human nutrition because of their nutrient and bioactive composition, as well as potential beneficial health effects. Opuntia ficus-indica (L.) Mill. and Annona cherimola Mill. are commonly known as prickly pear and cherimoya, respectively. These exotic fruits are highly appreciated due to their attractive sensorial properties [1]. However, considerable quantities of by-products from the production of these fruits are discarded, and these can be a valuable source of bioactive compounds. Therefore, this study aims to perform a comparison between the antioxidant activity, total phenolics, total flavonoids and vitamin C contents of the peels of prickly pear and cherimoya, in order to evaluate their potential to obtain added value natural extracts. Materials and methods: Samples of cherimoya were supplied by a company located in Madeira Island (Portugal) and samples of prickly pear were obtained at Herdade de Peliteiros (Silveiras, Montemor-o-Novo, Évora, Portugal). Then, samples were manually divided between edible portion (pulp) and non-edible portion (peel). Peels of the selected fruits were analysed concerning: (i) antioxidant activity by radical 2,2-diphenyl-1-picrylhidrazyl (DPPH•) scavenging activity method; (ii) total phenolics determined by Folin-Ciocalteu assay and expressed as mg of gallic acid equivalents (GAE)/g of sample; and (iii) total flavonoids, expressed as mg of epicatechin equivalents (ECE) per g of sample, through the interpolation of the calibration curve of epicatechin [2]. Total vitamin C content was determined by high performance liquid chromatography coupled to diode array detection. All analyses were performed in triplicate [1]. Results: EC50 is the concentration of the sample that decreases the initial DPPH• absorbance by 50%. Therefore, the highest antioxidant activity was observed for the peel of cherimoya (EC50, 0.18 ± 0.0 mg/mL). With respect to total phenolics, the obtained values were 0.195 ± 0.01 and 49.1 ± 1.0 mg of GAE/g of sample, for cherimoya and prickly pear peels, respectively. Also, prickly pear peel showed the highest total flavonoids content (3.01 ± 0.14 mg ECE/g) and total vitamin C content (132.4 ± 0.61 mg/100 g of sample). Discussion and conclusions: These results highlight the antioxidant properties of these by-products and support their employment as added value natural extracts in cosmetic, pharmaceutical and food processing industries. Furthermore, this work will contribute to maintain the biodiversity and to promote the sustainable development and exploitation of these exotic fruits.

Türkiye’de yumuşak ve sert çekirdekli meyvelerde ‘Candidatus Phytoplasma’ türlerinin moleküler çeşitliliği

Apple, pear and apricot trees showing phytoplasma associated symptoms from Ankara and Isparta provinces were sampled and investigated to verify the presence of phytoplasma-associated diseases. Totally 31 samples were tested with phytoplasma universal and group specific primers and the PCR products were restricted using Tru1I, RsaI and SspI endonucleases. Different RFLP profiles were obtained and selected samples were directly sequenced. The apple samples were found infected with 16SrX-A (‘Candidatus Phytoplasma mali’), while the majority of the pear samples were infected with 16SrX-A and 16SrX-C subgroup phytoplasmas in mixed infection. The 16SrX-B (‘Candidatus Phytoplasma prunorum’), 16SrX-C (‘Candidatus Phytoplasma pyri’) and mixed infection of 16SrX-A/16SrX-C and 16SrX-C/16SrI (aster yellows) were detected in the apricot samples. In this study the 16SrI phytoplasmas in apricot and the mixed phytoplasma infections in pear and apricot trees were detected in Turkey for the first time.

One-step immunoassay for the insecticide carbaryl using a chicken single-chain variable fragment (scFv) fused to alkaline phosphatase

Immunoassays provide a high-throughput method for monitoring pesticides in foods and the environment. Due to easy generation and capable of being manipulated, chicken single-chain variable fragment (scFv) is attractive in the development of immunoassays for pesticides. Two scFvs (X1 and X2) against the insecticide carbaryl were generated from a chicken immunized with hapten C1 conjugated to keyhole limpet hemocyanin and fused with alkaline phosphatase (AP) to develop a rapid one-step enzyme-linked immunosorbent assay for this pesticide. X2-AP showed higher binding affinity to carbaryl than X1-AP. The X2-AP-based ELISA had a half-maximum signal inhibition concentration of 15 ng mL−1 and a limit of detection of 1.6 ng mL−1. This assay showed negligible cross-reactivity with other carbamate pesticides (<0.1%) and low cross-reactivity with 1-naphthol (5%). The average recoveries of carbaryl spiked in soil, apple and pear samples by the one-step assay ranged from 90% to 114% and agreed well with those of high-performance liquid chromatography. The chicken scFv-based assay showed promise as a high-throughput screening tool for carbaryl in environmental and food matrices.

Aspergillus niger as the Source of Ochratoxin A of Contaminated Pyrus communis in Taif Market

Fruits are one of the most important agricultural products that supply the body with vitamins and essential minerals elements, but it is contaminated by fungi during the period of growth, harvesting and storage. A. niger is one of the species that grows on the fruit during the period of storage, and secretes mycotoxins especially ochratoxin A. This study was conducted with the purpose of isolating and identifying different strains of A. niger from 20 samples of pear collected from Taif markets and to determine the ability of these strains to produce OTA. It was observed that showed that out of 20 pear samples collected, 19 samples were detected to be contaminated with different strains of A. niger and the strains were able to produce OTA. From 27 isolates of A. niger which was used to test the ability of production OTA, 10 strains only produced OTA. The range of OTA in all strains were 0.18 to 9.5 ppb. Representative 27 strains of ochratoxigenic and non ochratoxigenic black Aspergilli isolated were subjected for detection of ochratoxin biosynthesis genes, by using two sets of primer for two genes involved in ochratoxin biosynthetic pathway. Bands of the fragments of PKS15C-MeT and PKS15KS genes visualized at 998 and 776 bp, respectively. Whereas, the presence of four tested genes is not sufficient marker for differentatin between aflatoxigenic and non aflatoxigenic isolates.