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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    Electrostatic separation for functional food ingredient production
    Wang, J. - \ 2016
    Wageningen University. Promotor(en): Maarten Schutyser, co-promotor(en): Remko Boom. - Wageningen : Wageningen University - ISBN 9789462576513 - 176
    particles - fractionation - separation - electrostatic separation - sieving - nitrogen - polystyrenes - wheat gluten - arabinoxylans - starch - milling - lupinus - rice bran - food - experiments - deeltjes - fractionering - scheiding - elektrostatische scheiding - zeven (activiteit) - stikstof - polystyrenen - tarwegluten - arabinoxylanen - zetmeel - maling - lupinus - rijstzemelen - voedsel - experimenten


    Dry fractionation is a promising alternative to wet extraction processes for production of food ingredients, since it uses hardly any water, consumes less energy and retains the native functionality of the ingredients. It combines milling and dry separation to enrich agro-materials in specific components such as protein. Electrostatic separation recently emerged as a novel dry separation process and it relies on electrostatic forces for separation. Though the potential of electrostatic separation to fractionate agro-materials has been demonstrated, the effectiveness in terms of purity and yield and the influence of process parameters on charging and separation of food ingredients have not yet been systematically studied. Therefore, the objective of this thesis was to gain better understanding of the charging and separation behaviour of model and agro-materials, provide insight in the critical factors for successful electrostatic separation and explore the potential of this separation method to different agro-materials.

    The charging step is critical to the effectiveness of electrostatic separation and is influenced by many factors. Chapter 2 presents characterization of the charging behaviour of single-component model particles in nitrogen gas flowing through aluminium tubes, using a lab-scale electrostatic separator. Polystyrene particles and wheat gluten were used as model particles. Higher gas velocities led to a higher specific charge by increasing the normal component of impact velocity. Smaller particles gained more specific charge than larger ones because of their higher surface to volume ratio and their sensitivity towards gas flow pattern changes. Longer charging tube lengths allowed more contact between the particles and the wall and therefore resulted in higher specific charge. The relative humidity of the nitrogen gas flow within the range 0 – 60% had no influence on the charging behaviour of both model particles.

    Chapter 3 demonstrates the potential of applying electrostatic separation to enrich arabinoxylans from wheat bran with the same lab-scale electrostatic separator. A combination of larger particle size, higher gas velocity and shorter charging tube was preferred for separation, because it sufficiently charged the particles while agglomeration was minimized. Electrostatic separation with the optimum setting achieved a similar enrichment in arabinoxylans (from 23% to 30% dry matter basis) as sieving does. However, the combination of electrostatic separation and sieving further improved the enrichment and resulted in a fraction with an arabinoxylans content of 43% dry matter basis, which is around the maximum achievable purity that can be reached by dry fractionation.

    To allow better defined charging and separation experiments, a bench-scale electrostatic separator was designed and constructed. With this custom-built separator, the charging and separation of model mixtures prepared from wheat gluten and starch were studied in chapter 4. The net charge of gluten-starch mixtures was not simply the sum of the charge of the two individual components, indicating that particle-particle interactions play an important role. We hypothesized that the formation of agglomerates between oppositely charged particles negatively influenced separation, which was supported by the fact that the dispersibility for mixtures of the two components was lower compared to that of individual components. We found that during electrostatic separation of mixtures, it is important to find the optimal condition that provides sufficient charge to charges, but avoids agglomeration between oppositely charged particles. This could be achieved by the combination of lower dosing rate and higher gas flow rate.

    Chapter 5 reports on dry fractionation by combining milling and electrostatic separation with the custom-built bench-scale separator, providing an alternative to wet extraction of protein from lupine seeds. Relatively coarse milling was preferred because it disclosed sufficient protein bodies from the matrix, while avoiding poor dispersibility of the powder due to its very fine particle size. With the optimal settings of single-step electrostatic separation, a fraction with 57.3 g/100 g dry solids could be obtained. The protein content was further improved to 65.0% dry matter basis after two more separation steps, which is 15% higher than obtained by air classification. The yield of the protein enriched fraction was further increased by recycling the fractions from the filter bags, but this was accompanied by a decrease in protein content and vice versa. A significant shift towards better yield and purities was achieved by re-milling the flour that was not collected on the electrodes. A final fraction with a protein content of 65.1% dry matter basis and a yield of 6% was obtained, which recovered 10% of the protein in the original flour.

    Chapter 6 explores the possibility of enriching dietary fibre from defatted rice bran by dry fractionation, where the custom-built bench-scale electrostatic separator was used. All three tested separation routes produced fibre-enriched fractions with similar yield (20 – 21 % of the milled flour) and fibre content (67 – 68 % dry matter basis), which recovered 42 – 48 % of the fibre from the original flour. The enriched fractions obtained by a two-step electrostatic separation process contained more small particles compared to the other two, which resulted in different functional properties. Compared to the total dietary fibre extracted by the enzymatic-gravimetric method, the enriched fractions by dry fractionation had a similar water retention capacity and oil binding capacity. This suggests that the fibre-enriched fractions by dry fractionation can be applied in foods and provide similar technological properties and physiological effects as the wet-extracted dietary fibre does.

    Chapter 7 concludes the thesis with a general discussion on the main findings, based on which two schemes for protein enrichment and fibre enrichment were proposed. Subsequently the challenges to achieve a successful electrostatic separation for agro-material and up-scaling are discussed. Finally, the chapter ends with an outlook on future research.

    This thesis provided insight in the key factors for successful electrostatic separation. It demonstrated the potential of applying this separation method for functional ingredient production from different agro-materials and also gave directions for further improvement and scaling-up.

    Met scheiding minder mestafvoer en lagere kunstmestkosten
    Evers, A.G. ; Galama, P.J. - \ 2016
    V-focus 2016 (2016)1. - ISSN 1574-1575 - p. 38 - 39.
    mestverwerking - kunstmeststoffen - agrarische bedrijfsvoering - scheiding - melkveehouderij - intensieve veehouderij - kosten-batenanalyse - kostenbeheersing - manure treatment - fertilizers - farm management - separation - dairy farming - intensive livestock farming - cost benefit analysis - cost control
    Toepassen van mestscheiding kan bij melkveehouders die veel mest moeten afvoeren een hoger inkomen opleveren. Besparing op kosten voor mestafvoer is mogelijk omdat de dikke fractie meer mineralen bevat dan drijfmest. Ook blijft er meer werkzame stikstof en kali uit dierlijke mest op het bedrijf, zodat minder kunstmestaankoop nodig is. In dit artikel is voor een intensief melkveebedrijf berekend hoeveel bespaard kan worden bij verschillende scheidingsrendementen en prijzen voor mestscheiding en -afzet.
    Production of mineral concentrates from animal manure using reverse osmosis : monitoring of pilot plants in 2012-2014
    Hoeksma, P. ; Buisonjé, F.E. de - \ 2015
    Wageningen : Wageningen UR Livestock Research (Livestock Research report 858) - 21
    livestock - animal manures - manure treatment - slurries - reverse osmosis - separation - vee - dierlijke meststoffen - mestverwerking - drijfmest - omgekeerde osmose - scheiding
    From 2009 to 2011 the agricultural, economic and environmental effects of the production and use of mineral concentrates, produced from animal slurry, were studied. Part of the study was the monitoring of the 8 participating full-scale (pilot) plants to assess the chemical composition of the half products and the end products of the process. In 2012 - 2014 the monitoring programme was continued with 9 pilot plants. In this programme additional data from the pilot plants were collected on the chemical composition of the raw slurry and the end products. Samples from these process streams were analysed on dry matter, volatile solids and the main nutrients N, P and K. The raw material of 8 pilot plants was pig slurry only. One plant used effluent from a biogas plant mixed with pig slurry as a feedstock.
    Nascheiden van verpakkingsglas uit gemengd huishoudelijk restafval : rapportage van een technische haalbaarheidsstudie
    Thoden van Velzen, E.U. - \ 2015
    Wageningen : Wageningen UR - Food & Biobased Research - ISBN 9789462575301 - 29
    recycling - afvalbeheer - scheiding - scheidingstechnologie - glas - haalbaarheidsstudies - afvalverwerking - recycling - waste management - separation - separation technology - glass - feasibility studies - waste treatment
    Het recyclingpercentage voor verpakkingsglas is voor 2012 door Nedvang vastgesteld op 71% en voor 2013 op 79%, terwijl de Nederlandse overheid streeft naar een percentage van 90%. [Nedvang 2012 en Nedvang 2013] Ten einde dit percentage te verhogen, is Nedvang begonnen met een publiciteitscampagne “Glas in ‘t Bakkie” en heeft zij opdracht gegeven voor deze verkennende studie naar de mogelijkheden om glas uit huisvuil na te scheiden.
    Complex coacervates and microgels for emulsions : robust, responsive, reversible
    Monteillet, H.J.M. - \ 2015
    Wageningen University. Promotor(en): Frans Leermakers, co-promotor(en): Mieke Kleijn; Joris Sprakel. - Wageningen : Wageningen University - ISBN 9789462574526 - 147
    emulsies - gels - stabilisatie - elektrolyten - scheiding - emulsions - gels - stabilization - electrolytes - separation

    The use of ionic liquids (ILs) as replacement of organic solvents in liquid-liquid extractions has shown great promise due to their low volatility, flammability and toxicity, tunable solvency to a wide variety of extractable compounds and mild- ness to delicate compounds such as biomolecules for pharmaceutical applications. However, the efficiency of extractions using ionic liquids is limited as the inher- ently high viscosity of ILs slows down the mass transfer. Increasing the interfacial area between the immiscible phases is an efficient way to increase the efficiency of liquid extractions; typically done by formulating emulsions, dispersions of fluid droplets suspended in a second immiscible continuous phase. While strategies to formulate stable emulsions from conventional apolar solvents, such as aliphatic or halogenated oils, in water are abundant, the peculiar properties of ionic liquids requires the exploration of new strategies to formulate stable emulsions; for exam- ple, common surfactant stabilization leads to rapid Ostwald ripening due to the inherent water solubility of many ionic liquids. Moreover, while the intended ionic liquid-in-water emulsions must be stable at operating temperatures for prolonged times, it should be possible to break the emulsion on-demand to recover the ex- tracted product. Also, the interfacial layer used for stabilization should not hinder the transfer of the intended product to the droplet phase. To increase the sus- tainability of extraction processes, recovery of both ionic liquid and stabilizer for re-use in a subsequent extraction step is highly desired. Aimed to establish new ways of stabilizing emulsions in general, and ionic liquid emulsions in specific, this thesis describes investigations into two novel stabilizers: interfacial electrostatic complexes and soft colloidal microgels.

    In Part I, we focussed on how oppositely charged polyelectrolytes interact and form complexes across an oil-water interface. In Chapter 2, we demonstrated a new method for emulsion stabilization, in which electrostatic complexes formed across a liquid interface between two polyelectrolytes, one dissolved in the aqueous phase, the other in the oil phase. Using tensiometry we followed the polyelectrolyte adsorption at the oil-water interface; while the presence of either polyelectrolyte alone leads to interfacial depletion, the presence of both species leads to strong adsorption at the interface. This was further confirmed using confocal fluorescence microscopy where the colocalization of both species at the interface was observed; the strong overlap of peak intensities at the interface suggests a strongly intermixed layer. Using this approach, we prepared stable emulsions, which could be reversibly broken and reformed by simple pH and salt triggers. Interestingly, oil-in-water but also water-in-oil emulsions could be produced. This is the first demonstration of using selective associative phase separation to stabilize a segregating system.

    The experimental results triggered questions on the nature of the interfacial layer, which was too thin to be ascertained in detail using microscopy. Therefore,

    we turned to self-consistent field (SCF) modelling to develop a deeper understand- ing of the structure and thermodynamics of this interfacially-templated complex- ation, as presented in Chapter 3. In analogy with our experiments, we use the Scheutjens-Fleer lattice method to consider mixtures of two solvents, an anionic oil- soluble polyelectrolyte, a cationic water-soluble polyelectrolyte, their counterions and additional indifferent monomeric electrolyte. We first considered a two-phase system with only one polyelectrolyte and salt. We found that the polyelectrolyte adsorption depends on its concentration. For polyelectrolyte concentrations lower than the salt concentration, the polyelectrolyte is depleted from the oil-water in- terface while for polyelectrolyte concentrations higher than the salt concentration, the polyelectrolyte adsorbs at this interface. This transition from depletion to ad- sorption originates from a competition between small ion and macroion adsorption, governed by the overall ionic strength. Upon introducing a second polyelectrolyte in the immiscible second solvent, a new phase spontaneously formed at the inter- face between oil and water. Surprisingly, our calculations showed that ion release entropy is not the driving force for complexation, as it often is in bulk complex coacervation; co-assembly is governed by enthalpic contributions. This is due to the solvent-selectivity of the polyelectrolytes in this scenario, which leads to low solvent content in the coacervate layer, hence close approach of the opposite charges resulting in a relatively large Coulombic enthalpy. Finally, we examined systems with asymmetric composition of the two polyelectrolytes within the same theoret- ical approach. This revealed an unusual pseudo-partial wetting scenario, due to interactions occurring at different length scales. When the electrostatic interactions are short ranged, the microscopically thin wetting film transitions to a mesoscopic thin film. However, charges built up on either side of the coacervate layer restrict the growth of the film to macroscopic dimensions. In our experiments we observe that the coacervate layer becomes turbid over time, suggesting structures on op- tical length scales, much larger than the typical dimensions of the polymer coils. This may be explained by the pseudo-partial wetting scenario due to the coexis- tence of a mesoscopic film with interfacial liquid droplets nucleating due to thermal fluctuations.

    In the second part of this thesis, Part II, we studied the adsorption and or- ganization of colloidal microgels at a variety of liquid interfaces. These soft and deformable hydrogel colloids have gained a lot of interest in recent years due to their excellent ability to stabilize emulsions. As a result of their polymeric nature and osmotic equilibrium with the bulk solution, microgels exhibit an interesting duality between colloidal properties and polymeric behaviour. Microscopic research into their interfacial behaviour is often made difficult as they offer little refractive index contrast to the continuous phase and covalent attachment of fluorophores is known

    to drastically alter their interactions. To overcome this problem, in Chapter 4 we introduce composite microgels, in which a solid fluorescent core is embedded in the centre of a soft and tunable hydrogel shell, thereby decoupling the imaging features of these microgels with the tunability of their softness, size, solvent-responsivity and interactions. We surprisingly find that while these microgels adsorb sponta- neously, without any energy barrier which is usual for the Pickering adsorption of micron-sized colloids, their anchoring at the liquid interface is irreversibly strong. Due to the high adsorption energy, saturated interfacial layers of these microgels show mild compression of the particles, increasing their packing density at the cost of elastic deformation. Moreover, we showed that these particles are able to stabilize a wide variety of oil-water interfaces and due to their spontaneous adsorp- tion allow the fabrication of Pickering droplets using microfluidics, which is usually hindered by the adsorption barrier for solid particles.

    In Chapter 5, we arrive at the ultimate aim of this thesis, i.e. to provide proof- of-concept for a fully sustainable extraction process based on IL-in-water emulsions. We first show how microgels are able to create emulsions of a wide variety of ILs in water and prevent their Ostwald ripening, resulting in extended stability at room temperature. Upon heating and applying centrifugal compression, the emulsion can be rapidly broken, with all of the microgels returning the aqueous phase which can then be re-used in a secondary extraction step. Finally, we demonstrated that through the use of a paramagnetic ionic liquid, the concentration and breaking step can be performed without energy input with a simple permanent magnet, rendering the process sustainable from start to end.

    Finally, in Chapter 6, we studied the adsorption and conformation of these composite microgels at solid-liquid interfaces. We first demonstrate how conven- tional sample preparation for studying microgels at solid interfaces, often involving a drying step, induces strong sample artefacts. We therefore developed a method to study the adsorption and conformation of microgels in-situ using liquid-state confocal and atomic force microscopy. Our results showed how the packing density for particle adsorption is governed by particle-particle repulsion, as adsorption en- ergies are typically very high. Using Quantitative Nanomechanical Mapping, the spatially-resolved mechanical analysis of surfaces using atomic force microscopy, we find that the degree of spreading of microgels during adsorption at a solid interface is governed by adsorption energy and particle softness as expected. This leads us to conclude that the unique properties of microgels at interfaces results from a subtle interplay between adsorption energy and internal elasticity.

    Functionality-driven fractionation of lupin seeds
    Berghout, J.A.M. - \ 2015
    Wageningen University. Promotor(en): Remko Boom, co-promotor(en): Atze Jan van der Goot. - Wageningen : Wageningen University - ISBN 9789462572287 - 165
    lupinen - eiwitisolaten - fractionering - scheiding - mechanische eigenschappen - voedselproducten - lupins - protein isolates - fractionation - separation - mechanical properties - food products
    Functionality-driven fractionation of lupin seeds

    The growth in the world population requires an increase in the production of protein-rich foods from plant-based materials. Lupin seeds have potential to become a novel plant protein source for food products because they are rich in protein (about 37 wt%) and they can be grown in moderate temperature climates as in north-western Europe. Besides a high protein content, lupin seeds are rich in dietary fibres (soluble and insoluble), contain about 7-10 wt% oil, and are low in starch. To optimally use the proteins present in lupin, a fractionation process has to be developed. For other legumes, refining of protein is usually performed through wet fractionation techniques. However, wet fractionation methods are resource-intensive, as a result of which the potential reduction in environmental impact when using plant-based materials for foods decreases.

    The aim of this thesis is to obtain understanding of the production of functional, protein-rich material from lupin seeds in a more efficient manner. In this thesis, it is shown that focus on functionality rather than purity can lead to simplified fractionation processes, which is a concept referred to as functionality-driven fractionation (Figure 1). The influence of these simplifications on protein functionality and on physical and chemical stability of the protein isolates was explored. Furthermore, we performed a sustainability assessment of fractionation processes, from which we concluded that focus on a dry product with high purity has a large impact on energy use. In case of lupin, avoiding the oil extraction step as well as the drying step could lead to large gains in sustainability.

    Figure 1 Upper scheme: conventional ingredient production and product processing route, focusing on protein and yield. Lower scheme: novel approach, focusing on functionality and sustainability.

    The results presented in this thesis provide steps towards more sustainable production of functional fractions for food applications obtained with simplified fractionation processes. This work provides future perspectives for functionality-driven fractionation processes that may be extended to other legumes and pulses as well. This approach leads to the development of ingredients and fractions of seeds and legumes that can be used for plant-based food products.

    Star+ : monovergisting mest van vleesvarkens
    Kasper, G.J. ; Verdoes, N. ; Classens, P.J.A.M. - \ 2015
    V-focus 12 (2015)1. - ISSN 1574-1575 - p. 29 - 31.
    varkenshouderij - vleesvee - vleesproductie - varkensstallen - innovaties - varkensmest - mestverwerking - scheiding - mestvergisting - biogas - beoordeling - pig farming - beef cattle - meat production - pig housing - innovations - pig manure - manure treatment - separation - manure fermentation - biogas - assessment
    De versgeproduceerde mest en de vermorste snijmais uit de innovatieve Star+- stal zijn onderzocht op samenstelling en gaspotentie. Daarbij lag de nadruk op de werking van de mestbanden, het optimale drogestofgehalte van de ingevoerde mest, de kwaliteit en kwantiteit van het biogas en de stabiliteit van het vergistingsproces.
    Technische haalbaarheid van het RMS bio-raffinage concept = Technical feasibility of the RMS bio-refinery concept
    Hoeksma, P. ; Buisonjé, F.E. de; Melse, R.W. - \ 2014
    Wageningen : Wageningen UR Livestock Research (Livestock Research rapport 791) - 27
    mestverwerking - mestvergisting - co-vergisting - scheiding - bioraffinage - biogas - haalbaarheidsstudies - biobased economy - manure treatment - manure fermentation - co-fermentation - separation - biorefinery - biogas - feasibility studies - biobased economy
    RMS heeft aangegeven dat zij een bioraffinageconcept hebben ontwikkeld waarmee mest en organische reststromen kunnen worden verwerkt tot een aantal waardevolle producten en waarmee tevens wordt ingespeeld op de plicht voor veehouders om een deel van het mestoverschot te verwerken en op de wens van de Nederlandse overheid om meer groen gas te produceren. Het doel van deze studie is de technische haalbaarheid van het RMS concept en de verwachtte emissies aan broeikasgassen, ammoniak, geur en fijnstof vast te stellen. Het doel is tevens om vast te stellen welke synergie-effecten mogelijk zijn bij realisatie van het RMS concept op de locatie Greenport Venlo, bijvoorbeeld door het inzetten in het bioraffinageproces van beschikbare organische reststromen en het benutten van CO2 op deze locatie.
    Enzyme-assisted separation and hydrolysis of gluten : options for intensification
    Hardt, N.A. - \ 2014
    Wageningen University. Promotor(en): Remko Boom, co-promotor(en): Atze Jan van der Goot. - Wageningen : Wageningen University - ISBN 9789462571228 - 165
    gluten - graaneiwitten - scheiding - enzymen - hydrolyse - voedseltechniek - watergehalte - watergebruik - gluten - cereal proteins - separation - enzymes - hydrolysis - food engineering - water content - water use

    The food industry is one of the largest water consumers in industry. Using large amounts of water, however, is undesirable from an environmental point of view because freshwater is a scarce good in many regions of the world and undesirable from an economic point of view because high water loadings require high amounts of energy for dehydration and signify high amounts of wastewater. This thesis uses wheat, one of the major crops in human nutrition, to study the influence of low water concentrations on two relevant processes in wheat processing:

    The separation of starch and gluten. Separation is often performed using 10–15 L water per kg dry matter. Instead, starch and gluten can be separated by inducing shear using 0.5 L water per kg dry matter. In this thesis we make use of xylanases to hydrolyze arabinoxylan present in wheat, thereby releasing the water associated with arabinoxylan. In doing so, shear-induced starch–gluten separation is performed at even more concentrated conditions. The influence of arabinoxylan hydrolysis in wheat dough at low water contents is studied in chapters 2 and 3.The hydrolysis of gluten. Hydrolysis is currently performed using approximately 4 L water per kg dry mater. In this thesis we perform gluten hydrolysis at solid concentrations of up to 70%, thereby investigating the changes in the hydrolysis reaction and the functionality of the resulting hydrolysates. Wheat gluten hydrolysis at low water contents is studied in chapters 4, 5 and 6.

    This thesis consists of seven chapters. Chapter 1 gives a general introduction of the thesis. In chapter 2, wheat dough rheology at low water contents below 40% and the influence of xylanases is studied. A reduction in water content from 43.5–44.8% (representing optimal Farinograph water absorption) to 34% (the lowest water content where a dough forms) results in a non-linear increase in the dough consistency, elastic modulus G’, and a decrease in the maximum creep compliance Jc,max of 1–2 orders of magnitude. Addition of xylanases has the same effect on the dough consistency, G’ and Jc,max as an increase in water content of 2–5% (on a water basis). Tan δ is hardly and Jel not influenced by xylanase addition showing that the influence of xylanases on the mechanism of hydration is negligible.

    In chapter 3, shear-induced starch–gluten separation with the help of xylanases is studied at water contents from 43.5% to 34%. Addition of xylanases at the standard water content of 43.5% results in a slurry without any separation. As a result, lower water contents are used. At water contents below 40%, the local formation of gluten clusters is observed with and without xylanases addition. However, opposed to shear-induced separation at 43.5% water without xylanase, the gluten patches do not migrate to the center of the cone because of the densely packed dough and an inhomogeneity in the shear field. Nevertheless, gluten clusters can be concentrated up to 60% (N×5.7) protein. Similar to chapter 2, xylanase addition allows water savings of 3–5% (on a water basis).

    Chapter 4 introduces enzymatic wheat gluten hydrolysis at high solid concentrations and describes the influence of high-solid hydrolysis on the resulting functional properties of the gluten hydrolysates. Wheat gluten can be hydrolyzed at solid concentrations of up to 60% (w/w). The water solubility of the dried hydrolysates is independent of the solid concentration during hydrolysis, just like the foam stabilizing properties at degrees of hydrolysis (DH%) below 8% At DH% above 8%, high solid concentrations even increase the foam stabilizing properties of the resulting hydrolysates, which is related to the presence of more peptides with a molecular mass >25 kDa. Furthermore, an increase in solid concentration results in an increase of the volumetric productivity.

    Despite the advantages of high-solid gluten hydrolysis, we also observe lower hydrolysis rates in high-solid gluten hydrolysis compared to low-solid gluten hydrolysis at constant enzyme-to-substrate ratios. The factors causing this hydrolysis rate limitation are investigated in chapter 5. It is shown that enzyme inhibition, the water activity, and mass transfer limitations do not impede the hydrolysis up to 50% solids. However, the hydrolysis rate limitation can be explained by a second-order enzyme auto-inactivation rate along with the higher enzyme concentrations used. At solid concentrations above 50%, the hydrolysis rate further decreases due to mass transfer limitations. Furthermore, the addition of enzyme after 24 h at high solid concentrations hardly increases the DH%, suggesting that the maximum attainable DH% decreases at high solid concentrations. This DH% limitation is explained by a reduced enzyme activity due to a decline in water activity.

    Based on the findings in chapters 4 and 5, a direct hydrolysis of gluten present in wheat flour at high solid concentrations is investigated in chapter 6, thereby omitting the starch–gluten separation. At a constant protein concentration, the protease activity is higher for wheat flour hydrolysis (at 40% total solids) than for vital wheat gluten hydrolysis (at 7.2% total solids) in the initial 6 h of hydrolysis, despite the high starch content in wheat flour and consequently lower water content. This is related to the starch granules in wheat flour, preventing the aggregation of (native) gluten. At wheat flour concentrations above 50% and for longer reaction times the positive effect of starch disappears. This is explained by mass transfer limitations and reduced water activities in the wheat flour slurry or dough, respectively.

    Chapter 7 summarizes and generalizes the main findings of this thesis and compares the current status in starch–gluten separation and gluten hydrolysis with the concentrated separation and hydrolysis processes developed in this study. Water and energy savings of at least 50% are possible when separating and hydrolyzing at concentrated conditions. In the end, future prospects in high-solid wheat gluten hydrolysis are briefly discussed.

    Specific conversion of amino acids as a means for their separation
    Teng, Y. - \ 2014
    Wageningen University. Promotor(en): Johan Sanders, co-promotor(en): Elinor Scott. - Wageningen : Wageningen University - ISBN 9789462570658 - 205
    aminozuren - scheiding - elektrodialyse - conversie - chemicaliën uit biologische grondstoffen - onderzoek - biobased economy - amino acids - separation - electrodialysis - conversion - biobased chemicals - research - biobased economy
    Aminozuren (AZ) zijn interessante uitgangspunten voor stikstofhoudende (amine) chemicaliën. Zij kunnen gewonnen worden als mengsel uit de hydrolyse van potentieel goedkope eiwitten verkregen van de bijproducten van de biobrandstofproductie of agrarische en voedselafvalstromen. Echter, AZ verkregen van zulke bronnen bevinden zich in een mengsel. Hierdoor is een scheiding nodig om de individuele AZ te verkrijgen voor vervolgomzettingen en toepassingen. Electrodialyse (ED) is een veelbelovende scheidingsmethode die toegepast kan worden in continue modus en op grote schaal.
    Deterministic ratchets for larger-scale separation of suspensions
    Lubbersen, Y.S. - \ 2014
    Wageningen University. Promotor(en): Remko Boom, co-promotor(en): Maarten Schutyser. - Wageningen : Wageningen University - ISBN 9789461739155 - 136
    suspensies - scheiding - scheidingstechnologie - stroming - microfluidics - suspensions - separation - separation technology - flow - microfluidics

    Solid-liquid separation is a very common process operation in the chemical and food industry. Current technologies, such as membrane separation, consume large amounts of energy and water and often suffer from fouling issues. A novel, promising separation principle was identified for possible large scale application. This principle has been studied in microfluidic systems and employs so-called deterministic ratchets. Ratchet separationrelies on particle interactions with a series of obstacle arrays positioned in a flow field. Particles above a critical size are forced from their streamlines and migrate into another direction than the main flow direction. The objective of this thesis was to understand the mechanisms relevant for suspension separation with deterministic ratchets and to develop guidelines for the design of this technology at a larger scale. An up-scaled device was developed to investigate separation of model suspensions with larger particles (~101 - ~102 µm). Experiments at increasing volume particle fractions yielded final particle concentrations up to 12 v/v% without particle accumulation. The separation efficiency was discovered strongly influenced by the hydrodynamic conditions. High speed camera images and fluid flow simulations provided insight that a vortex pair developed behind obstacles and that inertial forces improved displacement behavior of particles. Different designs suitable for larger-scale application were evaluated. A mirrored (axisymmetric) obstacle array was found more effective in displacement of particles. Different designs were identified for cleaning as well as concentration applications. Finally, a simple, but effective sparse ratchet design is proposed by replacing full obstacle arrays by selected single lines of obstacles. The degree of sparseness is found a design parameter for accommodating differences in concentrations. Although the application of the principle is still challenging for smaller particle diameters (~100 - ~101 µm), this study shows that the principle of deterministic ratchet separation holds potential for larger-scale separation of suspensions.

    Werken met de dunne fractie : bekijk de mestketen
    Verloop, K. ; Hilhorst, G.J. - \ 2013
    Nieuwsbrief Koeien & Kansen 2013 (2013)39.
    melkveehouderij - dierlijke meststoffen - mestverwerking - scheiding - ammoniakemissie - stikstof - dairy farming - animal manures - manure treatment - separation - ammonia emission - nitrogen
    Koeien & Kansen heeft ervaring opgebouwd met het scheiden van mest in een dunne en een dikke fractie. De gedachte daarachter: de dunne fractie bevat meer minerale stikstof dan drijfmest en werkt daardoor sneller. De ervaringen zijn echter wisselend. Analyse van de mestketen geeft inzicht in de oorzaken.
    Verwerking van digestaat uit co-vergisting
    Hoeksma, P. - \ 2013
    Lelystad : WUR - ACRRES (PPO 564) - 26
    digestaat - co-vergisting - mestverwerking - verwerking - scheiding - compostering - algenteelt - biobased economy - digestate - co-fermentation - manure treatment - processing - separation - composting - algae culture - biobased economy
    Verwerking van digestaat en benutting van de toepassingsmogelijkheden van de eindproducten kan het economisch rendement van covergisters verbeteren, temeer als daarbij de restwarmte die vrijkomt bij de omzetting van biogas in elektriciteit wordt benut. In deze notitie worden beschikbare verwerkingstechnieken en mogelijke toepassingen van de verwerkingsproducten op een rij gezet.
    Emissies uit vleesvarkensstallen voorzien van een v-vormige mestband voor het gescheiden afvoeren van mest en urine = Emissions from a housing system for fattening pigs with a v-shaped manure belt for separated removal of faeces and urine
    Ellen, H.H. ; Hol, J.M.G. ; Mosquera Losada, J. ; Aarnink, A.J.A. - \ 2013
    Lelystad : Wageningen UR Livestock Research (Rapport / Wageningen UR Livestock Research 620) - 25
    varkenshouderij - vleesproductie - varkensmest - varkensstallen - drijfmest - scheiding - urine - meting - stankemissie - ammoniakemissie - methaan - fijn stof - distikstofmonoxide - pig farming - meat production - pig manure - pig housing - slurries - separation - urine - measurement - odour emission - ammonia emission - methane - particulate matter - nitrous oxide
    This study reports the emissions of ammonia, odour, fine dust (PM10 and PM2.5), methane and nitrous oxide from an animal house for fattening pigs provided with the Kempfarm system.
    Werking dunne fractie mest valt nog tegen
    Verloop, J. ; Geerts, R.H.E.M. ; Hilhorst, G.J. - \ 2013
    V-focus 10 (2013)2. - ISSN 1574-1575 - p. 28 - 29.
    melkveehouderij - mestresultaten - drijfmest - mestverwerking - scheiding - stikstof - ammoniakemissie - dairy farming - fattening performance - slurries - manure treatment - separation - nitrogen - ammonia emission
    Veldproeven op een aantal Koeien & Kansen-bedrijven wijzen uit dat de stikstofwerking van de dunne fractie van gescheiden mest niet duidelijk hoger is dan die van drijfmest. Mogelijk komt dit doordat het gehalte aan minerale stikstof in de dunne fractie niet hoog genoeg is. Een andere mogelijke oorzaak is een hogere emissie van ammoniak uit de dunne fractie. Wat kan de huidige praktijk hier nu mee? En hoe verder met het onderzoek naar mestscheiding?
    Gebruik van de dunne en dikke fractie van rundveemest getest op Koeien & Kansen-melkveebedrijven : scheidingsresultaten 2010 en 2011 en 2012
    Verloop, K. ; Geerts, R.H.E.M. ; Oenema, J. ; Hilhorst, G.J. ; Haan, M.H.A. de; Evers, A.G. - \ 2012
    Lelystad : Wageningen UR Livestock Research (Rapport / Koeien & Kansen nr. 69) - 65
    melkveehouderij - projecten - dierlijke meststoffen - mestverwerking - scheiding - mineralen - stikstof - fosfor - gebruikswaarde - ammoniakemissie - dairy farming - projects - animal manures - manure treatment - separation - minerals - nitrogen - phosphorus - use value - ammonia emission
    Dit rapport is het resultaat van onderzoek naar het landbouwkundige en milieukundige effect van mestscheiding op het melkveebedrijf en op de uitvoering van de bemesting met de scheidingsproducten. Het onderzoek is gericht op de vraag of mestscheiding op bedrijfsschaal uitvoerbaar is en bijdraagt aan betere benutting van mineralen uit dierlijke mest. Dit moet het mogelijk maken om de afvoer van mest en de afhankelijkheid van kunstmest stikstof te verminderen. Het onderzoek belicht verschillende aspecten van mestscheiding. Dit rapport gaat in op: 1. De benutting van stikstof (N) en fosfor (P) door gewassen; 2. Effecten op emissie van broeikasgassen en van ammoniak; 3. De economie van mestscheiding; en 4. Controleerbaarheid en handhaafbaarheid van mestscheiding op het bedrijf.
    Gebruik van de dunne en dikke fractie van rundveemest getest op Koeien & Kansenmelkveebedrijven
    Verloop, K. ; Geerts, R.H.E.M. ; Hilhorst, G.J. - \ 2011
    Lelystad : Wageningen UR Livestock Research (Rapport / Plant Research International nr. 466) - 30
    melkveehouderij - dierlijke meststoffen - scheiding - vloeibare meststoffen - bemesting - mineralenopname - stikstof - graslandbeheer - dairy farming - animal manures - separation - liquid manures - fertilizer application - mineral uptake - nitrogen - grassland management
    Op 5 ‘Koeien & Kansen voorloperbedrijven’ wordt onderzoek uitgevoerd naar mestscheiding. Een deel van het onderzoek gaat over de benutting van stikstof (N) uit drijfmest en de daarvan afgescheiden scheidingsproducten, de dunne en dikke fractie. Dit verslag geeft de resultaten van 2010 en 2011 weer betreffende de waargenomen benutting van stikstof in gewassen, met de nadruk op grasland, bij gebruik van de dunne en dikke fractie als meststof op melkveebedrijven. Het onderzoek is gericht op de vraag of mestscheiding op bedrijfsschaal uitvoerbaar is en bijdraagt aan betere benutting van mineralen uit dierlijke mest. Dit moet het mogelijk maken om de afvoer van mest en de afhankelijkheid van kunstmest stikstof te verminderen.
    Resource recovery from source separated domestic waste(water) streams; Full scale results
    Zeeman, G. ; Kujawa, K. - \ 2011
    Water Science and Technology 64 (2011)10. - ISSN 0273-1223 - p. 1987 - 1992.
    urine - scheiding - afvalwaterbehandeling - afvalverwerking - afvalhergebruik - nieuwe sanitatie - huishoudens - terugwinning - urine - separation - waste water treatment - waste treatment - waste utilization - new sanitation - households - recovery - phosphorus - nutrients - water
    A major fraction of nutrients emitted from households are originally present in only 1% of total wastewater volume. New sanitation concepts enable the recovery and reuse of these nutrients from feces and urine. Two possible sanitation concepts are presented, with varying degree of source separation leading to various recovery products. Separate vacuum collection and transport followed by anaerobic treatment of concentrated black water (BW) demonstrated on a scale of 32 houses preserve 7.6 g/N/p/d and 0.63 gP/p/d amounting to respectively 69 and 48% of the theoretically produced N and P in the household, and 95% of the retained P was shown to be recoverable via struvite precipitation. Reuse of the anaerobic sludge in agriculture can substantially increase the P recovery. Energy recovery in the form of biogas from anaerobic digestion of concentrated BW, fits well in new concepts of sustainable, zero energy buildings. Nutrient recovery from separately collected urine lowers the percentage of nutrient recovery in comparison with BW but can, on the other hand, often be implemented in existing sanitation concepts. Theoretically 11gN/p/d and 1.0 g P/p/d are produced with urine, of which 38–63 and 34–61% were recovered in practice on a scale of 8–160 inhabitants in Sweden. New sanitation concepts with resource recovery and reuse are being demonstrated worldwide and more and more experience is being gained.
    Gebruik van de dunne en dikke fractie van rundmest getest op Koeien & Kansen-melkveebedrijven : vooronderzoek
    Verloop, K. ; Hilhorst, G.J. - \ 2011
    Lelystad : Wageningen UR Livestock Research (Rapport / Koeien & Kansen nr. 62) - 47
    melkveehouderij - dierlijke meststoffen - mestverwerking - scheiding - scheidingstechnologie - drijfmest - stikstof - fosfaat - dairy farming - animal manures - manure treatment - separation - separation technology - slurries - nitrogen - phosphate
    De studie naar mestscheiding op vijf ‘Koeien & Kansen-bedrijven’ heeft tot doel om te onderzoeken wat de landbouwkundige en milieukundige effecten zijn van mestscheiding op bedrijfsschaal. Dit rapport is een voorverkenning van onderzoek naar gebruik van de dunne en dikke fractie als meststof op melkveebedrijven. Het heeft tot doel het ontwerp van een kader, het oriënteren op de mogelijkheden (wat is realiseerbaar?), het vinden van een werkwijze voor het maken van bemestingsplannen en het aanduiden van kritische en dus te monitoren punten.
    Gebruik van de dunne en dikke fractie van rundmest getest op Koeien & Kansen-melkveebedrijven : scheidingsresultaten 2010 en 2011
    Verloop, K. ; Hilhorst, G.J. - \ 2011
    Lelystad : Wageningen UR Livestock Research (Rapport / Plant Research International nr. 423) - 39
    melkveehouderij - dierlijke meststoffen - mestverwerking - scheiding - scheidingstechnologie - drijfmest - stikstof - fosfaat - dairy farming - animal manures - manure treatment - separation - separation technology - slurries - nitrogen - phosphate
    Dit rapport gaat over de scheidingsresultaten van 2010 en 2011, waargenomen in het onderzoek naar gebruik van de dunne en dikke fractie als meststof op melkveebedrijven. Het onderzoek wordt uitgevoerd op 5 ‘Koeien & Kansen testbedrijven’, te weten de bedrijven: Dekker (Zeewolde), De Kleijne (Landhorst), Pijnenborg-Van Kempen (Ysselsteyn), Post (Nieuweroord) en Van Wijk (Waardenburg). De scheiding wordt in de meeste gevallen uitgevoerd met een schroefpers en een centrifuge. Dit rapport geeft een overzicht van de scheidingsresultaten en beschrijft de verschillen met de verwachte resultaten zoals weergegeven in Verloop et al., 2011. Bovendien geeft het de ervaringen van melkveehouders met mestscheiding op bedrijfsschaal weer.
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