Food fraud and the perceived integrity of European food imports into China.

BACKGROUND/AIMS: Persistent incidents of food fraud in China have resulted in low levels of consumer trust in the authenticity and safety of food that is domestically produced. We examined the relationship between the concerns of Chinese consumers regarding food fraud, and the role that demonstrating authenticity may play in relieving those concerns. METHODS: A two-stage mixed method design research design was adopted. First, qualitative research (focus groups n = 7) was conducted in three Chinese cities, Beijing, Guangzhou and Chengdu to explore concerns held by Chinese consumers in relation to food fraud. A subsequent quantitative survey (n = 850) tested hypotheses derived from the qualitative research and theoretical literature regarding the relationship between attitudinal measures (including risk perceptions, social trust, and perceptions of benefit associated with demonstrating authenticity), and behavioral intention to purchase "authentic" European products using structural equation modelling. RESULTS: Chinese consumers perceive food fraud to be a hazard that represents a food safety risk. Food hazard concern was identified to be geographically influenced. Consumers in Chengdu (tier 2 city) possessed higher levels of hazard concern compared to consumers in Beijing and Guangzhou (tier 1). Structural trust (i.e. trust in actors and the governance of the food supply chain) was not a significant predictor of attitude and intention to purchase authenticated food products. Consumers were shown to have developed 'risk-relieving' strategies to compensate for the lack of trust in Chinese food and the dissonance experienced as a consequence of food fraud. Indexical and iconic authenticity cues provided by food manufacturers and regulators were important elements of product evaluations, although geographical differences in their perceived importance were observed. CONCLUSIONS: Targeted communication of authenticity assurance measures, including; regulations; enforcement; product testing; and actions taken by industry may improve Chinese consumer trust in the domestic food supply chain and reduce consumer concerns regarding the food safety risks associated with food fraud. To support product differentiation and retain prestige, European food manufactures operating within the Chinese market should recognise regional disparities in consumer risk perceptions regarding food fraud and the importance of personal risk mitigation strategies adopted by Chinese consumers to support the identification of authentic products.

Coherent optical control of the spin of a single hole in an InAs/GaAs quantum dot.

We demonstrate coherent optical control of a single hole spin confined to an InAs/GaAs quantum dot. A superposition of hole-spin states is created by fast (10-100 ps) dissociation of a spin-polarized electron-hole pair. Full control of the hole spin is achieved by combining coherent rotations about two axes: Larmor precession of the hole spin about an external Voigt geometry magnetic field, and rotation about the optical axis due to the geometric phase shift induced by a picosecond laser pulse resonant with the hole-trion transition.

Population inversion in a single InGaAs quantum dot using the method of adiabatic rapid passage.

Preparation of a specific quantum state is a required step for a variety of proposed quantum applications. We report an experimental demonstration of optical quantum state inversion in a single semiconductor quantum dot using adiabatic rapid passage. This method is insensitive to variation in the optical coupling in contrast with earlier work based on Rabi oscillations. We show that when the pulse power exceeds a threshold for inversion, the final state is independent of power. This provides a new tool for preparing quantum states in semiconductor dots and has a wide range of potential uses.

Development and single-laboratory validation of an HPLC method for the determination of cyclamate sweetener in foodstuffs.

A method for the determination of cyclamate has been developed and single-laboratory validated for a range of foodstuffs including carbonated and fruit-juice drinks, fruit preserves, spreads, and dairy desserts. The method uses the peroxide oxidation of cyclamate to cyclohexylamine followed by derivatization with trinitrobenzenesulfonic acid and analysis by a modified reversed-phase high-performance liquid chromatography-ultraviolet light (HPLC-UV). Cycloheptylamine is used as an internal standard. The limits of detection were in the range 1-20 mg kg(-1) and the analysis was linear up to 1300 mg kg(-1) cyclamic acid in foods and up to 67 mg l(-1) in beverages. Analytical recovery was between 82% and 123%, and results were recovery corrected. Precision was within experimentally predicted levels for all of the matrices tested and Horrat values for the combined standard uncertainty associated with the measurement of cyclamate between 0.4 (water-based drinks) and 1.7 (spreads). The method was used successfully to test three soft drink samples for homogeneity before analytical performance assessment. The method is recommended for use in monitoring compliance and for formal testing by collaborative trial.

Structure determination of a new protein from backbone-centered NMR data and NMR-assisted structure prediction.

Targeting of proteins for structure determination in structural genomic programs often includes the use of threading and fold recognition methods to exclude proteins belonging to well-populated fold families, but such methods can still fail to recognize preexisting folds. The authors illustrate here a method in which limited amounts of structural data are used to improve an initial homology search and the data are subsequently used to produce a structure by data-constrained refinement of an identified structural template. The data used are primarily NMR-based residual dipolar couplings, but they also include additional chemical shift and backbone-nuclear Overhauser effect data. Using this methodology, a backbone structure was efficiently produced for a 10 kDa protein (PF1455) from Pyrococcus furiosus. Its relationship to existing structures and its probable function are discussed.

DON calibrant: Towards the production of certified B-trichothecene calibrants.

Within an EC-funded project calibrants with certified concentrations of Deoxynivalenol (DON), 3-Acetyl-Deoxynivalenol (3-Ac-DON), 15-Acetyl-Deoxynivalenol (15-Ac-DON) and Nivalenol (NIV) in acetonitrile have been produced. So far the project has led to improved isolation and purification of the solid toxins fromFusarium cultures. In addition, conditions for the production, ampouling and transport of the toxin solutions have been optimised. Further investigations should lead to knowledge about storage conditions and internationally accepted molar absorption coefficients for DON, 3-Ac-DON, 15-Ac-DON and NIV in acetonitrile. The intercomparison study which is currently carried out will also help to support knowledge and experience exchange between laboratories in the field ofFusarium mycotoxin analysis.

High-throughput production of Pyrococcus furiosus proteins: considerations for metalloproteins.

Free-living prokaryotic organisms contain all of the proteins required for the basic biochemical processes of life. As part of the Southeastern Collaboratory for Structural Genomics (SECSG), Pyrococcus furiosus is being used as a model system for developing a high-throughput protein expression and purification protocol. Its 1.9 million basepair genome encodes approximately 2200 putative proteins, less than 25% of which show similarity to any structurally characterized protein in the Protein Data Bank. The overall goal of the structural genomics initiative is to determine, in total, all existing protein folds. The immediate objective of this work is to obtain recombinant forms of all P. furiosus proteins in their functional states for structural determination. Proteins successfully produced by overexpression in another organism such as the bacterium Escherichia coli typically contain a single subunit, are soluble and do not contain (complex) cofactors. Analyses of the P. furiosus genome suggest that perhaps only a quarter of the genes encode proteins that would fall into this category. The hypothesis is that lack of the appropriate cofactor or of the partner protein(s) necessary to form a complex are major reasons why many recombinant proteins are insoluble. This work describes development of the production pipeline with attention to prediction and incorporation of cofactors.

Effects of storage time and temperature on the concentration of ethyl carbamate and its precursors in wine.

A 3-year study was carried out on the effects of time and temperature on the concentration of ethyl carbamate in wine. The study monitored the changing concentration of ethyl carbamate and of urea and citrulline, which are two major precursors of ethyl carbamate in wine. In addition to the formation of ethyl carbamate, both urea and citrulline decayed in other reactions. Kinetic analysis was carried out to model the formation of ethyl carbamate and its dependence on the concentrations of ethanol, urea and citrulline. This led to the development of an equation that can be used to predict the concentration of ethyl carbamate in wine at the point of consumption, resulting from any given storage time and temperature profile. The results were in good agreement with data obtained from similar studies.

Backbone solution structures of proteins using residual dipolar couplings: application to a novel structural genomics target.

Structural genomics (or proteomics) activities are critically dependent on the availability of high-throughput structure determination methodology. Development of such methodology has been a particular challenge for NMR based structure determination because of the demands for isotopic labeling of proteins and the requirements for very long data acquisition times. We present here a methodology that gains efficiency from a focus on determination of backbone structures of proteins as opposed to full structures with all sidechains in place. This focus is appropriate given the presumption that many protein structures in the future will be built using computational methods that start from representative fold family structures and replace as many as 70% of the sidechains in the course of structure determination. The methodology we present is based primarily on residual dipolar couplings (RDCs), readily accessible NMR observables that constrain the orientation of backbone fragments irrespective of separation in space. A new software tool is described for the assembly of backbone fragments under RDC constraints and an application to a structural genomics target is presented. The target is an 8.7 kDa protein from Pyrococcus furiosus, PF1061, that was previously not well annotated, and had a nearest structurally characterized neighbor with only 33% sequence identity. The structure produced shows structural similarity to this sequence homologue, but also shows similarity to other proteins, which suggests a functional role in sulfur transfer. Given the backbone structure and a possible functional link this should be an ideal target for development of modeling methods.

Simultaneous determination of aflatoxins and ochratoxin A in food using a fully automated immunoaffinity column clean-up and liquid chromatography-fluorescence detection.

An automated HPLC method for the simultaneous detection of aflatoxins (AF) and ochratoxin A (OA) has been developed. The method uses an immunoaffinity column containing antibodies specific to both AF and OA. The samples were extracted with an acetonitrile/water mixture and diluted with phosphate buffer saline (PBS). The aqueous extracts were then transferred to an ASPEC HPLC system for automated clean-up using AflaOchra immunoaffinity columns. OA and AF were quantified using HPLC with fluorescence detection, with a run time of approximately 40 min. Limits of quantification were estimated as 0.2 microg/kg for OA and AFB1, AFB2, AFG1 and AFG2. Initial validation of this method gave average recoveries of 72-101% for OA and AF for a range of food products (maize cereal products and peanut butter). Within laboratory RSDr and RSDR for a 5.0 microg/kg spike level in maize cereals was found to be 7.6-10.1% (AF and OA) and 10.2-13.8%, respectively.

Survey of chloropropanols in soy sauces and related products purchased in the UK in 2000 and 2002.

The results of surveys to investigate the levels of 3-monochloropropane-1,2-diol (3-MCPD) and 1,3-dichloropropanol (1,3-DCP) in UK retail samples of soy sauces and similar products are reported. The products, sampled in 2000 and 2002, were analysed for 3-MCPD using an established solvent extraction technique with a reporting limit of 0.01 mg kg(-1), which also detected 2-monochloropropane-1,2-diol (2-MCPD), and for 1,3-DCP by an automated headspace method with a reporting limit of 0.005 mg kg(-1), which also detected 2,3-dichloropropanol (2,3-DCP). In the 2000 survey, 3-MCPD was quantified in 32 of 100 samples. After normalization to 40% dry matter, it was quantified at or above 0.02 mg kg(-1) in 25 of the samples and in excess of 1 mg kg(-1) in 16 samples, the highest containing 82.8 mg kg(-1). 2-MCPD was found in 26 samples, at up to 17.6 mg kg(-1) after normalization to 40% dry matter. The presence of 1,3-DCP was detected in 17 of the samples, at levels between 0.006 and 0.345 mg kg(-1). 1,3-DCP was only detected where 3-MCPD was present, but the levels of 1,3-DCP and 3-MCPD were not correlated. 2,3-DCP was detected in 11 samples at levels ranging from 0.006 to 0.043 mg kg(-1). In the 2002 survey, 3-MCPD was quantified (> 0.01 mg kg(-1)) in only eight of 99 samples and 2-MCPD in three samples. After normalization to 40% dry matter, 3-MCPD was present at or above 0.02 mg kg(-1) in seven of these, the maximum level being 35.9 mg kg(-1). 1,3-DCP was detected in this sample alone, at 0.017 mg kg(-1).

Determination of 1,3-dichloropropanol in soy sauces by automated headspace gas chromatography-mass spectrometry.

There has been recent concern about the levels of carcinogenic chloropropanols in some soy sauces. We have devised and tested a new automated headspace GC-MS technique for the analysis of 1,3-dichloropropan-2-ol (1,3-DCP) in soy sauce and similar products. The method incorporates the use of cryogenic trapping and a deuterium-labelled internal standard. The limit of detection was 0.003 mg kg(-1). After in-house validation testing, the method was applied to soy sauce samples that had previously been analysed for the related contaminant 3-monochloropropanediol (3-MCPD). 1,3-DCP was detected in 10 of 40 sauces, all of which also contained 3-MCPD. The highest level was just >1 mg kg(-1). There was no correlation between the levels of 1,3-DCP and 3-MCPD.

Survey of 3-monochloropropane-1,2-diol (3-MCPD) in selected food groups, 1999-2000.

A survey of the levels of 3-monochloropropane-1,2-diol (3-MCPD) in a range of selected food products available in the UK is reported. The survey was carried out on behalf of the Food Standards Agency (FSA) to identify the food groups that might provide a significant contribution to 3-MCPD exposure from the diet. Three hundred samples comprising meat, dairy, cereal, soup and miscellaneous products were purchased from retail outlets and analysed using a GC-MS procedure, which had been formally validated by an earlier collaborative trial. 3-MCPD was detected in 89 (30%) of the samples. Three samples, all crackers, contained levels of 3-MCPD > 0.1 mg kg(-1), the highest level being 0.134 mg kg(-1). Levels of 3-MCPD were generally slightly higher in foods after cooking. In all cases where 3-MCPD was detected in cooked foods, it was also present in the uncooked sample.

Solution NMR characterization of the thermodynamics of the disulfide bond orientational isomerism and its effect of cluster electronic properties for the hyperthermostable three-iron cluster ferredoxin from the archaeon Pyrococcus furiosus.

The thermodynamics and dynamics of the Cys21-Cys48 disulfide "S" if "R" conformational isomerism in the three-iron, single cubane cluster ferredoxin (Fd) from the hyperthermophilic archaeon Pyrococcus furiosus (Pf) have been characterized by (1)H NMR spectroscopy in both water and water/methanol mixed solvents. The mean interconversion rate at 25 degrees C is 3 x 10(3) s(-1) and DeltaG(298) = -0.2 kcal/mol [DeltaH = 4.0 kcal/mol; DeltaS = 14 cal/(mol.K)], with the S orientation as the more stable form at low temperature (< 0 degrees C) but the R orientation predominating at >100 degrees C, where the organism thrives. The distinct pattern of ligated Cys beta-proton contact shifts for the resolved signals and their characteristic temperature behavior for the forms of the 3Fe Fd with alternate disulfide orientations have been analyzed to determine the influences of disulfide orientation and methanol cosolvent on the topology of the inter-iron spin coupling in the 3Fe cluster. The Cys21-Cys48 disulfide orientation influences primarily the spin couplings involving the iron ligated to Cys17, whose carbonyl oxygen is a hydrogen bond acceptor to the Cys21 peptide proton. Comparison of the Cys beta-proton contact shift pattern for the alternate disulfide orientations with the pattern exhibited upon cleaving the disulfide bridge confirms an earlier [Wang, P.-L., Calzolai, L., Bren, K. L., Teng, Q., Jenney, F. E., Jr., Brereton, P. S., Howard, J. B., Adams, M. W. W., and La Mar, G. N. (1999) Biochemistry 38, 8167-8178] proposal that the structure of the same Fd with the R disulfide orientation resembles that of the Fd upon cleaving the disulfide bond.

Deuterium/hydrogen isotope ratio measurement of water and organic samples by continuous-flow isotope ratio mass spectrometry using chromium as the reducing agent in an elemental analyser.

A rapid continuous-flow technique for quantitative determination of hydrogen isotope ratios in water and organic materials at natural abundance levels is described. Water and organic samples were reduced in a helium stream at temperatures in excess of 1000 degrees C over chromium metal. delta(2)H per thousand values of water and organic samples were determined by calibration against International Atomic Energy Agency reference materials V-SMOW and SLAP water. The accuracy of the method was demonstrated through the analysis of the intermediate water standard GISP and IAEA water intercomparison materials OH-1, OH-2 and OH-3. Values obtained using this technique compared well with reference values (maximum difference 2.2 per thousand). The precision of water analyses was less than 2.3 per thousand (1 sigma or 1 standard deviation) in all cases. No apparent memory effect was observed when measuring samples at the natural abundance level. The application of the technique to organic molecules and the salts of organic acids was successfully demonstrated by measuring the delta(2)H per thousand values of an n-hexadecane laboratory reference and anhydrous calcium formate versus water calibration materials.

The effects of domestic cooking on the levels of 3-monochloropropanediol in foods.

The results are reported of a study to determine the effect of domestic cooking procedures on the level of 3-monochloropropane-1,2-diol (3-MCPD) in selected foods. Samples of 23 foods comprising stock cubes, gravies, a cake mix, batters, breads, cheese and meats were subjected to a range of cooking procedures including grilling, toasting and microwaving. The resulting levels of 3-MCPD were compared with those present in the foods before cooking. Grilling and toasting produced substantial increases in the 3-MCPD content of bread, forming up to 0.3 mg/kg, and of most cheeses, resulting in levels of up to about 0.1 mg/kg. Microwave cooking produced elevated 3-MCPD levels in some cheeses. Frying laboratory-produced batters increased 3-MCPD levels to about 0.1 mg/kg whereas a retail batter contained no detectable 3-MCPD when fried. The remaining foods showed little or no discernible increase on cooking.

Determination of 3-chloro-1,2-propanediol in foods and food ingredients by gas chromatography with mass spectrometric detection: collaborative study.

The results of a collaborative study are reported for the determination of 3-chloro-1,2-propanediol (3-monochloropropane-1,2-diol; 3-MCPD) in a wide range of foods and food ingredients, using gas chromatography with mass spectrometric detection and incorporating the use of a deuterated internal standard. After a pretrial study, 12 laboratories (6 United Kingdom, 1 Switzerland, 1 Japan, 2 United States, 1 The Netherlands, and 1 from the European Commission) were asked to analyze 12 test materials (as known duplicates or split-level samples) by using a prescribed procedure. The test materials consisted of duplicate samples of acid-hydrolyzed vegetable protein (containing 3-MCPD at 0.029 mg/kg), malt extract (0.055 mg/kg), wholemeal bread crumbs (0.030 mg/kg), salami (0.016 mg/kg), cheese alternative (0.043 mg/kg), and soup powder (split levels at 0.045 and 0.041 mg/kg). Repeatability ranged from 0.005 to 0.013 mg/kg and reproducibility, from 0.010 to 0.027 mg/kg, for the samples tested. Precision values were well within statistically predicted levels (HORRAT values of <1 for 5 of the 6 matrixes tested) and within method criteria prepared by a joint working group composed of the United Kingdom Ministry of Agriculture, Fisheries and Food and industry representatives. The study demonstrated the satisfactory validation of the method for quantifying 3-MCPD at levels of > or = 0.010 mg/kg. The limit of detection derived from separate in-house studies was estimated to be 0.005 mg/kg. The method was adopted First Action by AOAC INTERNATIONAL.

Light and electron microscopy localization of the 11beta-hydroxysteroid dehydrogenase type I enzyme in the rat.

The 11beta-hydroxysteroid dehydrogenase type I enzyme (11betaHSD1) converts cortisone to cortisol in humans, and 11-dehydrocorticosterone to corticosterone in rodents. In the present study we used a new immunopurified polyclonal antibody, RAH113, to localize 11betaHSD1 at the light and electron microscopy levels in a wide range of rat tissues. 11betaHSD1 staining in the liver was of highest intensity around the central vein and decreased radially. In the lung, 11betaHSD1 was found at highest levels in the interstitial fibroblast, with levels in the type II pneumocyte an order of magnitude lower. RAH113 stained proximal tubules of the renal cortex and interstitial cells of the medulla and papilla. Adrenal 11betaHSD1 was confined to the glomerulosa and medulla, whereas the glucocorticoid-inactivating hydroxysteroid dehydrogenase isoform 11betaHSD2 was present in fascilulata/reticularis. 11betaHSD1 was found in parietal cells of the fundic region of the stomach, but not in the antrum. In the heart, 11betaHSD1 was detected in cells resembling interstitial fibroblasts of the endocardium and in the adventitial fibroblasts of blood vessels. Western blot analysis confirmed the presence of an antigen of the correct size (34 kDa) and intensity consistent with levels of enzyme activity previously reported in these tissues. Brain and testis also displayed the 34-kDa protein, confirming the expression of authentic 11betaHSD1 in these tissues. Electron microscopy of lung and kidney interstitial cells showed that 11betaHSD1 was localized both to the endoplasmic reticulum and the nuclear membrane. These results show that 11betaHSD1 is present in discrete cell populations where it may facilitate intracrine and paracrine glucocorticoid action in addition to its classical role of maintaining circulating glucocorticoids via activity in the liver.