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PubMed2004

Determination of vitamin B5 in a range of fortified food products by reversed-phase liquid chromatography-mass spectrometry with electrospray ionisation.

Methods for Vitamin B5 determination in food products remain limited by their low sensitivity and poor selectivity. Here, we have developed a liquid chromatography-mass spectrometry (LC-MS) method for Vitamin B5 determination in wide range of fortified food products. Vitamin B5 was extracted from food samples by heat treatment and analysed by LC-MS in the positive mode using electrospray ionisation (ESI). Vitamin B5 was quantified using hopantenic acid (HOPA) as internal standard after their separation on a C18 narrow-bore column with a gradient of mobile phase made of water/acetonitrile and trifluoroacetic acid (TFA) 0.025%. MS with single ion monitoring mode at mass m/z 220 was used for Vitamin B5 quantification. Calibration curve between 0.5 and 10 microg/ml of Vitamin B5 was linear (r2=0.9993) and the detection limit was determined to be 800 pg. The overall quantitative efficiency of the method was evaluated using Nestle reference sample (infant formula). The intra-assay RSD was 4.8% (n=8), the inter-assay RSD 6.4% (n=4) and the recoveries of the spiked samples were above 95%. Application of the LC-MS method to Vitamin B5 determination in wide range of fortified food products including three US National Institute of Standards and Technology (NIST) reference samples (RM 8435, RM 8415 and SRM 1546) shows consistent results with those obtained by microbiology and recoveries of Vitamin B5 between 93 and 104% for the spiked samples.

Calibration↗
PubMed2001

Transmission of a multiresistant Pseudomonas aeruginosa strain at a German University Hospital.

Over 15 months, 60 patients at a German University Hospital became infected or colonized by a multiresistant Pseudomonas aeruginosa strain, which was isolated from tracheal secretions, blood, urine, venous catheters, ascites and several wounds. Most patients had undergone invasive treatment (surgery, cancer therapy). The genetic relationship of the isolates was investigated by pulsed field gel electrophoresis. The isolates were resistant to beta-lactam antibiotics, including carbapenems and aztreonam, to aminoglycosides and quinolones. The only in vitro susceptibility was to polymyxin B. Extensive sampling was carried out to identify contaminated medical devices, surfaces or media (water, food). Samples were taken from doctors and nursing staff and various treatment procedures were observed for several weeks. The handling of respirators, resuscitation tubes, urine bottles, and bedpans resulted in the contamination of the patients' environment, although most devices were cleaned and disinfected with automatic washer/disinfectors. Several wash basins on the intensive care unit were contaminated, but none of the drinking water samples showed any growth of P. aeruginosa. We recommend the strict use of gloves and strict application of alcoholic hand disinfectants immediately after discarding the gloves. The chain of infection ceased after strict cohort isolation and the subsequent introduction of the specific hygiene regime.

Adult↗
PubMedDate not supplied

[Natural cadmium level in food products].

The natural (background) content of cadmium in some food products was determined by the method of multiple isotopic dilution with the use of a radioisotope without carrier. Microquantities of cadmium were found in all the products, with the cadmium content varying over a considerable range, depending on the region where food sampling has been performed. It is emphasized that the increased cadmium content in food products may be accounted for by industrial pollution of the biosphere.

Cadmium↗
PubMed1992

Quality control of food products purchased by the National School-Feeding Programme in Pernambuco, northeast Brazil, from 1985 to 1988.

The effectiveness of the Quality Control System (QCS) implemented by the Fundação de Assistência ao Escolar (FAE) for quality control of food products from different types and origins purchased by the National School-Feeding Programme (NSFP) in Pernambuco, Northeast Brazil, was evaluated. Physicochemical, microbiological, microscopical and organopetical analyses were performed in 4,860 food samples and the main causes of alterations were detected. Perishability was the characteristic used for distribution of food items into 3 main groups: A, B, and C. In accordance with 972 Quality Certificates between 1985 and 1988, 31.89 of the samples were rejected. The main reasons for rejection were innacuracies of net weight and drained weight and high moisture contents. Group B presented the smallest number of altered samples (27%); for Groups A and C these values were 33% and 44%, respectively. Our data lead to the conclusion that the QCS implemented by FAE is of paramount importance for an adequate quality control of foods provided to beneficiaries and for a good cost effectiveness of the school-feeding programme.

Brazil↗
PubMedDate not supplied

An improved high performance liquid chromatographic method for thiamin analysis in foods.

A high performance liquid chromatography (HPLC) procedure for the determination of thiamin in foods has been developed. Acid and enzymatic extracts of food samples were subjected to purification and chromatographic conditions which allowed the quantification of thiamin in foods with only a low content. Reverse-phase ion pair chromatography, using mixtures of sodium hexanesulfonate and sodium heptanesulfonate as counterions and detection at 254 nm, was employed. The lowest detection limit for thiamin was 0.5 ng/injection. Analyses of four samples of legumes and lyophilized meat and milk and the recovery for standard thiamin are given. Mean recovery values of extraction and purification procedure ranged over 97-98%.

Acetates↗
PubMed1985

Effect of color on judgments of food aroma and flavour intensity in young and elderly adults.

The hypothesis was tested that subjects' judgments of food aroma and flavour strength will be increasingly influenced by food color as the chemosensory differences between foods become less apparent. Elderly (n = 24) and young (n = 22) adults were presented with pairs of food samples and instructed to indicate which sample had the more intense aroma or flavor. The chemosensory discriminations varied in difficulty, and the color of the food pairs was also manipulated so that either they were similarly colored, or the color strength differed so that it was either positively or inversely correlated with flavour strength. Overall, the results failed to support the hypothesis that color alters the perceived intensity of the food aroma or flavor. There was a weak trend toward a greater number of errors among sample pairs that varied in color, especially when color strength was inversely related to flavor strength. Elderly and young adult groups did not differ in chemosensory ability or in their responses to food color differences, although the elderly adults were significantly more certain of the accuracy of their chemosensory judgments.

Adult↗
PubMed2003

A mass spectrometric validated high-performance liquid chromatography procedure for the determination of folates in foods.

A series of five food reference materials (RM) that had certified values of folate concentrations and five frozen food samples were analyzed for 5-methyltetrahydrofolic acid (5-MTHFA) and folic acid (FA) using a high-performance liquid chromatography (HPLC) method with fluorescence detection that was validated using an HPLC mass spectrometry (MS) method with electrospray ionization. Identical sample specimens were extracted and analyzed in triplicate using both instrumental methods, and a comparison was made of the mean values of 5-MTHFA and FA resulting from these determinations. The analytes were isolated on either a high capacity strong anion exchange solid phase extraction column (HPLC method) or a phenyl Bond Elut column (MS method) prior to analyses. For quantification of the analytes by MS, (13)C-labeled 5-MTHFA and FA were added to samples as internal standards prior to enzymatic digestion and conversion of the polyglutamate forms of 5-MTHFA to the monoglutamic acid. Quantification of FA and 5-MTHFA using the HPLC analysis was carried out using external standards. With the exception of one RM (pig liver), the values established for 5-MTHFA using these methods were highly comparable. In determining the variance associated with these two procedures, it was observed that the mean relative standard error for 5-MTHFA was 12 (range, 2-27%) and 11% (range, 5-25%) for the HPLC and MS methods, respectively. FA was detected in only three of the samples, and the values obtained for it by either method were similar. This is the first paper that describes a mass spectrometric method used in the validation of an HPLC determination of food folates across a wide range of sample matrixes. The comparable values for 5-MTHFA and FA suggest that HPLC analysis with fluorescent detection may be used to accurately quantify folates present in a variety of food matrixes.

Chromatography, High Pressure Liquid↗
PubMed1987

[Determination of purine compounds and purine bases in food].

The total purine content and the content of RNA, DNA, nucleotides, nucleosides and free purine bases has been determined in commercial raw food. After hydrolysing food samples with acid, the total purine content is enzymatically determined as uric acid. For the determination of the nucleic acid content, a method is chosen that allows for the analysis of the composition of nucleic acids. The amount of purine bound in nucleic acids and of purine bound in nucleotides, nucleosides and free bases is very different. The content of nucleic acids is especially high in the innards of veal, pork and beef. In these samples the quantity of purine bound in nucleotides, nucleosides and bases is very small. In trout and herring, however, more purine is bound in RNA and DNA. The same is true of roe, pork and beef muscle. Peas and beans have the lowest total purine content of all the samples examined.

Animals↗
PubMed2004

Development of new solid-phase microextraction fibers by sol-gel technology for the determination of organophosphorus pesticide multiresidues in food.

Allyloxy bisbenzo 16-crown-5 trimethoxysilane was first used as precursor to prepare the sol-gel-derived bisbenzo crown ether/hydroxyl-terminated silicone oil (OH-TSO) SPME coating. The coating procedure involving sol solution composition and conditioning process was presented. Compared with commercial SPME stationary phases, the new coatings showed higher extraction efficiency and therefore could provide higher sensitivity for organphosphorous pesticides (OPs). Limits of detection (LODs) were in the range of 0.003-1.0 ng/g for these OPs in food samples (honey, juice, orange and pakchoi). The optimal extraction conditions of the new coatings to OPs in these samples were investigated by adjusting extraction time, salt addition, extraction temperature, and dilution ratios of samples with distilled water by using SPME coupled with gas chromatography (GC)-flame photometric detection (FPD). The method was applied to determine the concentrations of OPs in real samples.

Chromatography, Gas↗
PubMed1991

Toxaphene: chemistry, biochemistry, toxicity and environmental fate.

The chemistry of toxaphene is now well developed; 20 isomers have been isolated and identified. The molecular weight and molecular formula are known for the remaining major components. The major metabolic degradation mechanisms for toxaphene in all organisms from bacteria to primates are now believed to the reductive dechlorination, reductive dehydrochlorination, and in some cases, oxidative dechlorination to produce hydroxyl derivatives, acids or ketones. Earlier reports that toxaphene was biodegradable were published before the advent of state-of-the-art analytical methodology which has permitted detection at levels in the range of ppb. Toxaphene residues have recently been documented throughout the biosphere as well as in human milk, even though its use was banned in 1982. This global persistence is against previous beliefs that toxaphene was easily biodegradable. During the last decade advances have been achieved in the selectivity, accuracy, and sensitivity of detection techniques so that the presence of toxaphene throughout the biosphere has been extensively documented. Through the use of GC/MS and electron capture GC, toxaphene can now be detected at ppb levels, making possible a more consistent and accurate assessment of the compound's presence in organisms as well as in soil, water, and ground water. Toxaphene residues have been detected in human populations, fish and wildlife, soil, water, and ground water as well as in food. An FDA Food Survey study found residues of toxaphene exceeding regulatory limits in only 1% of the 14,492 food samples. Toxaphene was reported to be among the most frequently occurring residues found in total dietary foods for the period 1982-84. It was found 48 times based on two food consumption surveys, a level higher than the frequency of DDT, DCPA, pentachloroaniline, and methoxychlor. Toxaphene has been detected in two large, pooled samples of human milk collected from mothers living in Uppsala and Stockholm at a concentration of 0.1 mg/kg of milk fat. Accumulation of toxaphene occurs in water in areas where the insecticide is in use, and it may be quite persistent. In some Canadian lakes it was found in toxic concentrations up to five yr after fish have been killed. Several studies have documented the presence of toxaphene in rain water, e.g. 9 ng/L in rain samples from Lake Michigan. It is now clear that toxaphene is a global pollutant like DDT, PCBs, and other organochlorines. Toxaphene is persistent in soils and lake sediments and has been found in fish, in the ringed seal, in rain water, and in human milk.(ABSTRACT TRUNCATED AT 400 WORDS)

Air Pollutants↗
PubMed1994

Estimates of trace element intakes in Chinese farmers.

Epidemiologic data on the average daily human dietary intake of the trace elements nickel, cadmium, molybdenum and silicon are scarce, worldwide, primarily because foods consumed vary widely over days and seasons. Available full year food allocation records for farmers in rural areas of China provide an unique opportunity to estimate dietary trace elements. In 1988, we measured the concentration of zinc, copper, iron, cadmium, nickel, molybdenum, silicon and selenium in different foods by using food samples collected from 232 villages (distributed among 21 communes). These measurements, combined with the food consumption information from existing food allocation records in each commune for an entire year, allowed us to estimate the average daily consumption of these trace elements by Chinese farmers. With one exception (an association of zinc and esophageal cancer), the variation of dietary trace elements did not show any association with mortality from several common diseases. The estimates for some of the dietary trace elements from some subpopulations were either less or more than current recommendations. No increases in mortality were found, however, from diseases normally associated with either dietary deficiencies or excesses of these elements.

Adult↗
PubMed1973

Polychlorinated biphenyl- and triphenyl-induced gastric mucosal hyperplasia in primates.

Polychlorinated biphenyl or triphenyl ingestion by subhuman primates for 3 months produced hyperplasia and dysplasia of the gastric mucosa. The concentration of the biphenyl within the experimental diet was less than an order of magnitude greater than that occurring in random food samples sold in the United States and less than levels which have occurred in food products as a result of industrial accidents. The increased cellularity, abnormal dysplastic growth pattern, and invasion of the adjacent tissue region indicate compromised gastric function and are suggestive of an eventual neoplastic transformation.

Administration, Oral↗
PubMed2001

Estimation of nutrient intake by the new version of Japanese food composition tables in comparison with that by the previous version.

This study was initiated to examine if the revision of the food composition tables from the 4th version to the 5th version has induced any substantial changes in nutrient intake estimation, and if so, in which nutrient item and to what extent. For this purpose, 24-hour duplicates of food samples were collected in 1996 to 1998 from 71 girl university students, together with food menus of the day. The nutrients in the duplicates were estimated by use of the 4th and the 5th version food composition tables in parallel, with supplements of other databases. The results of the estimation with the two databases were compared by Student's paired t-test. Compared with the results with the 4th version, the estimation utilizing the 5th version gave 3 to 8% increases in intakes of major nutrients including energy (except for protein), a 20% increase in vitamin A, and decreases in iron (-13%) and NaCl (-3%), whereas there were only small or essentially no changes in other minerals and vitamins. The largest increment in energy through the re-calculation came from the cereals (especially rice), and it was meats for the increment in lipid intake. The increment in vitamin A with the 5th version is primarily due to the re-evaluation of fruits and vegetables. The present observation suggests that care should be practiced in examining secular trends in nutrition when the basis of estimation is shifted from one database of the 4th version of food composition tables to another of the 5th version. Further study of a larger scale is apparently warranted to confirm the conclusions.

Adult↗
PubMed2003

Listeria monocytogenes: low levels equal low risk.

Because of the public health significance of L. monocytogenes, U.S. regulatory agencies established a policy whereby ready-to-eat foods contaminated with the organism at a detectable level are deemed adulterated. This "zero tolerance" policy, however, makes no distinction between foods contaminated at high and low levels. We have reported elsewhere that a survey of over 31,000 ready-to-eat retail food samples, representing eight product categories, showed an overall prevalence rate of 1.82% for these foods. In this study, we used the food survey data in combination with concurrent data regarding illness in the population consuming the foods, together with other variable factors, to derive a dose-response model. The confidence interval for prevalence was 1.68 to 1.97%. L. monocytogenes levels, which ranged from -2 to 6 log CFU/g, were adequately described by the distribution beta (0.29, 2.68, -1.69, 6.1). An exponential dose-response model was obtained, with an R value (essentially the probability of a single cell causing illness) of 1.76 x 10(-10) for the population at the highest risk. A microbial risk assessment based on the model shows that an alternative to the zero tolerance strategy has a greater risk reduction potential and suggests that a management strategy focusing on the concentration of L. monocytogenes rather than its presence alone may have a greater impact on the improvement of public health by facilitating the development of control measures to limit the maximum levels of L. monocytogenes in foods.

Colony Count, Microbial↗
PubMed2004

An outbreak of ammonia poisoning from chicken tenders served in a school lunch.

Although foodborne outbreaks of illness are relatively common, they are rarely caused by chemical agents. An outbreak of gastrointestinal illness occurred among students at two schools shortly after lunch was served. A cohort study, an environmental investigation, and microbiological and toxicological laboratory testing of food samples were performed. A case was defined as a student or teacher who ate food prepared in the kitchen at school A on 25 November 2002 (and served at schools A and B) and who later developed headache or symptoms of gastrointestinal tract irritation, with onset within 180 min of eating lunch. Among 312 persons interviewed, 157 persons became ill (attack rate = 49%; attack rate 41% for school A, 11% for school B). Onset of illness occurred within 60 min for 81% of cases; 91% of students reported that their chicken tenders smelled unusual. Eating chicken tenders that smelled unusual was associated with being a case (relative risk 9.2, 95% confidence interval 1.4 to 62.6, P < 0.05). Ammonia was detected in uncooked chicken tenders at levels as high as 2,468 ppm. The chicken had been contaminated during a warehouse leak of ammonia refrigerant. This outbreak of ammonia poisoning is only the second reported in food, and the first in a solid food. Heated chicken tenders contaminated with ammonia can cause acute illness within a short period of time.

Adolescent↗
PubMedDate not supplied

Use of the Microwave-Assisted Process in extraction of fat from meat, dairy, and egg products under atmospheric pressure conditions.

Fat from meat, dairy, and egg products was extracted by using Microwave-Assisted Process (MAP) technology under atmospheric pressure conditions. Fat content was determined gravimetrically after extraction with microwaves and organic solvents that are transparent to microwaves relative to the sample. (In situ hydrolysis was performed for dairy and egg products.) Fat from the food sample migrated completely to the extractant when samples were irradiated with focused microwave for a total of 3 min for meat products, 1 min for dairy products, and 4 min for egg products. Unlike current methods used for determining fat in meat products, the microwave-assisted method does not require a dry sample, because moisture in the sample (around 75%) enhances the efficiency of extraction. No preprocessing was required for meat samples other than homogenization, which is critical, as it is for other current methods. In addition to speed and ease of use, the features of this technology are low solvent consumption, low energy consumption, reproducibility, and recoveries similar to or even better than those of conventional extraction methods.

Atmospheric Pressure↗
PubMed2001

Automated simultaneous detection of low levels of listeriae and salmonellae in foods.

Salmonella spp. and Listeria monocytogenes continue to be major pathogens of concern to food processors. However, routine screening of food samples to detect these pathogens is generally labor intensive and costly. Automated optical procedures for the detection of salmonellae and listeriae in foods were developed in our laboratory. In the present study we report their adaptation to a simultaneous recovery and detection procedure. Milk, shell eggs, fresh and ready-to-eat (RTE) meats or raw chicken contaminated with a combination of sub-lethally injured salmonellae and listeriae (10-50 cells each) were incubated for 6 h at 35 degrees C in modified universal pre-enrichment broth (MUPB). Volumes (4 ml) were then transferred to vials containing selective liquid media for these pathogens (4 ml), and incubated overnight at 35 degrees C in a BioSys instrument. The presence of the pathogens was identified by a black coloration of the media and a sharp drop in light transmittance caused by hydrogen sulfide production (Salmonella organisms), or esculin hydrolysis (Listeria organisms). There was no difference in the detection time of salmonellae when incubated alone or with listeriae, but listeriae grew at a slower rate in the presence of salmonellae, resulting in a delay of < or = 1 h in their detection. Overall, the detection of 10-50 salmonellae and 10-50 listeriae in 25 g of the tested foods required a total of 24 h. Confirmation of the pathogens by PCR-based assay (6 h) was completed the following day directly from positive vials, requiring a total of < or = 30 h for detection and confirmation. Negative samples required no confirmation. The testing system was confirmed in 70 naturally contaminated foods.

Animals↗