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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Heat-induced changes in microstructure of spray-dried plant protein isolates and its implications on in vitro gastric digestion
Rivera del Rio, Andrea ; Opazo-Navarrete, Mauricio ; Cepero-Betancourt, Yamira ; Tabilo-Munizaga, Gipsy ; Boom, Remko M. ; Janssen, Anja E.M. - \ 2020
Food Science and Technology = Lebensmittel-Wissenschaft und Technologie 118 (2020). - ISSN 0023-6438
Gastric digestion - In vitro digestion - Pea protein isolate - Protein digestibility - Soy protein isolate - Spray-dried protein isolates

The quickly expanding field of plant-based food, generally uses protein concentrates or isolates as protein source. It is however not clear to what extent the intensive processing of these raw materials affects their digestibility. We here report on the in vitro gastric digestibility of the structures present in unheated and heated dispersions of spray-dried protein isolates of soybean and yellow pea. Unheated dispersions consist primarily of insoluble individual spray-dried particles, agglomerates of these and only a small fraction of soluble protein. Pepsin activity was followed in real-time through microscopic observations, showing the disassociation of agglomerates and inward-breakdown of individual particles, which are otherwise stable at gastric pH and ionic strength. This demonstrates that solubility is not necessarily an incentive for gastric protein digestion. Heating does not significantly affect the overall digestibility of protein isolate dispersions. Nevertheless, heating disrupts the structure of spray-dried particles, increasing the amount of smaller and better digestible particles that remain suspended after centrifugation. Conversely, heat-induced aggregates remain in the pellet and are up to 50% less digestible than their unheated counterparts. This impaired digestibility is counterbalanced by a reduced proportion of poorly-digestible species in the full system (up to 11% for soy and 23% for pea).

Drying kinetics and viscoelastic properties of concentrated thin films as a model system for spray drying
Both, E.M. ; Tersteeg, S.M.B. ; Boom, R.M. ; Schutyser, M.A.I. - \ 2020
Colloids and Surfaces. A: Physicochemical and Engineering Aspects 585 (2020). - ISSN 0927-7757
Maltodextrin - Morphology - Rheology - Structural arrest - Whey protein

Controlling the development of the particle morphology during spray drying is of large importance to obtain high quality powders. During drying of skin-forming materials it is still unknown how the rheological properties of the skin develop as a function of time, moisture content and temperature. We here studied films prepared from whey protein – maltodextrin mixtures as a model system for spray drying. The rheological properties were assessed by oscillatory shear measurements at relevant high dry matter contents (66–82 w/w%). During drying, the films high in whey protein became brittle and had slower evaporation compared to films high in maltodextrin. Rheological analysis showed that for whey protein rich systems (with higher ratio than 25:75 WP:MD) the films were in structural arrest at the dry matter contents measured. Maltodextrin films on the other hand showed typical viscoelastic polymer behavior, although as little as 1% addition of whey protein altered its viscoelastic properties drastically. The viscoelastic properties could be related to vacuole formation during single droplet drying: samples that undergo structural arrest at a lower dry matter content (high in whey protein), form less and larger vacuoles compared to samples that undergo structural arrest only at high concentration (high in maltodextrin).

The effect of monovalent (Na+, K+) and divalent (Ca2+, Mg2+) cations on rapeseed oleosome (oil body) extraction and stability at pH 7
Romero-Guzmán, Maria Juliana ; Petris, Vasileios ; Chirico, Simone De; Bari, Vincenzo di; Gray, David ; Boom, Remko M. ; Nikiforidis, Constantinos V. - \ 2020
Food Chemistry 306 (2020). - ISSN 0308-8146
Extraction - Natural emulsion - Oil bodies - Oleosomes - Rapeseed

Oleosomes are storage vehicles of TAGs in plant seeds. They are protected with a phospholipid-protein monolayer and extracted with alkaline aqueous media; however, pH adjustment intensifies the extraction process. Therefore, the aim of this work was to investigate the extraction mechanism of rapeseed oleosomes at pH 7 and at the presence of monovalent and divalent cations (Na+, K+, Mg2+ , and Ca+2). The oleosome yield at pH 9.5 was 64 wt%, while the yield at pH 7 with H2O was just 43 wt.%. The presence of cations at pH 7, significantly enhanced the yield, with K+ giving the highest yield (64 wt.%). The cations affected the oleosome interface and their interactions. The presence of monovalent cations resulted in aggregation and minor coalescence, while divalent cations resulted in extensive coalescence. These results help to understand the interactions of oleosomes in their native matrix and design simple extraction processes at neutral conditions.

Model development for conductive thin film drying processes
Qiu, Jun ; Boom, Remko M. ; Schutyser, Maarten A.I. - \ 2020
Journal of Food Engineering 268 (2020). - ISSN 0260-8774
Conductive drying - Drum drying - Heat transfer - Process modelling - Thin film

A heat-transfer governed model is proposed to describe drying in a lab-scale conductive thin film dryer, which was designed to investigate the drying kinetics relevant to drum drying. The model calculations were compared to experimental data from drying experiments with maltodextrin DE12 and potato starch, considering the three distinct periods (heating, boiling and conductive drying) of the lab-scale process. The model uses measured temperatures and evaporation rate during the boiling period as input to calculate the decrease in moisture content during the drying process. Model calculations were evaluated by determining the root-mean-square-error (RMSE) values. The RMSE were very small (<0.24) indicating that the model was successful in describing the film drying process. During the last drying period, the starch films exhibited a higher initial heat transfer resistance (~0.0004 (m2∙K)/W) compared to maltodextrin (~0.0002 (m2∙K)/W). This reflects the formation of larger vapour bubbles in the boiling period impeding the heat transfer for starch films. Subsequently, the model was modified to describe a pilot-scale drum drying process for maltodextrin suspensions. The initial heat transfer coefficient for drum drying of maltodextrin was obtained from the lab-scale experiments. The simulations indicated residual moisture contents and optimal drying times for different drying conditions.

Water redistribution determined by Time Domain NMR explains rheological properties of dense fibrous protein blends at high temperature
Schreuders, Floor ; Bodnár, Igor ; Erni, Philipp ; Boom, Remko ; Goot, Atze Jan van der - \ 2019
Selection and gene flow shape niche-associated variation in pheromone response
Lee, Daehan ; Zdraljevic, Stefan ; Cook, Daniel E. ; Frézal, Lise ; Hsu, Jung-Chen ; Sterken, Mark G. ; Riksen, Joost A.G. ; Wang, John ; Kammenga, Jan E. ; Braendle, Christian ; Félix, Marie-Anne ; Schroeder, Frank C. ; Andersen, Erik C. - \ 2019
Nature Ecology & Evolution 3 (2019). - ISSN 2397-334X - p. 1455 - 1463.
From quorum sensing in bacteria to pheromone signalling in social insects, chemical communication mediates interactions among individuals in local populations. In Caenorhabditis elegans, ascaroside pheromones can dictate local population density; high levels of pheromones inhibit the reproductive maturation of individuals. Little is known about how natural genetic diversity affects the pheromone responses of individuals from diverse habitats. Here, we show that a niche-associated variation in pheromone receptor genes contributes to natural differences in pheromone responses. We identified putative loss-of-function deletions that impair duplicated pheromone receptor genes (srg-36 and srg-37), which were previously shown to be lost in population-dense laboratory cultures. A common natural deletion in srg-37 arose recently from a single ancestral population that spread throughout the world; this deletion underlies reduced pheromone sensitivity across the global C. elegans population. We found that many local populations harbour individuals with a wild-type or a deletion allele of srg-37, suggesting that balancing selection has maintained the recent variation in this pheromone receptor gene. The two srg-37 genotypes are associated with niche diversity underlying boom-and-bust population dynamics. We hypothesize that human activities likely contributed to the gene flow and balancing selection of srg-37 variation through facilitating the migration of species and providing a favourable niche for the recently arisen srg-37 deletion.

A Systematic Parameter Study on Film Freeze Concentration
Vuist, J.E. ; Schutyser, M.A.I. ; Boom, R.M. - \ 2019
A Systematic Parameter Study on Film Freeze Concentration
Vuist, J.E. ; Boom, R.M. ; Schutyser, M.A.I. - \ 2019
A Systematic Parameter Study on Film Freeze Concentration
Vuist, Jan Eise ; Schutyser, Maarten ; Boom, Remko - \ 2019
In: 29th European Symposium on Computer Aided Process Engineering. - Elsevier B.V. (Computer Aided Chemical Engineering ) - ISBN 9780128186343 - p. 1501 - 1506.
freeze concentration - modelling - solute inclusion

Film freeze concentration is an alternative method to concentrate aqueous streams compared to suspension freeze concentration. Major advantage is that the equipment is less complex and thus capital costs are in principle lower. In our research we investigated especially how hydrodynamics, applied freezing temperatures and solution properties influence inclusion of solutes in ice and ice yield during film freeze concentration. For this we carried out both lab-scale experiments and CFD simulations. Model solutions of sucrose and maltodextrin were concentrated in a stirred vessel by growth of an ice layer at the bottom freezing plate. For varying stirring speeds, feed concentrations and freezing plate temperature profiles we determined the solute inclusion in the grown ice and the ice yield. When increasing stirrer speeds a decreasing amount of solute included in ice was found at constant freezing plate temperature. This can be explained because the transport of the solute molecules in the boundary layer is diffusion limited. An increase in shear above the surface reduces the thickness of this layer and therefore less solute is included in ice at high shear rates. CFD simulations were carried out to describe the hydrodynamics near the surface and to relate the shear rate to the impeller Reynolds number. Moreover, the CFD simulations could explain the increased solute inclusions for higher concentrations of sucrose as higher viscosities lead to significant reduction of shear rates close to the ice layer. The CFD simulations will facilitate easier translation of the obtained results for a differently designed film freeze concentration system. Sucrose and maltodextrin appeared to behave very similar with respect to inclusion behaviour, which may be explained from their similar diffusivities. Ice growth rate is found another important factor and is very much influence by applied freezing temperatures. Our experiments showed that there is a critical ice growth rate. If this ice growth rate is exceeded more solutes will be included in the ice layer. In this case the solute molecules will not have the chance to move away from the ice boundary. The next step in our research is modelling of the ice growth rate as function of the freezing plate temperature to optimise both ice yield and solute inclusion.

Op zoek naar het ‘hitte-eiland’ boven Amsterdam
Steeneveld, Gert-Jan ; Heusinkveld, Bert - \ 2019

Steden als Amsterdam lijden aan hittestress. Onderzoekers willen weten hoe ze de druk kunnen verminderen.

Moisture diffusivity in concentrated and dry protein-carbohydrate films
Siemons, I. ; Boom, R.M. ; Sman, R.G.M. van der; Schutyser, M.A.I. - \ 2019
Food Hydrocolloids 97 (2019). - ISSN 0268-005X
Casein - Free volume - Maltodextrin - Moisture diffusion coefficient - Thin film drying - Whey protein

Understanding moisture diffusivity behaviour over a wide range of moisture contents is pivotal for optimising drying operations. Generally, data on moisture diffusivity are scarce and the effect of matrix composition on moisture diffusivity at relevant temperature for drying processes is not yet well described. In this paper moisture diffusivity in protein-carbohydrate films is systematically investigated for a wide range of moisture contents at 80 °C. Diffusion data are obtained from controlled thin film drying experiments following the regular regime method and compared to theoretical models. Moisture diffusivity for binary maltodextrin-water and whey protein-water systems appeared similar and were reasonably well described with the Darken relation. Diffusivity was lower for casein-water systems at moisture contents above 0.15 kg water/kg, which may be explained by compartmentalization of water in the casein micelles. At low moisture contents all binary systems showed universal behaviour, which may be explained by random coil behaviour leading to similar water-molecule interactions. This behaviour could be well described by free-volume theory. In mixed systems of proteins and carbohydrates moisture diffusivity appeared strongly influenced by the presence of casein, probably due to their high voluminosity. Finally, it was surprisingly observed that diffusivity in multicomponent systems decreased sharply at lower water contents when compared to binary systems. This might be explained by a denser molecular packed system in the dry regime for multicomponent systems or water trapping by protein-carbohydrate complexes.

Analysing social-ecological interactions in disease control: An agent-based model on farmers’ decision making and potato late blight dynamics
Pacilly, Francine C.A. ; Hofstede, Gert Jan ; Lammerts van Bueren, Edith T. ; Groot, Jeroen C.J. - \ 2019
Environmental Modelling & Software 119 (2019). - ISSN 1364-8152 - p. 354 - 373.
Consumat - Phytophthora infestans - Resistance management - Social-ecological systems

In this paper we focus on potato late blight control in the Netherlands to analyse the social-ecological interactions between farmer behaviour and disease dynamics. An agent-based model was developed to analyse the use of crop resistance for sustainable disease control. The framework on farmers’ decision-making was based on a behavioural theory and supported by data from literature and interviews with Dutch potato farmers. This framework was integrated with a previously developed spatially explicit model on potato late blight dynamics. We assumed a scenario where a new resistant potato variety was introduced to the market. The model reproduced a boom-and-bust cycle: the percentage of farmers growing the resistant variety increased until resistance breakdown occurred by emergence and spread of a virulent strain, and in response farmers switched to other potato varieties and management strategies. Several factors and processes were identified that could contribute to the development of sustainable disease management strategies.

China’s Rosewood Boom : A Cultural Fix to Capital Overaccumulation
Zhu, Annah Lake - \ 2019
Annals of the American Association of Geographers (2019). - ISSN 2469-4452

Rosewood has become the world’s most trafficked group of endangered species, with global seizure values surpassing that of ivory, rhino horn, and big cats combined. This is almost entirely attributable to growth in demand from China over the past two decades. Since 2000, classical rosewood furniture that dates back to the Ming Dynasty has been revived as a hot cultural commodity. This article explores China’s recent rosewood renaissance, which has brought annual market sales up to nearly $26 billion. In contrast to accounts that attribute Chinese demand for endangered species to the conspicuous consumption of a rising elite, I focus on the speculative aspect of the demand. I argue that China’s rosewood boom is largely the result of speculative investment that functions as a “cultural fix” to the country’s growing problem of capital overaccumulation. As with Harvey’s spatial fix, a cultural fix pioneers new productive outlets for the accumulation of surplus value. Unlike Harvey’s spatial fix, however, a cultural fix seeks these new productive outlets in cultural realms—specifically, through the mutual convertibility of cultural and economic capital, as defined by Bourdieu. Given the oversaturation of more conventional investment avenues, Chinese investors have increasingly turned to rosewood and other culturally important endangered resources, such as ivory, rhino horn, and tiger parts, as a new outlet for the accumulation of surplus value. More than conspicuous consumption, China’s rosewood boom is the result of rampant financial speculation resulting from a cultural fix. Key Words: China, cultural capital, endangered species, overaccumulation, spatial fix.

Powder morphology development during spray drying
Both, Eline M. - \ 2019
Wageningen University. Promotor(en): M.A.I. Schutyser; R.M. Boom. - Wageningen : Wageningen University - ISBN 9789463439923 - 129
Multiphase effects in forming anisotropic calcium caseinate materials
Wang, Zhaojun - \ 2019
Wageningen University. Promotor(en): A.J. van der Goot; R.M. Boom. - Wageningen : Wageningen University - ISBN 9789463439954 - 130
Breedspoortrekker wordt populairder
Brouwer, Thie Arend ; Rijk, Joost - \ 2019
Comparing structuring potential of pea and soy protein with gluten for meat analogue preparation
Schreuders, Floor K.G. ; Dekkers, Birgit L. ; Bodnár, Igor ; Erni, Philipp ; Boom, Remko M. ; Goot, Atze Jan van der - \ 2019
Journal of Food Engineering 261 (2019). - ISSN 0260-8774 - p. 32 - 39.
Fibrous structures - Food processing - Plant protein - Shear cell processing - Shear-induced structuring

Pea protein isolate can be combined with wheat gluten into materials with a fibrous morphology using shear induced structuring combined with heating. Results are partly in-line with soy protein isolate-wheat gluten blends, but the latter yields anisotropic materials in a much broader temperature range. Both blends also have the ability to include air. Air bubbles were aligned and deformed at process conditions that gave the most pronounce fibrous products. Mechanically, the pea protein-gluten materials processed at 140 °C had a similar strength as soy protein blends. At 110 and 120 °C, the pea protein blends had a strength that was comparable to a chicken meat reference (50–100 kPa) but weaker than their counterparts with soy (220–300 kPa). Blends of pea protein-gluten show potential for preparing structured plant protein materials, but the application area might be different compared with potential applications of soy protein-gluten blends.

A classification scheme for interfacial mass transfer and the kinetics of aroma release
Weterings, Martijn ; Bodnár, Igor ; Boom, Remko M. ; Beyrer, Michael - \ 2019
Trends in Food Science and Technology (2019). - ISSN 0924-2244
Air water mass transfer - Aroma classification - Aroma release dynamics - Flavor release - Food modelling - food processing - Interfacial mass transfer

Background: The study of aroma release has gained popularity in food science. Nowadays, experiments become increasingly more complex. However, an application of theories on mass transfer, which may help to better explain the results, is lagging behind on these developments. Scope and approach: The goal of this review is to get together, in a concise way, the state of the art on fundamental knowledge of mass transfer in aroma release plus creating an extension of theory with a comprehensible classification that is useful for food scientists. The existing mathematical model is simplified and points that have received little attention are identified. Key findings and conclusions: An overview of experimental studies that focus on the influence of viscosity on aroma release show that there is heterogeneity in results and no consensus exists on the influence of viscosity. Such heterogeneity may be better understood with the effects of mass transfer. These effects are summarized by describing three implications based on non-proportional relationships between the partition coefficient and (A)the overall mass transfer coefficient, (B)the depletion and saturation time-scales, and (C)the peak value of the aroma concentration in the head space. A classification scheme is made to enable food scientists and technologists to apply the complex description in shorter and simpler terms that can be communicated and compared more easily. The scheme depends on a classification in two dimensions based on a thermodynamic factor, the partition coefficient, and a kinetic factor which divides aroma's and experiments into four different classes.

Agroforestry - klimaatneutraal voedsel produceren? : Plant je een boom dan plant je duurzaamheid
Blok, Alice ; Veluw, C. van - \ 2019
Ekoland (2019)1. - ISSN 0926-9142 - p. 62 - 63.
Hydrosocial territories, agro-export and water scarcity : capitalist territorial transformations and water governance in Peru’s coastal valleys
Damonte, Gerardo ; Boelens, Rutgerd - \ 2019
Water International 44 (2019)2. - ISSN 0250-8060 - p. 206 - 223.
agro-export - food security - hydrosocial territory - Ica - Peru - rural-urban relationships - Water governance

In recent decades, an agro-export boom has deeply transformed Peru’s coastal valleys, resulting in dramatic territorial changes and social inequality in the Ica Valley. This article explains how politico-economic and socio-institutional forces have triggered the emergence of a new ‘hydrosocial territory’, transforming the Ica Valley into a virtual-water extraction zone that produces luxury export crops for the North and China. In addition, it shows how these territorial reconfigurations have led to ecological damage, water scarcity and increasing rural–urban inequality sustained by a hegemonic development discourse that supports agribusiness-elite territorial dominance and discourages social unrest.

Eerste robottrekker actief in de polderklei
Veldhuisen, Bram - \ 2019
Maltodextrin promotes calcium caseinate fibre formation through air inclusion
Wang, Zhaojun ; Dekkers, Birgit L. ; Boom, Remko ; Goot, Atze Jan van der - \ 2019
Food Hydrocolloids 95 (2019). - ISSN 0268-005X - p. 143 - 151.
Air bubble - Anisotropy - Calcium caseinate - Fibrous appearance - Maltodextrin

Commercial calcium caseinate is available as spray-dried and roller-dried powder. Shearing a dense spray-dried calcium caseinate dispersion gives rise to a fibrous material, whereas shearing dense roller-dried calcium caseinate yields a layered material with only slight anisotropy in mechanical strength. The addition of a polysaccharide phase in a continuous protein phase may lead to formation of fibrous structures after shearing, which is hypothesized to be a result of the elongation and orientation of the dispersed polysaccharide domains. We report the effect of the addition of maltodextrin to roller-dried calcium caseinate on structure formation. The strength of the material increased with the addition of maltodextrin, which is partly caused by the withdrawal of water from the caseinate phase towards the maltodextrin phase, leading to a higher local caseinate concentration. The anisotropy of fracture stress and fracture strain were enhanced with up to 5 wt% maltodextrin. The effect of maltodextrin on the mechanical anisotropy and fibrous appearance could be ascribed to the greater air incorporation as a result of the presence of maltodextrin.

A systematic analysis on tomato powder quality prepared by four conductive drying technologies
Qiu, Jun ; Acharya, Parag ; Jacobs, Doris M. ; Boom, Remko M. ; Schutyser, Maarten A.I. - \ 2019
Innovative Food Science and Emerging Technologies 54 (2019). - ISSN 1466-8564 - p. 103 - 112.
Agitated thin film drying - Colour - Drum drying - Flavour properties - Lycopersicum esculentum - Refractance window drying

Four pilot-scale conductive dryers, namely a vacuum drum dryer (VDD), a drum dryer (DD), an agitated thin film dryer (ATFD) and a refractance window dryer (RWD), were used to dry tomato puree. Drying induced colour differences between the reconstituted puree and the original puree and strongly affected the volatile and non-volatile profiles of the powders. Principal component analysis (PCA) identified four separated groups corresponding to the different drying methods, indicating that the drying methods caused significant variance in compound profiles. Subsequently, pairwise comparison of different dried powders was performed by partial least square discriminant analysis (PLS-DA). This resulted in a selection of discriminative volatile and non-volatile markers. RWD and VDD produced powders with high volatile markers that may be related to aroma retention. Conversely, DD dried products contained more non-volatile markers that can be related to taste perception. ATFD processed powders had a lower level of discriminant compounds. Industrial relevance: Tomato products are frequently thermally processed and dehydrated. However, processing negatively affects the sensory quality of tomato products. In this study, four conductive drying processes, i.e. vacuum drum drying (VDD), drum drying (DD), agitated thin film drying (ATFD) and refractance window drying (RWD) were studied for being energy-efficient drying methods, while suitable for mild (e.g. due to the reduced pressure) drying of pastes and slurries, such as tomato puree. The pilot-scale drying experiments and subsequent statistical analyses of results on quality markers contributed to unravel the impact of the different conductive drying technologies on tomato powder quality. This study may be considered a starting point for selection of conductive drying technologies for the efficient production of high quality tomato powders and other vegetable powders.

The role of viscosity in morphology development during single droplet drying
Both, E.M. ; Siemons, I. ; Boom, R.M. ; Schutyser, M.A.I. - \ 2019
Food Hydrocolloids 94 (2019). - ISSN 0268-005X - p. 510 - 518.

Particle morphology influences the final quality of a powdered product. However, the mechanisms behind morphology formation are not completely understood yet. In this study particle morphology is linked to rheological properties of the concentrated liquid formulations at high concentration. Shear rate sweeps showed jamming of the whey protein at concentrations of ~50% (w/w), whereas maltodextrin remained liquid-like up to concentrations of ~70% (w/w). Morphology development of the latter components during single droplet drying showed that it could be influenced by altering initial droplet size and dry matter content. If droplets had a high initial dry matter (50% (w/w) morphology development started immediately, and the formed morphology could be explained by the rheological behavior of the mixture at that concentration. This indicated that measuring the rheological properties at high concentrations can provide insight in morphology development. Gaining insight on morphology development will eventually lead to higher quality powdered products.

Mild conductive drying of foods
Qiu, Jun - \ 2019
Wageningen University. Promotor(en): M.A.I. Schutyser; R.M. Boom. - Wageningen : Wageningen University - ISBN 9789463435796 - 169
Oligosaccharides fractionation cascades with 3 outlet streams
Rizki, Zulhaj ; Janssen, Anja E.M. ; Boom, Remko M. ; Padt, Albert van der - \ 2019
Separation and Purification Technology 221 (2019). - ISSN 1383-5866 - p. 183 - 194.
Membrane cascades - Modelling - Nanofiltration - Oligosaccharides

Fructooligosaccharides (FOS) were fractionated using nanofiltration cascades. Instead of creating one product and a residual stream, we report on configurations that create 3 separate product streams rich in: (1) monosaccharides (DP1), (2) DP3 and (3) DP ≥ 5. We developed a modular system allowing different operating pressures and membrane types at each stage. Two possible alternative configurations were assessed for a 3-stage cascade both experimentally and via simulation. The simulation was performed using a steady state model and was in a good agreement with the experimental data. Using the simulation model, the system was optimized towards 4 and 5 stage cascades. All designs were evaluated based on the purities and yields of 3 components of interest in the corresponding product streams. Selecting the correct set up, the cascade was able to reach maximum purity of monosaccharides to 66 wt% (from 9 wt%), DP3 to 33 wt% (from 24 wt%) and DP ≥ 5 to 54 wt% (from 34 wt%). Increasing the number of stages improved the maximum purities of the 3 fractions. However, a fifth stage did not increase the purification and the best purities were found using 4-stage rather than 5-stage cascades.

Polyelectrolyte-activated carbon composite electrodes for inverted membrane capacitive deionization (iMCDI)
Fritz, Pina A. ; Boom, R.M. ; Schroen, K. - \ 2019
Separation and Purification Technology 220 (2019). - ISSN 1383-5866 - p. 145 - 151.
Carbon electrodes - Desalination - Exergy analysis - Inverted capacitive deionization - Ion exchange membranes - Membrane capacitive deionization - Polyelectrolyte - Polymers

A new way of desalination using capacitive deionization (CDI) technology is by inverting the potential profile (inverted capacitive deionization iCDI). This means ions adsorb to the electrodes at 0 V and desorb when biasing the electrodes to larger potential differences. Previously, this operation was achieved by preparing electrode materials with anionic and cationic surface charges. Here we show, as a novelty, that an inverted CDI operation is also possible with conventional activated carbon electrodes when used in combination with ion exchange membranes (inverted membrane capacitive deionization iMCDI). Further we show that, the salt separation could be increased to 5.2 mg/g using 0 V for ion loading and −1.5 V for regeneration of polyelectrolyte-activated carbon composite electrodes. These are made with a water soluble styrene butadiene rubber binder and positively (poly(diallyldimethyl-ammoniumchloride)) and negatively charged (polystyrene sulfonate) polyelectrolytes and used in combination with ion exchange membranes. This leads to increased separation performance, and exergy efficiency, whereas cumulative exergy loss values remain low, indicating promising resource use efficiencies, competitive with conventional membrane capacitive deionization (MCDI).

Fine ultrafiltration of concentrated oligosaccharide solutions – Hydration and pore size distribution effects
Aguirre Montesdeoca, Victor ; Janssen, Anja E.M. ; Boom, R.M. ; Padt, A. van der - \ 2019
Journal of Membrane Science 580 (2019). - ISSN 0376-7388 - p. 161 - 176.
High concentration - Hydration - Maxwell-Stefan equations - Oligosaccharides - Pore size distribution

The effects of high concentration in the fine ultrafiltration of a solution of oligosaccharides were investigated both experimentally and using a mass transfer model based on the Maxwell-Stefan equations. At high concentrations, negative retentions were found for the smaller sugars, which cannot be ascribed to effects of ionic interaction, membrane adsorption or fouling. Instead, the behaviour could be quantitatively described by incorporating the effects of the thermodynamic non-ideality of the solutions and the effects of the pore size distribution. Experiments were performed to validate the model using as feed an oligosaccharide mixture with a concentration up to a 35% w/w. The model predictions allows the identification of an optimum feed concentration at which the efficiency of the separation is maximized. The results show that the fine ultrafiltration of sugars can be well described and predicted when taking into account the relevant thermodynamic interactions, the membrane pore size distribution and pressure effects.

Arabinoxylans-enriched fractions : From dry fractionation of wheat bran to the investigation on bread baking performance
Zhang, Lu ; Boven, Anneloes van; Mulder, Jorinde ; Grandia, Jeroen ; Chen, Xiao Dong ; Boom, Remko M. ; Schutyser, Maarten A.I. - \ 2019
Journal of Cereal Science 87 (2019). - ISSN 0733-5210 - p. 1 - 8.
Arabinoxylans - Bread baking - Dry fractionation - Valorization

Arabinoxylans- (AX-) enriched fractions were separated from wheat bran by dry fractionation and utilized for fiber fortification in bread. The obtained AX-enriched fractions (AXF) contained 39.2–55.8% arabinoxylans (dry basis). To produce bread with various AX-fortification levels, wheat flour was partially replaced with AXF in the recipe, i.e., 2%, 5% and 10% of flour weight. Results indicate 10% AX fortification led to decreased specific volume, harder and coarser crumb and darker color of bread, while 2% and 5% showed no significant influence. Next, the bread recipe was adjusted based on Farinograph water absorption and the AXF was pre-soaked in water (with or without xylanase) at 40 C for 16 h before dough mixing. The recipe and process adjustment reduced the detrimental effects of a high-level AX-fortification on bread quality. Bread with 10% AXF showed comparable quality properties as the control and its fiber content (11.75% dry basis) was found twice higher than the control (5.48% dry basis). However, usage of xylanase did not further improve the bread quality under tested conditions. In conclusion, this study shows that AX-enriched fractions from wheat bran have valorization potential for application in food.

Simultaneous Silicon Oxide Growth and Electrophoretic Deposition of Graphene Oxide
Fritz, Pina A. ; Lange, Stefanie C. ; Giesbers, Marcel ; Zuilhof, Han ; Boom, Remko M. ; Schroën, C.G.P.H. - \ 2019
Langmuir 35 (2019)10. - ISSN 0743-7463 - p. 3717 - 3723.

During electrophoretic deposition of graphene oxide (GO) sheets on silicon substrates, not only deposition but also simultaneous anodic oxidation of the silicon substrate takes place, leading to a three-layered material. Scanning electron microscopy images reveal the presence of GO sheets on the silicon substrate, and this is also confirmed by X-ray photoelectron spectroscopy (XPS), albeit that the carbon portion increases with increasing emission angle, hinting at a thin carbon layer. With increasing applied potential and increasing conductivity of the GO solution, the carbon signal decreases, whereas the overall thickness of the added layer formed on top of the silicon substrate increases. Through XPS spectra in which the Si 2p peaks shifted under those conditions to 103-104 eV, we were able to conclude that significant amounts of oxygen are present, indicative of the formation of an oxide layer. This leads us to conclude that GO can be deposited using electrophoretic deposition, but that at the same time, silicon is oxidized, which may overshadow effects previously assigned to GO deposition.

Modelling ultrafiltration performance by integrating local (critical) fluxes along the membrane length
Aguirre-Montesdeoca, Victor ; Janssen, Anja E.M. ; Padt, A. Van der; Boom, R.M. - \ 2019
Journal of Membrane Science 578 (2019). - ISSN 0376-7388 - p. 111 - 125.
Gel layer - Local critical flux - Maxwell-Stefan - Non-idealities - Protein ultrafiltration

Despite the vast number of studies on the understanding and estimation of the permeate flux in ultrafiltration, most of them base their estimations on either one or another mechanism, without pointing out a clear ‘bridge’ between them. The aim of this paper is to assess these mechanisms on the determination of the permeate flux, using as feed a multicomponent mixture of BSA, NaCl and H 2 O. Maxwell-Stefan Equations expressed as function of the components' volume fractions were used for an easier consideration of the non-idealities of the system. These non-idealities (hydration, adsorption, electrical interactions and volume exclusion) were critical in the local fluxes calculation, for which an increase in the thickness of the boundary layer along the filtration channel was considered. The developed model proved to be suitable for the estimation of fluxes lower than the limiting flux. Since the non-idealities of the system can be calculated along the concentration polarization layer, no extra information on the protein diffusivity was needed. Additionally, the fact that the model includes all the components from the solution offers the possibility of including the rejection of the accompanying ions in the calculations.

Understanding the role of air and protein phase on mechanical anisotropy of calcium caseinate fibers
Wang, Zhaojun ; Tian, Bei ; Boom, R.M. ; Goot, A.J. van der - \ 2019
Food Research International 121 (2019). - ISSN 0963-9969 - p. 862 - 869.
Calcium caseinate dispersions can be transformed into anisotropic, fibrous materials using the concept of shear-induced structuring. The aim of this study is to further investigate the relative importance of air bubbles and protein on the mechanical anisotropy of calcium caseinate material. In this study, the effect of air on mechanical anisotropy of these fibrous materials was described with a load-bearing model, with the void fraction, and the bubble length and width as input parameters. The anisotropy of the protein phase was estimated using materials obtained from deaerated dispersions after shearing at different shear rates. We concluded that the deformation of air bubbles can only partly explain the mechanical anisotropy; the anisotropy of the protein phase is more important. Based on all results, we further concluded that the anisotropy of the protein phase was affected by the air bubbles present during the structuring process. This effect was explained by locally higher shear rate in the protein matrix during the structuring process.
Ultrafiltration of non-spherical molecules
Aguirre Montesdeoca, Victor ; Bakker, Jaap ; Boom, R.M. ; Janssen, Anja E.M. ; Padt, A. van der - \ 2019
Journal of Membrane Science 570-571 (2019). - ISSN 0376-7388 - p. 322 - 332.
Capsule-shaped molecules - Elongated molecules - Hydration of sugars - Oligosaccharides - Pore size distribution

Information about the sizes of the solute molecules and membrane pores is needed to estimate solute rejection in filtration processes. Molecules are normally regarded as spheres, and the Stokes radius is commonly used to represent their molecular size. However, many molecules used in food and pharma processes are oligomers or polymers which are strongly elongated; therefore, considering them spherical affects the accuracy of the model predictions. We here adapt the so-called Steric Pore Model to a more realistic representation of the transfer of rigid elongated molecules into and through ultrafiltration membrane pores. To do so, sugars with different degree of polymerization were used as model molecules. They were considered to be capsule-shaped to facilitate their size estimation. In order to represent the system as accurately as possible, the effect of hydration on the sugars size was included, and the membrane pore size distribution was estimated based on rejection data. It was demonstrated that considering these molecules to be capsule-shaped instead of spherical generates better predictions over the entire rejection spectrum using a unique pore size distribution. Additionally, this capsular geometry lets us simplify the calculations, making the estimation of the rejection straightforward.

Corrigendum to ‘Revisiting the enzymatic kinetics of pepsin using isothermal titration calorimetry’
Luo, Qi ; Chen, Dongxin ; Boom, Remko M. ; Janssen, Anja E.M. - \ 2019
Food Chemistry 278 (2019). - ISSN 0308-8146 - 1 p.

The authors regret that the wrong unit was reported for the BSA solution, which should be 300 μM instead of 300 mM. It appears in two places: 1. In the paragraph after Eq. (5); 2. In the caption of Fig. 1. The authors would like to apologise for any inconvenience caused.

Analysis and modeling of enhanced green fluorescent protein diffusivity in whey protein gels
Luo, Qi ; Sewalt, Erik ; Borst, Jan Willem ; Westphal, Adrie H. ; Boom, Remko M. ; Janssen, Anja E.M. - \ 2019
Food Research International 120 (2019). - ISSN 0963-9969 - p. 449 - 455.
Diffusion - FCS - Gastric digestion - GFP - Modeling - Pepsin - Whey protein gel

During gastric digestion, hydrolysis of proteins by pepsin contributes largely to the breakdown of protein-rich food. We hypothesized that the effect of pepsin is limited by its diffusivity, which is co-determined by the food structure and the local pH in the food during digestion. To investigate the principle mechanism of enzyme diffusion in food matrices, we used enhanced green fluorescent protein (EGFP) as probe to study the diffusivity of proteins in whey protein isolate gels, using fluorescence correlation spectroscopy (FCS). Gels made with different ionic strength showed distinctive elastic moduli but did not show differences in diffusivity of EGFP. Some models for diffusion in hydrogels yield good description of the obtained data, and can approximate the enzyme diffusion in diverse food matrices. However, the enzyme pepsin is more complicated than the probe EGFP, to yield more accurate predictions, electrostatic and enzyme-substrate interaction also need to be considered.

The Influence of Starch and Fibre on In Vitro Protein Digestibility of Dry Fractionated Quinoa Seed (Riobamba Variety)
Opazo-Navarrete, Mauricio ; Tagle Freire, Danny ; Boom, Remko M. ; Janssen, Anja E.M. - \ 2019
Food Biophysics 14 (2019)1. - ISSN 1557-1858 - p. 49 - 59.
In vitro gastric digestion - Quinoa fibre - Quinoa protein - Quinoa starch

The in vitro gastric digestibility of the quinoa variety Riobamba was investigated, especially the influence of the quinoa matrix. Dry-fractionated quinoa protein concentrate, which is just milled and sieved, was much better digestible than the same concentrate that was reconstituted from wet fractionated quinoa protein isolate, quinoa starch isolate, and quinoa fibre isolate. In the reconstituted concentrate, the presence of quinoa starch and fibre next to quinoa protein reduces its in vitro gastric digestibility significantly. However, the effect of starch is partially counteracted if the fibre is also present. While the effects of starch and fibre separately can be understood from the decrease of the accessibility for pepsin to hydrolyse proteins, due to the hydrated starch and fibre, we suspect that the synergistic effect of starch and fibre may be due to a relative reduction of the hydration of starch due to the presence of the also strongly hydrating fibre. We concluded that the presence of starch and fibre decreases the protein in vitro gastric digestibility. Therefore, the presence of fibre partially countered the decreased of the protein digestibility of starch. Heating of the matrices to 120 °C generally resulted in much lower digestion rates, due to extensive aggregation of the protein.

Dynamic flavor release from chewing gum : Mechanisms of release
Hinderink, Emma B.A. ; Avison, Shane ; Boom, Remko ; Bodnár, Igor - \ 2019
Food Research International 116 (2019). - ISSN 0963-9969 - p. 717 - 723.
APCI-MS - Artificial mouth - Chewing gum - Flavor release - Food physics

Dynamic flavor release curves from chewing gum were measured using an Artificial Mouth coupled to the AFFIRM®. A flavor distribution model for chewing gum is proposed, where flavor is present as droplets in both the hydrophilic (water-soluble) and the hydrophobic (water insoluble) parts of the chewing gum and as molecularly dissolved in the hydrophobic part of the gum. During mastication, the flavor droplets in the water-soluble phase are released and responsible for an initial burst release. The flavor droplets captured in the gum-base are pushed towards the interface by mastication and are responsible for the subsequent release. The flavor molecules dissolved in the gum-base, released by diffusion, are only responsible for the release at very long time scales. It was found that the oil-water partition constant is an important parameter to explain the flavor release, where hydrophobic components show slower and longer release, while more hydrophilic components show more burst release.

Agitated thin-film drying of foods
Qiu, J. ; Boom, R.M. ; Schutyser, M.A.I. - \ 2019
Drying Technology 37 (2019)6. - ISSN 0737-3937 - p. 735 - 744.
Agitated thin-film drying (ATFD) has been proposed for efficient and mild drying of viscous liquid foods, pastes or pureed foods. We report a study on the influence of product and process parameters on ATFD. During ATFD of spinach leaf slurries, the wall temperature mainly affected the specific evaporation rate, while the absolute evaporation rate was proportional to the feed rate. The fact that blade rotation speed had limited effect on the drying rate suggested that the process is limited by heat transfer through the wall. ATFD is especially suited for slurries that show relatively limited sticky behavior during drying and liquid–solid phase transition with corresponding brittle viscoelastic behavior. This was demonstrated by drying juices from tomato and bell pepper, giving poor results, and by drying solutions from whey protein isolate (WPI) and sucrose, which could be successfully dried.
Evaluation of titanium dioxide and chromic oxide as digestibility markers in ponies fed alfalfa hay in relation to marker dosing frequency
Schaafstra, F.J.W.C. ; Doorn, D.A. van; Schonewille, J.T. ; Boom, R. Van Den; Verschuur, M. ; Blok, M.C. ; Hendriks, W.H. - \ 2019
Animal 13 (2019)4. - ISSN 1751-7311 - p. 702 - 708.
apparent digestibility - CrO - equines - TiO - total faeces collection

In equines, Cr2O3 is widely accepted as an indigestible marker, but there are health concerns regarding the carcinogenic properties of Cr2O3. Recently, TiO2 has been suggested to be an alternative digestibility marker in equines. However, a comparison between Cr2O3 and TiO2 has not been made in equines. Six Welsh pony geldings (initial BW: 254±3 kg; 7 years of age) fed chopped alfalfa hay were used to evaluate the use of TiO2 (Ti) and Cr2O3 (Cr) as markers for calculating apparent digestibility and to investigate the effect of frequency of marker administration on the measurement of digestibility values. Diets contained 4.65 kg dry matter (DM) chopped alfalfa hay supplemented with minerals, vitamins, TiO2 (3.3 g Ti/day) and Cr2O3 (3.2 g Cr/day). Ponies were dosed with either 3.3 g Ti and 3.2 g Cr once daily (DF1) or with 1.65 g Ti and 1.60 g Cr twice daily (DF2). After adaptation to the diets and procedures for 14 days, voluntary voided faeces were collected quantitatively over 7 days and analysed for moisture, ash, Ti and Cr. Apparent total tract DM digestibility (DMD) and organic matter digestibility (OMD) were calculated using the total faecal collection (TFC) and marker method (Ti and Cr). The overall mean cumulative faecal recovery of Cr and Ti (as % of intake) were 102.0% and 96.6%, respectively. Mean daily faecal recoveries of Cr as well as of Ti were not different (P=0.323; P=0.808, respectively) between treatments. Overall daily faecal recovery of Cr differed (P=0.019) from 100% when the marker was dosed once daily, whereas overall daily faecal recovery was similar to 100% for both administration frequencies when Ti was used as a marker. For both markers, the coefficient of variation of the mean faecal marker recovery between horses was lower when the markers were administrated twice per day. Across treatments, cumulative DMD and OMD estimated with Ti were similar (P=0.345; P=0.418, respectively) compared with those values determined by TFC method. When Cr was used, the calculated cumulative DMD tended (P=0.097) to be greater compared with those estimated with TFC, and cumulative OMD values were overestimated (P=0.013). Orally supplemented Ti recovery in the faeces of ponies fed chopped alfalfa hay with Ti administered once or twice daily was close to 100%, making it the preferred marker for digestibility trials in equines.

Air bubbles in calcium caseinate fibrous material enhances anisotropy
Wang, Zhaojun ; Tian, Bei ; Boom, Remko ; Goot, Atze Jan van der - \ 2019
Food Hydrocolloids 87 (2019). - ISSN 0268-005X - p. 497 - 505.
Air bubble - Anisotropy - Fibrous material - Mechanical property - Microstructure

Dense calcium caseinate dispersions can be transformed into hierarchically fibrous structures by shear deformation. This transformation can be attributed to the intrinsic properties of calcium caseinate. Depending on the dispersion preparation method, a certain amount of air gets entrapped in the sheared protein matrix. Although anisotropy is obtained in the absence of entrapped air, the fibrous appearance and mechanical anisotropy of the calcium caseinate materials are more pronounced with dispersed air present. The presence of air induces the protein fibers to be arranged in microscale bundles, and the fracture strain and stress in the parallel direction are larger compared with the material without air. The effects can be understood from the alignment of the fibers in the parallel direction, providing strain energy dissipation. This study shows that creation of anisotropy is the result of interactions between multiple phases.

Conductive thin film drying kinetics relevant to drum drying
Qiu, J. ; Kloosterboer, Koen ; Guo, Yang ; Boom, R.M. ; Schutyser, M.A.I. - \ 2019
Journal of Food Engineering 242 (2019). - ISSN 0260-8774 - p. 68 - 75.
Direct assessment of the kinetics of drum drying operation has been a difficult task as the mass and temperature profiles are hard to monitor. Still, developing better understanding of conductive drying would help to identify new operating windows for this technology. The drying kinetics was investigated by drying maltodextrin and starch suspensions with a novel custom-built laboratory-scale apparatus, which allows on-line monitoring of mass and temperatures. During drying, three separate periods were identified: the heating, the boiling and the conductive drying (declining rate) periods. The duration of the initial heating period was proportional to the film thickness and was responsible for a relatively small amount of water evaporated due to natural convection. During the boiling period, the drying rate kept constant while bubble formation impeded the heat transfer. Larger bubbles were observed for starch suspensions due to its viscoelastic properties. Thus, large temperature gradients between the heating pan and the film were observed for starch suspensions. During the conductive drying period, the initial amount of dry solids per surface area determines the drying rate as it determines the thickness of the semi-moist layer subjected to conductive drying. Application of a thin film is preferred to avoid boiling, especially at increasing solids content. This situation also better approaches double drum drying processes, where boiling occurs in the pool and conductive drying occurs on the drum.
Hot money, cold beer: Navigating the vanilla and rosewood export economies in northeastern Madagascar
Zhu, Annah - \ 2018
American Ethnologist 45 (2018)2. - ISSN 0094-0496 - p. 253 - 267.

Since 2000 northeastern Madagascar's subsistence-based communities have registered record profits thanks to a boom in vanilla and rosewood exports. Yet, rather than saving or investing these returns, much of the local earnings were spent in “hot money” sprees on cold beer, gambling, and other forms of immediate consumption. Far from being illogical or unproductive, hot-money spending and other practices associated with export economies help local communities navigate the volatility of global markets and domesticate foreign demands. Although these tactics come from the margins of global capitalism, they represent an acute cultural expression of some of the most sophisticated dynamics found at its core. [export economies, money, tactics, globalization, consumption, vanilla, rosewood, Madagascar].

CCDC 1858109: Experimental Crystal Structure Determination
Keisar, Hodaya ; Ruiter, Graham de; Velders, A.H. ; Milko, Petr ; Gulino, Antonino ; Evmenenko, Guennadi ; Shimon, Linda J.W. ; Diskin-Posner, Yael ; Lahav, Michal ; Boom, Milko E. van der - \ 2018
PIHQEF : fac-tris{4-methyl-4'-[2-(pyridin-4-yl)ethenyl]-2,2'-bipyridine}-osmium bis(hexafluorophosphate) benzene toluene unknown solvate
CCDC 1858110: Experimental Crystal Structure Determination
Keisar, Hodaya ; Ruiter, Graham de; Velders, A.H. ; Milko, Petr ; Gulino, Antonino ; Evmenenko, Guennadi ; Shimon, Linda J.W. ; Diskin-Posner, Yael ; Lahav, Michal ; Boom, Milko E. van der - \ 2018
PIHQIJ : mer-tris{4-methyl-4'-[2-(pyridin-4-yl)ethenyl]-2,2'-bipyridine}-osmium bis(hexafluorophosphate) unknown solvate
CCDC 1858108: Experimental Crystal Structure Determination
Keisar, Hodaya ; Ruiter, Graham de; Velders, A.H. ; Milko, Petr ; Gulino, Antonino ; Evmenenko, Guennadi ; Shimon, Linda J.W. ; Lahav, Michal ; Boom, Milko E. van der - \ 2018
PIHQAB : tris{4-methyl-4'-[2-(pyridin-4-yl)ethenyl]-2,2'-bipyridine}-ruthenium bis(hexafluorophosphate) unknown solvate
Mukusi boom groeit trager
Kruijt, Bart - \ 2018
Intracellular trehalose accumulation in probiotics during freeze- and spray drying
Vaessen, E.M.J. ; Besten, H.M.W. den; Boom, R.M. ; Schutyser, M.A.I. - \ 2018
Protein enrichment of defatted soy bean flour by fine milling and electrostatic separation
Xing, Qinhui ; Wit, M. de; Kyriakopoulou, K. ; Boom, R.M. ; Schutyser, M.A.I. - \ 2018
Quantifying the effect of air and protein on mechanical anisotropy of calcium caseinate fiber
Wang, Zhaojun ; Boom, R.M. ; Goot, A.J. van der - \ 2018
Investigating the variance of downwind spray deposits
Holterman, H.J. - \ 2018
In: International Advances in Pesticide Application. - Warwick UK : Association of Applied Biologists Warwick Enterprise Park (Aspects of Applied Biology ) - p. 309 - 315.
bed sprayer - optimizing distribution - simulation - model - patternator - field trials - boom movements - spray deposits - variance - simulations
For bed-grown crops, ideally the spray is applied evenly to the bed only, while no spray should be applied onto the paths between the beds. Usually these criteria cannot be fulfilled easily. The current study describes the development and use of a model to design adequate set-ups of nozzles on a sprayer boom optimized for bed-grown crops. Spray patterns of various single nozzles at different boom heights have been measured on a patternator. The model combines these spray patterns while varying nozzle types, nozzle spacing and the position and angling of end nozzles. Examples are given for designs using Lechler Varioselect fourfold nozzle bodies to find optimal solutions for beds with widths between 1.1 and 1.5 m and boom heights of 0.2 to 0.6 m above the crop, while being able to apply different dose rates depending on crop canopy height. A large number of potential set-ups are simulated, but only relatively few meet the requirements that can be defined by the user.
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