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Zhao L.,Gansu Agricultural University | Zhao L.,Chinese Academy of Agricultural Sciences | Zheng B.,Tangshan Livestock and Aquatic Products Quality Monitoring Center | Zheng N.,Chinese Academy of Agricultural Sciences | And 9 more authors.
Journal of Food, Agriculture and Environment | Year: 2014

The objective of this study was to investigate raw milk quality by measuring somatic cell count (SCC), total bacterial count (TBC), and milk protein. In addition, we compared raw milk quality between the milk stations of dairy farms and dairy cooperatives, respectively, in Tangshan city, which is the second-largest dairy-producing city in China. A total of 128 raw milk samples, comprising 70 samples from dairy farm milk stations and 58 samples from dairy cooperative milk stations, were collected in July 2011. The SCC ranged between 27.1×104 and 110.3×104 cells/ml, with 73.4% of the 128 samples being in accordance with the standards of United States Grade A Pasteurized Milk Ordinance of 75×104 cells/ml (2011). The TBC ranged between 0.55×104 and 40×104 CFU/ml, and was in compliance with the Chinese national standard (GB19301-2010) of 200×104 CFU/ml. A total of 73.5% of samples reached 10×104 CFU/ml, which is the standard of both the European Union and the United States. The protein content in the 128 samples was in the range of 2.82 -3.23 g/100 g, reaching the Chinese national standard (GB19301-2010) of 2.80 g/100 g. The SCC, TBC, and protein content values obtained showed that the quality of raw milk in Tangshan city was much higher than that stipulated in the Chinese legal limit. Further, the quality of the raw milk from the dairy farm milk stations was similar to that of the dairy cooperative milk stations, as indicated by the similar SCC, TBC and protein content values obtained (p>0.05). Source

Guo L.Y.,Gansu Agricultural University | Guo L.Y.,Laboratory of Quality and Safety Risk Assessment for Dairy Products Beijing | Guo L.Y.,Milk and Dairy Product Inspection Center Beijing | Guo L.Y.,Chinese Academy of Agricultural Sciences | And 11 more authors.
Food Control | Year: 2016

Total 530 samples of raw milk were collected from the dairy farms in the Tangshan region of north China during four seasons each year from 2012 to 2014, and aflatoxin M1 (AFM1) contents were measured using HPLC-MS/MS. The results showed that AFM1 was detected in 280 samples (52.8%) at the range of 10-200 ng L-1, and the mean level of AFM1 was 73.0 ng L-1, which was below the China and US legal limit of 500 ng L-1. The incidences of AFM1 contamination were 27.5% in spring, 39.0% in summer, 71.7% in autumn and 78.9% in winter, respectively. It indicated that seasonal variations should be considered for the AFM1 control particularly during winter season. In comparison with the data from different years, the incidences of AFM1 contamination in raw milk samples were 87.8% with a range of 10.0-160 ng L-1 in 2012, 29.9% with 10.0-190.0 ng L-1 in 2013 and 36.7% with 12.0-111.0 ng L-1 in 2014. Hence, present study exhibits a significant decrease in the incidence of AFM1 contamination in Tangshan region after 2012. © 2016 Elsevier Ltd. Source

Zheng N.,Chinese Academy of Agricultural Sciences | Zheng N.,Milk and Dairy Product Inspection Center Beijing | Zheng N.,Laboratory of Quality and Safety Risk Assessment for Dairy Products Beijing | Wang J.-Q.,Chinese Academy of Agricultural Sciences | And 11 more authors.
Food Additives and Contaminants: Part B Surveillance | Year: 2013

Aflatoxin M1 (AFM1) is the only mycotoxin that has a legal limit in milk all over the world. In the present study, 360 raw milk samples were collected from Beijing, Hebei, Shanxi, Shanghai and Guangdong provinces in China in September 2010, and their AFM1 levels were determined by using enzyme-linked immunosorbent assay (ELISA). More than three-fourths (78.1%) of the 360 raw milk samples contained AFM1 at concentrations of 5-123 ng L-1. AFM1 contents in all positive samples were far below the Chinese and US legal limit of 500 ng L-1, but 10% of the raw milk samples exceeded the EU legal limit of 50 ng L-1. Moreover, both incidence and content of AFM1 in milk collected from the southern provinces, including Shanghai and Guangdong, were higher than those collected from the northern provinces, including Beijing, Hebei and Shanxi. © 2013 Copyright Taylor and Francis Group, LLC. Source

Han R.W.,Qingdao Agricultural University | Zheng N.,Chinese Academy of Agricultural Sciences | Zheng N.,Milk and Dairy Product Inspection Center Beijing | Yu Z.N.,Qingdao Agricultural University | And 11 more authors.
Food Chemistry | Year: 2015

A selective and rapid method has been developed to determine, simultaneously, 38 veterinary antibiotic residues in raw milk by ultra-high-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). One milliliter of raw milk was diluted with 0.5 mL water and 3 mL acetonitrile, then purified using an Oasis HLB cartridge. The eluates were evaporated by nitrogen drying and then reconstituted to 4 mL with water/acetonitrile (8:1) before being injected into the UPLC-MS/MS system. The results indicated recoveries of 68-118% for 14 β-lactams, 79-118% for eight quinolones, 71-106% for eight sulfonamides, 76-116% for four tetracyclines, 78-106% for three macrolides, and 88-103% for one lincosamides, with coefficients of variation less than 15% for intraday and interday precisions. The limit of quantification for all antibiotics was 0.03-10 μg kg-1. This methodology was then applied to field-collected real raw milk samples and trace levels of four antibiotics were detected. © 2015 Elsevier Ltd. Source

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