Contaminants In Food Samples Research Articles

A review of recent, unconventional applications of ion mobility spectrometry (IMS)

The applications of ion mobility spectrometry (IMS) have grown exponentially beyond its uses for explosive, illicit drug and chemical warfare agent monitoring in recent years. Instrumental developments including new drift tube materials and ionization sources have enabled the manufacturing of more sophisticated and affordable IMS equipment for the advantageous analysis of samples with no pretreatment. The most recent applications of IMS include quality control and cleaning validation procedures in the pharmaceutical industry; determinations of contaminants in food samples; clinical analyses of biological fluids; environmental analyses of contaminants in gaseous, liquid and solid samples; and (bio)process quality control monitoring. Coupling IMS with MS n has enabled the analysis of very complex samples and the extraction of knowledge unavailable from isolated MS measurements, especially in the polymer and petroleomic industries.

Application potential of gas chromatography high speed time-of-flight mass spectrometry system in analysis of pesticides. Part 1

Analysis of pesticides and polychlorinated biphenyls in food matrices was provided by the method of complete two-dimensional gas chromatography/time-of-flight mass spectrometry. It was shown, that using of technology GC/GC is significantly improves separation of target compounds and decrease the limits of quantification in comparison with the common “one-dimensional” chromatography. Also, the study describes briefly the use of rapid separation for the analysis of trace contamination in food samples. High-speed temperature program, coupled with the possibility of deconvolution of spectra, using the TOF-type detector with the appropriate software, significantly reduces the total time of analysis compared with traditional methods.

Isolation of anti-listerial bacteriocin producing <italic>Lactococcus lactis</italic> CFR-B3 from Beans (<italic>Phaseolus vulgaris</italic>)

Contamination of food samples by Listeria monocytogenes is a major cause of food-borne infections. Controlling the growth of Listeria sp. by application of bacteriocin or bacteriocin producing-organism in foods is one of the challenges in the development of effective bio-preservation process. The objective of this study was to isolate and to characterize bacteriocinogenic strain Lactococcus lactis CFR-B3 from Indian beans. Bacterial strain of Pediococcus acidilactici NRRL B1153 was used as indicator to screen bacteriocin production. The culture was found to produce class IIa heat-stable anti-listerial bacteriocin of MW ~ 5 kDa. The use of food-grade organism as an indicator for screening bacteriocinogenic strains of lactic acid bacteria circumvent the need for using pathogenic cultures such as listeria spp. The native isolate Lc. lactis CFR-B3 finds its application in the preservation of vegetables due to its prevalence in the same ecological niche.

Simultaneous Detection of Multifood-Borne Pathogenic Bacteria Based on Functionalized Quantum Dots Coupled with Immunomagnetic Separation in Food Samples

This paper reports a method that simultaneously detects three food-borne pathogenic bacteria, Salmonella typhimurium, Shigella flexneri, and Escherichia coli O157:H7, via an approach that combines magnetic microparticles for the enrichment and antibody-conjugated semiconductor quantum dots (QDs) as fluorescence markers. Using the water-in-oil reverse microemulsions method, the gamma-Fe(2)O(3) magnetic nanoparticles were coated with silica to empower the particles with high dispersibility and broad compatibility to biomacromolecules. The magnetic beads were then modified with amino silane, which could immobilize antibodies by glutaraldehyde treatment. The immunized magnetic beads and pathogenic bacteria formed "bead-cell" complexes in the enrichment procedure. QDs with different emission wavelengths (620, 560, and 520 nm) were immobilized with anti-S. typhimurium antibody, anti-S. flexneri antibody, and anti-E. coli O157:H7 antibody, respectively. Fluorescence microscope images and the fluorescence intensity of QDs labeled "sandwich" complexes (conjungated with antibodies against S. typhimurium, S. flexneri, and E. coli O157:H7, respectively) demonstrated that antibody-conjugated QDs could attach to the surface of bacterial cells selectively and specifically. In our method, we could detect food-borne pathogen bacteria in a food matrix at 10(-3) cfu/mL. We determined that a high concentration of proteins in food matrix would decrease the sensitivity of this method. This method, of which the detection procedures are completed within 2 h, can be applied to the rapid and cost-effective monitoring of bacterial contamination in food samples.

A real-time PCR for Detection of Pathogenic Yersinia enterocolitica in food combined with an Universal Internal Amplification Control System

A real-time PCR system with an internal amplification control was developed for detection of pathogenic Yersinia) enterocolitica in food samples. The chromosomally encoded ail gene was chosen as PCR target. Sequences of plasmid pUC19 served as target for the internal amplification control. The method was validated in combination with sample enrichment in PSB and TSB broth using different food matrices spiked with Y. enterocolitica and naturally contaminated slaughterhouse samples. The results of the real-time PCR with internal control were verified by the cultural method according to EN ISO 10273:2003. The sensitivity of the real-time PCR with internal control is about 5 genome copies per reaction. Artificial contamination of food samples resulted in a detection level of 5 cfu per 25 g Y. enterocolitica in food samples. 100% of porcine tonsils and about 22% meat from pig heads were contaminated. The screening of samples by PCR prior to cultural analysis allows focusing on positive samples in routine analysis. This could result in a higher detection rate by cultural analysis.

Fumonisin B1 contamination of home-grown corn in high-risk areas for esophageal and liver cancer in China

Fumonisin B1 (FB1) is reportedly the causative agent of several animal mycotoxicoses and has etiologically been linked to human oesophageal and liver cancer in certain areas of South Africa and China. To study a possible relationship between exposure to FB1 and human cancer risk, the current status of FB1 contamination in food samples in Huaian and Fusui, where incidences of oesophageal and liver cancer are amongst the highest in China, was investigated. A total of 259 corn samples were collected from individual households in five villages of different townships in Huaian during December 2001 and December 2002, and in four villages of different townships in Fusui during May 2001 and May 2002. Corn samples were also collected from individual households in two villages in Huantai, an area with low incidences of both cancers. Enzyme-linked immunosorbent assays (ELISA) and immunoaffinity–HPLC methods were used for FB1 analysis. In corn samples from Huaian, FB1 was detectable in 95.7% (112/117) of the samples, with an average of 2.84 mg kg−1 (range 0.1–25.5 mg kg−1). FB1 was detected in 83.0% (78/94) of the Fusui samples, with an average of 1.27 mg kg−1 (range 0.1–14.9 mg kg−1), and in 83.3% (40/48) of Huantai samples, with an average of 0.65 mg kg−1 ranging from 0.1 to 5.7 mg kg−1. The level of FB1 in corn samples from Huaian was significantly higher than from Huantai (P < 0.001). In addition, 47 of 112 (42.0%) positive Huaian samples had FB1 level greater than 2.0 mg kg−1, which was significantly higher than 10.0% (4/40) of Huantai samples (P < 0.001). Furthermore, variations were found between samples collected in different years and different villages. The high contamination rates of FB1 found in food from these areas, along with previous reports, suggest a possible contributing role of FB1 in human esophageal- and hepato-carcinogenesis.

Monitoring of bacterial contamination in food samples using capillary zone electrophoresis.

A capillary electrophoresis method with UV detection is proposed for the identification and quantitation of bacterial contamination in food samples. The electrophoretic separation relies on the differential mobility of bacteria in the capillary. Electrophoretic resolution is improved by using calcium and myoinositol hexakisphosphate as specific ions that interact with the bacterial surface changing its electrical properties and electrophoretic mobility. The proposed method allows the effective separation of eight different types of bacteria in only 25 min. It was successfully used to detect the presence of bacteria in contaminated food. The precision of the analysis of real spiked samples ranges from 3.3 to 7.0%, and the overall analysis time is 7 h, which is much shorter than the 24-48 h typically required for plate counts. The validity of the method was established by comparison with the standard plate counting method.