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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    Biomassa voor de circulaire economie : Alles wat je wilde weten over biomassa maar nooit durfde te vragen
    Groenestijn, Johan van; Harmsen, Paulien ; Bos, Harriëtte - \ 2019
    Wageningen : Wageningen Food & Biobased Research (Groene grondstoffen 23) - ISBN 9789463439541 - 100
    biobased economy - biomassa - bio-energie - verwerking - chemische technologie - diervoeding - compost - biobased economy - biomass - bioenergy - processing - chemical technology - animal nutrition - composts
    Nederland en de meeste andere landen willen het gebruik van koolstofhoudende fossiele grondstoffen zoals aardolie, steenkool en aardgas verminderen. De twee belangrijkste motivaties hiervoor zijn de klimaatproblematiek en de eindigheid van de voorraden van deze grondstoffen. Het gebruik van fossiele brandstoffen en kunststoffen die gemaakt zijn uit fossiele grondstoffen verandert het klimaat doordat na verbranding of na biologische afbraak koolstofdioxide vrijkomt dat zich ophoopt in de atmosfeer en daar het broeikaseffect versterkt. Een atmosfeer met een verhoogd gehalte aan koolstofdioxide houdt de warmte beter vast en verhoogt daardoor de temperatuur van de atmosfeer, zoals een broeikas dat doet. Sinds het jaar 1750, het begin van de industriële revolutie, is de koolstofdioxideconcentratie met 48% toegenomen en veel klimatologen gaan er vanuit dat dat de hoofdoorzaak is van de eveneens toegenomen temperatuur op aarde. Volgens hen zal deze temperatuursverhoging leiden tot een stijging van de zeespiegel en extremer weer (stormen, droogte, overstromingen).
    Lignocellulolytic capacities of Geobacillus thermodenitrificans: towards consolidated bioprocessing
    Daas, Martinus J.A. - \ 2017
    Wageningen University. Promotor(en): J. van der Oost; R. van Kranenburg. - Wageningen : Wageningen University - ISBN 9789463431644 - 180
    lactic acid - thermophiles - geobacillus - processing - bioenergy - melkzuur - thermofielen - geobacillus - verwerking - bio-energie

    The growing demand for consumables and energy, combined with increasing consciousness over environmental issues like global warming, faces us with the challenge to find alternatives for fossil resources. Alternative production methods for energy, like windmills, solar panels and hydroelectricity plants, are far developed and have become economically competitive to fossil resourcebased production processes. However, the production of many (bulk) chemicals and products is still dominated by the petroleum industry. One such chemical is lactic acid, a fermentation product of many bacteria and a compound that is gaining interest as a building block for poly lactic acid (PLA). PLA is a polymer used to produce bioplastics, and thereby provides an alternative to petroleumbased plastic production. As described in Chapter 1, economically feasible production of lactic acid is envisioned through consolidated bioprocessing (CBP). In a CBP process, pretreated lignocellulosic biomass is hydrolyzed to fermentable sugars and those sugars are subsequently fermented to desired product in one reaction vessel. The organism of choice for this hydrolyzation and fermentation is preferentially a thermophile, capable of enzyme production and lactic acid fermentation. Species from the genus Geobacillus have many of the desired characteristics, and in Chapter 2 we have enriched and isolated facultative anaerobic (hemi)cellulolytic Geobacillus strains from compost samples. By selecting for growth on both cellulose and xylan, 94 strains were isolated. Subsequent screening for lactic acid production was carried out from C6 and C5 sugar fermentations and a selection of the best lactic acid producers was made. The denitrifying Geobacillus thermodenitrificans T12 was selected for further research and was rendered genetically accessible with a transformation efficiency of 1.7×105 CFU/µg of plasmid DNA. In fermentations on a mixture of glucose and xylose, a total of 20.3 g of lactic acid was produced with a yield of 0.94 g product/g sugar consumed. In addition, we demonstrated that strain T12 is capable of direct conversion of beechwood xylan to mainly lactic acid in minimal media. Chapter 3 describes the genome sequencing and several features of G. thermodenitrificans T12. The genome of strain T12 consists of a 3.64 Mb chromosome and two plasmids of 59 kb and 56 kb. It has a total of 3.676 genes with an average genomic GC content of 48.7%. The T12 genome encodes a denitrification pathway, allowing for anaerobic respiration. The identity and localization of the responsible genes is similar to those of the denitrification pathways found in strain NG80-2. The host-defence systems present comprise a Type II and a Type III restriction-modification system, as well as a CRISPR-Cas Type II system that could potentially be exploited as a genome editing tool for thermophiles. Furthermore, the hemicellulose utilisation (HUS) locus of strain T12 appeared to have orthologues for all the genes that are present in strain T-6 except for the arabinan degradation cluster. Instead, the HUS locus of strain T12 contains genes for both an inositol and a pectate degradation pathway. The HUS-locus associated gene, GtxynA1, encodes an extracellular endoxylanase of strain T12, and belongs to the family 10 glycoside hydrolases (GH10). In Chapter 4, we describe the cloning, expression and characterization of GtXynA1. The recombinant endoxylanase was purified to homogeneity and showed activity between 40°C and 80°C, with an optimum activity at 60°C, while being active between pH 3.0 to 9.0 with an optimum at pH 6.0. Its thermal stability was high and GtXynA1 showed 85% residual activity after 1 h of incubation at 60°C. Highest activity was demonstrated towards wheat arabinoxylan (WAX), beechwood xylan (BeWX) and birchwood xylan (BiWX). GtXynA1 can degrade WAX and BeWX producing mainly xylobiose and xylotriose. To determine its mode of action, we compared the hydrolysis products generated by GtXynA1 with those from the well-characterized GH10 endoxylanase produced from Aspergillus awamori (AaXynA). The main difference in the mode of action between GtXynA1 and AaXynA on WAX is that GtXynA1 is less hindered by arabinosyl substituents and can therefore release shorter oligosaccharides. The extensive hydrolysis of branched xylans makes this enzyme particularly suited for the conversion of a broad range of lignocellulosic substrates.

    The enzymatic conversion of cellulose to glucose requires the synergistic action of three types of enzymes: exoglucanases, endoglucanases and β-glucosidases. The thermophilic, hemicellulolytic Geobacillus thermodenitrificans T12 was shown to be a potential candidate for CBP but lacks the desired endo and exoglucanases needed for the conversion of cellulose. In Chapter 5 we report the heterologous expression of endoglucanases and exoglucanases by G. thermodenitrificans T12, in an attempt to complement the enzymatic machinery of this strain and its suitability for consolidated bioprocessing. A metagenome screen was performed on the metagenome of 73 G. thermodenitrificans strains using HMM profiles of all known CAZy families that contain endo and/or exoglucanases. Two putative endoglucanases, GE39 and GE40, belonging to glucoside hydrolase family 5 were isolated and expressed in both E. coli and G. thermodenitrificans T12. Structure modeling of GE39 revealed a folding similar to a GH5 exo-1,3-βglucanase from S. cerevisiae. However, we determined GE39 to be a β-xylosidase having most activity towards p-nitrophenyl-β-dxylopyranoside. Structure modelling of GE40 revealed a protein architecture similar to a GH5 endoglucanase from B. halodurans, and its endoglucanase activity was confirmed by enzymatic analysis against 2-HE-cellulose, CM-cellulose and barley β-glucan. In addition, we successfully expressed the earlier characterized Geobacillus sp. 70PC53 endoglucanase celA and the C. thermocellum exoglucanase celK in strain G. thermodenitrificans T12. The native hemicellulolytic activity and the heterologous cellulolytic activity described in this research provide a good basis for the further development of Geobacillus thermodenitrificans T12 as a host for consolidated bioprocessing. In Chapter 6, we provided more insight in the genetic variation of the hemicellulolytic utilization cluster of G. thermodenitrificans. This variation is far greater than described before and gives ample opportunities for the further development of Geobacillus spp. for hemicellulose degradation. The production of cellulases in Geobacillus species is demonstrated to be successful, and we have expanded on that knowledge with the expression of both endo and exoglucanases from C. thermocellum. However, in line with previous studies, direct cellulose fermentation by geobacilli is not yet achieved, most likely due to insufficient cellulase production and/or secretion. With a rapidly expanding genetic toolbox for thermophiles, now including a thermostable Cas9, we expect that the successful development of Geobacillus spp. for consolidated bioprocessing is just a matter of time.

    Intracellular & extracellular lipolysis : regulation by the PPAR targets ANGPTL4 & HILPDA
    Dijk, Wieneke - \ 2016
    Wageningen University. Promotor(en): Sander Kersten. - Wageningen : Wageningen University - ISBN 9789462579460 - 248
    foams - foaming - milk products - processing - aggregates - casein - micelles - physical properties - schuim - schuimen - melkproducten - verwerking - bodemdeeltjes - caseïne - micellen - fysische eigenschappen

    The body efficiently stores energy in the form of triglyceride (fat) molecules. However, triglycerides cannot directly enter or exit our cells, but first need to be degraded to so-called fatty acids before moving in or out a cell. This degradation process, called lipolysis, is crucial for human physiology and is tightly regulated to prevent the accumulation of fats either within organs or within the bloodstream - hallmarks of diseases such as obesity and cardiovascular disease.

    To allow for uptake by underlying organs, triglycerides in the circulation are efficiently broken down by an enzyme called lipoprotein lipase (LPL) that sits in the bloodstream of multiple organs (extracellular lipolysis). In this thesis, we characterized a protein named angiopoietin-like 4 (ANGPTL4) that potently inhibits LPL and, thereby, inhibits the breakdown of triglycerides in the bloodstream. Our data show that by adjusting the tissue expression levels of ANGPTL4, different organs collaborate to ensure that triglycerides are distributed to organs in need of energy. Moreover, we uncovered that, in the fat tissue, ANGPTL4 starts to inhibit LPL before LPL arrives in the bloodstream. By preventing the arrival of LPL in the bloodstream, ANGPTL4 is capable of rapidly adjusting the rates of triglyceride degradation and the concomitant uptake of fatty acids from the circulation to the energy requirements of the underlying organ.

    To exit our cells, stored triglycerides, such as present in our fat tissue, need to be broken down to fatty acids. Subsequently, the released fatty acids can fuel other organs in need of energy. To further clarify the mechanisms underlying this process of intracellular lipolysis, we investigated the role of a promising new protein called HILPDA. Our data show, however, that loss of HILPDA did not impact the release of fatty acids from the fat tissue, while a high abundance of HILPDA only had a mild attenuating effect on the release of fatty acids. This suggests that HILPDA is not a major physiological regulator of intracellular lipolysis in fat cells.

    In conclusion, in this thesis, we have clarified the regulation of intracellular and extracellular lipolysis by studying the respective roles of the proteins ANGPTL4 and HILPDA. Such efforts are clinically relevant, as regulators of lipolysis are potential therapeutic targets to lower cardiovascular disease risk.

    The feasibility of direct processing of sugar beets in Slovenia: a quick scan
    Jongeneel, R.A. ; Smit, A.L. ; Bakker, Tom ; Jager, J.H. - \ 2015
    LEI Wageningen UR (Report / LEI Wageningen UR 2015-149) - ISBN 9789086157280 - 25
    sugarbeet - processing - arable farming - ethanol production - biofuels - economic viability - slovenia - cap - european union - biobased economy - suikerbieten - verwerking - akkerbouw - ethanolproductie - biobrandstoffen - economische haalbaarheid - slovenië - gemeenschappelijk landbouwbeleid - europese unie - biobased economy
    This study presents a quick scan of the economic feasibility of direct processing of sugar beet for ethanol production in Slovenia, using the Betaprocess technology. The outcome is that given the prices for sugar, sugar beets, ethanol and other relevant arable crops that are expected to prevail after the liberalisation of the EU’s sugar policy in 2017, direct processing of sugar beets is a profitable activity. This result is conditional on a number of requirements.
    Kinetic modelling of enzymatic starch hydrolysis
    Bednarska, K.A. - \ 2015
    Wageningen University. Promotor(en): Tiny van Boekel; Remko Boom, co-promotor(en): Anja Janssen. - Wageningen : Wageningen University - ISBN 9789462573086 - 159
    hydrolyse - enzymen - zetmeel - stochastische modellen - verwerking - hydrolysis - enzymes - starch - stochastic models - processing

    Kinetic modelling of enzymatic starch hydrolysis – a summary

    K.A. Bednarska

    The dissertation entitled ‘Kinetic modelling of enzymatic starch hydrolysis’ describes the enzymatic hydrolysis and kinetic modelling of liquefaction and saccharification of wheat starch. After the background information about the enzymes, the substrate and the basics of the model in the first chapter, we describe a model predicting the outcome of wheat starch liquefaction by α-amylase from Bacillus licheniformis at 50°C in chapter 2. We demonstrate the ability of the model to predict starch hydrolysis products larger than the oligosaccharides considered in the existing models. The model in its extended version follows all the products of wheat starch hydrolysis separately, and despite the quantitative differences, the qualitative predictions are satisfactory. We also show that the difference between the experimental and computed data might stem from the inaccuracy of the subsite map.

    In the following chapters the model is used to find a better description of the hydrolysis data at two temperatures (50°C and 80°C), by varying the energy values of the subsite map and evaluating the inhibition. We hypothesize that a subsite map that is based on the cleavage patterns of linear, short molecules does not account for the complexity of hydrolysis of amylopectin. The branched structure of amylopectin molecules influences the composition of the hydrolysis products by restricting the access to some of the bonds. The presence of branches creates steric obstacles for the enzyme. The used α-amylase has difficulties hydrolysing and accommodating α-(1,6)-glycosidic bonds, which imposes on the hydrolysis of the α-(1,4)-glycosidic bonds located in its proximity. On this basis, we analyse the subsite maps in detail and suggest which of the subsites are crucial when making predictions about the product composition of starch hydrolysates. On top of that we propose new subsite maps that allow a quantitative description of the experimental data.

    After the model was shown to work at different experimental conditions, we also test it at increased the dry matter content during wheat starch hydrolysis. We follow both the liquefaction by BLA and the saccharification process by glucoamylase from Aspergillus niger at low moisture content. The liquefaction model, is used to predict all of the products of wheat starch hydrolysis at higher dry matter contents (30-60 w/w%). The liquefaction model also creates the substrate matrices representing maltodextrins to be used in the saccharification model. The saccharification of liquefacts to glucose is followed with a new mechanistic model, also using the assumptions of the subsite theory. The saccharification model predicts all of the reaction products using the subsite maps of glucoamylase available in literature.

    The findings described in the thesis are summarized and put in context in the general discussion. We demonstrate how the parameters of the liquefaction model at low moisture contents were chosen. The outcomes of the model are also compared with the experimental data at 30-60 w/w%. Next, we test our liquefaction model with starch hydrolysis data at 5 and 60 w/w% taken from literature, to verify both the approach we used and the validity of the parameters we obtained in previous chapters. The method used to improve the subsite maps is also tested on another enzyme, Bacillus amyloliquefaciens α-amylase. After discussing the factors that influence saccharification at high dry matter contents, we conclude the chapter with describing the potential of stochastic modelling and its practical use.

    The making of quality : a technography of small-scale women's groups and a medium-scale firm processing oil palm in Ghana
    Adjei, B.E. - \ 2014
    Wageningen University. Promotor(en): Paul Richards, co-promotor(en): Sietze Vellema. - Wageningen : Wageningen University - ISBN 9789462571143 - 162
    palmoliën - kwaliteit - verwerking - vrouwen - groepen - kleine bedrijven - middelgrote bedrijven - agrobiodiversiteit - duurzaamheid (sustainability) - ghana - palm oils - quality - processing - women - groups - small businesses - medium sized businesses - agro-biodiversity - sustainability - ghana


    Palm oil is an important product in local diets and domestic markets in the South. The current attention for market quality standards and certification schemes in the palm oil sector has the risk to marginalise the role of palm oil in local food security and to direct public and private investments exclusively to industrial and export-oriented production systems. The rise of a variety of standards in the oil palm sector in recent times particularly the Roundtable for Sustainable Palm Oil (RSPO) has impacted on agricultural practices and the social and ecological environments of oil palm production worldwide. In this way, standards shape the way food provision is governed, with a consequence for how to organise production.

    This thesis was motivated by the dominance of a technological trajectory organised around hybrid oil palm varieties, the strong focus on standards as instruments for sustainable development, and the formation and inclusion of organised farmers in the Ghanaian oil palm sector. The widespread use of red palm oil in local diets, processed from Dura oil palm fruits, and the employment and income opportunities for grouped women are less present in policy documents and scholarly literature. Oil palm sector policy in Ghana is largely biased towards the use of the high yielding hybrid planting materials and industrial processing. This raises a question how small-scale processors are able to make quality red palm oil, which utilises the unique traits of Dura? Starting point for this thesis is the array of opportunities for employment and income generation, especially for small-scale processors in Ghana, grounded in the making of oil with specific quality traits from a specific oil palm (elaeis guineensis).

    The original assumption of the research was to explore whether a niche market for the specific traits of red palm oil, particularly in the diaspora, would offer new opportunities to combine sustainable livelihoods for women and the conservation of agro-biodiversity. Preliminary field work, however, showed that such a linear relationship does not exist. Hence, the research shifted attention to an important interface in the chain of red palm oil, namely the groups of women processing the fruits. The focus of the research shifted to first understand how women processors actually make this quality and how they organise around this process of material transformation. This is in line with the research program that takes a strong interest in developing a theory of practice, wherein the actual process of material transformation is linked to matters of social organisation, i.e. individual women working jointly in a group formation. This led to the question how the women’s groups processing oil palm organise and stay intact for longer periods (> 10 years), despite fluctuations in the availability of fruits, uncertainties in the market, and different social positions and organisational roles of the women members.

    The objective of the thesis was to investigate social organisation and technological choices in the practices of material transformation in small-scale palm oil processing, and to assess to what extent and in what ways these practices, grounded in changeful natural and socio-economic environments, are reshaped or constrained by public policy, quality standards and value chain governance. This thesis investigates the making of quality with the aim i) to unravel the interactions between social action and organisation and material transformation processes in the making of quality; ii) to examine how non-localised rules and routines (e.g. in public policy and chain governance) affect collective performance. The thesis adopted a case study around the performance of groups of women processing palm oil and how they performed the tasks of milling, cooking and sourcing practices. It is through the performance of such tasks that the groups relates to its social, the natural and institutional environments. The findings were generated by using a technographic line of inquiry to unravel the socio-technical and institutional arrangements in the making of palm oil.

    Contrasting the case study of how the women’s groups organise to perform the making of oil with the normative organisational model for organising value chains and production helped to put in context the observed threats posed by the market and policy environments.

    The introductory chapter introduces the palm oil, the oil palm sector, as well as the dominant role of women in small-scale processing. Next the thesis investigates how women organise and manoeuvre changeful natural and institutional environments in two empirical chapters (2&3). The thesis makes a shift to a meso level analysis of standards based on a single case study (chapter 4). The concluding chapter discusses the additional value of the main findings from separate empirical chapters and their theoretical implications and policy recommendation for the wider oil palm sector.

    Chapter 2: analyses everyday practices of the women’s groups, revealing how they organise to perform different tasks in processing. The practice of processing includes descriptions of how women join together in milling the fruits, ensure quality, and manage risks, transfer skill, techniques, and know-how leading to learning and inclusion of new members. The chapter questions why the women combines collectivity and individuality which underlies the performance of tasks and persist? It substantiate that the group form, structure and functioning responds to the making of quality. Consequently, group organisation is considered as a continuous process based on evolving practices rather than as an organisational fix based on technicalities and incentives. The case study reveals collection action as an emergent outcome which does not resemble more formal perspectives on how an organisation is supposed to work. The performance of tasks also links the groups to agro ecological conditions which are investigated in chapter 3.

    Chapter 3 investigates the stability of the groups in relation to seasonal fluctuation in the supply of fruits. It argues that group persistence lies in the capacity of the groups to manoeuvre changeful institutional and material environments within which they perform. The chapter provides insight into how the practice of processing is linked to agro-ecological conditions and the mixture of crops grown on the farms. It identifies strategies and arrangements used in sourcing by individual women within the groups and network relationships. It documents the different institutional arrangements for securing fruits all year round and how they are managed. The chapter shows how the differentiation within the groups provides the flexibility and capacity to handle fluctuation in raw material supply.

    A complementary focus of the research is on two processes that may enable or constrain collective performance. Chapter 4 analyses a case study of a medium-scale firm which processes palm oil for the local and the diaspora market. It argues that market standards may create a hidden imbalance in favour of better endowed (oil palm) firms while those with internal strength for developing products with unique qualities may be stifled. The chapter investigates how firm manages quality in the market, sourcing and cooking different recipes of palm oil of specific quality. The analytical question underlying this chapter is to unravel how firms respond to trade ad industrial standards. The data show that fluctuation in fruit supply required the use of different strategies to source both fruits and oil from other sources to ensure regular supply of product on the market. The evolving practices in cooking different recipes also required the use of skill, techniques, and know-how in processing to make palm oil with certain consistency in taste, colour, and texture that consumers require similar to the practices of the groups of women. The study shows that evolving practices in the making of quality palm oil may contradict prescribed standards. The case studies (2,3 &4) reveal diversity in the way firms and groups targeting different end use markets manage skilful tasks, use skill, tools and techniques which draws upon endogenous capabilities to manoeuvre changeful environments to make quality. The chapter opens a discussion on the RSPO, that its form of governance lacks the flexibility exhibited by the women’s groups and the firm to handle changeful environments in the making quality oil palm.

    Chapter 5 explores how small-scale groups continue to perform with regards to policies focusing on hybrid varieties and industrial production of palm oil. The chapter argues that policies which tend to rely strongly on single recipes, e.g. expansion of hybrids or certification may have a lower level of flexibility to handle unpredicted situations. The chapter substantiates this by re-visiting the original assumption of the thesis that the unique qualities of Dura will translate into its conservation. It shows that market-led strategies which primarily considers mono-cropping systems and aims to realise biodiversity conservation outside the boundaries of local production systems may constrain the capacity of farmers to navigate in changeful natural and economic conditions. It underscores preference for Dura in food preparation, threats to the conservation Dura, and the different configurations: based on small-scale processing embedded in diverse farming systems and agro-ecological conditions, which supports Dura conservation.

    The general discussion (Chapter 6) builds upon the main findings from the empirical to conclude that it is the diversity in groups, firms, and plant material that explains quality as an emergent property. It synthesises the technographic insights and findings and critically discusses the linear explanation of collective action. It shows why an evolutionary and processual perspective, related to task performance and materiality, should be brought into the discussion. This insight has important implication for methodologies, policies, and development interventions, which are more inclined to strive for uniform practices rather than building on the nitty-gritty details of the making of quality by small, female processors or medium, processing firms. The thesis relates the social analysis of performance and collectivity in the making of palm oil to the wider pattern of declining agro-biodiversity, and, accordingly, contributes to a broader discussion on organisational processes and management of development in agricultural food systems/ systems of food provision.

    Improving the quality of crude palm oil: transdisciplinary research on artisanal processing in Kwabibirem District, Ghana
    Osei-Amponsah, C. - \ 2013
    Wageningen University. Promotor(en): Leontine Visser; M.K. Abekoe, co-promotor(en): Tjeerd-Jan Stomph; O. Sakyi-Dawson. - Wageningen : Wageningen UR - ISBN 9789461737588 - 146
    palmoliën - kwaliteit - verbetering - verwerking - olieproducten - plattelandsontwikkeling - ghana - palm oils - quality - improvement - processing - oil products - rural development - ghana
    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.
    Afvoer en verwerking van N-rijke gewasresten, thema: duurzame mineralen BO-12.03-002-004
    Ruijter, F.J. de - \ 2011
    stikstof - verwerking - stikstofgehalte - gewasanalyse - afvoer - nitrogen - processing - nitrogen content - plant analysis - discharge
    Afvoeren van stikstofrijke gewasresten in het najaar verlaagt de nitraatuitspoeling. Na afvoer moeten de gewasresten op een goede manier verwerkt worden, zodat de verliezen niet op een andere plaats of in een andere vorm plaatsvinden. De hier beschreven studie richt zich op de meest geschikte methoden voor verwerking van afgevoerde gewasresten en kijkt naar de gehele keten: van afvoer t/m hergebruik
    Hydrolysis inhibition of complex biowaste
    Vasconcelos Fernandes, T. - \ 2010
    Wageningen University. Promotor(en): Jules van Lier, co-promotor(en): Grietje Zeeman. - [S.l.] : S.n. - ISBN 9789085856818 - 182
    agrarische afvalstoffen - dierlijke meststoffen - drijfmest - biomassa - hydrolyse - verwerking - anaërobe behandeling - anaërobe afbraak - afvalverwerking - biogas - biomassaconversie - agricultural wastes - animal manures - slurries - biomass - hydrolysis - processing - anaerobic treatment - anaerobic digestion - waste treatment - biogas - biomass conversion
    The increasing demand of renewable energy sources and reuse of wastes, challenges our society for better technological solutions for energy production. Co-digestion of agricultural biowaste, such as animal manure and plant residues, offers an interesting contribution to the renewable energy strategies. The biogas plants, where the complex substrates, such as agricultural biowaste, get converted into biogas, are then able to produce electricity and heat, which can be used in the farm and delivered to the main electricity grid. Moreover, due to its decentralised nature, the implementation of small-scale biogas plants can supply renewable energy to people without the need for large-scale infrastructural networks such as electricity grids, thereby solving part of the populations’ energy demands.
    The production of biogas from complex biowaste is rate-limited by the hydrolysis step of the anaerobic digestion process. However the hydrolysis step has been poorly described and not very well understood, resulting in non-optimized anaerobic digester volumes. Due to that, a review on the anaerobic hydrolysis step is in this thesis presented, together with ways to accelerate the hydrolysis, either by mitigating the revealed inhibiting compounds, by pre-treating difficultly hydrolysable substrates, or as is nowadays also applied, by adding hydrolytic enzymes to full scale biogas co-digestion plants.
    In this thesis two compounds were studied in terms of its inhibiting effect on hydrolysis: ammonia nitrogen and Humic Matter (HM). Ammonia nitrogen did not show an inhibiting effect on anaerobic hydrolysis. On the other hand Humic acids-like (HAL) and Fulvic acids-like (FAL) extracted from fesh cow manure and silage maize, and in this thesis extensively described in terms of its chemical characteristics, showed a strong inhibiting effect on the hydrolysis step.
    Plant matter is high in lignocellulosic biomass. Lignocellulosic biomass consists of lignin, which is resistant to anaerobic degradation, cellulose and hemicelluloses. Pre-treatment of plant material, is particularly important in order to increase biogas production during co-digestion of manure. Calcium hydroxide pre-treatment was shown, in this thesis, to improve the biodegradability of lignocellulosic biomass, especially for high lignin content substrates. Maleic acid generated the highest percentage of dissolved COD during pre-treatment, however its high market price makes it not so attractive as calcium hydroxyde.
    Enzyme addition has recently gained the attention of biogas plants’ operators in order to accelerate hydrolysis, however further research is needed.

    Celluloseplastics: eigenschappen en toepassingen
    Bolck, C.H. ; Bos, H.L. - \ 2010
    cellulose - verwerking - biobased economy - bioplastics - biopolymeren - cellulose - processing - biobased economy - bioplastics - biopolymers
    Deze info sheet geeft een overzicht van de herkomst en toepassingsmogelijkheden van bioplastics uit cellulose.
    Melk indikken op de boerderij
    Lenssinck, F.A.J. ; Poelarends, J.J. ; Vrielink, S. - \ 2009
    [Lelystad etc.] : Wageningen UR Livestock Research [etc.]
    melkveehouderij - melkvee - indikken (bulking) - verwerking - melk - dairy farming - dairy cattle - bulking - processing - milk
    Brochure met informatie over een project waarin het indikken van melk wordt onderzocht
    Development of starch-based materials
    Habeych Narvaez, E.A. - \ 2009
    Wageningen University. Promotor(en): Remko Boom, co-promotor(en): Atze Jan van der Goot. - [S.l. : S.n. - ISBN 9789085854333 - 144
    zetmeel - mechanische eigenschappen - fysicochemische eigenschappen - verwerking - polymeerchemie - biopolymeren - starch - mechanical properties - physicochemical properties - processing - polymer chemistry - biopolymers
    Starch-based materials show potential as fully degradable plastics. However, the current
    applicability of these materials is limited due to their poor moisture tolerance and
    mechanical properties. Starch is therefore frequently blended with other polymers to make
    the material more suitable for special or severe circumstances. By varying the components
    of the blend and the process conditions, the morphology and hence the properties can be
    controlled. A clear understanding over the structure formation process will allow the
    development of new, biodegradable blends based on starch-based materials with better
    properties. The overall goal of this thesis was thus to develop insight in how the material
    (blend) properties depend on the processing, and based on this insight, explore new
    processing routes.
    Structure-function relationships: exploring a polymer science approach
    In Chapter 2, we discuss the relation between the performance of a plasticized starchbased
    film, in terms of permeation of volatile components, and its composition. Estimations
    of the Maxwell-Stefan diffusion rates of trace volatile components through plasticized
    starch films were developed based on free-volume theory and the Flory-Huggins-Maxwell-
    Stefan (FHMS) equation. The model correctly predicted the order of magnitude of the
    permeation fluxes of diacetyl and carvone through starch films. The results of this chapter
    show that blending of starch with hydrophobic polymers could be an effective way to
    improve the barrier properties of the film.
    In Chapter 3, the influence of alternative plasticizers (i.e., glucose and glycerol) on the
    gelatinization and melting of concentrated starch mixtures was studied, using differential
    scanning calorimetry (DSC) and wide angle X-ray scattering (WAXS). The results were
    interpreted using an extended form of the well-known Flory-Huggins equation. The chapter
    exemplified the possibilities of using theories that were traditionally applied to synthetic
    polymers, to biomaterials, in spite of their much greater complexity. This approach led to
    quantitative and qualitative understanding of the influence of small plasticizers of industrial
    relevance on the gelatinization and melting of starch. Comparing the Flory-Huggins model
    results with experimental results, showed that the approach is useful for interpreting and
    predicting the gelatinization and melting behavior of ternary starch-based systems. It also
    showed that since the experiments were complex, systems were often not in true
    equilibrium and other disturbing effects were easily encountered. Therefore, one should be
    cautious to use experimental results for characterizing the thermodynamics of gelatinization
    in multicomponent systems.
    Processing: the use of simple shear
    In Chapter 4, the use of simple shear as an instrument for structure formation of
    plasticized starch-protein blends was introduced. A novel shearing device was developed to
    explore the formation of new types of microstructures in concentrated starch-zein blends.
    This device was used to process different ratios of starch and zein (0–20% zein, dry basis)
    to study the influence of the matrix composition and processing conditions on the
    properties of the final material. Confocal scanning laser microscopy and field emission
    scanning electron microscopy showed that under shearless conditions, the starch-zein blend
    forms a co-continuous blend. Shear transformed this structure into a dispersion, with zein
    being the dispersed phase. The large deformation properties were examined by tensile tests
    in the flow and the vorticity directions; they could be described using a model for blends
    having poor adhesion between the continuous and dispersed phases.
    In Chapter 5, we studied the effect of compatibilization, i.e., improvement of the adhesion
    between the continuous and dispersed phases in starch-zein blends through the
    incorporation of a component having affinity for both phases. Aldehyde starch was
    synthesized by introducing a reactive functional group (aldehyde). This group then reacted
    in the blend with zein (and/or other components), forming a macromolecular compatibilizer
    in situ. The effect of this compatabilizer on the interfacial properties of the blend was
    studied using different zein ratios. The blends showed improved adhesion between the zein
    and starch phases compared to the blends described in chapter 4. The aldehyde starch
    however also influenced the properties of the starch matrix (higher viscosity, stronger
    molecular breakdown, browning), which indicates that indeed physical or chemical
    crosslinks were formed inside the starch matrix, but on the other hand posed a limitation for
    practical applicability.
    Chapter 6 presented the use of rise bran extract as a food-grade compatibilizer for starchzein
    blends. This material was extracted from rice brans using super-critical water,
    probably contains Maillard components and shows activity as radical scavenger,
    antioxidant and surfactant. The influence of rice bran extract as compatibilizer was
    compared with that of aldehyde starch by preparing blends under shear conditions. Field
    emission scanning electron microscopy showed that both compatibilizers improved the
    adhesion between the zein and starch phases. The mechanical properties of the blends
    compatibilized with aldehyde starch showed poorer mechanical properties after storage
    under controlled conditions, possibly caused by retrogradation of starch. The use of rice
    bran extract as compatibilizer however led to good compatibilization with good stability
    during storage. The good compatibilization by rice bran extract was suggested to be caused
    by polysaccharide-protein complexes, which are also responsible for its emulsifying
    In Chapter 7, the conclusions of the preceding chapters were collectively interpreted. First,
    the use of a heuristic approach for the rational design of thermoplastic starch-based
    materials was described. Then the use of the ternary diagram for the system starch-waterglucose
    developed in Chapter 3 was used to evaluate alternatives routes for the
    intensification of the enzymatic hydrolysis of starch.
    Finally, future trends in the development of starch-based materials were presented
    following the insights obtained in this thesis. These include the use of established theories
    developed for synthetic polymers, further exploration of the concept of compatibilization of
    starch-based blends, and the development of new processing equipment dedicated to
    material structuring.
    Bedrijfspraktijktoets op Erwinia in hyacint : geef de bol stress!!
    Doorn, J. van; Vreeburg, P.J.M. ; Dees, R.H.L. ; Martin, W.S. ; Leeuwen, P.J. van; Korsuize, C.A. - \ 2009
    BloembollenVisie 2009 (2009)164. - ISSN 1571-5558 - p. 22 - 23.
    proeven op proefstations - tuinbouwbedrijven - bloembollen - hyacinten - erwinia - sorteren - verwerking - station tests - market gardens - ornamental bulbs - hyacinths - erwinia - sorting - processing
    Om een goed beeld te krijgen van de plaatsen waar risico's zitten in de verwerking van hyacinten is de afgelopen jaren onderzoek door PPO gedaan. Vooral sorteren en vallen blijken belangrijke stimulansen voor de ontwikkeling van een Erwinia-aantasting. Verder werd duidelijk dat partijen soms al latent flink met Erwinia besmet kunnen zijn
    Het onderzoek van Martin van Dam : 'Nieuw licht op rol ethyleen' : een interview met Martin van Dam
    Dwarswaard, A. ; Dam, M.F.N. van - \ 2009
    BloembollenVisie 2009 (2009)161. - ISSN 1571-5558 - p. 37 - 37.
    bloembollen - fusarium - oogsten - verwerking - ethyleen - rijp worden - ornamental bulbs - fusarium - harvesting - processing - ethylene - ripening
    De serie : Het onderzoek.. van laat onderzoekers vertellen waar zij op dit moment mee bezig zijn. In deze aflevering PPO-onderzoeker Martin van Dam over ethyleen en zuur in tulpen
    Research news : industrial fibre crops
    Dam, J.E.G. van - \ 2008
    vezelgewassen - verwerking - plantenvezels - biobased economy - wetenschappelijk onderzoek - fibre plants - processing - plant fibres - biobased economy - scientific research
    Poster met informatie over onderzoek dat de Agrotechnology & Food Sciences Group (AFSG) van Wageningen UR uitvoert naar het gebruik van vezelgewassen.
    Research news : new enzyme technologies for fibre modification
    Valk, H.C.P.M. van der - \ 2008
    enzymen - natuurlijke vezels - verwerking - wetenschappelijk onderzoek - biobased economy - enzymes - natural fibres - processing - scientific research - biobased economy
    Poster met informatie over het onderzoek dat de Agrotechnology & Food Sciences Group (AFSG) van Wageningen UR uitvoert naar de modificatie van plantenvezels. AFSG richt zich op de ontwikkeling van nieuwe markten en nieuwe toepassingen van (hernieuwbare) biologische grondstoffen, gecombineerd met fundamenteel en en toegepast onderzoek.
    Praktische tips om de kans op snot te verkleinen
    Vreeburg, P.J.M. ; Weijden, B. v.d. - \ 2008
    Wageningen : Praktijkonderzoek Plant & Omgeving B.V.
    erwinia - bollen - plantenziekteverwekkende bacteriën - gewasbescherming - bloembollen - verwerking - erwinia - bulbs - plant pathogenic bacteria - plant protection - ornamental bulbs - processing
    Erwinia (agressief snot en witsnot) wordt vooral verspreid via vermeerdering en mechanische overdracht bij verwerking. In deze handleiding staan praktische tips om Erwinia te voorkomen. De tips gelden niet alleen voor de teelt maar ook voor de verwerking. De adviezen zijn mede gebaseerd op het Erwinia-onderzoek van PPO op 18 teeltbedrijven en 5 exportbedrijven in 2007
    Biomassastromen voor bioraffinage in Nederland
    Corré, W.J. - \ 2008
    Wageningen : Plant Research International (Rapport / Plant Research International 200) - 16
    biomassa - verwerking - agrarische afvalstoffen - vervangbare hulpbronnen - nederland - duurzaamheid (sustainability) - raffineren - bioraffinage - biobased economy - biomass - processing - agricultural wastes - renewable resources - netherlands - sustainability - refining - biorefinery - biobased economy
    Verwerking hyacinten veroorzaakt meer schade dan verwacht
    Vreeburg, P.J.M. ; Korsuize, C.A. - \ 2008
    BloembollenVisie (2008)143. - ISSN 1571-5558 - p. 30 - 31.
    hyacinthus - bollen - schadepreventie - verwerking - plantenziekten - landbouwkundig onderzoek - bloembollen - hyacinthus - bulbs - loss prevention - processing - plant diseases - agricultural research - ornamental bulbs
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