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PubMed1980

Quality assurance in the analysis of foods and trace constituents.

An examination of the results of over 50 interlaboratory collaborative studies conducted by the AOAC on various commodities for numerous analytes shows a relationship between the mean coefficient of variation (CV), expressed as powers of 2, with the mean concentration measured, expressed as powers of 10, independent of the determinative method. Some typical CV values are: drug formulations at a 1% concentration, 2%; sulfonamides in feeds at a 0.01% concentration, 4%; pesticide residues and toxic elements, 10(-6) (1 ppm), 16%; and aflatoxins 10(-8) (10 ppb), 32%. Analytical work at trace levels must be constantly monitored through analysis of reference materials and surrogate samples, and by independent replication.

Aflatoxins↗
PubMed1980

Analysis of foods for lead, cadmium, copper, zinc, arsenic, and selenium, using closed system sample digestion: collaborative study.

A method for the determination of cadmium, lead, copper, arsenic, selenium, and zinc is presented. This method involves digesting a food sample with nitric acid under pressure and using aliquots of the solution for analysis by suitable techniques. Cadmium, lead, and copper are determined by anodic stripping voltammetry (ASV) after heating with equimolar sodium nitrate/potassium nitrate; arsenic and selenium are determined by atomic absorption spectrophotometry (AAS) after generation of their respective hydrides; zinc is determined by conventional AAS. The combined recoveries and reproducibilities (CVR) of the collaborative study on this multi-element analysis are: Cd, 89.14 (17.65) at 0.10-1.0 microgram/g; Zn, 96,53 (5.59) at 16.7 and 66.7 microgram/g; As, 99.50 (17.02) at 0.5 and 2.0 microgram/g; Se, 95.17 (16.52) at 0.5 and 2.0 microgram/g; Pb, 92.57 (15.22) at 0.3-3.0 microgram/g; Cu, 108.39 (18.30) at 1.0-10.0 microgram/g. The method has been adopted as official first action for cadmium, lead, arsenic, selenium, and zinc.

Arsenic↗
PubMed2006

Solid-phase microextraction in the analysis of food taints and off-flavors.

Selected food taints and off flavors, for which solid phase microextraction (SPME) has been used as a method for volatiles isolation, are the subject of review. Compounds responsible for musty and earthy odor off-flavors and taints in foods are discussed. This group contains haloanisoles, geosmin, and methylisoborneol. Chlorophenols are discussed as precursors of chloroanisoles and compounds impairing the flavor of food. Also described are volatile phenolic compounds responsible for medicinal off flavors, mainly ethyl phenols and vinyl phenols. Sulfur compounds that contribute to off-flavor are also discussed. Finally, a group of volatile compounds being the products of lipid oxidation are summarized. A short review of the formation, occurrence, and information on odor properties of all of these groups of compounds is given. Examples of SPME use for the analysis of compounds belonging to all described groups are shown. Elaboration of method parameters, fiber selection, experimental conditions, and quantitation of compounds are subjects of interest. Also, applications of SPME as a method for introduction of volatiles in mechanical olfaction technologies are shortly outlined.

Food Analysis↗
PubMed1991

Automated aflatoxin analysis of foods and animal feeds using immunoaffinity column clean-up and high-performance liquid chromatographic determination.

A commercially available system is described for the fully automated clean-up and high-performance liquid chromatographic (HPLC) analysis of aflatoxins in foods and animal feeds. The system marketed primarily for handling solid-phase extraction columns has modified software to facilitate use with immunoaffinity columns. Sample extract clean-up followed by injection onto an HPLC column with post-column iodination and fluorescence detection is carried out completely unattended. A coefficient of variation of 5.1% for aflatoxin B1 analysis was obtained, and the accuracy of the system was demonstrated by the analysis of peanut butter certified reference material.

Aflatoxins↗
PubMedDate not supplied

Sulphite analysis of food ingredients: false positive responses with butter flavourings in the optimized Monier-Williams method.

The analysis of commercial butter flavouring materials for sulphite by the optimized Monier-Williams method revealed detectable levels of apparent sulphur dioxide (1810 ppm for butter oil, 5760 ppm for butter flavour, and 14.5 ppm for butter derivative) even though the manufacturers claimed that no sulphites were used in processing these ingredients. The presence of volatile fatty acids in these ingredients may explain the anomalous results. Volatile fatty acids were found to interfere with the optimized Monier-Williams method for sulphite determination, detectable levels of titratable acid being found in the hydrogen peroxide trap with amounts of volatile fatty acids as low as 0.3 g. The levels of volatile fatty acids in foods would not be predicted to cause significant interference in the analysis of sulphite residues by the optimized Monier-Williams method. However, this analytical procedure is not recommended for the analysis of sulphite residues in food ingredients containing substantial amounts of volatile fatty acids. Alternative methods for the detection of residual sulphite, such as the sulphite oxidase assay and the colorimetric para-rosaniline method, are not subject to interference by volatile fatty acids.

Butter↗
PubMed1998

The star plot: an alternative display method for multivariate data in the analysis of food and drugs.

The star plot (SP) is a method of displaying multivariate data. It can be used to display data with more than two variables. Combined with principal component analysis (PCA), more than two PCs can be displayed in one plane. Different variants of this method are applied to an atomic absorption spectrometry (AAS) data set and to three near infra-red (NIR) spectral data sets. The results show that SP offers an easy way of visualising the multivariate data for food and drugs in a plane, and it is able to help the analyst to identify and to detect different qualities of food and drug composition. Moreover, when an object is added or removed, the PC's must be computed all over again, which is not the case for the SP-plot. The application of SP to the examples presented in the text suggests that the SP approach can be applied as an alternative method for displaying multivariate chemometric data in place of PCA or, to improve visualisation of the results already obtained with PCA.

Bread↗
PubMed1995

The costs of eating: a behavioral economic analysis of food refusal.

Behavioral economic concepts were applied to the analysis and treatment of pediatric feeding disorders in a clinical setting. In Experiment 1, children who chronically refused food were presented with varying amounts of food on a spoon (empty, dipped, quarter, half, and level). Each child exhibited a different but orderly demand function of response (acceptance, expulsion, and mouth clean) by cost (increasing spoon volume) for a constant pay-off of toys and social interaction. In Experiment 2, physical guidance or nonremoval of the spoon for food refusal was initiated at the smallest spoon volume with low levels of acceptance, and was subsequently introduced at the largest spoon volume with moderate levels of acceptance. Treatment was effective in increasing acceptance, and these effects generalized hierarchically across untargeted spoon volumes. The results of both studies provide preliminary support that increasing spoon volume can be equated conceptually with increasing response effort, and that the change from differential reinforcement to physical guidance or nonremoval of the spoon appears to have altered the elasticity of each child's demand function.

Behavior Therapy↗
PubMed2003

Occurrence of Yersinia enterocolitica and Campylobacter spp. in slaughter pigs and consequences for meat inspection, slaughtering, and dressing procedures.

The purpose of the present investigation was to assess the occurrence of Yersinia enterocolitica and Campylobacter spp. in the lymphoid tissues and intestinal tract in pigs and the risk for contamination during the compulsory meat inspection procedures and the procedures during slaughtering and dressing. Another objective of the investigation was to compare traditional isolation methods, the use of a polymerase chain reaction (PCR) method (BUGS'n BEADS bacterial DNA isolation kit) and an ELISA method (VIDAS CAM) as tools in risk management in the slaughterhouse. The results indicate that the compulsory procedure for the incision of the submaxillary lymph nodes represents a cross-contamination risk for virulent Yersinia. In the screening of 97 animals in 1999, 5.2% of the samples were positive, and by the sampling of 24 samples in 2000-2001, 12.5% of the samples were positive. In the last case, Y. enterocolitica O:3 was found in the kidney region in one of the subsequent carcasses that was only touched by the meat inspection personnel before sampling. In addition, incision of the mesenteric lymph nodes might represent a cross-contamination risk since 8.3% of the samples were positive. The association between antibody titres and the occurrence of virulent yersiniae in the tonsils (21-18) was striking, with virulent yersiniae found in the tonsils in most pigs with high titres. The contents of the stomach, ileum, caecum, and colon also represent contamination risks for Y. enterocolitica O:3 if the slaughterhouse personnel cuts into the viscera with their knives by accident; the frequency of virulent Yersinia varied from 4.2% to 16.7% within these sections. Campylobacter was detected in the gastrointestinal tract of all pigs, and the high contamination of tonsils (66.7%) and intestinal tract (100%) might represent an occupational health hazard. There was no statistical difference between the traditional method for isolation of Y. enterocolitica [International Organization for Standardization, 1994. Microbiology-General Guidance for the Detection of Presumptive Pathogenic Yersinia enterocolitica (ISO 10273). International Organization for Standardization, Genève, Switzerland (16 pp.)] and the BUGS'n BEADS detection method for virulent Y. enterocolitica. Likewise, there was no statistical difference between the traditional method for isolation of Campylobacter spp. [Nordic Committee on Food Analysis, 1990. Campylobacter jejuni/coli. Detection in Food. Method No. 119, 2nd ed. Nordic Committee on Food Analysis, Esbo (7 pp.)] and the BUGS'n BEADS detection method or the VIDAS CAM method for detection of Campylobacter spp.

Abattoirs↗
PubMed1998

Trienzyme treatment for food folate analysis: optimal pH and incubation time for alpha-amylase and protease treatment.

Recent reports have indicated that trienzyme treatment before folate determination is essential to obtain the proper folate content in foods. Trienzyme treatment is performed by using alpha-amylase and protease for folate extraction from carbohydrate and protein matrices, and folate conjugase for the hydrolysis of polyglutamyl folates. We evaluated the conditions of pH and incubation time for the treatment with alpha-amylase and protease. Four food items, including fresh beef, white bread, cow's milk, and fresh spinach, were selected for this investigation. We found that optimal pHs for alpha-amylase treatment of beef and cow's milk were 7.0 and 5.0, respectively, whereas those for white bread and spinach were not distinctive at pHs from 2.0 to 7.0. The optimal incubation time for alpha-amylase was 4 h for fresh beef and cow's milk, whereas no distinctive optimal incubation period was found for white bread and fresh spinach. Our data indicate that the conditions for enzyme treatments vary depending on food items. Trienzyme treatment resulted in an increase of more than 50% in the mean folate content over folate conjugase treatment alone. It is necessary to treat food samples with not only traditional folate conjugase, but also with alpha-amylase and protease before folate determination to obtain the actual folate content.

Animals↗
PubMed1991

The use of stable isotopes for food web analysis.

General aspects in isotope biogeochemistry was summarized with emphasis on delta 15N and delta 13C contents in plants and animals in natural ecosystems. In the estuary, the variation of isotope ratios were principally governed by the mixing of land-derived organic matter, marine phytoplankton, and seagrasses. A clear cut linear relationship between animal delta 15N and its trophic level was obtained in the Antarctic food chain system. Several current efforts to use the stable isotopes for food web analysis were demonstrated for some terrestrial and marine systems as well as human food web.

Animals↗
PubMedDate not supplied

Total N-nitroso group analysis of foods. II. Further studies on the precision and sensitivity of the assay.

The total N-nitroso content of foods can be measured by chemical denitrosation with hydrogen bromide and chemiluminescence detection of the cleaved nitric oxide radical. The denitrosation reagent itself causes a significant detector response which has limited the application of the technique to trace analysis. A procedure is described in which the errors associated with this interference are minimized. Application of this method to the trace analysis of aqueous and solid samples is reported together with an investigation of the effects of sample size on the accuracy and sensitivity of the assay as applied to aqueous analytes. The magnitude and significance of the false-positive response from nitrate is discussed in relation to the analysis of cured meats.

Animals↗
PubMed2004

An application of meta-analysis in food safety consumer research to evaluate consumer behaviors and practices.

Meta-analysis provides a structured method for combining results from several studies and accounting for and differentiating between study variables. Numerous food safety consumer research studies often focus on specific behaviors among different subpopulations but fail to provide a holistic picture of consumer behavior. Combining information from several studies provides a broader understanding of differences and trends among demographic subpopulations, and thus, helps in developing effective risk communication messages. In the illustrated example, raw/undercooked ground beef consumption and hygienic practices were evaluated according to gender, ethnicity, and age. Percentages of people engaging in each of the above behaviors (referred to as effect sizes) were combined using weighted averages of these percentages. Several measures, including sampling errors, random variance between studies, sample sizes of studies, and homogeneity of findings across studies, were used in the meta-analysis. The statistical significance of differences in behaviors across demographic segments was evaluated using analysis of variance. The meta-analysis identified considerable variability in effect sizes for raw/undercooked ground beef consumption and poor hygienic practices. More males, African Americans, and adults between 30 and 54 years (mid-age) consumed raw/undercooked ground beef than other demographic segments. Males, Caucasians, and Hispanics and young adults between 18 and 29 years were more likely to engage in poor hygienic practices. Compared to traditional qualitative review methods, meta-analysis quantitatively accounts for interstudy differences, allows greater consideration of data from studies with smaller sample sizes, and offers ease of analysis as newer data become available, and thus, merits consideration for its application in food safety consumer research.

Adult↗
PubMed1987

A computerized quantitative food frequency analysis for the clinical setting: use in documentation and counseling.

Documentation of nutrition counseling effectiveness is essential to reinforce its value in an era of escalating health care costs. Counseling effectiveness can be determined definitively only if dietary assessment is made both before and after intervention. Unfortunately, methods currently available have drawbacks that limit feasibility of routine use. A directly computer-readable Quantitative Food Frequency Analysis method, which eliminates the need for manual data entry, has been developed and instituted at the University of Southern California School of Medicine, Los Angeles, for outpatient counseling. A 1-hour interview, focusing upon "usual" intake, is conducted using pictorial menus for food items. Feedback is available to the patient and health care team immediately. The data base is derived from the National Heart, Lung, and Blood Institute Food Table; the intake of 61 nutrients, including 23 fatty acids, is computed. The computer printout consists of four components: a summary; an alert for foods high in fat, cholesterol, sucrose, alcohol, and/or sodium; a listing of all foods consumed by frequency, accompanied by their nutrient contribution to daily intake; and a bar graph relating current nutrient intake to recommended levels. This document serves as a counseling tool and can support claims for third-party payment.

Computers↗