Analysis of the impact of drying on common wheat quality and safety.

Mycotoxin contamination in grain has been an ongoing concern in the world. Wheat, as a staple crop in China, is particularly notable for its mycotoxin contamination. The main mycotoxins in wheat include deoxynivalenol (DON) and its derivates, zearalenone (ZEN) and aflatoxin B1 (AFB1). After harvest, drying process is an effective technique and a necessary step to ensure the long-term safe storage of wheat. In this study, the moisture content, the concentrations of total fungi and main mycotoxins in post-harvest wheat of three wheat growing areas in the North China Plain were examined, and the effect of different drying methods on wheat quality was evaluated. The results showed that 87.5% of wheat samples were simultaneously contaminated with two or more mycotoxins. Due to the pre-harvest heavy rainfall, the moisture content, the levels of total fungi and mycotoxins in wheat samples of Liaocheng city were significantly higher compared to other regions. Moreover, the effects of different drying methods on the starch gelatinization and viscosity properties of wheat were investigated. The results showed that both natural air drying and dryer drying altered the crystal structure within starch particles and affected the gelatinization and viscosity properties of wheat starch. However, there is no significant difference between the wheat samples treated with two drying methods.

A Novel, Rapid Screening Technique for Sugar Syrup Adulteration in Honey Using Fluorescence Spectroscopy.

The adulteration of honey with different sugar syrups is common and difficult to detect. To ensure fair trade and protect the interests of apiarists, a rapid, simple and cost-effective detection method for adulterants in honey is needed. In this work, fluorescence emission spectra were obtained for honey and sugar syrups between 385 and 800 nm with excitation at 370 nm. We found substantial differences in the emission spectra between five types of honey and five sugar syrups and also found differences in their frequency doubled peak (FDP) intensity at 740 nm. The intensity of the FDP significantly declined (p < 0.01) when spiking honey with ≥10% sugar syrup. To validate this method, we tested 20 adulterant-positive honey samples and successfully identified 15 that were above the limit of detection. We propose that fluorescence spectroscopy could be broadly adopted as a cost-effective, rapid screening tool for sugar syrup adulteration of honey through characterization of emission spectra and the intensity of the FDP.

Development and evaluation of a novel visual and rapid detection assay for toxigenic Fusarium graminearum in maize based on recombinase polymerase amplification and lateral flow analysis.

Maize ear rot caused by Fusarium graminearum is one of the most severe maize diseases in global maize-growing regions. It reduces maize yield in the field and is also responsible for mycotoxin contamination of grains during the postharvest period. F. graminearum is one of the major deoxynivalenol (DON), nivalenol (NIV), and zearalenone (ZEN) producers. The ingestion of these mycotoxins represents a risk for human and animal health. Hence, early detection and identification of F. graminearum are crucial to controlling these mycotoxins along the food or feed supply chains. In this study, the recombinase polymerase amplification with lateral flow dipstick (RPA-LFD) assay targeting the gaoA gene that codes for galactose oxidase was developed. The reaction conditions were optimized to make the method rapid, sensitive, and cost-effective. The developed RPA-LFD assay could detect the presence of 20 fg of the target genomic DNA per reaction within 25 min at 40 °C. Moreover, 52 field samples were tested using the developed RPA-LFD assay and compared with conventional PCR-based methods. The positive rate between RPA-LFD and the conventional PCR-based method was 100%. In conclusion, the developed method provides a novel alternative for the rapid, sensitive, and specific detection and identification of F. graminearum. It is not only workable for bulk maize samples without using sophisticated lab equipment but is also potentially useful for other agriculturally important toxigenic fungi.

A metabolomics approach revealed an Amadori compound distinguishes artificially heated and naturally matured acacia honey.

Acacia honey is a popular and high-value monofloral honey. On the honey market, immature acacia honey is sometimes thermally dehydrated, yielding a fraudulent product - artificially heated acacia honey (AHAH). Typical physicochemical indices are not sufficient to distinguish AHAH from naturally matured acacia honey (NMAH). Using a UHPLC-Q-TOF-MS-based metabolomics approach, we compared the aqueous solutions of 33 NMAH and 33 AHAH samples, and uncovered a differential compound with a mass of 327.1321 Da. Structural analysis, employing high resolution-mass spectrometry (HR-MS) combined with nuclear magnetic resonance (NMR), identified it as N-(1-deoxy-1-fructosyl) phenylalanine (Fru-Phe), an Amadori compound that forms in the initial stages of the Maillard reaction and can be as a sensitive index for thermal treatment. According to quantitation via UHPLC-MS/MS, Fru-Phe was < 1.54 mg/kg in NMAH and > 10.00 mg/kg in AHAH, showing Fru-Phe is a potential indicator of artificial heating acacia honey.

Distribution, accumulation, migration and risk assessment of trace elements in peanut-soil system.

Trace elements contamination is mainly originated from industrial emission, sewage irrigation and pesticides, and poses a threat to the environment and human health. This study analyzed the trace element pollutants in peanut-soil systems, the enrichment and translocation capacity of peanut to trace elements, and the potential risk of trace elements to environment and human health. The results indicated that Cd and Ni in peanut kernels exceeded the standard limits in 2019, and the exceeding rate were 9% and 31%, respectively. Cd in 8% of soil samples and As in 98% of soil samples exceeded the risk screening value of trace elements. The concentration of trace elements in peanuts was related to varieties and planting regions. In addition, there was a significant positive correlation between the concentration of Cd in peanut kernel and its concentration in soil. Compared with other trace elements, peanut kernels had stronger ability to enrich and transport Cd, Cu, and Zn, the BFs were 0.45, 0.51 and 0.47, respectively. After oil extraction, trace elements were mainly concentrated in peanut meal, and only 0.25% of Cd was in oil. The RI of trace elements was less than 150, indicating that the study area was under low degree of ecological risk. However, As and Cd might pose moderate risk to environment. Trace elements in soil and peanut could not cause non-carcinogenic and carcinogenic risks to human, but the HI and CR value of As (0.59 and 9.54 × 10-5) in soil and CRing value of Cd (9.25 × 10-7) in peanut were close to the critical value. We conclude that Cd pollution in peanut kernel, and Cd and As pollution in soil should be monitored to enter into the food chain or environment and to avoid the possible health hazards and environment risks.

Comprehensive Transcriptome and Proteome Analyses Reveal the Modulation of Aflatoxin Production by Aspergillus flavus on Different Crop Substrates.

As a natural severe contaminant of stored grains and other crops worldwide, Aspergillus flavus can produce aflatoxins (AFs), the most powerful naturally producing toxic and hepatocarcinogenic compounds. AFs production is regulated by diverse factors including AFs cluster genes, transcription factors, regulators, and environmental factors. Among them, crop substrate is one of the most important factors. Here, we found that AFB1 production was significantly higher in maize and rice broth than in peanut broth. To clarify the mechanisms involved, complementary transcriptomic and proteomic analyses were performed to identify changes in A. flavus incubated in the three crop substrates. The results indicated that fewer genes and proteins were differentially expressed between maize and rice substrates, whereas more differentially expressed genes were observed between maize/rice broth and peanut broth. In particular, the genes involved in the initial step of AFs biosynthesis (aflA, aflB, and aflC) and the ACCase-encoding gene accA were significantly upregulated on the maize and rice substrates. Kyoto Encyclopedia of Genes and Genomes (KEGG) and Gene Ontology (GO) enrichment analyses indicated that carbon-metabolism-related genes were obviously enriched in the maize broth, and the genes involved in acetyl-CoA accumulation and consumption were up- and downregulated, respectively. Several genes involved in the regulation of AFs biosynthesis, including veA, ppoB, snf1, and the G-protein-coupled receptor (GPCR) genes, were differentially expressed on the three substrates, suggesting that these genes may be also involved in sugar signal sensing, transfer, and regulation. Interestingly, by the correlation analyses of transcriptome and proteome, trehalose metabolism genes, aldehyde dehydrogenase gene, and tryptophan synthase gene were found to be relevant with the regulation of AFs production on different crop substrates. Taken together, the differential expressions of the AFs cluster genes, several regulatory genes, and carbon metabolism genes were involved in the comprehensive modulation of AFs production on different crop substrates.

Determining multi-pesticide residues in teas by dispersive solid-phase extraction combined with speed-regulated directly suspended droplet microextraction followed by gas chromatography-tandem mass spectrometry.

In this study, an effective speed-regulated directly suspended droplet microextraction method was developed to condense pesticide residues from teas through dispersive solid-phase extraction prior to analysis by gas chromatography with tandem mass spectrometry. The extractant was intentionally dispersed into the sample solution in the form of globules through high-speed agitation. This procedure increases the contact area between the binary phases and shortens the distribution equilibrium time. The fine globules reassembled by decelerating stirring speed, the extractant could be taken out for gas chromatography with tandem mass spectrometry. Recovery studies were performed under optimized extraction conditions by using matrix blanks fortified with pesticides at three concentrations (10, 50, and 100 µg/kg). Over 87% of the recoveries for the analytes in four tea matrices were acceptable given their recovery ranges of 70-120% and relative standard deviations of ≤20%. The limits of quantification of most pesticides were lower than 10 µg/kg and thus satisfied the requirements for maximum residue levels prescribed by the European Community. A total of 38 tea samples from local markets were analyzed by using the proposed method. Results showed that chlorpyrifos was the most frequently detected pesticide in teas. The method is a potential choice for the routine monitoring of pesticide residues in complex matrices.

Rapid identification of "mad honey" from Tripterygium wilfordii Hook. f. and Macleaya cordata (Willd) R. Br using UHPLC/Q-TOF-MS.

Cases of honey poisoning have been reported widely, meaning there is a need for methods that detect "mad honey" or honey contaminated with plant-derived toxins to protect human health. In this study, we compared whole flower extracts and honey from Tripterygium wilfordii Hook. f. (TwHf) and Macleaya cordata (Willd) R. Br (McRB) using QuEChERS (quick, easy, cheap, effective, rugged, and safe) and ultra-high-performance liquid chromatography/quadrupole time-of-flight mass spectrometry (UHPLC/Q-TOF-MS). The results revealed several compounds common to whole flowers and honey samples. Triptolide and protopine were selected as potential markers for identifying "mad honeys" from these plants. The developed method can easily detect different honey varieties that were spiked with 5% TwHf and McRB honey samples. Additionally, 90 commercial honey samples were analyzed and determined as free from contamination. The method described in this report could be useful for studies on honey from other poisonous nectar and pollen plants.

Analysis of sulfonamides, tilmicosin and avermectins residues in typical animal matrices with multi-plug filtration cleanup by liquid chromatography-tandem mass spectrometry detection.

The frequent use of various veterinary drugs could lead to residue bioaccumulation in animal tissues, which could cause dietary risks to human health. In order to quickly analyze the residues, a liquid chromatography tandem mass spectrometry (LC-MS/MS) method was developed for detecting Sulfonamides, Tilmicosin and Avermectins (AVMs) residues in animal samples. For sample preparation, modified QuEChERS (quick, easy, cheap, effective, rugged and safe) and ultrasound-assisted extraction (UAE) methods were used. For sample cleanup, n-Hexane delipidation and multi-plug filtration cleanup (m-PFC) method based on primary-secondary amine (PSA) and octadecyl-silica (C18) were used, followed by LC-MS/MS analysis. It was validated on 7 animal matrices (bovine, caprine, swine meat and their kidneys, milk) at two fortified concentration levels of 5 and 100µg/kg. The recoveries ranged from 82 to 107% for all analytes with relative standard deviations (RSDs) less than 15%. Matrix-matched calibrations were performed with coefficients of determination above 0.998 for all analytes within concentration levels of 5-500µg/kg. The developed method was successfully used to analysis veterinary drugs of real animal samples from local markets.

Multiplug filtration cleanup method with multi-walled carbon nanotubes for the analysis of malachite green, diethylstilbestrol residues, and their metabolites in aquatic products by liquid chromatography-tandem mass spectrometry.

The food safety supervision in aquatic products has raised public concern in recent years. In this study, a liquid chromatographic-tandem mass spectrometric (LC-MS/MS) method for the simultaneous quantification and identification of four residues of the ever widely used analytes (including malachite green, leucomalachite green, diethylstilbestrol, and dienestrol) in aquaculture samples was developed. For sample preparation, a modified QuEChERS (quick, easy, cheap, effective, rugged, and safe) method was used, which was initially developed for pesticide residue analysis. For cleanup procedure, low-temperature cleanup method was combined with multiplug filtration cleanup (m-PFC) method based on multi-walled carbon nanotubes (MWCNTs). The volume of water, extraction solvent, cleanup sorbents, and m-PFC procedure were optimized for carp, striped bass, and giant salamander matrices. It was validated by analyzing four residues in each matrix spiked at three concentration levels of 0.5, 5, and 50 µg/kg (n = 5). The method was successfully validated according to the 2002/657/EC guidelines. After optimization, spike recoveries were within 73-106 % and <15 % relative standard deviations (RSDs) for all analytes in the tested matrices. Limits of quantification (LOQs) for the proposed method ranged from 0.10 to 0.50 µg/kg. Matrix-matched calibrations were performed with the coefficients of determination >0.998 between concentration levels of 0.5 and 200 µg/kg. The developed method was successfully applied to the determination of residues in market samples. Graphical abstract Flow chart of multi-plug filtration cleanup combined with low-temperature cleanup method.

Quantification of nitroimidazoles residues in swine liver by liquid chromatography-mass spectrometry with atmospheric pressure chemical ionization.

A liquid chromatography-mass spectrometry method was developed for the simultaneous determination of ronidazole (RNZ), metronidazole (MNZ) and dimetridazole (DMZ) residues in swine liver. Following liquid-liquid extraction, the HLB solid-phase extraction was used for further purification. The targets were detected by atmospheric pressure chemical ionization (APCI) following the reverse phase liquid chromatography separation. Consequently, the detection limits for the method were 0.5 microg/kg for MNZ, 1.0 microg/kg for RNZ and 0.5 microg/kg for DMZ, respectively. The accuracies were determined using swine liver samples fortified at levels of 0.5, 1, 2, and 4 microg/kg and the mean recoveries of the analytes were between 66% and 81%.

[Determination of residues of three stilbene drugs in animal tissues using gas chromatography-mass spectrometry].

A method has been developed to determine residual stilbenes such as diethylstilbestrol (DES), dienestrol (DIS) and hexestrol (HS) in animal tissues using solid phase extraction (SPE) and gas chromatography-mass spectrometry (GC-MS). The procedures for extraction, cleanup on an LC-Si solid phase extraction cartridge and derivatization of stilbenes were established and optimized. The analytes were detected by mass spectrometer with electron impact source in selected ion monitoring mode (EI/SIM), and quantified with an external standard calibration curve method. Linear calibration curves were obtained in the concentration ranges from 5 to 500 microg/L for HS and from 10 to 1000 microg/L for DES and DIS (the correlation coefficients were above 0.99). Recoveries of the stilbenes were 73.0%-86.5%, and the relative standard deviations were between 1.0% and 7.2%. The limits of detection were 0.30 microg/kg for cis-DES, 0.10 microg/kg for trans-DES and HS and 0.15 microg/kg for DIS in pork and swine liver.

Analysis of amino acids by capillary zone electrophoresis with electrochemical detection.

The precapillary derivatization of 20 amino acids with naphthalene-2,3-dicarboxaldehyde (NDA) and CN(-) was investigated. All these derivatized amino acids could be oxidized on the carbon fiber microdisk bundle electrode except proline. Capillary zone electrophoresis with electrochemical detection was employed for the analysis of 19 amino acids. The optimum conditions of separation and detection were borate, pH 9.48, for the electrolyte, 18 kV for the separation voltage and 1.15 V versus a saturated calomel electrode for the detection potential. Limits of detection of concentration or mass for individual amino acids were between 1.7 x 10(-7) and 1.8 x 10(-6) mol/L or 84 and 893 amol (according to the signal-to-noise ratio of 3) for the injection voltage of 6 kV and injection time of 10 s. The relative standard deviations were between 0.80 and 2.3% for the migration times and 1.4 and 6.4% for the electrophoretic peak currents. From a mixture of 19 amino acids, 10 amino acids (Arg, Lys, Orn, Try, Ser, Ala, Gly, Cys, Glu, Asp) could be well separated. The other 9 amino acids appeared on three electrophoretic peaks. From the samples, in which the nine amino acids do not exist simultaneously, some of them could also be detected. The method was applied to the determination of amino acids in beer by the standard addition method. The recovery for the amino acids in beer was 91-109%.