OBJECTIVEThe loop-mediated isothermal amplification (LAMP) detection method was applied to detect Listeria monocytogenes in food. The specificity and sensitivity of this method were evaluated through comparing it with Real-time PCR and conventional detection method.

METHODSThe LAMP primers were designed based on hly gene of Listeria monocytogenes. The LAMP method was applied to detect 88 Listeria monocytogenes, 1 reference strain ATCC 15313 of Listeria monocytogenes and 33 non-targets bacteria strains; base-material addition test and practical food samples detection were also conducted. Both of Real-time PCR and ISO 11290-1 methods were used as parallel detection method in addition to LAMP. The three kinds of methods were compared by specificity, sensitivity, detection limit and the detection result of practical food samples.

RESULTSBoth detection results of LAMP and Real-time PCR for 89 Listeria monocytogenes were positive (100%, 89/89), 33 non-targets bacteria strains were negative (100%, 33/33). The sensitivity of LAMP was 2 × 10² CFU/ml, which was consistent with Real-time PCR method (2 × 10² CFU/ml) and better than ISO 11290-1 method (2 × 10² CFU/ml). Base-material addition test result showed that the detection limit of the three kinds of methods were 3 CFU/25 g samples. And the result of practical food samples displayed the same detection rate of 4% in the three methods (2/45).

CONCLUSIONThe LAMP method of Listeria monocytogenes established in this study has good specificity and sensitivity, which can be applied to the rapid detection of Listeria monocytogenes.

Food Contamination ; analysis ; Food Inspection ; methods ; Food Microbiology ; Listeria monocytogenes ; genetics ; isolation & purification ; Nucleic Acid Amplification Techniques ; methods

OBJECTIVETo improve the mini-modified semi solid rappaport vassiliadis most probable number (mini-MSRV MPN) method for Salmonella detection.

METHODSBased on the mini-MSRV MPN method,Buffered Peptone Water (BPW) was modified as one step enrichment medium and Modified Semi Solid Rappaport Vassiliadis (MSRV) medium was ameliorated as modified MSRV for Salmonella detection under standard Salmonella addition recovery. A total of 154 raw chicken samples, 48 swabs of pheasantry and 48 poultry dung samples were collected to compare the detection results of Salmonella by using improved mini-MSRV MPN, mini-MSRV MPN and regular most probable number (MPN) method.

RESULTSSalmonella recovery was < 2.7 MPN/g when the standard Salmonella addition was at the concentration of 0.9 CFU/g when the mini-MSRV MPN method was employed. If the standard Salmonella addition were at 9.0 and 90.0 CFU/g, the recoveries of bacteria were 10.1 and 94.0 MPN/g, and the average recovery rate was 112% and 104%, respectively. Salmonella detection rate of modified mini-MSRV MPN, mini-MSRV MPN and regular MPN method was 18.4% (46/250), 5.2% (13/250) and 6.0% (15/250), respectively. The detection rate was higher for modified mini-MSRV MPN method than of the other two methods (χ(2) values were 19.68 and 17.82, respectively, all P values < 0.05). The detection quantity of Salmonella (medians were 21.0, < 2.7 and < 3.0 MPN/g, respectively). The quantity detected by modified mini-MSRV MPN method was higher than that of the other two methods (both Z values were 5.71, both P values < 0.05).

CONCLUSIONModified mini-MSRV MPN method is an accurate method for foodborne Salmonella detection.

Animals ; Chickens ; microbiology ; Culture Media ; Food Contamination ; analysis ; Food Inspection ; methods ; Salmonella ; isolation & purification

To assure the effective operation of certification and accreditation in the laboratory management system, further strengthen the instruments and equipment management, and provide specific recommendations on improvement of internal audit, management review and continuous improvement of management system. The inspector program had been firstly established and complemented. Through the inspection, we identified many deficiencies, made many specific recommendations for improvement. After inspection, the working procedures were improved; data from department were more rigorous, scientific and just; hardware foundation was established for international mutual recognition.
Accreditation ; Food Inspection ; legislation & jurisprudence ; Laboratories ; standards ; Pharmacy Administration ; legislation & jurisprudence

OBJECTIVETo observe the ethyl carbamate concentrations in different commercial fermented foods in Hangzhou in 2010.

METHODSIn 2010, 237 commercial fermented food samples of eight categories, including yellow wine, white spirit, wine, beer, cooking wine, sauce, vinegar and fermented bean curd, were purchased from 3 different size markets respectively in Hangzhou. The ethyl carbamate was measured by gas chromatography-mass spectrometry in selection ion mode, after the samples were coupled with D5-ethyl carbamate, and purified by diatomite solid phase extraction column.

RESULTSThe results showed that ethyl carbamate was detected in all samples analyzed (100%) with the range from 2.0 µg/kg to 515.0 µg/kg. The ethyl carbamate average (median) levels in 8 food categories were descending with fermented red bean curd (182.2 µg/kg (161.2 µg/kg)), yellow wine (159.6 µg/kg (121.0 µg/kg)), cooking wine (86.8 µg/kg (95.6 µg/kg)), white spirit (72.0 µg/kg (60.5 µg/kg)), soy sauce (47.2 µg/kg (40.7µg/kg)), vinegar (26.7 µg/kg (31.8 µg/kg)), wine (15.7 µg/kg (16.8 µg/kg)) and beer (2.2 µg/kg (2.3 µg/kg)).

CONCLUSIONThe ethyl carbamate was detected in all fermented foods in Hangzhou in 2010, and the levels of ethyl carbamate in red bean curd and yellow wine were higher than others.

Acetic Acid ; analysis ; Alcoholic Beverages ; analysis ; Beer ; analysis ; China ; Fermentation ; Food Analysis ; Food Contamination ; analysis ; Food Inspection ; Gas Chromatography-Mass Spectrometry ; methods ; Urethane ; analysis ; Wine ; analysis

China ; Food ; Food Contamination ; prevention & control ; Food Inspection ; methods ; Plants ; chemistry

OBJECTIVETo investigate Benzo (a) pyrene (BaP) residue in retail food of Xiamen.

METHODSBaP residue in 121 retail food samples collected from Xiamen were determined by a rapid BaP detector based on derivative constant-energy synchronous fluorescence technique.

RESULTSBaP was detected in 84.3% samples and the concentration were ranged from 0.17 to 59.0 microg/kg. There were 49.6% samples exceeding 5.00 microg/kg, and most of them were roasting food (1.44 - 54.10 microg/kg), processed meat products (0.17 - 59.00 microg/kg) and aquatic products (2.79 - 36.80 microg/kg). The BaP concentration in 34 samples collected from roadside stands were 1.78 - 49.60 microg/kg, of which the rate of the samples exceeding 5.00 microg/kg was 88.2%.

CONCLUSIONThe BaP contamination in retail food samples from Xiamen is serious.

Benzo(a)pyrene ; analysis ; China ; Food Contamination ; analysis ; Food Inspection ; methods ; Meat Products ; analysis

OBJECTIVETo investigate the pollution level and development trend of lead in the preserved egg in our country.

METHODSBy the national food contamination monitoring system and under the strict analysis quality control, the content of lead in the preserved eggs was analyzed according to the national standard method (GB/T 5009.12-2003) in fourteen provinces from 2000 to 2006.

RESULTSAll 1358 data on contents of lead in the preserved eggs were obtained during seven years, the total average was 1.782 mg/kg, the maximum was 334.0 mg/kg, P90 was 3.50 mg/kg, P95 was 7.397 mg/kg and P97.5 was 12.01 mg/kg, all exceeded 2 mg/kg of the national limit standard, and the rate of violated samples exceeded 10.0%. Analyzing from time, contents of lead in the preserved eggs were depressive from 2.994 mg/kg to 1.138 mg/kg year after year.

CONCLUSIONThe lead contamination in preserved eggs was serious in whole country. It shows that the continuous work of monitoring and forewarning should be carried out to make the contamination of lead in preserved eggs to reduce year by year.

China ; Eggs ; analysis ; Food Contamination ; analysis ; Food Handling ; methods ; Food Inspection ; methods ; Lead ; analysis

OBJECTIVETo develop a method for determining arsenobetaine (AsB), arsenite (AsIII), arsenate (AsV), Monomethylarsonic acid (MMA) and Dimethylarsenic acid (DMA) with liquid chromatography (LC), on-line UV-decomposition (UV), hydride generation (HG) and atomic fluorescence spectrometry (AFS) in animal origin seafood samples.

METHODSArsenic compounds were extracted in an ultrasonic bath with methanol-water (9:1) solvent from the animal origin seafood samples. The extracts were evaporated with N2 and dissolved in water. The solvent was extracted by hexane to remove lipids. And then, the aqueous solution was diluted to 10 ml. The extracts were filtered before analysis by LC-AFS. The mobile phase consisted of 0.5 mmol/L NH4H2PO4 (pH 9.0) and 20 mmol/L NH4H2PO4 (pH 6.0). Arsenic species were separated with an anion exchange column Hamilton PRPX-100 and gradient elution, detected by LC-UV-HG-AFS.

RESULTSThe established separation condition could achieve a better separation for five arsenic species. Detection Limits (LOD) were ranged from 0.0025 to 0.0032 mg/L, AsB was the predominant arsenic species in the animal origin seafood samples. AsIII and DMA were detected in certain shellfish samples at trace level. The accuracy of total arsenic measurement was tested by the analysis of NBS 1566 (Oyster Tissue). The accuracy of arsenic species measurement was tested by the analysis of BCR 627 (Tuna Fish). The data were tallied with the certified value.

CONCLUSIONArsenic species were specifically detected by LC-UV-HG-AFS in the animal origin seafood samples.

Animals ; Arsenic ; analysis ; Arsenicals ; analysis ; Chromatography, High Pressure Liquid ; methods ; Food Inspection ; methods ; Seafood ; analysis ; Spectrometry, Fluorescence ; methods

OBJECTIVETo investigate the lead and cadmium pollution in edible mushrooms sold in Beijing.

METHODS146 samples of 14 species were collected form 25 markets during the period of Mar. through May, 2007 in Beijing. The pollution of lead and cadmium were analyzed respectively according to the standard of GB/T5009. 12-2003 and GB 7096-2003.

RESULTSThe content of lead and cadmium in edible mushrooms was ND--1.592 mg/kg, ND--0.550 mg/kg, respectively, both lower than the allowable content prescribed by The National Ministry of Health.

CONCLUSIONThe contents of lead and cadmium in the mushrooms marketed in Beijing are in safe ranges. It is worthy of mentioning the variation coefficients of heavy metal concentrations existing in edible mushrooms.

Agaricales ; Cadmium ; analysis ; China ; Food Contamination ; statistics & numerical data ; Food Inspection ; Lead ; analysis

OBJECTIVETo establish a comprehensive analytical high performance liquid chromatography fluorescence detection (HPLC-FL) in detecting bisphenol A (BPA), nonylphenol (NP) and octylphenol (OP) in canned food sold in Beijing markets.

METHODSBPA, NP and OP was extracted with methanol and dichloroacetamide and concentrated. The samples were purified on an solid extraction cartridges. The HPLC system consisted of Waters XTerra MS C18 column, a mixture of methanol and water as mobile phase and fluorescence detector with the excitation and emission wavelength at 225 nm and 310 nm respectively.

RESULTSThe method established had a linear relationship, showing the detection limit of BPA, OP and NP being 0.5, 0.1 and 0.1 microg/kg in canned vegetable and instant noodle and 1, 0.5 and 0.5 microg/kg in canned fish and meat can, respectively. The recoveries of BPA, NP and OP were 74.9%-95.1% , 76.3%-103.6% and 72.1%-109.2%. The precision was 4.98%-11.2% , 2.35%-8.88% and 5.61%-12.3%, respectively.

CONCLUSIONThe method is simple with high sensitivity and selectivity, suitable for the determination of NP, OP and BPA in canned food.

Benzhydryl Compounds ; Chromatography, High Pressure Liquid ; Food Inspection ; methods ; Phenols ; analysis