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At least 217 records · Page 12Linked to original sources
PubMedDate not supplied

Exposure to cadmium from foods, estimated by analysis and calculation--comparison of the methods.

Cadmium intake of 40 middle-aged Finnish men was determined both by calculation based on computer files and by analysis of duplicate portions. A significant difference was observed between intake estimates of the two methods. The average calculated cadmium intake was 15.8 micrograms/day compared to the 8.2 micrograms/day obtained by analysis. Factors causing the difference between the methods and affecting the comparability are: (i) expression of concentrations below the detection limit; (ii) the calculation is based on the analysis of foods being only washed and peeled whereas duplicate portions are normally processed; (iii) when duplicate portions are prepared using non-representative lots or brands of food, their cadmium content differs from average values used in calculation; (iv) the level of cadmium content in duplicate portion samples is very low affecting the accuracy of the results. The analytical level of cadmium during the analysis of duplicate portions was somewhat lower as compared to the analysis on which the food composition file and the calculation is based. It seems that the complicating factors identified in the present study potentially affect the reliability and comparability of studies of trace element intakes. Therefore one has to be careful when comparing intake estimates derived independently or by different methods.

Cadmium↗
PubMedDate not supplied

Problems of official methods and new techniques for analysis of foods and feeds for vitamin A.

The official methods for measuring vitamin A and carotene in foods and feeds have evolved over several decades. New procedures are needed to permit the use of modern analytical techniques such as liquid chromatography (LC), and to expand the application of official methods to a wide variety of foods. Recent improvements in methodology are reviewed. Emphasis is often placed on the separations achieved by LC, but all factors that affect quantitation, such as sampling, preparation of standards, and protection of the vitamin against oxidation, must be considered in the development of new methods. Many approaches to analysis are possible because of the versatility of LC but not all of them can be used in official methods. Methods for milk, margarine, and feeds can be prepared now for collaborative assays. Although straightforward methods can be developed for the measurement of beta-carotene in certain foods, a full examination of provitamins will probably continue to require a flexible approach and special expertise.

Animal Feed↗
PubMed1995

Cancer risk of heterocyclic amines in cooked foods: an analysis and implications for research.

Heterocyclic amines (HAs) are formed as pyrolysis products during the cooking of meats/fish. These substances are potent mutagens in the Ames/Salmonella assay and are also carcinogens in laboratory animals. In order to assess the magnitude of the cancer risk posed by their presence in the US diet, we estimated the average intakes of HAs, based on analyses of the concentrations of HAs in cooked foods and data from a dietary survey of the US population and quantified the cancer potencies of the individual compounds using dose-response data from animal bioassays. Measured concentrations of HAs in cooked foods were taken from a major review of the open literature. Only those concentrations that were associated with normal cooking conditions were chosen for use in estimating dietary intakes. The average consumption of HA-bearing foods was determined by analyzing statistically the intakes of 3563 individuals who provided 3 day dietary records in a USDA sponsored random survey of the US population during 1989. Dietary intakes of the five principal HAs in descending order were 2-amino-1-methyl-6-phenylimidazo [4,5-b]pyridine (PhIP) > 2-amino-9H-pyrido[2,3-b]indole (A alpha C) > 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx) > 2-amino-3,4,8-trimethylimidazo[4,5-f]quinoxaline (DiMeIQx) > 2-amino-3-methylimidazo[4,5-f]quinoline (IQ). The carcinogenic potencies, in contrast, were almost the reverse order: IQ > DiMeIQx > MeIQx > PhIP > A alpha C. An upper-bound estimate of the incremental cancer risk is 1.1 x 10(-4), using cancer potencies based on a body surface area basis. Nearly half (46%) of the incremental risk was due to ingestion of PhIP. Consumption of meat and fish products contributed the most (approximately 80%) to total risk.

Amines↗
PubMed1994

Use of a programmed temperature vaporizer for off-line SFE/GC analysis in food composition studies.

A simple procedure is proposed for off-line supercritical fluid extraction and capillary gas chromatography using a programmed temperature vaporizer (PTV) injector. The independent control of flow and temperature of the supercritical fluid is achieved by means of a variable restrictor (i.e., nozzle). The described system combines some advantages of the on-line coupling SFE/GC (high sensitivity and reduced sample handling) and the off-line approach (simpler performance and depressurization outside the chromatographic column). The proposed procedure and the solvent recovery method used to collect the extracted analytes are applied to the analysis of the essential oil obtained from Rosmarinus officinalis L. Also, a comparative study with the extracts obtained by using the simultaneous distillation extraction technique (SDE) is presented.

Chromatography, Gas↗
PubMed1985

[The mycotoxin problem: results of food monitoring].

From more than 67 reports on food analysis of aflatoxin, patulin and ochratoxin, the results between 1980-1983 were evaluated and tabulated. The following number of samples were investigated: aflatoxin 15 550, patulin 356 and ochratoxin 437. The amount of Control samples for aflatoxins has reached such a high number that rapid methods for sampling, preparation and analysis are necessary. Out of the many foods investigated, only 9-10 might really be jeopardized, whereby the tendency of contamination-reduction was observed.

Animals↗
PubMed1978

Gas-liquid chromatography of triazine herbicides as heptafluorobutyryl derivatives and some applications to analysis in foods.

The heptafluorobutyryl (HFB) derivatives of ten triazine herbicides were prepared by reacting the pesticides with heptafluorobutyric anhydride in benzene, in the presence of trimethylamine or pyridine as catalyst. The reactions produced mainly the mono-HFB products while some of the herbicides had small quantities of the di-HFB derivatives present. The derivatives were 300 fold to several thousand fold more sensitive to electron-capture detection than the underivatized triazines. They also were 5-10 fold more sensitive than the parents by electrolytic conductivity detection in the halogen mode while they were of similar sensitivity with the same detector in the nitrogen mode. The derivatives eluted in the same general order as the parent triazines on stationary phases of OV-1, OV-101, OV-101/QF-1, and OV-210. This method was successfully applied to the analysis of potatoes, peas and tomatoes spiked with various triazines at levels of 0.13-0.86 ppm.

Chromatography, Gas↗
PubMed1991

[Analysis of food and feed by partial sequences of characteristic protein components (carrier peptides). 1. Isolation and structural determination of wheat-specific peptides from chymotryptic hydrolysates of gliadin].

Gliadins from wheat flour were extracted with 70% aqueous ethanol and hydrolyzed with alpha-chymotrypsin. Eight peptides, which seemed adequate as specific indicators for wheat ('Leitpeptide'), were isolated from the partial hydrolysate by RP-HPLC and analyzed for their amino acid sequences. Six of them were attributed to gliadin sequences already described in the literature, whereas two peptides represented novel sequence variations. Parallel investigations on the corresponding partial hydrolysates of prolamins from rye, barley, oats and maize showed that the isolated peptides were specific for wheat. A search in the protein data bank MIPS X (as of January 23 rd, 1990) did not produce any identical sequence. The 'Leitpeptide' allows the sensitive and specific recognition of wheat in complex and heated systems by RP-HPLC. They could be used also as the basis for immunochemical tests which would be convenient in routine analysis.

Amino Acid Sequence↗
PubMedDate not supplied

Assessment of human exposure to chemical contaminants in foods.

One of the most important factors in assessing risk to human health from potentially harmful chemicals in foods is the availability of good data on the exposure of the public to such substances. The means of acquiring these data generally involves monitoring programmes using appropriate sampling procedures and reliable analytical methods for measuring the compounds of concern in a variety of substrates. Two approaches are generally employed: a biological monitoring programme which measures substances in human fluids and tissues, and a food analysis monitoring programme, preferably a total diet study, wherein food is prepared for consumption prior to analysis. The choice of approach to use and chemicals to monitor depend on the situation within a particular country. The analysis of food has the advantage of short term impact since problems can be identified relatively quickly and control measures established. Biological monitoring on the other hand tends to indicate both accumulated and current exposure from all sources, including air, water and food. In Canada both approaches have been used for a number of years with major surveys of human milk and adipose tissue, and the total diet study, being conducted approximately every five years. Details of these programmes together with some of the pertinent findings are presented.

Animals↗
PubMed1986

Cluster analysis of food consumption patterns of older Americans.

This study uses data from the 1977-78 Nationwide Food Consumption Survey (NFCS) to develop a classification scheme for differentiating individuals into groups that have similar patterns of food consumption. The article examines the nutritional adequacy of those food patterns and identifies the socioeconomic factors associated with each pattern. Cluster analysis is used to identify the food consumption patterns of a nationally representative sample of persons aged 65 through 74 years. The results indicate that the food patterns of older persons can be well categorized as light eaters, heavy eaters, or consumers of large amounts of alcoholic beverages, salty snack products, animal fat products, legumes, or sweets and desserts. Following those different food patterns leads to noteworthy differences in nutrient intakes. Ethnic group membership and residence status are found to be the most important socioeconomic factors associated with differences in the food patterns followed.

Aged↗
PubMed1986

Tannin analysis of food products.

Phenolic substances occur primarily in fruits and vegetables and in the seeds of certain pigmented cultivars of sorghum, millets, and legumes. One of the major difficulties encountered in polyphenol research is the lack of a standard quantitative method for the analysis of phenolics that would be suitable for a wide range of seeds, forage crops, and food products and under a variety of experimental conditions. Some methods measure "total phenol", which may not be a true index of the nutritional quality of foods and thus does not distinguish polyphenols of nutritional concern from other low-molecular-weight phenols that also occur naturally in these products. Tannic acid (a hydrolyzable gallotannin) is commonly used as a "reference standard", but this may be a questionable practice since its biological properties differ from those of tannins of flavonoid origin. Polyphenols of cereals and legumes are predominantly of the latter type. Also, commercially available tannic acid has been shown to be a mixture of four phenolic compounds, the relative proportions of which vary with the samples. Thus, the choice of a suitable standard for tannin analysis is also important. The quantitative extraction of the condensed tannins from plant tissue is always difficult, since it may be complexed to a carbohydrate or protein matrix which could be quite insoluble due to a high degree of polymerization. The literature on tannin methodology is diverse and at times conflicting. Currently available methods for tannin analysis range from simple colorimetric, UV spectrophotometric, chromatographic, and enzymic to more sophisticated and expensive nuclear magnetic resonance (NMR) techniques. None of these methods of analyses is completely satisfactory nor can it be applied to different food products with the same degree of success. This review covers physical and chemical methods for tannin analysis of different food products, the problems in analysis and interpretation of data, and future research needs in this area.

Benzaldehydes↗
PubMedDate not supplied

Emergence of rapid methods for identifying microbial pathogens in foods.

Because of the complexities of food analysis, conventional microbiological methods must use time-consuming enrichment steps for culturing viable bacterial cells in foods. With rapid advancements in technology, however, numerous so-called rapid methods were introduced into the field of food microbiology in a relatively short time. Culture methods that were once used to obtain profiles for bacterial identification were simplified or automated. Many microbiological procedures were also streamlined or automated to reduce assay time, labor, and materials. Nucleic acid-based assays are used to identify gene sequences in foodborne bacteria, and antibody-based assays are used in numerous formats to detect bacterial pathogens and toxins in foods. The difficulties of analyzing food, however, remain challenging, and rapid methods need to be evaluated thoroughly before they are used for routine food analysis.

Food Microbiology↗
PubMed1985

[High resolution liquid chromatography (HPLC) analysis of the vitamin A and beta-carotene content of heat-treated precooked food].

Vitamin A and beta-carotene contents in 22 samples of precooked foods were determined before and after the use of various reheating techniques. The method used includes saponification by boiling with etOH and KOH, diethyl ether extraction in the presence of BHT as antioxidant, drying under controlled conditions and detection of the vitamins by HPLC. The results suggest good applicability of the procedure to food analysis and show how reheating processes can have a significant influence on the vitamin content of such foodstuffs.

Carotenoids↗
PubMed2004

Application of antibodies for the identification of polysaccharide gum additives in processed foods.

Anti-carbohydrate antibodies with specificities for polysaccharide gums were isolated from the serum of rabbits that were immunized with a solution of the gums and Freund's complete adjuvant. The primary objective was to test an immunological method for the detection of the polysaccharide gums as additives to processed foods. Analysis involved the extraction of food with phosphate buffer and the testing of the extract for a reaction with anti-gum antibodies by the agar diffusion method. Reaction by a specific gum with the homologous antibodies establishes the presence of the gum in the food. The method is a novel application of antibodies. The antibody method is highly specific for a gum and thus possesses advantages over other methods of analysis for polysaccharide gums as additives in processed foods.

Animals↗
PubMed2005

Meta-analysis of food safety information based on a combination of a relational database and a predictive modeling tool.

The management of microbial risk in food products requires the ability to predict growth kinetics of pathogenic microorganisms in the event of contamination and growth initiation. Useful data for assessing these issues may be found in the literature or from experimental results. However, the large number and variety of data make further development difficult. Statistical techniques, such as meta-analysis, are then useful to realize synthesis of a set of distinct but similar experiences. Moreover, predictive modeling tools can be employed to complete the analysis and help the food safety manager to interpret the data. In this article, a protocol to perform a meta-analysis of the outcome of a relational database, associated with quantitative microbiology models, is presented. The methodology is illustrated with the effect of temperature on pathogenic Escherichia coli and Listeria monocytogenes, growing in culture medium, beef meat, and milk products. Using a database and predictive models, simulations of growth in a given product subjected to various temperature scenarios can be produced. It is then possible to compare food products for a given microorganism, according to its growth ability in these products, and to compare the behavior of bacteria in a given foodstuff. These results can assist decisions for a variety of questions on food safety.

Databases, Factual↗
PubMed1993

Computerized analysis of food records: role of coding and food composition database.

Reported dietary intake records of 30 subjects (26 men and 4 women) were analysed by three different centres using their own computerized nutrient database systems. The agreement between systems was evaluated by different statistical criteria (the correlation coefficient, the mean difference and the proportion of individuals placed in the same thirds of distribution). Significant differences between the three systems were found in the calculation of alcohol, polyunsaturated fatty acids, saturated fatty acids, linoleic acid, linolenic acid, cholesterol, magnesium, sodium and water. To ascertain the extent of mean differences that could be attributed to the coding process or to the database used, coding forms of each centre were forwarded to the other two centres. Analysis of variance showed that differences in the data obtained by the three systems were mainly due to the food composition database used.

Analysis of Variance↗