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PubMed2004

Solid-phase microextraction coupled with high-performance liquid chromatography for the analysis of heterocyclic aromatic amines.

Solid-phase microextraction (SPME) coupled with high-performance liquid chromatography (HPLC) with UV diode array detection (DAD) for the analysis of heterocyclic aromatic amines (HAs) is described. Four kinds of fiber coatings: Carbowax-templated resin (CW-TPR), Carbowax-divinylbenzene (CW-DVB), poly(dimethylsiloxane)-divinylbenzene (PDMS-DVB) and polyacrylate (PA) were evaluated for extraction of nine most biologically active heterocyclic aromatic amines. Different parameters affecting to the microextraction and determination of HAs were studied, such as absorption and desorption time, desorption mode, composition of the solvent for desorption, pH, ionic strength, and percentage of methanol in the sample. To determine these amines in food samples a new simplified procedure is proposed, consisting of treatment of the sample with methanolic NaOH prior microextraction by CW-TPR fiber coating and HPLC-DAD determination. The advantages of this new method are the reduced amounts of time and organic solvents required.

Amines↗

PubMed2005

Occurrence and biological significance of proanthocyanidins in the American diet.

Dietary intake of proanthocyanidins (PAs) has been largely unknown because of the lack of reliable values for their content in foods. Recent development of an analytical method for PAs has allowed the quantification of individual oligomers and polymers. This method has been employed to analyze food samples collected under the USDA National Food and Nutrition Analysis Program. A database of the PA content in common foods and also infant foods has been established. It has been shown that PAs account for a major fraction of flavonoids ingested in the US diet and infants and children appear to ingest more PAs than adults on the basis of body weight. These data will provide an opportunity to examine the association between PA intake and health and disease outcomes in epidemiological studies. PA analysis and the significance of PAs in nutrition and diet are reviewed.

Antioxidants↗

PubMed2002

Method development and analysis of retail foods for annatto food colouring material.

Analytical methods for the determination of the permitted food colouring annatto (E160b) have been developed or refined to encompass the wide range of food commodity types permitted to contain it. Specific solvent extraction regimens have been used depending upon the food commodity analysed and HPLC analysis techniques coupled with spectral confirmation have been used for the determination of the major colouring components. Qualitative and quantitative data on the annatto content of 165 composite and two single retail food samples covering a wide range of foods at levels above the limit of quantification (0.1 mg kg(-1)) is reported. Quantitative results are given for the major colour principals 9'-cis-bixin, 9'-cis-norbixin and trans-bixin. Semi-quantitative results are given for the minor bixin and norbixin isomers monocis- (not 9'-), di-cis- and trans-norbixin, for which authentic reference standards were not available. Repeat analyses (n = 4-9) of 12 different types of food commodity (covering the permitted range) spiked with annatto at levels between 1.7 and 27.7 mg kg(-1) gave mean recoveries between 61 and 96%. The corresponding relative SDs (RSD) were between 2.1 and 7.9%.

Animals↗

PubMed1996

Acquired aversions as the basis for varied diets of ruminants foraging on rangelands.

Ruminants eat an array of plant species that vary in nutrients and toxins. This selection makes intuitive sense, but no theories adequately explain this diversity. Some maintain it reduces the likelihood of overingesting toxins, whereas others contend it meets nutritional needs. Nevertheless, herbivores seek variety even when toxins are not a concern and nutritional needs are met. I offer another explanation for this behavior, one which encompasses the avoidance of toxins and the acquisition of nutrients. A key concept in this theory is aversion, the decrease in preference for food just eaten as a result of sensory input (a food's taste, odor, texture, i.e., its flavor) and postingestive effects (effects of nutrients and toxins on chemo-, osmo-, and mechano-receptors) unique to each food. Aversions are pronounced when foods contain toxins or high levels of rapidly digestible nutrients; they also occur when foods are deficient in specific nutrients. Aversions occur even when animals eat nutritionally adequate foods because satiety (satisfied to the full) and surfeit (filled to nauseating excess) represent points along a continuum, and there is a fine line between satiety and aversion. Thus, eating any food is likely to cause a mild aversion, and eating a food too frequently or in excess is likely to cause a strong aversion. Aversions are involuntary and are not the result of conscious decisions by an animal. Aversions yield benefits (e.g., obtain a balanced diet, reduce ingestion of toxic foods, optimize foraging and rumination times, sample foods, maintain a diverse microflora in the rumen) that are often mistaken as the cause of varied diets. In this article, I discuss the subtle ways in which aversions diminish preference and cause animals to eat a variety of foods.

Animal Feed↗

PubMedDate not supplied

Total arsenic in foods after sequential wet digestion, dry ashing, coprecipitation with ammonium pyrrolidine dithiocarbamate, and graphite-furnace atomic absorption spectrometry.

A graphite-furnace atomic absorption (GFAAS) method is described for determining total arsenic (organic and inorganic compounds) in foods. Samples ranging from 1 to 40 g (depending on moisture content) were digested with HNO3 and dry-ashed at 500 degrees C overnight after addition of MgO. After dissolution in HCl, the arsenic was reduced with iodide and ascorbic acid and precipitated with ammonium pyrrolidine dithiocarbamate (APDC) in the presence of nickel carrier. Precipitates were collected on 0.3 micron cellulose acetate filters and dissolved in 10% HNO3 containing modifier. Ba(NO3)2 was added to remove a sulfate interference resulting from decomposition of APDC. Arsenic was determined using GFAAS. Accuracy of the method was good for 7 U.S. National Bureau of Standards (NBS) Standard Reference Materials and 3 National Research Council of Canada (NRCC) round-robin samples. Recovery of arsenic(V) from foods averaged 99.2% for peak heights and 97.1% for peak areas, with relative standard deviations (RSD) of 2.2% for peak heights and 3.3% for peak areas for all NBS and NRCC materials. Detection limit of the method was ca 10 ng arsenic.

Arsenic↗

PubMed2002

Simultaneous and sensitive analysis of Cu, Ni, Zn, Co, Mn, and Fe in food and biological samples by ion chromatography.

A sensitive and simple method for the simultaneous determination of nutritionally important minerals in food samples is in great demand. Ion chromatography coupled with UV-vis detection is shown to be an appropriate technique for this objective. The method is based on the formation of mineral complexes by pyridine-2,6-dicarboxylic acid in the mobile phase. The complexes are then postcolumn derivatized with 4-(2-pyridylazo)resorcinol (PAR), resulting in mineral-PAR complexes that are detected by UV-vis absorption at 500 nm. This facilitates the simultaneous separation and quantification of minerals in one chromatographic run. Within 16 min, Cu, Ni, Zn, Co, Mn, and Fe are analyzed. When a 50 microL injection volume is used, the average detection limit is 5 ppb in the injection liquid. The detection limit makes it a superior alternative to AAS and, in several applications, also an alternative to ICP-MS techniques. Different sample treatments were evaluated. The concentration of acid in the treated sample varied with the sample treatment, which may cause a limitation for the injection volume. A crucial prerequisite to achieve the reported detection limits and to obtain reliable results is to completely exclude all contamination from instruments and materials.

Calibration↗

PubMed2003

Application of an automated immunomagnetic separation-enzyme immunoassay for the detection of Salmonella spp during an outbreak associated with a retail premises.

AIMS: The application of an automated immunomagnetic separation-enzyme immunoassay (AIMS-EIA) during the investigation of a suspected outbreak of Salmonella food poisoning at a retail premises. METHODS AND RESULTS: Six food samples and 24 environmental swabs were taken from the retail premises and six food handlers' submitted faecal samples during the investigation of the outbreak. Isolation and identification of Salmonella from these samples was performed according to established standard operating procedures and by AIMS-EIA. Twelve of the 18 (67%) Salmonella culture positive samples were AIMS-EIA positive on testing pre-enrichment samples after 24 h, whilst 17 (94%) samples were AIMS-EIA positive following selective enrichment for a further 48 h. One food handler was found to be positive for Salmonella by both culture and AIMS-EIA. All Salmonella isolates were confirmed as Salmonella Enteritidis phagetype 21c. CONCLUSIONS: The AIMS-EIA protocol compliments the conventional culture approach to produce more timely results for the management of the risk to public health without significantly increasing the workload of the laboratory. SIGNIFICANCE AND IMPACT OF THE STUDY: The food production premise investigated in this study was heavily contaminated with Salmonella Enteritidis. Application of the AIMS-EIA was significant in the effective intervention of control measures for the protection of public health.

Animals↗

PubMed1982

Polychlorinated biphenyls in Mexican cereals and their packings.

The content of polychlorinated biphenyls in Mexican cereals and in their packaging materials was determined. All the samples had polychlorinated biphenyls. In all the food samples and in 73% of the packings, the concentrations of polychlorinated biphenyls exceeded the tolerance limits established by the U.S. Food and Drug Administration. A correlation was found between the values for polychlorinated biphenyls in the cereals and those in their packings, therefore, it is concluded that the main source of polychlorinated biphenyls in Mexican cereals is the transference of those present in the recycled paperboard used for the packings.

Edible Grain↗

PubMed2006

[Stability of hpt marker gene in transgenic rice in different food matrices and under varying food-processing conditions].

OBJECTIVE: To estimate the likelihood of horizontal gene transfer from transgenic rice to bacteria of the food chain and human gut, the stability of s86 transgenic rice hpt gene in different food matrices and under varying food-processing conditions was studied. METHODS: Degradation of DNA was monitored by fragment -multiplex polymerase chain reaction. Integrity of hpt gene in various food samples was tested. RESULTS: A PCR system for the hpt gene of genetically modified rice has been established to detect fragments ranging between 236bp and 910bp. Detection of hpt and rbcl gene fragments was carried out in various food-processed samples by this PCR system. The data showed that the fragments up to 500 bp were detected in rice and congee, while the fragment length more than 236bp was not detected in crispy rice and popcorn-like rice. CONCLUSION: These results suggested that there are significant differences in DNA degradation by different food-processing methods. The likelihood of the large hpt gene fragments transfer from transgenic rice processed food to bacteria is reduced by food process.

Food Handling↗

PubMed1978

[Introduction in mycotoxin problems (author's transl)].

In Part I the occurrence of mycotoxins is discussed in general terms with emphasis on how they originate in the food, taking full account of presence as secondary contaminants. Further discussions emphasize the occurrence of aflatoxin in foods with a detailed table containing 106 references. Finally, the discussion goes into the factors which influence the formation of mycotoxins and the consequences for the consumer. Part II is concerned with problems in sampling foods with aflatoxin. Difficulties in sampling arise from the different levels of aflatoxins present and from their instability in foods. Based on proposals of different investigators, sample quantities of more than 1 kg are recommended. Regulatory agencies expect concrete plans for statistical evaluation similar to those used for determination of salmonellae. It is particularly important that a solution should be found for the sampling of packaged foods so that a fair and reliable control is possible.

Aflatoxins↗

PubMed1998

Chromatographic analysis of lipoic acid and related compounds.

The analysis of lipoic acid and related compounds, such as its reduced form dihydrolipoic acid, its amide form lipoamide and other analogues, in biological and food samples is important in biochemistry, nutritional and clinical chemistry. This review summarizes the chromatographic methods for the determination of lipoic acid and related compounds, and their applications to various samples such as bacteria, tissues, drugs and food. Gas chromatographic methods with flame ionization detection and flame photometric detection are commonly used for the quantification of lipoic acid present as its protein-bound form, after acid or base hydrolysis of these samples. High-performance liquid chromatographic methods with ultraviolet, fluorescence and electrochemical detection are mainly used for the determination of free lipoic acid and related compounds, such as dihydrolipoic acid, lipoamide and other analogues. Moreover, gas chromatography-mass spectrometry and capillary electrophoresis methods are also developed.

Animals↗

PubMed2004

Real-time PCR detection of the thermostable direct hemolysin and thermolabile hemolysin genes in a Vibrio parahaemolyticus cultured from mussels and mussel homogenate associated with a foodborne outbreak.

Molecular methods have become vital epidemiological tools in the detection and characterization of bacteria associated with a foodborne outbreak. We used both culture and real-time PCR to detect a Vibrio parahaemolyticus isolate associated with a foodborne outbreak. The outbreak occurred in July 2002 in Polk County, Florida, and originated at a Chinese buffet, with one person being hospitalized. The hospital isolated V. parahaemolyticus from the patient but destroyed the sample after diagnosis. From an onsite visit of the restaurant, food samples that possibly contributed to the outbreak were collected and sent to the Florida Department of Health, Tampa Branch Laboratory. Crab legs, crabsticks, and mussel samples were homogenized and incubated according to the Food and Drug Administration Bacteriological Analytical Manual culture protocol. Three sets of primers and a TaqMan probe were designed to target the tdh, trh, and tlh genes and used for real-time PCR. This study was successful in isolating V. parahaemolyticus from a mussel sample and detecting two of its genes (tdh and tlh) in food and pure culture by real-time PCR.

Animals↗

PubMed1987

Ingestion intake of fallout Pu in Japan.

Ingestion intakes of fallout Pu throughout Japan in the 1959-1962 and 1978-1980 periods were measured by analyzing composite samples of each foodstuff or duplicate composite food samples consumed by five persons for a period of 1 d. Cumulative ingestion intake in Tokyo for the period from 1954-1980 was estimated by regression analysis. The cumulative ingestion intake, calculated by simple regression analysis between the natural log of the intake and that of annual fallout deposition of Pu, was estimated to be 450 pCi. Calculated by a multiple regression analysis, including the natural log of annual fallout deposition rates for a previous year as an additional independent variable, it was estimated to be 600 pCi. Considering in combination an ingestion intake, the value of which is calculated by the multiple regression analysis; an absorption ratio from the gastrointestinal tract of 0.001 (a recently reported value for low-level soluble Pu independent of chemical form); and the metabolic model in ICRP Publication 30, it is possible to estimate that the contribution of ingestion intake to liver and bone burden would be approximately 30%.

Body Burden↗

PubMed1998

Comparison of the SimPlate total plate count method with Petrifilm, Redigel, conventional pour-plate methods for enumerating aerobic microorganisms in foods.

The SimPlate Total Plate Count (TPC) method, developed by IDEXX Laboratories, Inc., is designed to determine the most probable number of aerobic microorganisms in foods. The 24-h test was compared to the conventional plate count agar (PCA) method, the Petrifilm Aerobic Count plates, and the Redigel Total Count procedure for enumerating microflora in 751 food samples. Results using the SimPlate TPC method were highly correlated (r > or = 0.96) with results from other test methods. Slopes (0.96-0.97) were not significantly different from 1, and y intercepts (-0.03-0.08) were not different from O. The SimPlate has a high counting range (> 1600 most probable number per single dilution), thus requiring fewer dilutions of samples compared to other methods evaluated. Some foods, e.g., raw liver, wheat flour, and nuts, contain enzymes that gave false-positive reactions on SimPlates. Overall, however, the SimPlate TPC method is a suitable alternative to conventional PCA, Petrifilm, and Redigel methods for estimating populations of mesophilic aerobic microorganisms in a wide range of foods.

Aerobiosis↗

PubMed2004

[Drug resistant coagulase-positive staphylococci strains in food].

From the 1572 food samples, examined in Microbiology Department of Frozen Food Industry Research Laboratory in Lódź, 79 (5.0%) coagulase-positive staphylococci strains were isolated. All the strains were sensitive to vancomycin, gentamycin and chloramphenicol. Only individual staphylococci strains were resistant to erythromycin (1.3%), lincomycin (2.5%) and ciprofloxacin (2.5%). 20.3% strains, isolated mainly from raw meat, were resistant to doxycycline and 6.3% to oxacillin. 38.0% of coagulase-positive staphylococci strains had positive results of cefinase test. One strain isolated from minced meat was resistant to methicillin and at the same time it was producing beta-lactamases.

Coagulase↗

PubMed1997

Establishment of microbiological safety criteria for foods in international trade. International Commission on Microbiological Specifications for Foods.

Microbiological safety is achieved by applying good hygienic practices throughout the food chain, "from farm to fork". Governmental food control is traditionally based on inspection of the facilities where foods are handled, and on testing food samples. Testing is usually applied to imported foods, when no information concerning the safety of a consignment is available. The microbiological safety is judged by means of microbiological criteria. Such criteria should, in the context of the WTO/SPS measures, be scientifically justified, and established according to the principles described by the Codex Alimentarius. However, microbiological testing is not a very reliable tool for consumer protection; the emphasis is currently shifting to the application of food safety management tools such as the Hazard Analysis Critical Control Point system (HACCP).

Food Contamination↗

PubMedDate not supplied

Interferences in radioimmunoassay of aflatoxins in food and fodder samples of plant origin.

Cross-reactions and resulting nonspecific binding of substances with structures resembling aflatoxins (derivatives of coumarin, and cinnamonic and benzoic acids, etc.) were investigated. The concentrations of these substances causing erroneously high or false positive values in radioimmunoassay were determined. One microgram aflatoxin B1/kg sample may be simulated by the occurrence of 5 g coumarin, 10 g caffeic acid, 16 g chlorogenic acid, or 15 g vanillin/kg fodder or food sample.

Aflatoxins↗

PubMed1989

Further study on fallout 3H ingestion in Akita, Japan.

To study fallout 3H ingestion in Japan, 16 separate food-group samples were collected from Akita City in northern Japan during early summer and late autumn in 1986. Furthermore, total diet samples which are duplicate composite food samples consumed by five or six persons for a period of 1 d were also obtained in Akita City. The 3H concentration in free water and that in a tissue-bound form were determined separately. Seasonal changes of 3H concentration in the food samples and the total diet samples were not found clearly. The average 3H concentration in the free water including tap water was 1.6 Bq L-1. The mean ratio of specific activity of tissue-bound 3H to that of 3H in free water was found to be 1.2. The average total 3H ingestion was estimated to be 4.0 Bq d-1, while the proportion of tissue-bound form 3H ingestion to total 3H ingestion was 11%. Cereal was the greatest contributing food group to ingestion of tissue-bound 3H. These findings were consistent with our previous results for food samples collected in 1985.

Food Contamination, Radioactive↗