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.

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    Effects of beetroot (Beta vulgaris) preparations on the Maillard reaction products in milk and meat-protein model systems
    Rackauskienea, I. ; Pukalskas, A. ; Rimantas Venskutonis, P. ; Fiore, A.M. ; Troise, A.D. ; Fogliano, V. - \ 2015
    Food Research International 70 (2015). - ISSN 0963-9969 - p. 31 - 39.
    advanced glycation endproducts - mutagenic/carcinogenic heterocyclic amines - absorbency capacity orac - antioxidant activity - beef patties - end-products - red - identification - phip - root
    The effects of beetroots (Beta vulgaris) on the formation of Maillard reaction (MR) products possessing health, nutritional and sensory implications were studied. The effect of dried beetroot juice on the formation of Ne-(carboxymethyl)lysine (CML) and Ne-(2-furoylmethyl)-L-lysine (furosine) was determined in a milk model system. Beetroot juice reduced furosine formation more than CML, inferring that betalain compounds present in the juice are more effective in reducing the formation of MR products in the early stage than in the advanced stage of MR. Beetroot water extract was fractionated on Sephadex LH20 and obtained three beetroot fractions were used to assess their effect on the formation of heterocyclic amines in a meat-protein model system. Beetroot fraction possessing the highest antioxidant capacity and containing the highest betalain content reduced the amounts of 2-amino-1-methyl-6-phenylimidazo-[4,5-b]-pyridine (PhIP), 2-amino-3,8-dimethyl-imidazo-[4,5-f]-quinoxaline (MeIQx), and 2-amino-3-methylimidazo-[4,5-f]-quinoline (IQ) by approximately 60, 77 and 87%, respectively. Beetroot preparations were characterized by ultra performance liquid chromatography quadrupole time of flight mass spectrometry (UPLC–Q-TOF–MS/MS). The antioxidant activities of beetroot preparations were also evaluated by 2,2'-azinobis (3-ethylbenzothiazoline-6-sulfonic acid) radical cation (ABTSradical dot+) scavenging capacity, oxygen radical absorbance capacity (ORAC) and total phenolic compound assays. Our findings could be useful for creating novel source of functional ingredients exerting anti-carcenogenic and antiglycation activities.
    Colour, pleasantness, and consumption behaviour within a meal
    Piqueras Fiszman, B. ; Spence, C. - \ 2014
    Appetite 75 (2014). - ISSN 0195-6663 - p. 165 - 172.
    sensory-specific satiety - subsequent food-intake - in-home consumption - stimulus specificity - variety - choice - flavor - cues - red - acceptance
    It is often claimed that colour (e.g., in a meal) affects consumption behaviour. However, just how strong is the evidence in support of this claim, and what are the underlying mechanisms? It has been shown that not only the colour itself, but also the variety and the arrangement of the differently-coloured components in a meal influence consumers’ ratings of the pleasantness of a meal (across time) and, to a certain extent, might even affect their consumption behaviour as well. Typically, eating the same food constantly or repeatedly leads to a decrease in its perceived pleasantness, which, as a consequence, might lead to decreased intake of that food. However, variation within a meal (in one or several sensory attributes, or holistically) has been shown to slow down this process. In this review, we first briefly summarize the literature on how general variety in a meal influences these variables and the major theories that have been put forward by researchers to explain them. We then go on to evaluate the evidence of these effects based mainly on the colour of the food explaining the different processes that might affect colour-based sensory-specific satiety and, in more detail, consumption behaviour. In addition, we also discuss the overlap in the definitions of these terms and provide additional hypothesis as to why, in some cases, the opposite pattern of results has been observed.
    Responses of supplemental blue light on flowering and stem extension growth of cut chrysanthemum
    Jeong, S.W. ; Hogewoning, S.W. ; Ieperen, W. van - \ 2014
    Scientia Horticulturae 165 (2014). - ISSN 0304-4238 - p. 69 - 74.
    plant-growth - spectral filters - red - morifolium - photosynthesis - gibberellins - phytochrome - end - photoperiod - inhibition
    To determine the effects of blue (B) spectrum supplemental lighting on flower bud formation and stem elongation growth of cut chrysanthemum, plants of ‘Zembla’ cultivar were grown for 42 days under 4 different light treatments. Treatments comprised: RB (11 h of mixed red and blue [RB] light), RB + B (11 h of mixed RB light and then 4 h of supplemental B light), LRB + B (15 h of mixed RB light and then 4 h of supplemental B light) and RB + LB (11 h of mixed RB light and then 13 h of B light) by using light-emitting diodes. Diurnal patterns in the net assimilation rate were observed, depending on light-quality combinations. Under mixed RB light, the net assimilation rate increased rapidly, then slightly decreased under B light, and finally dropped to negative values during darkness. Final stem length was the highest in plants grown under RB + LB, followed by LRB + B, RB + B and then RB treatment. The stem lengths under RB + B, LRB + B and RB + LB were 1.3, 1.5 and 1.7 times longer than that of RB treatment, respectively. However, fully developed flower buds were formed under RB and RB + B treatments only. The extended final stem length of RB + B plants was determined by internode extension. Overall, our results indicate that supplemental B light, at least in part, may promote stem and internode elongation growth without any inhibitory effect on flower bud formation. The results of this study present a useful practical technique for optimizing cut chrysanthemum production in greenhouse horticulture.
    The effect of temperature and time on the quality of natural fermented marula (Sclerocarya birrea subsp. Caffra) juice
    Hiwilepo-van Hal, P. ; Bille, P.G. ; Verkerk, R. ; Dekker, M. - \ 2013
    Food Science and Technology = Lebensmittel-Wissenschaft und Technologie 53 (2013)1. - ISSN 0023-6438 - p. 70 - 75.
    antioxidant activity - vitamin-c - tropical fruits - wines - power - red
    This paper presents the effects of fermentation on the retention of vitamin C, total polyphenols and antioxidant activity in the naturally fermented marula juice. The fermentation conditions have been varied: temperature ranged between 20 and 40 °C and fermentation time from 1 to 8 days. Marula juice fermented at higher temperatures ranged between 30 and 40 °C for 6 to 4 days retained high antioxidant activities, and they were positively correlated to its ascorbic acid and phenolic content. The values obtained ranged between 0.0239 ± 0.0051 and 0.029 ± 0.0038 µmol/mg for Trolox Equivalence Antioxidant Capacity, 870 ± 80 and 960 ± 130 mg/100 ml for total phenolic content and 90 ± 6 and 159 ± 15 mg/100 ml for ascorbic acid. Overall, fermented marula juice can be used as a good source for natural antioxidants.
    Retrieval of spruce leaf chlorophyll content from airborne image data using continuum removal and radiative transfer
    Malenovsky, Z. ; Homolova, L. ; Zurita-Milla, R. ; Lukes, P. ; Kaplan, V. ; Hanus, J. ; Gastellu-Etchegorry, J.P. ; Schaepman, M.E. - \ 2013
    Remote Sensing of Environment 131 (2013). - ISSN 0034-4257 - p. 85 - 102.
    canopy reflectance models - optical-properties model - area index - hyperspectral data - forest canopies - precision agriculture - vegetation canopies - red - band - absorption
    We investigate combined continuum removal and radiative transfer (RT) modeling to retrieve leaf chlorophyll a & b content (Cab) from the AISA Eagle airborne imaging spectrometer data of sub-meter (0.4 m) spatial resolution. Based on coupled PROSPECT-DART RT simulations of a Norway spruce (Picea abies (L.) Karst.) stand, we propose a new Cab sensitive index located between 650 and 720 nm and termed ANCB650–720. The performance of ANCB650–720 was validated against ground-measured Cab of ten spruce crowns and compared with Cab estimated by a conventional artificial neural network (ANN) trained with continuum removed RT simulations and also by three previously published chlorophyll optical indices: normalized difference between reflectance at 925 and 710 nm (ND925&710), simple reflectance ratio between 750 and 710 nm (SR750/710) and the ratio of TCARI/OSAVI indices. Although all retrieval methods produced visually comparable Cab spatial patterns, the ground validation revealed that the ANCB650–720 and ANN retrievals are more accurate than the other three chlorophyll indices (R2 = 0.72 for both methods). ANCB650–720 estimated Cab with an RMSE = 2.27 µg cm- 2 (relative RRMSE = 4.35%) and ANN with an RMSE = 2.18 µg cm- 2 (RRMSE = 4.18%), while SR750/710 with an RMSE = 4.16 µg cm- 2 (RRMSE = 7.97%), ND925&710 with an RMSE = 9.07 µg cm- 2 (RRMSE = 17.38%) and TCARI/OSAVI with an RMSE = 12.30 µg cm- 2 (RRMSE = 23.56%). Also the systematic RMSES was lower than the unsystematic one only for the ANCB650–720 and ANN retrievals. Our results indicate that the newly proposed index can provide the same accuracy as ANN except for Cab values below 30 µg cm- 2, which are slightly overestimated (RMSE = 2.42 µg cm- 2). The computationally efficient ANCB650–720 retrieval provides accurate high spatial resolution airborne Cab maps, considerable as a suitable reference data for validating satellite-based Cab products.
    Fluorescent protein vectors for promoter analysis in lactic acid bacteria and Escherichia coli
    García-Cayuela, T. ; Cadiñanos, L.P. de; Mohedano, M.L. ; Palencia, P.F. de; Boden, D. ; Wells, J. ; Peláez, C. ; López, P. ; Requena, T. - \ 2012
    Applied Microbiology and Biotechnology 96 (2012)1. - ISSN 0175-7598 - p. 171 - 181.
    lactococcus-lactis - streptococcus-pneumoniae - genetic tools - in-vitro - green - cremoris - red - transformation - expression - faecalis
    Fluorescent reporter genes are valuable tools for real-time monitoring of gene expression in living cells. In this study we describe the construction of novel promoter-probe vectors containing a synthetic mCherry fluorescent protein gene, codon-optimized for lactic acid bacteria, divergently linked, or not, to a gene encoding the S65T and F64L variant of the green fluorescent protein. The utility of the transcriptional fusion vectors was demonstrated by the cloning of a single or two divergent promoter regions and by the quantitative evaluation of fluorescence during growth of Lactococcus lactis, Enterococcus faecalis, and Escherichia coli.
    Extraction of antioxidant pigments from dye sorghum leaf sheaths
    Kayode, A.P.P. ; Bara, C.A. ; Dalode-Vieira, G. ; Linnemann, A.R. ; Nout, M.J.R. - \ 2012
    Food Science and Technology = Lebensmittel-Wissenschaft und Technologie 46 (2012)1. - ISSN 0023-6438 - p. 49 - 55.
    phenolic-compounds - anthocyanins - 3-deoxyanthocyanidins - vegetables - varieties - capacity - assay - acid - food - red
    Extraction of antioxidant biocolorant pigments from leaf sheaths of dye sorghum was optimized. Effects of temperature and ethanol concentration of the extraction solvent on the concentrations of the 3-deoxyanthocyanidins, total phenolics and total anthocyanins, and the colour parameters of the biocolorant extract were evaluated using the response surface methodology. Extraction parameters affected the extraction rate of the biocolorant pigments and the colour characteristics of the extract. Maximum pigment yields were obtained at 50 °C and an ethanol concentration of the solvent of 51 mL 100 mL-1. Addition of HCl (1 mL 100 mL-1) to the solvent significantly improved the extractability of the biocolorant pigments. The crude extract from the leaf sheaths showed high antioxidant capacity with a total antioxidant capacity of 1026 mg of Trolox equivalent (TE) g-1 of DM. --------------------------------------------------------------------------------
    Uncommonly high levels of 3-deoxyanthocyanidins and antioxidant capacity in the leaf sheaths of dye sorghum
    Kayode, A.P.P. ; Nout, M.J.R. ; Linnemann, A.R. ; Hounhouigan, J.D. ; Berghofer, E. ; Siebenhandl-Ehn, S. - \ 2011
    Journal of Agricultural and Food Chemistry 59 (2011)4. - ISSN 0021-8561 - p. 1178 - 1184.
    pigment characterization - phenolic-compounds - grain sorghum - anthocyanins - varieties - red - accumulation - stability - genotypes - purple
    Extracts from leaf sheaths of farmers varieties of dye sorghum cultivated and used in Benin as a source of biocolorings were analyzed for their anthocyanidin and phenolic contents, as well as their antioxidant capacity. The aim was to identify and quantify the types of anthocyanin and phenolic acids. The total anthocyanin content of the leaf sheaths ranged from 13.7 to 35.5 mg of cyanidin 3-glucoside equivalent/g of dry matter (DM), with an average of 27.0 mg/g. The total anthocyanin content is 90 times higher than levels usually reported in fruits and vegetables. Anthocyanin consisted essentially of apigeninidin and luteolinidin, two 3-deoxyanthocyanidins with many applications in food, beverage, and pharmaceutical industries. The apigeninidin content of the leaf sheaths was 30 times higher than that in cereal bran and ranged from 14.7 to 45.8 mg/g, with an average of 31.3 mg/g. The amount of luteolinidin ranged from 0.4 to 2.4 mg/g, with a mean of 1.2 mg/g. The total phenolic content expressed as gallic acid equivalent averaged 95.5 mg/g. The free phenolic acids identified were benzoic acid, p-coumaric acid, and o-coumaric acid at amounts of 801.4, 681.6, and 67.9 µg/g, respectively. The leaf sheaths of dye sorghum have an antioxidant capacity [3.8-5.6 mmol of Trolox equivalent (TE)/g of DM] much higher than that reported for cereal bran and fruits and vegetables
    Spectral dependence of photosynthesis and light absorptance in single leaves and canopy in rose
    Paradiso, R. ; Meinen, E. ; Snel, J.F.H. ; Visser, P.H.B. de; Ieperen, W. van; Hogewoning, S.W. ; Marcelis, L.F.M. - \ 2011
    Scientia Horticulturae 127 (2011)4. - ISSN 0304-4238 - p. 548 - 554.
    optical-properties - visible radiation - quintinia-serrata - quantum yield - crop plants - red - quality - growth - green - anthocyanins
    Little is known about the effects of leaf pigmentation (related to leaf ontogeny), on the spectral dependence of photosynthesis and most observations have been limited so far to single leaves. This study aimed to investigate photosynthesis and the related optical properties of two types of rose leaves, young reddish leaves and middle age green leaves, and to quantify the spectral dependence of photosynthesis at the canopy level. Photosynthesis was measured with CO2/H2O gas analyzer on intact leaves of rose ‘Akito’ at narrow band light of 18 wavelengths. Subsequently, the optical properties (transmittance, absorptance and reflectance) were measured with spectrophotometer. A mechanistic crop model was used for up scaling measurements at the single leaf level to the crop level (crop with LAI = 3). The green and the reddish leaves had similar total PAR absorptance, even though absorptance around 550 nm was slightly lower in the green leaves. The maxima of photosynthesis efficiency were at 640–680 nm for quantum yield (per absorbed light unit) and at 660–680 nm for action spectrum (per incident light unit), regardless the colour of the leaf blade. In the range 500–580 nm, both the quantum yield and the action spectrum were lower in reddish than in green leaves. Differences in optical properties and photosynthetic behaviour were related to the higher content of anthocyanins in red leaves. The spectral dependence of light absorption and photosynthesis at the canopy level differed distinctly from that at leaf level. The spectral differences in absorption at the leaf level almost disappeared at the canopy level. Consequently, while the action spectrum of green light (520–570 nm) was only 67% of that of red light (680 nm) at the leaf level, it increased to 79% at the crop level. Young reddish leaves had higher absorptance but lower action spectrum and quantum yield at green light. Spectral differences in photosynthesis at the canopy level are much smaller than at the leaf level. Our short term measurements suggest that optimizing spectral output of LED lamps may increase photosynthesis up to 12% for a canopy with green leaves and up to 17% for a canopy with reddish leaves when compared to the spectrum of HPS lamps.
    Retrieval of chlorophyll concentration from leaf reflectance spectra using wavelet analysis
    Blackburn, G.A. ; Ferwerda, J.G. - \ 2008
    Remote Sensing of Environment 112 (2008)4. - ISSN 0034-4257 - p. 1614 - 1632.
    hyperspectral data - vegetation - calibration - prospect - pigment - spectroscopy - indexes - models - red
    The dynamics of foliar chlorophyll concentrations have considerable significance for plant¿environment interactions, ecosystem functioning and crop growth. Hyperspectral remote sensing has a valuable role in the monitoring of such dynamics. This study focussed upon improving the accuracy of chlorophyll quantification by applying wavelet analysis to reflectance spectra. Leaf-scale radiative transfer models were used to generate very large spectral data sets with which to develop and rigorously test refinements to the approach and compare it with existing spectral indices. The results demonstrated that by decomposing leaf spectra, the resultant wavelet coefficients can be used to generate accurate predictions of chlorophyll concentration, despite wide variations in the range of other biochemical and biophysical factors that influence leaf reflectance. Wavelet analysis outperformed predictive models based on untransformed spectra and a range of spectral indices. The paper discusses the possibilities for further refining the wavelet approach and for extending the technique to the sensing of a variety of vegetation properties at a range of spatial scales.
    Forest health and vitality: The detection and monitoring of Pinus patula trees infected by Sirex noctilio using digital multispectral imagery
    Ismail, R. ; Mutanga, O. ; Bob, U. - \ 2007
    Southern Hemisphere Forestry Journal 69 (2007)1. - ISSN 1991-931X - p. 39 - 47.
    vegetation indexes - chlorophyll concentration - fabricius hymenoptera - spruce budworm - narrow-band - landsat tm - broad-band - damage - red - plantations
    The Eurasian woodwasp, Sirex noctilio, causes considerable tree mortality in commercial pine plantations in southern KwaZulu-Natal, South Africa. Broad-scale visual assessments of infestation provided by forest managers are currently used to measure forest health and vitality. The effectiveness of visual assessments is questionable because they are qualitative, subjective and dependent on the skill of the surveyor. Remote sensing technology provides a synoptic view of the canopy and thus offers an alternative to the conventional methods of monitoring forest health and vitality. In this study, high resolution (0.5 × 0.5m) digital multispectral imagery (DMSI) was acquired over commercial Pinus patula trees of varying age classes, which had been ground assessed and ranked on an individual tree crown basis using a severity scale. The severity scale was based on a hierarchy of decline symptoms that are visibly apparent on the infested tree and are represented in this study as the green, red and grey stages. A series of ratio- and linear-based vegetation indices were then calculated and compared to the different crown condition classes as determined by severity scale. Of the vegetation indices derived from the high-resolution DMSI, significant differences between the pre-visual (healthy and green stages) and visual (red and grey stages) crown condition classes were obtained. Canonical variate analysis further revealed that greater discriminatory power between the different crown condition classes is obtained when using the normalised difference vegetation index (NDVI). Overall the study demonstrated the potential benefit of using high-resolution DMSI to discriminate between healthy trees and trees that were in the visual stage of infestation.
    Leaf development and photosynthetic properties of three tropical tree species with delayed greening
    Cai, Z.Q. ; Slot, M. ; Fan, Z.X. - \ 2005
    Photosynthetica 43 (2005)1. - ISSN 0300-3604 - p. 91 - 98.
    young leaves - rain-forest - expansion - stress - photoinhibition - anthocyanins - syzygium - plants - damage - red
    Leaf developmental patterns were characterized for three tropical tree species with delayed greening. Changes in the pigment contents, photosynthetic capacity, stomata development, photosystem 2 efficiency, rate of energy dissipation, and the activity of partial protective enzymes were followed in developing leaves in an attempt to elucidate the relative importance of various photoprotective mechanisms during leaf ontogeny. Big leaves of Anthocephalus chinensis, a fast-growing light demanding species, expanded following an exponential pattern, while relatively small leaves of two shade-tolerant species Litsea pierrei and Litsea dilleniifolia followed a sigmoidal pattern. The juvenile leaves of A. chinensis and L. pierrei contained anthocyanin located below the upper epidermis, while L. dilleniifolia did not contain anthocyanin. Leaves of A. chinensis required about 12 d for full leaf expansion (FLE) and photosynthetic development was delayed 4 d, while L. pierrei and L. dilleniifolia required 18 or 25 d for FLE and photosynthetic development was delayed 10 or 15 d, respectively. During the leaf development the increase in maximum net photosynthetic rate was significantly related to changes in stomatal conductance and the leaf maturation period was positively related to the steady-state leaf dry mass per area for the three studied species. Dark respiration rate of leaves at developing stages was greater, and pre-dawn initial photochemical efficiency was lower than that of mature leaves. Young leaves displayed greater energy dissipation than mature leaves, but nevertheless, the diurnal photoinhibition of young L. dilleniifolia leaves was higher than that of mature leaves. The young red leaves of A. chinensis and L. pierrei with high anthocyanin contents and similar diurnal photoinhibition contained more protective enzymes (superoxide dismutase, ascorbate peroxidase) than mature leaves. Consequently, red leaves may have higher antioxidant ability.
    Serosurveillance of wild deer and wild boar after the epidemic of foot-and-mouth disease in the Netherlands in 2001
    Elbers, A.R.W. ; Dekker, A. ; Dekkers, L.J.M. - \ 2003
    Veterinary Record 153 (2003)22. - ISSN 0042-4900 - p. 678 - 681.
    modeling control strategies - british deer - feral pigs - virus - surveillance - fallow - roe - red
    Blood samples from 140 wild deer and 208 wild boar shot in the aftermath of the epidemic of foot-and-mouth disease in the Netherlands in 2001 were examined for antibodies to foot-and-mouth disease virus. They were all negative
    Simulation of Leaf Area Development Based on Dry Matter Partitioning and Specific Leaf Area for Cut Chrysanthemum
    Lee, J.H. ; Heuvelink, E. - \ 2003
    Annals of Botany 91 (2003). - ISSN 0305-7364 - p. 319 - 327.
    plant-density - growth-model - temperature - tomato - morifolium - radiation - lettuce - onion - crop - red
    This work aims to predict time courses of leaf area index (LAI) based on dry matter partitioning into the leaves and on specific leaf area of newly formed leaf biomass (SLA(n)) for year-round cut chrysanthemum crops. In five glasshouse experiments, each consisting of several plant densities and planted throughout the year, periodic destructive measurements were conducted to develop empirical models for partitioning and for SLA(n). Dry matter partitioning into leaves, calculated as incremental leaf dry mass divided by incremental shoot dry mass between two destructive harvests, could be described accurately (R-2 = 0.93) by a Gompertz function of relative time, R-t. R-t is 0 at planting date, at the start of short-days, and 2 at final harvest. SLA(n), calculated as the slope of a linear regression between periodic measurements of leaf dry mass (LDM) and LAI, showed a significant linear increase with the inverse of the daily incident photosynthetically active radiation (incident PAR, MJ m(-2) d(-1)), averaged over the whole growing period, the average glasshouse temperature and plant density (R-2 = 0.74). The models were validated by two independent experiments and with data from three commercial growers, each with four planting dates. Measured shoot dry mass increase, initial LAI and LDM, plant density, daily temperature and incident PAR were input into the model. Dynamics of LDM and LAI were predicted accurately by the model, although in the last part of the cultivation LAI was often overestimated. The slope of the linear regression of simulated against measured LDM varied between 0.95 and 1.09. For LAI this slope varied between 1.01 and 1.12. The models presented in this study are important for the development of a photosynthesis-driven crop growth model for cut chrysanthemum crops. (C) 2003 Annals of Botany Company.
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