Time filter

Source Type

Chen L.,Chinese Academy of Agricultural Sciences | Chen L.,Xinjiang Agricultural University | Chen L.,Ministry of Agriculture Milk and Dairy Product Inspection Center Beijing | Wen F.,Chinese Academy of Agricultural Sciences | And 11 more authors.
Food Chemistry | Year: 2017

A fluorescent assay for the rapid, sensitive and specific detection of Aflatoxin B1 (AFB1) was developed in this study. Initially, a DNA/DNA duplex was formed between a fluorescein-labeled AFB1 aptamer and its partially complementary DNA strand containing a quencher moiety, resulting in fluorescence quenching due to the close proximity of fluorophore and quencher. Upon the addition of AFB1, an aptamer/AFB1 complex was generated to release the quencher-modified DNA strand, thus recovered the fluorescence of fluorescein and enabled quantitative detection for AFB1 by monitoring fluorescence enhancement. Under optimized conditions, this assay exhibited a linear response to AFB1 in the range of 5–100 ng/mL with a detection limit down to 1.6 ng/mL. Trials of this assay in infant rice cereal with satisfactory recovery in the range of 93.0%–106.8%, demonstrate that the new assay could be a potential sensing platform for AFB1 determination in food. © 2016 Elsevier Ltd


Zheng N.,Chinese Academy of Agricultural Sciences | Zheng N.,Ministry of Agriculture Milk and Dairy Product Inspection Center Beijing | Li S.L.,Chinese Academy of Agricultural Sciences | Li S.L.,Ministry of Agriculture Milk and Dairy Product Inspection Center Beijing | And 8 more authors.
Food Control | Year: 2017

In the present study, a total of 1550 raw cow milk samples were collected from Southern, Northern, Northeast, and Western regions of China during the four seasons from 2013 to 2015. Samples were analyzed for aflatoxin M1 (AFM1) using high performance liquid chromatography (HPLC). In 2013, AFM1 was detected in 21% of 366 raw cow milk samples with levels ranging between 0.01 and 0.24 μg/L. In 11.7% of samples, AFM1 levels were >0.05 μg/L, which is the legal limit in the European Union. The mean and median of positive samples were 0.069 ± 0.052 μg/L and 0.056 μg/L, respectively. In 2014, AFM1 was detected in 28.5% of 624 raw cow milk samples, with levels ranging from 0.01 to 0.25 μg/L. Of these samples, 7.7% had AFM1 levels exceeding 0.05 μg/L, with a mean of 0.042 ± 0.039 μg/L and median of 0.028 μg/L. AFMI was detected in 14.1% of 560 raw cow milk samples in 2015, with levels ranging from 0.01 to 0.144 μg/L. In 1.8% of these samples, AFM1 levels were above 0.05 μg/L, with a mean of 0.026 ± 0.024 μg/L and median of 0.017 μg/L. Our results demonstrate that AFM1 levels of the samples did not exceed the legal limit of 0.5 μg/L in China, the United States, and Codex Alimentarius Commission. Geographically, AFM1 contamination was more predominant in raw cow milk samples from Southern China than in those from other regions, with a higher number of samples containing AFM1 levels above 0.05 μg/L in 2013, 2014, and 2015. AFM1 levels were higher in autumn than in the other seasons during the entire study period. According to our survey, AFM1 contamination has been well-controlled in China during recent years; however, some samples still exceeded the European Union (EU) legal limit. Better prevention and management of aflatoxins in both feed and milk should be considered especially in Southern regions of China and in autumn. © 2017 Elsevier Ltd


Huang L.C.,Chinese Academy of Agricultural Sciences | Huang L.C.,Anhui Agricultural University | Huang L.C.,Ministry of Agriculture Milk and Dairy Product Inspection Center Beijing | Zheng N.,Chinese Academy of Agricultural Sciences | And 14 more authors.
Food Chemistry | Year: 2014

In this study, a sensitive and rapid method has been developed for the simultaneous determination of aflatoxin M1, ochratoxin A, zearalenone and α-zearalenol in milk by ultra high performance liquid chromatography combined with electrospray ionisation triple quadrupole tandem mass spectrometry (UHPLC-ESI-MS/MS). The milk samples were purified using Oasis HLB cartridge. The matrix effects were evaluated by determining the signal suppression- enhancement (SSE) and corrected by external matrix-matched calibration. The limits of quantity (LOQ) of the mycotoxins were in the range of 0.003-0.015 μg kg-1. The high correlation coefficients (R2 ≥ 0.996) were obtained in the range of 0.01-1.00 μg kg-1 of the mycotoxins, along with good recovery (87.0-109%), repeatability (3.4-9.9%) and intra-laboratory reproducibility (4.0-9.9%) at the concentrations of 0.025, 0.1 and 0.5 μg kg-1. The detected rates of the mycotoxins were from 16.7% to 96.7% in raw milk, liquid milk and milk powder samples collected from the dairy farms and supermarkets in Beijing. The method proposed is suitable for the simultaneous determination of aflatoxin M1, ochratoxin A, zearalenone, and α-zearalenol, and could be performed for analysing the mycotoxins in milk. © 2013 Elsevier Ltd. All rights reserved.


Yang J.,Chinese Academy of Agricultural Sciences | Yang J.,Ministry of Agriculture Milk and Dairy Product Inspection Center Beijing | Zheng N.,Chinese Academy of Agricultural Sciences | Zheng N.,Ministry of Agriculture Milk and Dairy Product Inspection Center Beijing | And 5 more authors.
Nongye Gongcheng Xuebao/Transactions of the Chinese Society of Agricultural Engineering | Year: 2016

Infrared spectrum (IR) reflects the molecular structure of unknown material, and responds with varied chemical bonds. So it is used to determine chemical composition contents and evaluate product quality in livestock products extensively. Milk is a key part in human nutrition intake. And the exact determination of nutrients and the proper evaluation of quality have important significance for milk production. This paper introduced the application of IR in each link of milk production. Fat and protein contents in milk vary in different dairy farms, and many factors affect milk quality, which contribute to the final price of raw milk in acquisition. Milk composition determination using IR is likely to give a quick and comprehensive evaluation for milk quality. Unknown and undeclared adulterants of milk threaten consumers' health seriously. Qualitative and quantitative analysis models provide a convenient identification method for milk adulteration based on spectrum variation of adulterants. Milk trait related to cow health and robustness is very important for dairy farm management. Diagnosis of ketoacidosis and body energy status using IR instruments is helpful for accurate breeding in dairy farm. This paper reviewed recent literatures in order to evaluate the general trends of infrared spectroscopy application on milk production. On the basis of introducing the data processing and model building, this paper presented a review of the overseas and domestic researches on milk composition and milk coagulation properties using IR, especially for milk protein fraction and fatty acids composition. We compared the model performance of optical spectroscopy from different research reports. The effects of reference method, sample size and unit on model parameters were discussed in particular. Moreover, IR was efficient for phenotypes assessment and genetic selection based on these models. The variances of absorption on IR caused by adulterants spiked in milk not only indicated the appearance of milk adulteration, but also displayed the difference between cow milk and soy milk. Milk spectrum was proved to be heritable in specified wavelength, while some other bands varied with different enviromental factors. And many literatures confirmed the correlation between cow's feed and milk optical characteristic. Although nonnegligible random error and data variability existed in sampling, IR reflected energy status of dairy cows with moderate accuracy. Mid-IR has been also studied as a potential tool to predict several milk traits related to cow health, such as ketone bodies, which were closely related to cow fertility and production. IR was also used to predict methane emissions from cow digestive tract. The advantages of infrared spectroscopy analysis were emphasized, and we also listed potential challenges existing in instrument setting, data collection and model building. The objective of this paper was to highlight the application of infrared spectroscopy on milk traits, which was related to milk composition and quality, and dairy farm management. Considering the overall trends, we proposed some future research directions of this methodology on milk production, including prediction of trace nutrients, uniformity of references methods and units, possibility of spectrum assessment, and diagnosis of disorder and fertility. With the future developments in these areas, infrared methods would be more popular in milk composition determination, quality control, and dairy farm managements, with higher accuracy, efficiency and convenience. © 2016, Editorial Department of the Transactions of the Chinese Society of Agricultural Engineering. All right reserved.


Han R.W.,Chinese Academy of Agricultural Sciences | Han R.W.,Ministry of Agriculture Milk and Dairy Product Inspection Center Beijing | Han R.W.,Laboratory of Quality and Safety Risk Assessment for Dairy Products Beijing | Han R.W.,Qingdao Agricultural University | And 15 more authors.
Food Control | Year: 2013

In August 2010, 200 feed samples for dairy cow and 200 milk samples were collected from ten major milk-producing provinces in China. The feed samples were analysed for Aflatoxin (AF) B1, B2, G1 and G2, using the HPLC method. AFM1 in the milk samples was determined using the ELISA method. AFB1 and AFB2, but not AFG1 and AFG2 were detected in the feed samples. In the feeds, 42% of the samples contained AFB1 in the range of 0.05-3.53μg/kg, and 36% of the samples were detected positive for AFB2, with the content ranging from 0.03μg/kg to 0.84μg/kg. The content of AFB1 was significantly (P<0.05) higher than that of AFB2 in the feeds, but it was still below the legal limits of 5μg/kg (in EU) and 10μg/kg (in China), respectively. The total content of AFs was below the U.S. legal limit of 20μg/kg. For the milk samples, 32.5% were detected positive for AFM1, in the range of 5.2-59.6ng/L, far below the legal limit of 500ng/L in China and the US. However, three samples contained AFM1 at the levels of exceeding 50ng/L of the EU legal limit. Furthermore, there was no significant (P>0.05) difference between the north and the south of China in the AF contents in both the dairy cow feed samples and the milk samples. © 2013 Elsevier Ltd.


Guo X.,Chinese Academy of Agricultural Sciences | Guo X.,Xinjiang Agricultural University | Guo X.,Ministry of Agriculture Milk and Dairy Product Inspection Center Beijing | Wen F.,Chinese Academy of Agricultural Sciences | And 10 more authors.
Biosensors and Bioelectronics | Year: 2014

Contamination of feed and food by aflatoxin B1 (AFB1), one of the most toxic of the mycotoxins, is a global concern. To prevent food safety scares, and avoid subsequent economic losses due to the recall of contaminated items, methods for the rapid, sensitive and specific detection of AFB1 at trace levels are much in demand. In this work, a simple, ultrasensitive, and reliable aptasensor is described for the detection of AFB1. An AFB1 aptamer was used as a molecular recognition probe, while its complementary DNA played a role as a signal generator for amplification by real-time quantitative polymerase chain reaction (PCR). Under optimal conditions, a wide linear detection range (5.0×10-5 to 5.0ngmL-1) was achieved, with a high sensitivity (limit of detection (LOD)=25fgmL-1). In addition, the proposed aptasensor exhibited excellent specificity for AFB1 compared with eight other mycotoxins, with no obvious Ct value change. This aptasensor can also be used in quantifying AFB1 levels in Chinese wildrye hay samples and infant rice cereal samples, demonstrating satisfactory recoveries in the range of 88-127% and 94-119%, respectively. This detection technique has a significant potential for high-throughput, quantitative determination of mycotoxin levels in a large range of feeds and foods. © 2014 Elsevier B.V.


Guo X.,Chinese Academy of Agricultural Sciences | Guo X.,University of Liège | Guo X.,Ministry of Agriculture Milk and Dairy Product Inspection Center Beijing | Wen F.,Chinese Academy of Agricultural Sciences | And 8 more authors.
Analytical and Bioanalytical Chemistry | Year: 2016

Aflatoxin M1 (AFM1), one of the most toxic mycotoxins, imposes serious health hazards. AFM1 had previously been classified as a group 2B carcinogen [1] and has been classified as a group 1 carcinogen by the International Agency for Research on Cancer (IARC) of the World Health Organization (WHO) [2]. Determination of AFM1 thus plays an important role for quality control of food safety. In this work, a sensitive and reliable aptasensor was developed for the detection of AFM1. The immobilization of aptamer through a strong interaction with biotin–streptavidin was used as a molecular recognition element, and its complementary ssDNA was employed as the template for a real-time quantitative polymerase chain reaction (RT-qPCR) amplification. Under optimized assay conditions, a linear relationship (ranging from 1.0 × 10−4 to 1.0 μg L−1) was achieved with a limit of detection (LOD) down to 0.03 ng L−1. In addition, the aptasensor developed here exhibits high selectivity for AFM1 over other mycotoxins and small effects from cross-reaction with structural analogs. The method proposed here has been successfully applied to quantitative determination of AFM1 in infant rice cereal and infant milk powder samples. Results demonstrated that the current approach is potentially useful for food safety analysis, and it could be extended to a large number of targets. © 2016 Springer-Verlag Berlin Heidelberg


Li M.,Chinese Academy of Agricultural Sciences | Li M.,Ministry of Agriculture Milk and Dairy Product Inspection Center Beijing | Wen F.,Chinese Academy of Agricultural Sciences | Wen F.,Ministry of Agriculture Milk and Dairy Product Inspection Center Beijing | And 12 more authors.
International Journal of Molecular Sciences | Year: 2016

Targeting threonyl-tRNA synthetase (ThrRS) of Brucella abortus is a promising approach to developing small-molecule drugs against bovine brucellosis. Using the BLASTp algorithm, we identified ThrRS from Escherichia coli (EThrRS, PDB ID 1QF6), which is 51% identical to ThrRS from Brucella abortus (BaThrRS) at the amino acid sequence level. EThrRS was used as the template to construct a BaThrRS homology model which was optimized using molecular dynamics simulations. To determine the residues important for substrate ATP binding, we identified the ATP-binding regions of BaThrRS, docked ATP to the protein, and identified the residues whose side chains surrounded bound ATP. We then used the binding site of ATP to virtually screen for BaThrRS inhibitors and got seven leads. We further characterized the BaThrRS-binding site of the compound with the highest predicted inhibitory activity. Our results should facilitate future experimental effects to find novel drugs for use against bovine brucellosis. © 2016 by the authors; licensee MDPI, Basel, Switzerland.


Zhang Y.D.,Chinese Academy of Agricultural Sciences | Zhang Y.D.,Ministry of Agriculture Milk and Dairy Product Inspection Center Beijing | Zheng N.,Chinese Academy of Agricultural Sciences | Zheng N.,Ministry of Agriculture Milk and Dairy Product Inspection Center Beijing | And 11 more authors.
Food Control | Year: 2014

This study examines 94 samples of ultra high temperature (UHT) milk and 26 samples of pasteurized milk from China's top dairy brands (I, II, III, IV), using the ELISA method to assess their contamination with tetracyclines, sulfonamides, sulfamethazine and quinolones. All of the samples were collected from China's market in September 2010. The percentage of UHT milk samples containing detectable levels of tetracyclines, sulfonamides, sulfamethazine and quinolones were 0%, 20.2%, 7.4% and 95.7%, respectively, and 7.7%, 15.4%, 0% and 61.5%, respectively, in pasteurized milk samples. The maximum concentrations ofthe tetracyclines, sulfonamides, sulfamethazine and quinolones in all liquid milk samples were 47.7μgkg-1, 20.24μgkg-1, 14.62μgkg-1 and 20.49μgkg-1, respectively. None of the samples exceeded the maximum residue levels (MRLs) set by China, the European Union (EU) and the Codex Alimentarius Commission (CAC). However, because of the high detection rates of some veterinary drug residues in the liquid milk, stringent control measurements for these residues need to remain in effect, in order to guarantee that the milk is safe for people to drink. © 2013 Elsevier Ltd.


Chen M.,Chinese Academy of Agricultural Sciences | Chen M.,Ministry of Agriculture Milk and Dairy Product Inspection Center Beijing | Wen F.,Chinese Academy of Agricultural Sciences | Wen F.,Ministry of Agriculture Milk and Dairy Product Inspection Center Beijing | And 6 more authors.
Food Additives and Contaminants - Part A Chemistry, Analysis, Control, Exposure and Risk Assessment | Year: 2016

Research on the storage stability of antibiotic residues in milk is important for method development or validation, milk quality control and risk assessment during screening, confirmation, qualitative or quantitative analysis. This study was conducted using UPLC-MS/MS to determine the stability of six quinolones – ciprofloxacin (CIP), danofloxacin (DAN), enrofloxacin (ENR), sarafloxacin (SAR), difloxacin (DIF) and flumequine (FLU) – in raw milk stored under various conditions to investigate if quinolones degrade during storage of milk, and finally to determine optimal storage conditions for analysis and scientific risk assessment of quinolone residues in raw milk. The storage conditions included different temperatures and durations (4°C for 4, 8, 24 and 48 h; –20°C for 1, 7 and 30 days; –80°C for 1, 7 and 30 days), thawing temperatures (25, 40 and 60°C), freeze–thaw cycles (1–5), and the addition of different preservatives (sodium thiocyanate, sodium azide, potassium dichromate, bronopol and methanal). Most quinolones exhibited high stability at 4°C for up to 24 h, but began to degrade after 48 h. In addition, no degradation of quinolones was seen when milk samples were stored at –20°C for up to 7 days; however, 30 days of storage at –20°C resulted in a small amount of degradation (about 30%). Similar results were seen when samples were stored at –80°C. Moreover, no losses were observed when frozen milk samples were thawed at 25, 40 or 60°C. All the quinolones of interest, except sarafloxacin, were stable when milk samples were thawed at 40°C once and three times, but unstable after five freeze–thaw cycles. Preservatives affected the stability of quinolones, but the effects differed depending on the preservative and quinolone. The results of this study indicate optimum storage protocols for milk samples, so that residue levels reflect those at the time of initial sample analysis, and should improve surveillance programmes for quinolones in raw milk. © 2016 Informa UK Limited, trading as Taylor & Francis Group

Loading Ministry of Agriculture Milk and Dairy Product Inspection Center Beijing collaborators
Loading Ministry of Agriculture Milk and Dairy Product Inspection Center Beijing collaborators