Search

In this study, a molecularly imprinted polymer (MIP) was synthesized using trichlorfon as a template molecule. The MIP exhibited a high adsorption capacity toward trichlorfon. Using bovine serum albumin as a carrier, trichlorfon hapten was indirectly labeled with luminol, which competed with free trichlorfon for the combination with a biomimetic antibody of MIP. Based on this direct competitive format, a high throughput flow-injection chemiluminescent biomimetic immunoassay method was developed for fast detection of trace trichlorfon. The influencing factors were investigated and optimized. Under the optimal condition, a lower limit of detection (IC15) of 0.0024 mg/L was obtained using this method. This method was also used to detect the trichlorfon spiked in carrot and cabbage samples, and the results were also verified using the method of gas chromatography. [ABSTRACT FROM AUTHOR]

Abstract: In this study, a molecularly imprinted polymer (MIP)‐fluorescent probe based on hydrophobic CdSe/ZnS quantum dots (CdSe/ZnS@MIP) was designed and synthesized by bulk polymerization for detecting methamidophos (MAP). The CdSe/ZnS@MIP was characterized by Fourier‐transform infrared spectroscopy, thermo‐gravimetric analysis and adsorption properties, and it exhibited good adsorption capacity and fluorescent stability, and excellent selectivity. Under optimal conditions, the fluorescence showed a good linear decrease in the range of 3.50 × 10−7–0.71 × 10−3 mol/L with a correlation coefficient of 0.995. The limit of detection of the fluorescent probe was 9.16 × 10−8 mol/L, and the relative standard deviation of the method for nine replicate analyses of 4.0 × 10−6 mol/L MAP was 4.1%. Apple and pear samples spiked with MAP at three levels were extracted and determined by the presented method with good recoveries (89.7%–94.9%). The accuracy of the method was verified by gas chromatography for the detection of kidney beans, leek and cucumber samples, and no significant difference was observed for the results of two methods. [ABSTRACT FROM AUTHOR]

Abstract: In this study, a new sensor of molecularly imprinted solid‐phase extraction coupled with flow‐injection chemiluminescence for the detection of monocrotophos was fabricated. The molecularly imprinted polymer was synthesized by the bulk polymerization, using monocrotophos, methacrylic acid, and ethylene glycol dimethacrylate as the template molecule, functional monomer, and cross‐linker, respectively. The adsorption and recognition ability of the imprinted polymer toward monocrotophos was investigated. Factors influencing preconcentration of the analytes and sensitivity of the method were optimized. Under the optimal conditions, the chemiluminescence intensity was linearly proportional to the concentration of monocrotophos range from 0.0023 to 10 mg/L, and the limit of detection of the method was 0.001 mg/L. Rape (Brassica napus) and pakchoi (Brassica rapa subsp. chinensis) samples spiked with monocrotophos at three levels were analyzed by the developed method with recoveries between 89.3% and 105.9%. This method was successfully applied to the determination of monocrotophos in spinach samples, and the results were verified by gas chromatography method. [ABSTRACT FROM AUTHOR]

Abstract: In this study, a magnetic molecularly imprinted polymer (MMIP) based on Fe3O4@SiO2@CdTe (CdTe@MMIP) was synthesized using trichlorfon as template molecule, methacrylic acid (MAA) as the functional monomer, and ethylene glycol dimethacrylate (EGDMA) as the cross‐linker. The prepared MMIP was characterized, and the results showed that it exhibited good recognition and selective ability, offered a faster kinetics for the adsorption of trichlorfon. Scatchard analysis indicated that the binding sites in the CdTe@MMIP had two distinct groups (the high and low affinity binding sites). The saturated adsorption capacity (Qmax1) was 63.2 mg/g due to the low affinity binding sites, and another saturated adsorption capacity (Qmax2) was 71.4 mg/g due to the high affinity binding sites. Using it as sorbent, a method of molecularly imprinted magnetic solid‐phase extraction coupled with capillary electrophoresis (MIMSPE‐CE) for selective extraction, magnetic separation, and fast determination of trace trichlorfon in vegetable samples was developed. Under optimal conditions, appreciable sensitivity was achieved with a LOD of 30 μg/kg (S/N = 3) for the developed method. The relative standard deviation (RSD) for five replicate extractions of 0.05 mg/L trichlorfon standard solution was 4.2%. To evaluate the accuracy of this method, the blank cucumber and cauliflower samples spiked with trichlorfon were extracted and analyzed by this method with good recoveries ranging from 78.7% to 96.6%. Moreover, this method was applied to the quantitative detection of the trichlorfon residues in rape samples, and the results correlated well with that obtained from the gas chromatography method. [ABSTRACT FROM AUTHOR]

BACKGROUND Black garlic is a type of garlic product that is generally produced by heating raw garlic at high temperature with controlled humidity for more than 30 days. Black garlic has appeared on the market for many years. It is crucial to investigate the characteristics of quality formation of black garlic during processing at various temperatures. RESULTS In this study, fresh garlic was processed to black garlic at temperatures of 60, 70, 80 and 90 °C. Moisture, amino acid nitrogen and allicin contents decreased gradually during thermal processing of various temperatures. Reducing sugar, 5-hydroxymethylfurfural, total phenols, total acids contents and browning increased. The changing rate of quality indicators and flavour of black garlic varied at different temperatures. Browning intensity reached about 74 when black garlic aged. The sensory score was significantly higher in black garlic aged at 70 °C (39.95 ± 0.31) compared with that at other temperatures, suggesting that 70 °C might facilitate formation of good quality and flavour of black garlic during processing. CONCLUSION Temperature had a remarkable impact on the quality and flavour of black garlic. © 2015 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

BACKGROUND Acrylamide ( AA) is of concern worldwide because of its neurotoxicity, genotoxicity and reproductive/developmental toxicity. Consequently, methods for minimizing AA formation during food processing are vital. RESULTS In this study, the formation and elimination of AA in an asparagine/glucose low-moisture model system were investigated by response surface methodology. The effect of garlic powder on the kinetics of AA formation/elimination was also evaluated. The AA content reached a maximum level (674.0 nmol) with 1.2 mmol of glucose and 1.2 mmol of asparagine after heating at 200 °C for 6 min. The AA content was greatly reduced with the addition of garlic powder. Compared to without garlic powder, an AA reduction rate of 43% was obtained with addition of garlic powder at a mass fraction of 0.05 g. Garlic powder inhibited AA formation during the generation-predominant kinetic stage and had no effect on the degradation-predominant kinetic stage. The effect of garlic powder on AA formation in bread and bread quality was also investigated. Adding a garlic powder mass fraction of 15 g to 500 g of dough significantly ( P < 0.05) reduced the formation of AA (reduction rate of 46%) and had no obvious effect on the sensory qualities of the bread. CONCLUSION This study provides a possible method for reducing the AA content in bread and other heat-treated starch-rich foods. © 2015 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Because freezing treatment can destroy the cell structure of garlic, we investigated the effect of freezing pretreatment on black garlic processing with the traditional processing method as contrast. Results showed that freezing for 30 h had the greatest impact on the reducing sugar content. The control garlic processing 21-24 days had the best quality. Freezing pretreatment can affect the black garlic quality through the browning degree, reducing sugar content, amino- N content, total phenolic content and 5-hydroxymethyl-2-furaldehyde (5- HMF) levels. The freezing garlic had a faster color change than control samples. When the processing ended, the reducing sugar content, total phenols content and 5- HMF content of freezing pretreated garlic were increased by 51.88, 58.54, 25%, respectively, compared with the control samples. The amino- N content of freezing-pretreated garlic decreased 50.97% compared with the control one. The results indicated that freezing pretreatment can promote the generation of functional materials. Practical Applications Although garlic has been used worldwide as food or herbal supplement, some people feel discomfort because of its strong pungent odor. Black garlic is one of the garlic-processed products, eliminating its stimulating odor. However, the quality of black garlic products on the market is varied and the processing time is long. As is known, freezing is widely used to destroy cell structure. In the present study, the use of freezing pretreatment in black garlic processing can promote the generation of functional materials and significantly reduce processing time from 60-90 to 22 days. These provided potential method to the black garlic processing. [ABSTRACT FROM AUTHOR]

BACKGROUND Acrylamide has attracted worldwide concerns because of its demonstrated neurotoxicity, genetoxicity and reproductive-development toxicity. It is necessary to control acrylamide production during food processing and protect human health. RESULTS In this study, a functionalised material was synthesised by immobilising an ionic liquid onto an activated silica gel surface. The adsorption ability of the material towards acrylamide was evaluated, and the results showed that it had high adsorption capacity. Scatchard analysis indicated that the binding sites in the prepared material had two distinct groups (high and low affinity binding sites). The saturated adsorption capacity ( Qmax,1) was 7.9 mg g−1 due to the high affinity binding sites, and another saturated adsorption capacity ( Qmax,2) was 2.3 mg g−1 due to the low affinity binding sites. This prepared material also offered fast kinetics for adsorption of the acrylamide. Using this material as sorbent, a method of solid-phase extraction coupled with high-performance liquid chromatography ( SPE-HPLC) for analysis of acrylamide in foods was developed. Under optimal conditions, the limit of detection ( S/ N = 3) of this method for acrylamide was 2.1 µg kg−1, and the RSD for five replicate extractions of 50 μL−1 acrylamide was 4.5%. The blank potato and bread crumb samples spiked with acrylamide at different levels of 10.0 and 15.0 µg kg−1 were extracted and determined respectively by this developed method, and recoveries ranging from 83.0% to 89.1% were obtained. Finally, this method was applied to quantitative detection of acrylamide in bread crust and cracker samples. CONCLUSION With high sensitivity and pre-treatment simplicity, this SPE-HPLC method could provide a new tool for the rapid determination of acrylamide in the food samples. © 2013 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

BACKGROUND Organophosphate pesticide residues are harmful to human health because of their potential mutagenic and carcinogenic properties. Therefore, it is of great importance to development an accurate and reliable analytical method to prevent their uncontrolled effects on environmental pollution and human health. RESULTS This study reports a new method of molecularly imprinted solid-phase extraction coupled with high-performance liquid chromatography (MISPE-HPLC) for simultaneous determination of two organophosphate pesticides residues. Two types of molecularly imprinted polymers (MIPs) were prepared using the trichlorfon and monocrotophos as the template molecule, respectively, methacrylic acid as the functional monomer, and ethylene glycol dimethacrylate as the cross-linker. The recognition ability and adsorption-desorption dynamic of each imprinted polymer toward the trichlorfon or monocrotophos were characterised. Using the mixture of trichlorfon-MIP and monocrotophos-MIP (20:80, wt/wt) as solid-phase extraction sorbent, the factors affecting the pre-concentration on the analytes and the sensitivity of the MISPE-HPLC method were optimised. Under optimal condition, the linear range was 0.005-1.0 mg L−1. The limit of detection was 4.2 µg g−1 for trichlorfon, and 1.2 ng g−1 for monocrotophos. The peak area precision [Relative standard deviation (RSD)] for three replicates was 2.9-4.5%. The blank rape and cauliflower samples spiked with trichlorfon and monocrotophos at 0.05 and 0.005 µg g−1 levels were extracted and determined by this method with recoveries ranging from 88.5% to 94.2%. Moreover, this method was successfully applied to the quantitative detection of the trichlorfon and monocrotophos residues in leek samples. CONCLUSION With good properties of high sensitivity, simple pre-treatment and low cost, this MISPE-HPLC method could provide a new tool for the rapid determination of multi-pesticide residues in the complicated food samples. © 2013 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

BACKGROUND Acrylamide has attracted worldwide concern due to its neurotoxicity, genotoxicity, reproductive-development toxicity. It is necessary to develop an accurate and reliable analytical method to prevent the harm on the human health. RESULTS In this study, a sensitive and fast analytical method of direct competitive biomimetic enzyme-linked immunosorbent assay ( BELISA) was developed using a hydrophilic imprinted membrane as biomimetic antibody. This novel imprinted membrane was directly synthesised on the well surface of MaxiSorp polystyrene 96-well plates in an aqueous environment, and it exhibited high binding ability and specificity toward acrylamide. Under the optimal conditions, the established BELISA method had a good sensitivity ( IC50, 8.0 ± 0.4 mg L−1) and a low limit of detection ( IC15, 85.0 ± 4.2 µg L−1). The blank potato samples spiked with acrylamide at three levels of 100, 250 and 500 µg L−1 were extracted and determinate by the proposed method, and good recoveries ranging from 90.0% to 110.5% were obtained. This presented method was applied to the quantitative detection of the acrylamide in French fries and cracker samples. Also, the results were correlated well with that obtained by the gas chromatography method. CONCLUSION With good properties of high sensitivity, simple pre-treatment and low cost, this BELISA could be a promising screening method in food sample analysis. © 2013 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

In this paper, a new separation sorbent of magnetic chitosan microsphere was prepared by means of suspension process using magnetic-Fe3O4 nanoparticles as magnetic material and glutaraldehyde as the cross-linker. The morphology and properties of magnetic chitosan microspheres were characterized by FT-IR, SEM and adsorption test, and the results showed that they had good recognition, high selective ability and fast adsorption-desorption dynamics for estriol (E3), 17β-estradiol (E2) and diethylstilbestrol (DES). Applying this material as SPE sorbent, a method for separation, enrichment and analysis of estrogens in samples coupled with HPLC was developed. Under the optimized condition, the detection limit ( S/ N=3) for three estrogens was 3.2-20.1 ng/L, and the RSD for five replicate extractions of 50 μg/L E3, E2 and DES was 4.6-8.3%. The blank river water spiked with E3, E2 and DES at 0.05 and 0.2 mg/L levels were extracted and determined by the developed method with good recoveries ranging from 85.5 to 103.7%. [ABSTRACT FROM AUTHOR]

Fructose and its polysaccharides are widely found in fruits and vegetables, with the Maillard reaction of fructose affecting food quality. This study aimed to investigate the Maillard reaction of fructose using a fructose–histidine model system. The reaction process was characterized using fluorescence spectroscopy and ultraviolet spectroscopy. The effects of temperature, initial reactant concentration, initial fructose concentration, initial histidine concentration, and initial pH value on the different stages of the Maillard reaction were studied. Reactant reduction, ultraviolet and fluorescence spectra, acetic acid content, 5-hydroxymethylfurfural (5-HMF) content, and browning intensity were evaluated. The results showed that increasing the temperature and reactant concentration promoted the condensation reaction of fructose and amino acid in the early stage, the formation of intermediate products with ultraviolet absorption and fluorescence in the intermediate stage, and the formation of pigment in the final stage. The 5-HMF concentration decreased with increasing histidine concentration and initial pH value. Changes in the shape of ultraviolet and fluorescence spectra showed that the initial pH value affected not only the reaction rate, but also the intermediate product types. The 1,1-diphenyl-2-picrylhydrazyl (DPPH) scavenging rate of the Maillard reaction products increased with increasing temperature, reactant concentration, and initial pH value. [ABSTRACT FROM AUTHOR]

Fructose and its polysaccharides are widely found in fruits and vegetables, with the Maillard reaction of fructose affecting food quality. This study aimed to investigate the Maillard reaction of fructose using a fructose⁻histidine model system. The reaction process was characterized using fluorescence spectroscopy and ultraviolet spectroscopy. The effects of temperature, initial reactant concentration, initial fructose concentration, initial histidine concentration, and initial pH value on the different stages of the Maillard reaction were studied. Reactant reduction, ultraviolet and fluorescence spectra, acetic acid content, 5-hydroxymethylfurfural (5-HMF) content, and browning intensity were evaluated. The results showed that increasing the temperature and reactant concentration promoted the condensation reaction of fructose and amino acid in the early stage, the formation of intermediate products with ultraviolet absorption and fluorescence in the intermediate stage, and the formation of pigment in the final stage. The 5-HMF concentration decreased with increasing histidine concentration and initial pH value. Changes in the shape of ultraviolet and fluorescence spectra showed that the initial pH value affected not only the reaction rate, but also the intermediate product types. The 1,1-diphenyl-2-picrylhydrazyl (DPPH) scavenging rate of the Maillard reaction products increased with increasing temperature, reactant concentration, and initial pH value.

Introduction: Increasing evidence has expanded the role of green tea from a traditional beverage to a source of pharmacologically active molecules with diverse health benefits. However, conclusive clinical results are needed to better elucidate the cancer-preventive and therapeutic effects of green tea polyphenols (GTPs). Areas covered: The authors describe GTPs' chemical compositions and metabolic biotransformations, and their recent developments in drug discovery, focusing on their cancer chemopreventive and therapeutic effects. They then review the recent development of GTP-loaded nanoparticles and GTP prodrugs. Expert opinion: GTPs possess potent anticarcinogenic activities through interfering with the initiation, development and progression phases of cancer. There are several challenges (e.g. poor bioavailability) in developing GTPs as therapeutic agents. Use of nanoparticle-based delivery systems has provided unique advantages over purified GTPs. However, there is still a need to determine the actual magnitude and pharmacological mechanisms of GTPs encapsulated in nanoparticles, in order to address newly emerging safety issues associated with the potential 'local overdose' effect. The use of Pro- epigallocatechin gallate (Pro-EGCG) as a prodrug appears to offer improved in vitro stability as well as better in vivo bioavailability and efficacies in a number of animal studies, suggesting its potential as a therapeutic agent for further study and development.

Pesticide residue in vegetables is a serious problem that has adverse effects on human health. In our study, we designed and synthesized a molecularly imprinted polymer that can selectively recognize trichlorfon. Using the polymer material as biomimetic antibody, we developed a biomimetic immunoassay-capillary electrophoresis method with improved sensitivity for the detection of trichlorfon. We evaluated the competitive reactions between HRP labeled trichlorfon hapten and free trichlorfon with the biomimetic antibody. Factors that affected the sensitivity of our method were tested in detail. Under optimal conditions, the limit of detection (LOD, IC 15 ) and the sensitivity (IC 50 ) of this method were 0.16mgL -1 and 0.13μgL -1 for trichlorfon. We used this method to determine the trichlorfon spiked in the kidney bean and cucumber samples with recoveries ranging from 78.8% to 103%. We also detected residual trichlorfons in the leek samples, and these results were verified by gas chromatography method., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Black garlic produced from fresh garlic under controlled high temperature and humidity has strong antioxidant properties. To determine these compounds, five fractions (from F1 to F5) were separated and purified by elution with chloroform:methanol at different ratios (8:1, 6:1, 4:1, 2:1, and 0:1; v/v). The antioxidant activity of each fraction was analyzed. The results showed that F3 and F4 had higher phenolic contents and stronger 2,2-diphenyl-2-picrylhydrazyl radical scavenging activity than the others. Seven purified individual components were further separated using semipreparation high-performance liquid chromatography from these two intensely antioxidant fractions (F3 and F4), their structures were elucidated by high-performance liquid chromatography coupled to diode array detection, electrospray ionization, mass spectrometry, 1 H nuclear magnetic resonance, and 13 C nuclear magnetic resonance spectrometry. Three compounds including adenosine, uridine, and 2-acetylpyrrole were first identified in black garlic, except for 5-hydroxymethylfurfural, (1S, 3S)-1-methyl-1,2,3,4-tetrahydro-β-carboline-3-carboxylic acid, and (1R, 3S)-1-methyl-1,2,3,4-tetrahydro-β-carboline-3-carboxylic acid. The cellular antioxidant activities of uridine, adenosine, carboline alkaloids, 5-hydroxymethylfurfural, and ethyl acetate extracts were consistent with the results of in vitro experimental antioxidant properties. The results provide useful information for understanding the health benefits of black garlic products., (Copyright © 2016. Published by Elsevier B.V.)