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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    Size reduction in feed technology and methods for determining, expressing and predicting particle size: A review
    Lyu, F. ; Thomas, M. ; Hendriks, W.H. ; Poel, A.F.B. van der - \ 2020
    Animal Feed Science and Technology 261 (2020). - ISSN 0377-8401
    Breakage function - Particle size - Pelleting - Pig feed - Size reduction

    Particle size of diets or ingredients plays an important role in pig growth and gut health. The way the size of particles is measured and expressed, however, is limited in explaining pig growth performance differences. This review explores new possibilities to determine, express and predict particle size. Different grinding methods, including the use of roller mills, hammer mills, multicracker and multi-stage grinding were reviewed. Roller milling tends to produce a more uniform particle size distribution (PSD) and consumes less energy, whilst hammer mills have a greater grinding capacity and a higher reduction ratio compared to roller mill. The multicracker system, a more recently developed technology, can be considered cost-effective and ensures grinding capacity. Since the effects of different grinding methods vary, multi-stage grinding, combining different grinding methods, might be a solution to obtain a defined PSD. Particle size determination techniques, including dry/wet sieving, laser diffraction, microscopy, and static/dynamic image analysis are described and compared. It is concluded that more characteristics of particles (e.g. shape, volume or surface area) should be investigated. Besides geometric mean diameter (GMD), particle size can also be expressed with parameters such as D50, D4,3 and span of PSD. Equivalent particle size (EPS) is introduced as a mean of describing the size of particles related to a functional trait of the particles. A meta-analysis was performed by collecting particle size and pig performance data from scientific studies examining the effect of recalculated EPS on pig performance (feed conversion ratio, FCR). Regression/linear modelling shows that recalculated EPS was not better than GMD in explaining pig performance differences due to the high variation among studies. Different expressions of PSD may result in different conclusions. An introduction of describing the breaking behavior of diet ingredients via mathematical models is provided. The development in breakage functions of wheat in roller milling in food preparations indicates that breakage functions are applicable in predicting the output PSD. Functions may also be extended to diet ingredients to be ground in animal feed manufacture. In feed manufacturing diagrams, particle size reduction for downstream processes (e.g. pelleting, extruding, expander processing) should be taken into account when the relationship between pig performance and particle size of diets is investigated. In conclusion, the determination, expression and prediction of particle size can be a new direction for controlling the grinding process in the feed mill to better explain its relationship with pig performance.

    Use of iron oxide nanoparticles for immobilizing phosphorus in-situ : Increase in soil reactive surface area and effect on soluble phosphorus
    Koopmans, G.F. ; Hiemstra, T. ; Vaseur, C. ; Chardon, W.J. ; Voegelin, A. ; Groenenberg, J.E. - \ 2020
    Science of the Total Environment 711 (2020). - ISSN 0048-9697
    Immobilization - Iron oxide sludge - Particle size - Phosphate - Siliceous ferrihydrite - Specific surface area

    Phosphorus (P) immobilization has potential for reducing diffuse P losses from legacy P soils to surface waters and for regenerating low-nutrient ecosystems with a high plant species richness. Here, P immobilization with iron oxide sludge application was investigated in a field trial on a noncalcareous sandy soil. The sludge applied is a water treatment residual produced from raw groundwater by Fe(II) oxidation. Siliceous ferrihydrite (Fh) is the major Fe oxide type in the sludge. The reactive surface area assessed with an adapted probe ion method is 211–304 m2 g−1 for the Fe oxides in the sludge, equivalent to a spherical particle diameter of ~6–8 nm. This size is much larger than the primary Fh particle size (~2 nm) observed with transmission electron microscopy. This can be attributed to aggregation initiated by silicate adsorption. The surface area of the indigenous metal oxide particles in the field trial soils is much higher (~1100 m2 g−1), pointing to the presence of ultra-small oxide particles (2.3 ± 0.4 nm). The initial soil surface area was 5.4 m2 g−1 and increased linearly with sludge application up to a maximum of 12.9 m2 g−1 when 27 g Fe oxides per kg soil was added. In case of a lower addition (~10–15 g Fe oxides per kg soil), a 10-fold reduction in the phosphate (P-PO4) concentration in 0.01 M CaCl2 soil extracts to 0.3 µM was possible. The adapted probe ion method is a valuable tool for quantifying changes in the soil surface area when amending soil with Fe oxide-containing materials. This information is important for mechanistically predicting the reduction in the P-PO4 solubility when such materials are used for immobilizing P in legacy P soils with a low P-PO4 adsorption capacity but with a high surface loading.

    Effect of pore size distribution and particle size of porous metal oxides on phosphate adsorption capacity and kinetics
    Suresh Kumar, Prashanth ; Korving, Leon ; Keesman, Karel J. ; Loosdrecht, Mark C.M. van; Witkamp, Geert Jan - \ 2019
    Chemical Engineering Journal 358 (2019). - ISSN 1385-8947 - p. 160 - 169.
    Adsorption kinetics - Diffusion - Particle size - Phosphate adsorption - Pore size distribution - Porous metal oxide

    Phosphate is a vital nutrient but its presence in surface waters even at very low concentrations can lead to eutrophication. Adsorption is often suggested as a step for reducing phosphate down to very low concentrations. Porous metal oxides can be used as granular adsorbents that have a high surface area and hence a high adsorption capacity. But from a practical point of view, these adsorbents also need to have good adsorption kinetics. The surface area of such adsorbents comes from pores of varying pore size and the pore size distribution (PSD) of the adsorbents can affect the phosphate adsorption kinetics. In this study, the PSD of 4 different adsorbents was correlated with their phosphate adsorption kinetics. The adsorbents based on iron and aluminium (hydr)oxide were grinded and the adsorption performance was studied as a function of their particle size. This was done to identify diffusion limitations due to the PSD of the adsorbents. The phosphate adsorption kinetics were similar for small particles of all the adsorbents. For larger particles, the adsorbents having pores larger than 10 nm (FSP and DD6) showed faster adsorption than adsorbents with smaller pores (GEH and CFH). Even though micropores (pores < 2 nm) contributed to a higher portion of the adsorbent surface area, pores bigger than 10 nm were needed to increase the rate of adsorption.

    Tuning particle properties to control rheological behavior of high internal phase emulsion gels stabilized by zein/tannic acid complex particles
    Zou, Yuan ; Yang, Xiaoquan ; Scholten, Elke - \ 2019
    Food Hydrocolloids 89 (2019). - ISSN 0268-005X - p. 163 - 170.
    Charge density - High internal phase emulsion gel (HIPE-gel) - Microstructure - Particle size - Rheological behavior - Zein/tannic acid complex particle (ZTP)

    In the present work, we studied the influence of particle size and charge density on the structure formation and rheological property of high internal phase emulsion gels (HIPE-gels) stabilized with zein/tannic acid complex particles (ZTPs). The size (68 and 108 nm) and charge density (+38, +20, and +1 mV) of ZTPs were controlled by adjusting the pH during the preparation of the particles and in the respective particle suspensions. Extensive centrifugation of the emulsions stabilized by those ZTPs resulted in stable HIPE-gels with an oil content ranging between 72 and 87% (w/w) and a particle concentration of 0.7–1.4% (w/w) only. Microscopy showed that even at these high oil volume fractions, limited coalescence between the oil droplets occurred. A decrease in the particle size resulted in a decrease in the oil content in the HIPE-gels, due to a more efficient particle network in the continuous phase. This increased the storage modulus of the HIPE gels, indicating that this particle network plays an important role for the gel strength. When increasing the interactions between the particles (by lowering the charge density), the gel strength increased even further. It was noted that the gel strength was independent of the oil content, suggesting that the oil droplets do not contribute a lot to the gel strength. These HIPE-gels with tunable rheological property may have various applications in industry.

    Ferrihydrite interaction with silicate and competing oxyanions : Geometry and Hydrogen bonding of surface species
    Hiemstra, Tjisse - \ 2018
    Geochimica et Cosmochimica Acta 238 (2018). - ISSN 0016-7037 - p. 453 - 476.
    Adsorption - Arsenate - Arsenite - ATR-IR - Charge distribution - Competition - Ferrihydrite - Geometry - MO/DFT - Particle size - PDF - Phosphate - Polymerization - Proton - Silicate - Siliceous ferrihydrite - Surface area - Surface complexation modeling - Titration - XAS - XPS

    Silicic acid is omnipresent in nature and interacts with ferrihydrite (Fh) changing the environmental fate of elements. For freshly prepared ferrihydrite, pH and electrolyte dependency of the Si adsorption was measured and interpreted with the charge distribution (CD) model using reactive site densities derived with a surface structural analysis. Proton adsorption data disclose the surface area (A ∼ 610 m2 g−1) and mean particle size (d ∼ 2.5 nm) of the Fh studied. Similarly, a range of A ∼ 530–710 g m−2 and d ∼ 2.3–2.8 nm Fh is found for Fh used in literature. Modeling of our Si adsorption data indicates the formation of Si-oligomers alongside with a Si-monomer. There is quantitative agreement with spectroscopy (ATR-IR, XPS, IR). Innersphere complexation of monomeric Si results in the formation of a mononuclear monodentate complex. However, one of the Si–OH ligands strongly interacts with an adjacent [tbnd]FeOH group, forming an extraordinary hydrogen (O⋯H–O) bond in which the H+ ion is significantly shifted, transferring supplementary proton charge (ΔsH = ∼0.20 v.u.) towards the surface changing the interfacial charge distribution coefficients of the complex, in agreement with the adsorption data. The shift of charge inhibits the protonation of the [tbnd]FeOH surface group, leading to a stable [tbnd]FeOH–FeOSi(OH)3 configuration. Depending on pH and Si-loading, oligomers are present as a Si trimer and some Si tetramer. These complexes have a double-mononuclear Fe2Si2 structure in which two Si tetrahedra are connected to two Fe octahedra each via a single Fe–O–Si bond. The various MO/DFT (B3LYP and BP86) optimized geometries can reproduce the mean Fe-Si distances of 324 and 331 pm found with differential PDF analysis. The outer ligands of the Si-monomer remain protonated, whereas one of the outer ligands of the Si-oligomers is deprotonated, in line with the structural model derived. Competition experiments identified phosphate as a very good competitor for silicate, implying that in nature, siliceous Fh can only be formed in sub-neutral systems that are low in phosphate and rich in silicate, in agreement with reported chemical compositions. Nearly all Si can be removed from the surface by phosphate at sub neutral pH despite a 10–100 times lower phosphate equilibrium concentration in comparison to silicic acid (H4SiO4). Siliceous Fh particles in lab and field are smaller than two-line Fh synthesized in the absence of Si, and have a larger specific surface area. At oxidative removal of Fe(II) from groundwater with 0.3 mM Si at circum-neutral pH, small (d = 2.0 ± 0.2 nm) siliceous Fh particles (Si/Fe = 0.18, P/Fe = 0.016) are formed with a surface area near ∼900 m2 g−1. The size is in good agreement with the length of the coherent scattering domain (CSD) reported in literature for synthetic Si-Fe(III) co-precipitates having a primary particle structure in excellent agreement with the surface depletion model for Fh. The competitive interaction of silicate (SiO4) with phosphate (PO4), arsenite (As(OH)3), and arsenate (AsO4) can be predicted very well with the CD model using affinity constants (logK) collected in monocomponent systems only.

    Foam and thin films of hydrophilic silica particles modified by β-casein
    Chen, M. ; Sala, G. ; Valenberg, H.J.F. van; Hooijdonk, A.C.M. van; Linden, E. van der; Meinders, M.B.J. - \ 2018
    Journal of Colloid and Interface Science 513 (2018). - ISSN 0021-9797 - p. 357 - 366.
    Foam - Particle size - Silica particle - Thin film - β-casein
    Hypothesis Foaming properties of particle dispersions can be modified by addition of amphiphiles. The molar ratio between particles and amphiphiles will influence the wetting properties of the particles as well as the bulk concentration of the amphiphiles. This will have an effect on air/water interfacial composition as well as on the thin film and foam stability of the mixed system. Experiments In this research foams and thin films of hydrophilic silica particles in presence of β-casein (β-CN) were investigated with different particle sizes and varying β-CN/silica weight ratios (between 1:10 and 1:100). Samples were characterized for particles size, morphology as well as contact angle and related to their foaming, interfacial, and thin film properties. Findings A threshold weight ratio of β-CN/silica was found to be 1:50 for foam stabilization with mixtures containing silica particles no larger than 1 μm and 1:30 for film stabilization with mixtures containing larger particles. At the interface, the modified silica particles were rather diluted without much interaction for surface compressions up to 30%. Large silica particles (0.0015% β-CN, Csilica ≤ 0.15%) were dragged to the periphery of the thin liquid films but no decrease of the inner film draining rate by a decrease of capilary pressure gradient across the film was observed. The depletion of β-casein in the bulk by particles played a major role in foam destabilization.
    Myofibrillar protein oxidation affects filament charges, aggregation and water-holding
    Bao, Yulong ; Boeren, Sjef ; Ertbjerg, Per - \ 2018
    Meat Science 135 (2018). - ISSN 0309-1740 - p. 102 - 108.
    Carbonyls - Free thiols - Histidine - Isoelectric point - Particle size

    Hypochlorous acid (HClO) is a strong oxidant that is able to mediate protein oxidation. In order to study the effect of oxidation on charges, aggregation and water-holding of myofibrillar proteins, extracted myofibrils were oxidized by incubation with different concentrations of HClO (0, 1, 5, and 10 mM). Loss of free thiols, loss of histidine and formation of carbonyls were greater with increasing oxidation level and the particle size increased. Water-holding in the 5 and 10 mM HClO groups were greater than in the non-oxidized control. Isoelectric focusing (IEF) showed that the isoelectric point (pI) of oxidized proteins were lower compared to non-oxidized ones. The lower pI values of oxidized proteins suggests that oxidation increased the overall net negative charge of myofibrillar proteins solubilized for IEF. Here we propose a hypothesis that oxidation-induced increase in net negative charges is the driving force for improved water-holding in myofibrils, whereas protein cross-linking and aggregation have an opposing effect by decreasing the water-holding.

    The effect of particle size and amount of inoculum on fungal treatment of wheat straw and wood chips
    Kuijk, Sandra J.A. van; Sonnenberg, Anton S.M. ; Baars, Johan J.P. ; Hendriks, Wouter H. ; Cone, John W. - \ 2016
    Journal of Animal Science and Biotechnology 7 (2016)1. - ISSN 1674-9782
    Amount of inoculum - Fungal treatment - In vitro rumen degradability - Lignin degradation - Lignocellulosic biomass - Particle size

    Background: The aim of this study was to optimize the fungal treatment of lignocellulosic biomass by stimulating the colonization. Wheat straw and wood chips were treated with Ceriporiopsis subvermispora and Lentinula edodes with various amounts of colonized millet grains (0.5, 1.5 or 3.0 % per g of wet weight of substrate) added to the substrates. Also, wheat straw and wood chips were chopped to either 0.5 or 2 cm. Effectiveness of the fungal treatment after 0, 2, 4, 6, or 8 wk of incubation was determined by changes in chemical composition, in vitro gas production (IVGP) as a measure for rumen degradability, and ergosterol content as a measure of fungal biomass. Results: Incomplete colonization was observed for C. subvermispora treated wheat straw and L. edodes treated wood chips. The different particle sizes and amounts of inoculum tested, had no significant effects on the chemical composition and the IVGP of C. subvermispora treated wood chips. Particle size did influence L. edodes treatment of wheat straw. The L. edodes treatment of 2 cm wheat straw resulted in a more selective delignification and a higher IVGP than the smaller particles. Addition of 1.5 % or 3 % L. edodes inoculum to wheat straw resulted in more selective delignification and a higher IVGP than addition of 0.5 % inoculum. Conclusion: Particle size and amount of inoculum did not have an effect on C. subvermispora treatment of wood chips. At least 1.5 % L. edodes colonized millet grains should be added to 2 cm wheat straw to result in an increased IVGP and acid detergent lignin (ADL) degradation.

    Effect of microparticulated whey protein on sensory properties of liquid and semi-solid model foods
    Liu, K. ; Stieger, M.A. ; Linden, E. van der; Velde, Fred van de - \ 2016
    Food Hydrocolloids 60 (2016). - ISSN 0268-005X - p. 186 - 198.
    MWP - lubrication - Particle size - creaminess - roughness - sensory
    This work describes the sensory properties of microparticulated whey protein (MWP) particles in relation to their rheological and tribological properties. The aim of this work is to obtain a better understanding of the sensory perception of MWP particles compared to oil droplets in liquid and semi-solid matrices. We used liquid MWP-o/w emulsions with controlled viscosities and semi-solid MWP-emulsion-filled gelatin gels as food model systems. Consistent with our previous findings, MWP showed good lubrication properties probably due to ball bearing mechanism in both liquid and semi-solid systems. Sensory results (QDA) revealed that small MWP particles contributed to perception of creaminess due to their lubrication property. Large MWP contributed to the rough and powdery perception, and thus suppressed perception of creaminess. MWP did not contribute to perception of fattiness in contrast to oil droplets. The perception of fattiness was probably related to the film formation properties of oil. As a result, MWP in liquid emulsions were generally perceived as rough but not creamy. In the case of MWP-emulsion-filled gels, although the gel matrix restrained the lubrication function of MWP particles, it also masked the rough perception of big MWP particles. Due to the combined effect of both oil droplets and MWP particles, MWP in gels resulted in an overall positive effect on the creamy perception. We conclude that MWP contributes to fat-related sensations in a different way than oil does. The perception of MWP particles is related to the size of the particle as well as the properties of the surrounding matrix.
    Endo-glucanase digestion of oat β-Glucan enhances Dectin-1 activation in human dendritic cells
    Sahasrabudhe, N.M. ; Tian, Lingmin ; Berg, Marco van den; Bruggeman, Geert ; Bruininx, Erik ; Schols, H.A. ; Faas, M.M. ; Vos, Paul de - \ 2016
    Journal of Functional Foods 21 (2016). - ISSN 1756-4646 - p. 104 - 112.
    Dectin-1 - Dendritic cells - Endo-glucanase - Oat - Particle size - β-(1-3, 1-4) Glucan

    Oat β-Glucans were studied for their immunological impact before and after enzymatic digestion in order to enhance the efficacy of oat β-Glucans for application in functional foods. Oat β-Glucan is reported to have minimal impact compared to its fungal counterpart in vitro. Digestion with endo-glucanase enhanced its efficacy towards stimulating MCP-1, RANTES, IL-8, and IL-production in human dendritic cells as compared to the nondigested β-Glucan. This effect resulted from an enhanced activation of the Dectin-receptor. Our data suggest that the immune-stimulation was dependent on the β-(1-3) linkages and the reduced particle size of digested β-Glucans. Thus, we show that enzymatic pre-digestion of dietary fibres such as oat β-Glucan enhances its impact on specific immune receptors. We also demonstrate that particle size and/or molecular weight of oat β-Glucans and exposure of specific binding sites for the receptors might be important tools for designing efficacious functional feed and food additives.

    Non-structural carbohydrates in woody plants compared among laboratories
    Quentin, Audrey G. ; Pinkard, Elizabeth A. ; Ryan, Michael G. ; Tissue, David T. ; Baggett, Scott L. ; Adams, Henry D. ; Maillard, Pascale ; Marchand, Jacqueline ; Landhäusser, Simon M. ; Lacointe, André ; Gibon, Yves ; Anderegg, William R.L. ; Asao, Shinichi ; Atkin, Owen K. ; Bonhomme, Marc ; Claye, Caroline ; Chow, Pak S. ; Clément-Vidal, Anne ; Davies, Noel W. ; Dickman, Turin L. ; Dumbur, Rita ; Ellsworth, David S. ; Falk, Kristen ; Galiano, Lucía ; Grünzweig, José M. ; Hartmann, Henrik ; Hoch, Günter ; Hood, Sharon ; Jones, Joanna E. ; Koike, Takayoshi ; Kuhlmann, Iris ; Lloret, Francisco ; Maestro, Melchor ; Mansfield, Shawn D. ; Martínez-Vilalta, Jordi ; Maucourt, Mickael ; McDowell, Nathan G. ; Moing, Annick ; Muller, Bertrand ; Nebauer, Sergio G. ; Niinemets, Ülo ; Palacio, Sara ; Piper, Frida ; Raveh, Eran ; Richter, Andreas ; Rolland, Gaëlle ; Rosas, Teresa ; Joanis, Brigitte Saint ; Sala, Anna ; Smith, Renee A. ; Sterck, Frank ; Stinziano, Joseph R. ; Tobias, Mari ; Unda, Faride ; Watanabe, Makoto ; Way, Danielle A. ; Weerasinghe, Lasantha K. ; Wild, Birgit ; Wiley, Erin ; Woodruff, David R. - \ 2015
    Tree Physiology 35 (2015)11. - ISSN 0829-318X - p. 1146 - 1165.
    Extraction and quantification consistency - Non-structural carbohydrate chemical analysis - Particle size - Reference method - Soluble sugars - Standardization - Starch

    Non-structural carbohydrates (NSC) in plant tissue are frequently quantified to make inferences about plant responses to environmental conditions. Laboratories publishing estimates of NSC of woody plants use many different methods to evaluate NSC. We asked whether NSC estimates in the recent literature could be quantitatively compared among studies. We also asked whether any differences among laboratories were related to the extraction and quantification methods used to determine starch and sugar concentrations. These questions were addressed by sending sub-samples collected from five woody plant tissues, which varied in NSC content and chemical composition, to 29 laboratories. Each laboratory analyzed the samples with their laboratory-specific protocols, based on recent publications, to determine concentrations of soluble sugars, starch and their sum, total NSC. Laboratory estimates differed substantially for all samples. For example, estimates for Eucalyptus globulus leaves (EGL) varied from 23 to 116 (mean = 56) mg g-1 for soluble sugars, 6-533 (mean = 94) mg g-1 for starch and 53-649 (mean = 153) mg g-1 for total NSC. Mixed model analysis of variance showed that much of the variability among laboratories was unrelated to the categories we used for extraction and quantification methods (method category R2 = 0.05-0.12 for soluble sugars, 0.10-0.33 for starch and 0.01-0.09 for total NSC). For EGL, the difference between the highest and lowest least squares means for categories in the mixed model analysis was 33 mg g-1 for total NSC, compared with the range of laboratory estimates of 596 mg g-1. Laboratories were reasonably consistent in their ranks of estimates among tissues for starch (r = 0.41-0.91), but less so for total NSC (r = 0.45-0.84) and soluble sugars (r = 0.11-0.83). Our results show that NSC estimates for woody plant tissues cannot be compared among laboratories. The relative changes in NSC between treatments measured within a laboratory may be comparable within and between laboratories, especially for starch. To obtain comparable NSC estimates, we suggest that users can either adopt the reference method given in this publication, or report estimates for a portion of samples using the reference method, and report estimates for a standard reference material. Researchers interested in NSC estimates should work to identify and adopt standard methods.

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