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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.

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.

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

Guo X.,Chinese Academy of Agricultural Sciences | Guo X.,University of Liege | 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

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