Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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    The diversion of 2-C-methyl-D-erythritol-2,4-cyclodiphosphate from the 2-C-methyl-D-erythritol 4-phosphate pathway to hemiterpene glycosides mediates stress responses in Arabidopsis thaliana
    Gonzalez-Cabanelas, D. ; Wright, L.P. ; Paetz, C. ; Onkokesung, N. ; Gershenzon, J. ; Rodriguez-Concepcion, M. ; Phillips, M.A. - \ 2015
    The Plant Journal 82 (2015)1. - ISSN 0960-7412 - p. 122 - 137.
    plant defensin gene - isoprenoid biosynthesis - salicylic-acid - gas-chromatography - mass-spectrometry - mep pathway - synthase - resistance - jasmonate - reveals
    2-C-Methyl-D-erythritol-2,4-cyclodiphosphate (MEcDP) is an intermediate of the plastid-localized 2-C-methyl-D-erythritol-4-phosphate (MEP) pathway which supplies isoprenoid precursors for photosynthetic pigments, redox co-factor side chains, plant volatiles, and phytohormones. The Arabidopsis hds-3 mutant, defective in the 1-hydroxy-2-methyl-2-(E)-butenyl-4-diphosphate synthase step of the MEP pathway, accumulates its substrate MEcDP as well as the free tetraol 2-C-methyl-D-erythritol (ME) and glucosylated ME metabolites, a metabolic diversion also occurring in wild type plants. MEcDP dephosphorylation to the free tetraol precedes glucosylation, a process which likely takes place in the cytosol. Other MEP pathway intermediates were not affected in hds-3. Isotopic labeling, dark treatment, and inhibitor studies indicate that a second pool of MEcDP metabolically isolated from the main pathway is the source of a signal which activates salicylic acid induced defense responses before its conversion to hemiterpene glycosides. The hds-3 mutant also showed enhanced resistance to the phloem-feeding aphid Brevicoryne brassicae due to its constitutively activated defense response. However, this MEcDP-mediated defense response is developmentally dependent and is repressed in emerging seedlings. MEcDP and ME exogenously applied to adult leaves mimics many of the gene induction effects seen in the hds-3 mutant. In conclusion, we have identified a metabolic shunt from the central MEP pathway that diverts MEcDP to hemiterpene glycosides via ME, a process linked to balancing plant responses to biotic stress.
    Comparison of PCBs and PAHs levels in European coastal waters using mussels from the Mytilus edulis complex as biomonitors
    Olenycz, M. ; Sokolowski, A. ; Niewinska, A. ; Wolowicz, M. ; Namiesnik, J. ; Hummel, H. ; Jansen, J.M. - \ 2015
    Oceanologia = Oceanology 57 (2015). - ISSN 0078-3234 - p. 196 - 211.
    polycyclic-aromatic-hydrocarbons - polychlorinated biphenyl congeners - chromatography mass-spectrometry - toxic equivalency factors - baltic sea - blue mussels - seasonal-variations - gas-chromatography - organic pollutants - marine-environment
    Mussels from the Mytilus edulis complex were used as biomonitors for two groups of organic pollutants: polychlorinated biphenyls (PCBs, congeners: 28, 52, 101, 118, 138, 153 and 180) and polycyclic aromatic hydrocarbons (PAHs, naphthalene, acenaphthylene, acenaphthene, fluorene, phenanthrene, anthracene, fluoranthene, pyrene, benz(a)anthracene, chrysene, benzo(b)fluoranthene, benzo(k)fluoranthene, benzo(a)pyrene, indeno(1,2,3-cd)pyrene, dibenz(a,h)anthracene, benzo(g,h,i)perylene) at 17 sampling sites to assess their relative bioavailabilities in coastal waters around Europe. Because of the temporal differences in PCBs and PAHs concentrations, data were adjusted using Seasonal Variation Coefficients (SVC) before making large-scale spatial comparisons. The highest concentrations of PCBs were found near estuaries of large rivers flowing through urban areas and industrial regions. Elevated bioavailabilities of PAHs occurred in the vicinity of large harbors, urban areas, and regions affected by petroleum pollution as well as in some remote locations, which indicated long-range atmospheric deposition.
    Current issues involving screening and identification of chemical contaminants in foods by mass spectrometry
    Lehotay, S.J. ; Sapozhnikova, Y. ; Mol, J.G.J. - \ 2015
    TrAC : Trends in Analytical Chemistry 69 (2015). - ISSN 0165-9936 - p. 62 - 75.
    performance liquid-chromatography - pesticide-residue analysis - ion mobility spectrometry - information-dependent acquisition - pressure desorption ionization - supersonic molecular-beams - veterinary drug residues - flow-injection analysis - gas-chromatography
    Although quantitative analytical methods must be empirically validated prior to their use in a variety of applications, including regulatory monitoring of chemical adulterants in foods, validation of qualitative method performance for the analytes and matrices of interest is frequently ignored, or general guidelines are assumed to be true for specific situations. Just as in the case of quantitative method validation, acceptable method performance criteria should be established for qualitative analysis purposes to suit the analytical needs for given applications, and empirical method validation should be conducted to demonstrate the qualitative performance capabilities the method. This critical review article is intended to describe and discuss recent developments with of respect to qualitative aspects in mass spectrometry, and to make recommendations for validation of qualitative methods that meet common needs for monitoring of chemical contaminants in foods.
    metaMS: An open-source pipeline for GC–MS-based untargeted metabolomics
    Wehrens, H.R.M.J. ; Weingart, G. ; Mattivi, F. - \ 2014
    Journal of Chromatography. B, Analytical technologies in the biomedical and life sciences 966 (2014). - ISSN 1570-0232 - p. 109 - 116.
    chromatography/mass spectrometry data - mass-spectrometry - compound identification - gas-chromatography - metabonomics - extraction - alignment - toolkit
    Untargeted metabolomics are rapidly becoming an important tool for studying complex biological samples. Gas chromatography–mass spectrometry (GC–MS) is the most widely used analytical technology for metabolomic analysis of compounds that are volatile or can be chemically derivatised into volatile compounds. Unfortunately, data processing and analysis are not straightforward and the field is dominated by vendor-supplied software that does not always allow easy integration for large laboratories with different instruments. This paper presents an open-source pipeline for high-throughput GC–MS data processing, written in the R language and available as package metaMS. It features rapid annotation using in-house databases, and also provides support for building and validating such databases. The results are presented in simple-to-use tables, summarising the relative concentrations of identified compounds and unknowns in all samples. The use of the pipeline is illustrated using three experimental data sets.
    Quantification of Methylated Selenium, Sulfur, and Arsenic in the Environment
    Vriens, B. ; Ammann, A.A. ; Hagendorfer, H. ; Lenz, M. ; Berg, M. ; Winkel, L.H.E. - \ 2014
    PLoS ONE 9 (2014)7. - ISSN 1932-6203
    plasma-mass spectrometry - atomic fluorescence spectrometry - solid-phase microextraction - gas-chromatography - speciation analysis - volatile selenium - natural-waters - icp-ms - elements - air
    Biomethylation and volatilization of trace elements may contribute to their redistribution in the environment. However, quantification of volatile, methylated species in the environment is complicated by a lack of straightforward and field-deployable air sampling methods that preserve element speciation. This paper presents a robust and versatile gas trapping method for the simultaneous preconcentration of volatile selenium (Se), sulfur (S), and arsenic (As) species. Using HPLC-HR-ICP-MS and ESI-MS/MS analyses, we demonstrate that volatile Se and S species efficiently transform into specific non-volatile compounds during trapping, which enables the deduction of the original gaseous speciation. With minor adaptations, the presented HPLC-HR-ICP-MS method also allows for the quantification of 13 non-volatile methylated species and oxyanions of Se, S, and As in natural waters. Application of these methods in a peatland indicated that, at the selected sites, fluxes varied between 190–210 ng Se·m-2·d-1, 90–270 ng As·m-2·d-1, and 4–14 µg S·m-2·d-1, and contained at least 70% methylated Se and S species. In the surface water, methylated species were particularly abundant for As (>50% of total As). Our results indicate that methylation plays a significant role in the biogeochemical cycles of these elements
    Determination of T-2 and HT-2 toxins in food and feed: an update
    Krska, R. ; Malachova, A. ; Berthiller, F. ; Egmond, H.P. van - \ 2014
    World Mycotoxin Journal 7 (2014)2. - ISSN 1875-0710 - p. 131 - 142.
    tandem mass-spectrometry - performance liquid-chromatography - fusarium mycotoxin content - in-house validation - lc-ms/ms method - a trichothecenes - immunoaffinity cleanup - fluorescence detection - gas-chromatography - masked mycotoxins
    Based on the recent scientific opinion of the European Food Safety Authority (EFSA) Panel on Contaminants in the Food Chain on the risks to human and animal health related to the presence of T-2 and HT-2 toxins in food and feed that was published by EFSA in the EFSA Journal, this article provides an update on the determination of these Fusarium mycotoxins. After a brief introduction into the chemistry of these toxins, both chromatographic and immuno-analytical methods are discussed for the determination of these type A trichothecenes. During the last decade, liquid chromatography with (tandem) mass spectrometry has become the most frequently used method for the determination of T-2 and HT-2 toxins, often within a multi-analyte approach. However, complex matrices and the resulting signal suppression effects, as observed particularly in electrospray-mass spectrometry methods owing to matrix effects, may require careful optimisation of clean-up, usage of matrix matched standards, or e.g. the use of internal standards. For specific purposes where extremely low limits of quantification are needed, e.g. for the analysis of duplicate diets, a dedicated gas chromatography method with multistage mass spectrometry has become available. Other novel analytical approaches to determine T-2 and HT-2 toxins in food and feed include biosensor-based methods in surface plasmon resonance and electrochemical formats, as well as DNA microchip assays. For rapid screening, several immunochemical methods (mostly ELISAs) have become available and some are sold as commercial test kits. Whereas these methods work fast, cross-reactivities with other trichothecenes can have an undesired effect on their accuracy. While proficiency tests including T-2 and HT-2 toxins have been carried out, none of the chromatographic or immunochemical methods have been formally validated in interlaboratory validation studies. There are no certified reference materials available for T-2 and HT-2 toxins.
    Capturing flavors from Capsicum baccatum by introgression in sweet pepper
    Eggink, P.M. ; Tikunov, Y.M. ; Maliepaard, C.A. ; Haanstra, J.P.W. ; Rooij, H. de; Vogelaar, A. ; Gutteling, E.W. ; Freymark, G. ; Bovy, A.G. ; Visser, R.G.F. - \ 2014
    Theoretical and Applied Genetics 127 (2014)2. - ISSN 0040-5752 - p. 373 - 390.
    plastid compartment size - lycopersicon-esculentum - volatile compounds - anthracnose resistance - chemical-composition - gas-chromatography - sensory evaluation - mass-spectrometry - candidate gene - essential oils
    The species Capsicum baccatum includes the most common hot peppers of the Andean cuisine, known for their rich variation in flavors and aromas. So far the C. baccatum genetic variation remained merely concealed for Capsicum annuum breeding, due to post-fertilization genetic barriers encountered in interspecific hybridization. However, to exploit the potential flavor wealth of C. baccatum we combined interspecific crossing with embryo rescue, resulting in a multi-parent BC2S1 population. Volatile and non-volatile compounds plus some physical characters were measured in mature fruits, in combination with taste evaluation by a sensory panel. An enormous variation in biochemical composition and sensory attributes was found, with almost all traits showing transgression. A population-specific genetic linkage map was developed for QTL mapping. BC2S1 QTLs were validated in an experiment with near-isogenic lines, resulting in confirmed genetic effects for physical, biochemical and sensory traits. Three findings are described in more detail: (1) A small C. baccatum LG3 introgression caused an extraordinary effect on flavor, resulting in significantly higher scores for the attributes aroma, flowers, spices, celery and chives. In an attempt to identify the responsible biochemical compounds few consistently up- and down-regulated metabolites were detected. (2) Two introgressions (LG10.1 and LG1) had major effects on terpenoid content of mature fruits, affecting at least 15 different monoterpenes. (3) A second LG3 fragment resulted in a strong increase in Brix without negative effects on fruit size. The mapping strategy, the potential application of studied traits and perspectives for breeding are discussed.
    Metabolomics in melon: A new opportunity for aroma analysis
    Allwood, J.W. ; Cheung, W.W.L. ; Xu, Y. ; Mumm, R. ; Vos, C.H. de; Deborde, C. ; Biais, B. ; Maucourt, M. ; Berger, Y. ; Schaffer, A. ; Rolin, D. ; Moing, A. ; Hall, R.D. ; Goodacre, R. - \ 2014
    Phytochemistry 99 (2014). - ISSN 0031-9422 - p. 61 - 72.
    charentais cantaloupe melons - volatile organic-compounds - oxidase antisense gene - cucumis-melo - gas-chromatography - flavor compounds - cv makdimon - fruit - constituents - sulfur
    Cucumis melo fruit is highly valued for its sweet and refreshing flesh, however the flavour and value are also highly influenced by aroma as dictated by volatile organic compounds (VOCs). A simple and robust method of sampling VOCs on polydimethylsiloxane (PDMS) has been developed. Contrasting cultivars of C. melo subspecies melo were investigated at commercial maturity: three cultivars of var. Cantalupensis group Charentais (cv. Cézanne, Escrito, and Dalton) known to exhibit differences in ripening behaviour and shelf-life, as well as one cultivar of var. Cantalupensis group Ha’Ogan (cv. Noy Yisre’el) and one non-climacteric cultivar of var. Inodorus (cv. Tam Dew). The melon cultivar selection was based upon fruits exhibiting clear differences (cv. Noy Yisre’el and Tam Dew) and similarities (cv. Cézanne, Escrito, and Dalton) in flavour. In total, 58 VOCs were detected by thermal desorption (TD)-GC–MS which permitted the discrimination of each cultivar via Principal component analysis (PCA). PCA indicated a reduction in VOCs in the non-climacteric cv. Tam Dew compared to the four Cantalupensis cultivars. Within the group Charentais melons, the differences between the short, mid and long shelf-life cultivars were considerable. 1H NMR analysis led to the quantification of 12 core amino acids, their levels were 3–10-fold greater in the Charentais melons, although they were reduced in the highly fragrant cv. Cézanne, indicating their role as VOC precursors. This study along with comparisons to more traditional labour intensive solid phase micro-extraction (SPME) GC–MS VOC profiling data has indicated that the high-throughput PDMS method is of great potential for the assessment of melon aroma and quality.
    Hyphenation of optimized microfluidic sample preparation with nano liquid chromatography for faster and greener alkaloid analysis
    Shen, Y. ; Beek, T.A. van; Zuilhof, H. ; Chen, B. - \ 2013
    Analytica Chimica Acta 797 (2013). - ISSN 0003-2670 - p. 50 - 56.
    aqueous 2-phase extraction - microchannel system - gas-chromatography - chip - membrane - droplet - cells
    A glass liquid–liquid extraction (LLE) microchip with three parallel 3.5 cm long and 100 µm wide interconnecting channels was optimized in terms of more environmentally friendly (greener) solvents and extraction efficiency. In addition, the optimized chip was successfully hyphenated with nano-liquid chromatography with ultraviolet and mass spectrometric detection (nanoLC–UV–MS) for on-line analysis. In this system, sample pretreatment, separation and detection are integrated, which significantly shortens the analysis time, saves labor and drastically reduces solvent consumption. Strychnine was used as model analyte to determine the extraction efficiency of the optimized 3-phase chip. Influence of organic solvent, pH of feed phase, type of alkaloid, and flow rates were investigated. The results demonstrated that the 3-phase chip nanoLC–UV/MS hyphenation combines rapid (~25 s) and efficient (extraction efficiency >90%) sample prep, with automated alkaloid analyses. The method was applied to real samples including Strychnos nux-vomica seeds, Cephaelis ipecacuanha roots, Atropa belladonna leaves, and Vinca minor leaves.
    Organophosphorus flame-retardant and plasticizer analysis, including recommendations form the first worldwide interlaboratory study
    Brandsma, S.H. ; Boer, J. de; Leonards, P.E.G. ; Cofino, W.P. ; Covaci, A. - \ 2013
    TrAC : Trends in Analytical Chemistry 43 (2013). - ISSN 0165-9936 - p. 217 - 228.
    tandem mass-spectrometry - indoor environments - gas-chromatography - population characteristics - chemical-ionization - organic-compounds - phthalate-esters - water samples - new-model - air
    The first worldwide interlaboratory study on organophosphorus flame retardants (PFRs) was organized to improve the quality of the data reported in the literature. The study involved standard solutions, dust, fish oil and sediment samples. The differences in coefficients of variation (CV) between the samples were related more to PFR concentration (with high blanks being reported by some laboratories) and less to matrix type. Not all participating laboratories suffered from blank problems, which indicated that it was possible to control the blanks. We include recommendations on how to improve analytical performance, especially to reduce contamination of blanks.
    Differentiation of specialty coffees by proton transfer reaction-mass spectrometry
    Özdestan, Ö. ; Ruth, S.M. van; Alewijn, M. ; Koot, A.H. ; Romano, A. ; Cappelin, L. ; Biasioli, F. - \ 2013
    Food Research International 53 (2013)1. - ISSN 0963-9969 - p. 433 - 439.
    near-infrared spectroscopy - volatile organic-compounds - geographical origin - roasted coffee - ptr-ms - gas-chromatography - authentication - discrimination - products - identification
    In the coffee sector a diversity of certifications is available, with the most well-known being organic and fair trade. Intrinsic markers of products may help to assure the authenticity of food products and complement administrative controls. In the present study 110 market coffees with special production traits were characterized by high sensitivity proton transfer reaction mass spectrometry (HS PTR-MS) and volatiles were tentatively identified by PTR-time of flight MS. Espresso coffees, Kopi Luwak coffee and organic coffees could be distinguished by their profiles of volatile compounds with the help of chemometrics. A PLS-DA classification model was estimated to classify the organic and regular coffees by their HS PTR-MS mass spectra. Cross validation showed correct prediction of 42 out of the 43 (98%) organic coffee samples and 63 out of the 67 (95%) regular coffee samples. Therefore, the presented strategy is a promising approach to rapid organic coffee authentication.
    Authentication of geographical origin of palm oil by chromatographic fingerprinting of triacylglycerols an partial least square-discriminant analysis
    Ruiz-Samblas, C. ; Arrebola-Pascual, C. ; Tres, A. ; Ruth, S.M. van; Cuadros-Rodriquez, L. - \ 2013
    Talanta 116 (2013). - ISSN 0039-9140 - p. 788 - 793.
    charged aerosol detection - gas-chromatography - vegetable-oils - universal response - fatty-acids - olive oil - chemometrics - detector - markers
    Main goals of the present work were to develop authentication models based on liquid and gas chromatographic fingerprinting of triacylglycerols (TAGs) from palm oil of different geographical origins in order to compare them. For this purpose, a set of palm oil samples were collected from different continents: South eastern Asia, Africa and South America. For the analysis of the information in these fingerprint profiles, a pattern recognition technique such as partial least square discriminant analysis (PLS-DA) was applied to discriminate the geographical origin of these oils, at continent level. The liquid chromatography, coupled to a charged aerosol detector, (HPLC–CAD) TAGs separation was optimized in terms of mobile phase composition and by means of a solid silica core column. The gas chromatographic method with a mass spectrometer was applied under high temperature (HTGC–MS) in order to analyze the intact TAGs. Satisfactory chromatographic resolution within a short total analysis time was achieved with both chromatographic approaches and without any prior sample treatment. The rates of successful in prediction of the geographical origin of the 85 samples varied between 70% and 100%.
    Endocrine disrupting effects of thioxanthone photoinitiators
    Reitsma, M. ; Bovee, T.F.H. ; Peijnenburg, A.A.C.M. ; Hendriksen, P.J.M. ; Hoogenboom, L.A.P. ; Rijk, J.C.W. - \ 2013
    Toxicological sciences 132 (2013)1. - ISSN 1096-6080 - p. 64 - 74.
    tandem mass-spectrometry - cell-line - liquid-chromatography - gas-chromatography - in-vitro - expression - bioassay - itx - steroidogenesis - protein
    Photoinitiators used in food packaging ink, such as 2-isopropylthioxanthone (2-ITX), have been shown to migrate into food and beverages. Recently, several studies indicated that 2-ITX might be an endocrine disrupting chemical. In the present work, the effects of 2-ITX, 4-isopropylthioxanthone (4-ITX), 2,4-diethylthioxanthone (2,4-diethyl-TX), 2-chlorothioxanthone (2-chloro-TX) and 1-chloro-4-propoxythioxanthone (1-chloro-4-propoxy-TX) on steroidogenesis and androgen and estrogen receptor-mediated transcription activation have been studied using human H295R adrenocarcinoma cells and yeast hormone bioassays, respectively. None of the compounds showed androgenic or estrogenic activities, but clear anti-androgenic as well as anti-estrogenic activities were observed for 2-ITX, 4-ITX and 2,4-diethyl-TX, while 2-chloro-TX showed only anti-androgenic activity. In an adapted version of the H295R steroidogenesis assay, using gas chromatography-tandem mass spectrometry analysis of H295R media, all five compounds increased levels of 17ß-estradiol and estrone. H295R cells incubated with 2-ITX also showed significantly reduced androgen and increased pregnenolone and progesterone levels. Expression of particular steroidogenic genes, including the one encoding for aromatase (CYP19A1), were significantly up-regulated after incubation of H295R cells with 2-ITX, 4-ITX and 2,4-diethyl-TX. In line with the increased CYP19A1 mRNA expression, 2-ITX increased catalytic activity of aromatase in H295R cells as measured by cognate aromatase assays. The results indicate that thioxanthone derivatives can act as potential endocrine disruptors both at the level of nuclear receptor signalling and steroid hormone production.
    Biorefinery of microalgae for food and fuel
    Vanthoor-Koopmans, M. ; Wijffels, R.H. ; Barbosa, M.J. ; Eppink, M.H.M. - \ 2013
    Bioresource Technology 135 (2013). - ISSN 0960-8524 - p. 142 - 149.
    pulsed electric-field - ionic liquids - capillary-electrophoresis - microfluidic devices - gas-chromatography - stationary phases - orange juice - extraction - separation - proteins
    Microalgae are a promising source for proteins, lipids and carbohydrates for the food/feed and biofuel industry. In comparison with soya and palm oil, microalgae can be grown in a more efficient and sustainable way. To make microalgae production economically feasible it is necessary to optimally use all produced compounds. To accomplish this focus needs to be put on biorefinery techniques which are mild and effective. Of the techniques described, Pulsed Electric Field (PEF) seems to be the most developed technique compared to other cell disruption applications. For separation technology ionic liquids seems most promising as they are able to both separate hydrophobic and hydrophilic compounds. But additional studies need to be evolved in the coming years to investigate their relevance as novel cell disruption and separation methods. We propose a complete downstream processing flow diagram that is promising in terms of low energy use and state of the art knowledge.
    A taste of sweet pepper: Volatile and non-volatile chemical composition of fresh sweet pepper (Capsicum annuum) in relation to sensory evaluation of taste
    Eggink, P.M. ; Maliepaard, C.A. ; Tikunov, Y.M. ; Haanstra, J.P.W. ; Bovy, A.G. ; Visser, R.G.F. - \ 2012
    Food Chemistry 132 (2012)1. - ISSN 0308-8146 - p. 301 - 310.
    bell peppers - gas-chromatography - tomato - fruit - flavor - metabolomics - frutescens - diversity - quality - aroma
    In this study volatile and non-volatile compounds, as well as some breeding parameters, were measured in mature fruits of elite sweet pepper (Capsicum annuum) lines and hybrids from a commercial breeding program, several cultivated genotypes and one gene bank accession. In addition, all genotypes were evaluated for taste by a trained descriptive sensory expert panel. Metabolic contrasts between genotypes were caused by clusters of volatile and non-volatile compounds, which could be related to metabolic pathways and common biochemical precursors. Clusters of phenolic derivatives, higher alkanes, sesquiterpenes and lipid derived volatiles formed the major determinants of the genotypic differences. Flavour was described with the use of 14 taste attributes, of which the texture related attributes and the sweet-sour contrast were the most discriminatory factors. The attributes juiciness, toughness, crunchiness, stickiness, sweetness, aroma, sourness and fruity/apple taste could be significantly predicted with combined volatile and non-volatile data. Fructose and (E)-2-hexen-1-ol were highly correlated with aroma, fruity/apple taste and sweetness. New relations were found for fruity/apple taste and sweetness with the compounds p-menth-1-en-9-al, (E)-beta-ocimene, (Z)-2-penten-1-ol and (E)-geranylacetone. Based on the overall biochemical and sensory results, the perspectives for flavour improvement by breeding are discussed.
    A review of analytical strategies for the detection of endogenous' steroid abuse in food production
    Scarth, J.P. ; Kay, J. ; Teale, P. ; Akre, C. ; Bizec, B. le; Brabander, H.F. de; Vanhaecke, L. ; Ginkel, L.A. van; Points, J. - \ 2012
    Drug Testing and Analysis 4 (2012). - ISSN 1942-7603 - p. 40 - 49.
    tandem mass-spectrometry - performance liquid-chromatography - carbon-isotope analysis - meat-producing animals - gas-chromatography - anabolic-steroids - residue analysis - doping control - veal calves - pattern-recognition
    Detection of the abuse of synthetic steroids in food production is nowadays relatively straightforward using modern techniques such as gas or liquid chromatography coupled to mass spectrometry (GC-MS/MS or LC-MS/MS, respectively). However, proving the abuse of endogenous (or naturally occurring) steroids is more difficult. Despite these difficulties, significant progress in this area has recently been made and a number of methods are now available. The aim of the current review was to systematically review the available analytical approaches, which include threshold concentrations, qualitative marker metabolites, intact steroid esters, gas chromatography-combustion-isotope ratio mass spectrometry (GC-C-IRMS), longitudinal testing and omics biomarker profiling. The advantages/disadvantages of these methods are considered in detail, but the choice of which to adopt is dictated by a number of practical, political, and economic factors, which vary in different parts of the world. These include the steroid/species combination requiring analysis, the matrix tested, whether samples are collected from live or slaughtered animals, available analytical instrumentation, sample throughput/cost, and the relevant legal/regulatory frameworks. Furthermore, these approaches could be combined in a range of different parallel and/or sequential screening/confirmatory testing streams, with the final choice being determined by the aforementioned considerations. Despite these advances, more work is required to refine the different techniques and to respond to the ever increasing list of compounds classified as endogenous. At this advanced stage, however, it is now more important than ever for scientists and regulators from across the world to communicate and collaborate in order to harmonize and streamline research efforts. (c) 2012 HFL Sport Science (LGC Ltd) and (c) Her Majesty the Queen in Right of Canada.
    Triacylglycerol and melting profiles of milk fat from several species
    Smiddy, M.A. ; Huppertz, T. ; Ruth, S.M. van - \ 2012
    International Dairy Journal 24 (2012)2. - ISSN 0958-6946 - p. 64 - 69.
    goat milk - cholesterol composition - triglyceride analysis - gas-chromatography - dairy-products - camel - buffalo - mares - acid
    Gas chromatography and differential scanning calorimetry (DSC) were used to differentiate the fats of cow, goat, sheep, water buffalo, donkey, horse and camel milk (n = 20 for each species). Principal component analysis of triacylglycerol (TAG) composition allowed classification into groups according to species; profiles from species of greater genetic similarity were more alike. According to TAG profiles, cow, water buffalo, sheep and goat milk fat were grouped together, as were horse and donkey milk fat, whereas camel milk fat was in a third group. DSC was used to study the melting of milk fat. Similarities were apparent from melting data of cow, water buffalo, sheep and goat milk fat, while clear distinctions could again be made between these milk fats and horse and camel milk fat. Correlating TAG and DSC data highlighted that predominantly the higher molecular weight TAGs (C40 and greater) determined the DSC melting profiles for the various species.
    Guidelines for the validation of qualitative multi-residue methods used to detect pesticides in food
    Mol, J.G.J. ; Reynolds, S.L. ; Fussell, R.J. ; Stajnbaher, D. - \ 2012
    Drug Testing and Analysis 4 (2012)Supplement S1. - ISSN 1942-7603 - p. 10 - 16.
    mass-spectrometric detection - gas-chromatography - liquid-chromatography - vegetables - fruits
    There is a current trend for many laboratories to develop and use qualitative gas chromatography–mass spectrometry (GC-MS) and liquid chromatography-mass spectrometry (LC-MS) based multi-residue methods (MRMs) in order to greatly increase the number of pesticides that they can target. Before these qualitative MRMs can be used for the monitoring of pesticide residues in food, their fitness-for-purpose needs to be established by initial method validation. This paper sets out to assess the performances of two such qualitative MRMs against a set of parameters and criteria that might be suitable for their effective validation. As expected, the ease of detection was often dependent on the particular pesticide/commodity combinations that were targeted, especially at the lowest concentrations tested (0.01¿mg/kg). The two examples also clearly demonstrated that the percentage of pesticides detected was dependent on many factors, but particularly on the capabilities of the automated software/library packages and the parameters and threshold settings selected for operation. Another very important consideration was the condition of chromatographic system and detector at the time of analysis. If the system was relatively clean, then the detection rate was much higher than if it had become contaminated over time from previous injections of sample extracts. The parameters and criteria suggested for method validation of qualitative MRMs are aimed at achieving a 95% confidence level of pesticide detection. However, the presence of any pesticide that is ‘detected’ will need subsequent analysis for quantification and, depending on the qualitative method used, further evidence of identity.
    Source and transformations of lignin in Carex-dominated peat
    Schellekens, J. ; Buurman, P. ; Kuyper, T.W. - \ 2012
    Soil Biology and Biochemistry 53 (2012)Oct.. - ISSN 0038-0717 - p. 32 - 42.
    chromatography-mass-spectrometry - soil organic-matter - pyrolysis-gc-ms - gas-chromatography - cell-walls - ombrotrophic peat - phenolic-acids - vegetation succession - coumaric acid - plant-tissues
    We identified the effects of vegetation changes, and aerobic and anaerobic decay on the lignin composition in the Penido Vello peat record (Galicia, Spain). The ombrotrophic part of this peat record was dominated by graminoids and has significant contributions of ericoids at some depths. The organic matter (OM) of different peat fractions (bulk, NaOH-extractable fraction, and non-extractable residues) of 15 samples from the upper meter was analysed with pyrolysis-gas chromatography/mass spectrometry (pyrolysis-GC/MS). In addition, the dominant plant species were analysed, including Carex durieui, Agrostis curtisii, Molinia caerulea, Deschampsia flexuosa, Festuca rubra, Eriophorum angustifolium, Erica mackaiana and Calluna vulgaris, and their lignin composition compared to that of the peat OM. The high abundance of guaiacol and 4-formylguaiacol in fresh plant tissue compared to peat OM suggests that in addition to p-coumaric and ferulic acid (which are abundant in graminoids), other non-lignin phenolic monomers are contributed by graminoid species. For the non-lignin phenolics, graminoids differed from ericoids in the high abundance of ferulic acid (4-vinylguaiacol), while p-coumaric acid (4-vinylphenol) showed high and similar abundances in ericoids and graminoids. This result suggests that ratios between p-hydroxyphenyl (or p-coumaric acid) and other lignin moieties in (pyrolysates of) peat cannot be used as source indicator. Comparison of plant and peat fractions using factor analysis allowed a distinction between the effects of source (plant identity) and decay on the lignin composition of the Penido Vello peat, and different stages of decomposition were identified. Preferential decay of guaiacyl over syringyl moieties was found for the first stage of decay. This preferential decay is probably related to the large abundance of guaiacyl moieties in easily degradable non-lignin phenolics. Preferential decay of syringyl moieties occurred during subsequent aerobic decay.
    Rapid control of Chinese star anise fruits and teas for neurotoxic anisatin by Direct Analysis in Real Time (DART) high resolution mass spectrometry
    Shen, Y. ; Beek, T.A. van; Claassen, F.W. ; Zuilhof, H. ; Chen, B. ; Nielen, M.W.F. - \ 2012
    Journal of Chromatography. A, Including electrophoresis and other separation methods 1259 (2012). - ISSN 0021-9673 - p. 179 - 186.
    illicium-anisatum - gas-chromatography - ambient conditions - verum - identification - consumption - infants - intoxication - adulterant - desorption
    After ingestion, products containing Chinese star anise (Illicium verum) contaminated or adulterated with Japanese star anise (Illicium anisatum) or other Illicium species, can cause epilepsy, hallucinations, and nausea due to the rare neurotoxic sesquiterpene dilactone anisatin that is present in Japanese star anise. Thus a rapid, simple and unambiguous method for distinguishing between the morphologically similar Chinese star anise and toxic Japanese star anise is important for food safety issues. Direct Analysis in Real Time (DART) ambient ionisation coupled with orbitrap high resolution mass spectrometry allowed the recording of mass spectra of anisatin in solid star anise fruits in seconds without any prior sample pretreatment. Spectra could be obtained in both positive ([M+NH4]+ at m/z 346.1496, C15H24NO8) and negative mode ([M-H]- at m/z 327.1074, C15H19O8) and gave the same outcome provided a mass resolution of at least 27,000 is available. The anisatin signal was typically >1000 times larger in Japanese star anise than in Chinese star anise thus allowing an unequivocal qualitative determination. Herbal teas containing star anise fragments too small to be visually recognised, could be analysed by preparing a tea in 6 min and subsequently sampling ~2 µL of tea on a glass rod. None of the 8 investigated retail teas contained significant quantities of anisatin. Spiking a complex herbal tea containing Chinese star anise with an equally concentrated tea prepared from Japanese star anise provided a linear calibration curve (R2 = 0.995) after normalising on a native constituent of Chinese star anise (standard addition method). This showed that adulteration down to 1% (w/w) is still measurable. Compared with existing PCR, TLC, GC–MS and HPLC–ESI-MS/MS procedures, the proposed DART–HRMS procedure is faster and simpler and moreover measures the actual biotoxin
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