Agrotechnology and Food science group

AA, Netherlands

Agrotechnology and Food science group

AA, Netherlands

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Wegkamp A.,TI Food and Nutrition | Wegkamp A.,NIZO food research | Mars A.E.,TI Food and Nutrition | Mars A.E.,Agrotechnology and Food science group | And 12 more authors.
Microbial Cell Factories | Year: 2010

Background: Using a functional genomics approach we addressed the impact of folate overproduction on metabolite formation and gene expression in Lactobacillus plantarum WCFS1. We focused specifically on the mechanism that reduces growth rates in folate-overproducing cells.Results: Metabolite formation and gene expression were determined in a folate-overproducing- and wild-type strain. Differential metabolomics analysis of intracellular metabolite pools indicated that the pool sizes of 18 metabolites differed significantly between these strains. The gene expression profile was determined for both strains in pH-regulated chemostat culture and batch culture. Apart from the expected overexpression of the 6 genes of the folate gene cluster, no other genes were found to be differentially expressed both in continuous and batch cultures. The discrepancy between the low transcriptome and metabolome response and the 25% growth rate reduction of the folate overproducing strain was further investigated. Folate production per se could be ruled out as a contributing factor, since in the absence of folate production the growth rate of the overproducer was also reduced by 25%. The higher metabolic costs for DNA and RNA biosynthesis in the folate overproducing strain were also ruled out. However, it was demonstrated that folate-specific mRNAs and proteins constitute 8% and 4% of the total mRNA and protein pool, respectively.Conclusion: Folate overproduction leads to very little change in metabolite levels or overall transcript profile, while at the same time the growth rate is reduced drastically. This shows that Lactobacillus plantarum WCFS1 is unable to respond to this growth rate reduction, most likely because the growth-related transcripts and proteins are diluted by the enormous amount of gratuitous folate-related transcripts and proteins. © 2010 Wegkamp et al; licensee BioMed Central Ltd.


Teekens A.M.,Vilentum Hogeschool | Bruins M.E.,Agrotechnology and Food science Group | van Kasteren J.M.,Vilentum Hogeschool | Hendriks W.H.,Animal Nutrition Group | Sanders J.P.,Agrotechnology and Food science Group
Journal of the Science of Food and Agriculture | Year: 2016

Processing biomass into multi-functional components can contribute to the increasing demand for raw materials for feed and bio-based non-food products. This contribution aims to demonstrate synergy between the bio-based industry and the feed industry through biorefinery of currently used feed ingredients. Illustrating the biorefinery concept, rapeseed was selected as a low priced feed ingredient based on market prices versus crude protein, crude fat and apparent ileal digestible lysine content. In addition it is already used as an alternative protein source in diets and can be cultivated in European climate zones. Furthermore, inclusion level of rapeseed meal in pig diet is limited because of its nutritionally active factors. A conceptual process was developed to improve rapeseeds nutritional value and producing other bio-based building blocks simultaneously. Based on the correlation between market prices of feed ingredients and its protein and fat content, the value of refined products was estimated. Finally, a sensitivity analysis, under two profit scenario, shows that the process is economically feasible. This study demonstrates that using biorefinery processes on feed ingredients can improve feed quality. In conjunction, it produces building blocks for a bio-based industry and creates synergy between bio-based and feed industry for more efficient use of biomass. © 2015 Society of Chemical Industry.


Langeveld J.W.A.,Biomass Research | Kalf R.,KEMA | Elbersen H.W.,Agrotechnology and Food Science Group
Biofuels, Bioproducts and Biorefining | Year: 2010

Development of bioenergy production in the Netherlands is lagging. This paper presents an inventory of problems met by new bioenergy chains and compares these to literature and to other countries. Theoretical frameworks suggest that five elements are crucial for successful bioenergy chain development: (i) availability of (proven) technology; (ii) access to information; (iii) access to feedstocks, financial means, and markets; (iv) locations for new installations; and (v) efficient lobby activities and public support. Nine bioenergy chains were interviewed. Problems that are reported relate to insufficient knowledge of new technological concepts, and of nuisances (noise, emission, odor, and other) caused during bioenergy production. Feedstock markets (wood, byproducts, waste) and product markets (heat, CO 2) are underdeveloped, while some chains are experiencing extra problems finding a suitable location or obtaining necessary permits. Problems related to insufficient public support are most relevant for bioenergy chains depending on tax exemptions (pure vegetation oil transportation fuels) or requiring adaptation of legislation (location permits for farm fermenters). An international comparison to barriers for biofuel suggests that economic factors (including lack of capital), limitations in know-how and institutional capacities, underdeveloped biomass and carbon markets, problems in chain coordination, and limited public support are largest problems for new bioenergy chains. Recommendations to stimulate bioenergy production in the Netherlands refer to performance standards for new installation types, information on feedstock availability, protocols for heat exchange and on improved credit facilities. © 2010 Society of Chemical Industry and John Wiley & Sons, Ltd.


Huijbrechts A.M.L.,Wageningen University | Huijbrechts A.M.L.,Agrotechnology and Food science Group | Haar R.t.,Wageningen University | Schols H.A.,Wageningen University | And 4 more authors.
Carbohydrate Polymers | Year: 2010

Epoxy starch derivatives were synthesized by epoxidation of allylated starch. The reaction was performed with low substituted 1-allyloxy-2-hydroxypropyl-waxy maize starch (AHP-WMS; degree of substitution (DS) of 0.23) using hydrogen peroxide and acetonitrile Via a two step spectrophotometric assay, it was determined that epoxy-WMS contained 0.13 ± 0.03 mmol epoxy groups per gram dry allylated starch which corresponds to DS value of 0.025. Enzymatic digestibility, swelling capacity and solubility were significantly reduced after epoxidation. The detailed chemical structure of epoxy-WMS was characterized by enzymatic hydrolysis followed by chromatographic and mass spectrometric techniques. Only a small amount of epoxidized oligomers was found in the enzymatic digested products of epoxy-WMS. Apparently, the epoxidation reaction is highly efficient but subsequent reactions of epoxy groups lead to a considerable amount of cross-links and diol groups. Additionally, epoxy starch derivatives were successfully applied as carrier matrix for immobilization of an enzyme. © 2009 Elsevier Ltd. All rights reserved.


Skrzeszewska P.J.,Wageningen University | Skrzeszewska P.J.,Dutch Polymer Institute | Jong L.N.,Wageningen University | De Wolf F.A.,Agrotechnology and Food science Group | And 2 more authors.
Biomacromolecules | Year: 2011

In this article we study shape-memory behavior of hydrogels, formed by biodegradable and biocompatible recombinant telechelic polypeptides, with collagen-like end blocks and a random coil-like middle block. The programmed shape of these hydrogels was achieved by chemical cross-linking of lysine residues present in the random coil. This led to soft networks, which can be stretched up to 200% and "pinned" in a temporary shape by lowering the temperature and allowing the collagen-like end blocks to assemble into physical nodes. The deformed shape of the hydrogel can be maintained, at room temperature, for several days, or relaxed within a few minutes upon heating to 50 °C or higher. The presented hydrogels could return to their programmed shape even after several thermomechanical cycles, indicating that they remember the programmed shape. The kinetics of shape recovery at different temperatures was studied in more detail and analyzed using a mechanical model composed of two springs and a dashpot. © 2011 American Chemical Society.


Van Dinther A.M.C.,Agrotechnology and Food science Group | Schroen C.G.P.H.,Agrotechnology and Food science Group | Vergeldt F.J.,Laboratory of Biophysics | Van Der Sman R.G.M.,Agrotechnology and Food science Group | And 2 more authors.
Advances in Colloid and Interface Science | Year: 2012

Microfluidic devices are an emerging technology for processing suspensions in e.g. medical applications, pharmaceutics and food. Compared to larger scales, particles will be more influenced by migration in microfluidic devices, and this may even be used to facilitate segregation and separation. In order to get most out of these completely new technologies, methods to experimentally measure (or compute) particle migration are needed to gain sufficient insights for rational design. However, the currently available methods only allow limited access to particle behaviour. In this review we compare experimental methods to investigate migration phenomena that can occur in microfluidic systems when operated with natural suspensions, having typical particle diameters of 0.1 to 10 μm. The methods are used to monitor concentration and velocity profiles of bidisperse and polydisperse suspensions, which are notoriously difficult to measure due to the small dimensions of channels and particles. Various methods have been proposed in literature: tomography, ultrasound, and optical analysis, and here we review and evaluate them on general dimensionless numbers related to process conditions and channel dimensions. Besides, eleven practical criteria chosen such that they can also be used for various applications, are used to evaluate the performance of the methods. We found that NMR and CSLM, although expensive, are the most promising techniques to investigate flowing suspensions in microfluidic devices, where one may be preferred over the other depending on the size, concentration and nature of the suspension, the dimensions of the channel, and the information that has to be obtained. The paper concludes with an outlook on future developments of measurement techniques. © 2012 Elsevier B.V. All rights reserved.


Van Dinther A.M.C.,Agrotechnology and Food science Group | Schroen C.G.P.H.,Agrotechnology and Food science Group | Boom R.M.,Agrotechnology and Food science Group
Journal of Membrane Science | Year: 2011

We here report on the separation of yeast cells, with micro-engineered membranes having pores that are typically five times larger than the cells. The separation is due to neither shear-induced diffusion, nor initial lift, but to an effect similar to fluid skimming. The separation performance is linked to the ratio between cross-flow and transmembrane flux, and could be captured with a dimensionless number relating those. On the basis of this dimensionless number, flux and transmission of the cells could be predicted.The mechanism rests on having a sufficiently high cross-flow velocity, such that particles are not dragged too deep in the pore, but are dragged with the cross-flow back into the feed stream. The separation factor can simply be changed by changing the ratio between crossflow velocity and transmembrane flux.Since the membranes have very large pores, fouling does not play a role. Constant high transmembrane flux values of 200-2200L/m2h were reached for transmembrane pressures ranging from 0.02 to 0.4bar (typical industrial fluxes are 150L/m2hbar with a maximum of 2000L/m2hbar for short periods of time, comparable to 50-400L/m2h [1,2]). Although the effect is strongest with monodispersed pores, it will be possible to exploit the mechanism with conventional membranes. As such, it may open up a new route towards non-fouling crossflow microfiltration. © 2011 Elsevier B.V.


Randles L.G.,University of Cambridge | Randles L.G.,Maidstone Hospital | Dawes G.J.S.,University of Cambridge | Dawes G.J.S.,Agrotechnology and Food science Group | And 4 more authors.
FEBS Journal | Year: 2013

Studying the effects of pathogenic mutations is more complex in multidomain proteins when compared with single domains: mutations occurring at domain boundaries may have a large effect on a neighbouring domain that will not be detected in a single-domain system. To demonstrate this, we present a study that utilizes well-characterized model protein domains from human spectrin to investigate the effect of disease- and non-disease-causing single point mutations occurring at the boundaries of human spectrin repeats. Our results show that mutations in the single domains have no clear correlation with stability and disease; however, when studied in a tandem model system, the disease-causing mutations are shown to disrupt stabilizing interactions that exist between domains. This results in a much larger decrease in stability than would otherwise have been predicted, and demonstrates the importance of studying such mutations in the correct protein context. © 2012 The Authors Journal compilation © 2012 FEBS.


van Dinther A.M.C.,Agrotechnology and Food science Group | Schroen C.G.P.H.,Agrotechnology and Food science Group | Boom R.M.,Agrotechnology and Food science Group
Journal of Membrane Science | Year: 2013

In membrane filtration, the pore size of the membrane determines the size of 'particles' that should be rejected, leading to accumulation of particles on the membrane surface and changed particle retention in time. A process without accumulation and thereby constant retention as function of time would be well suited for fractionation of components close in size.In this research, emulsions consisting of small droplets (~2.0μm) and large droplets (~5.5μm), with total concentrations between 10% and 47%, were fractionated. The cross-flow module consisted of a closed channel to allow particles to migrate, followed by a membrane area with 20μm pores where emulsion fractions could be removed. Under appropriate process conditions, the permeate consisted of only small droplets, at concentrations higher than in the original emulsion, leading to very high selectivities. Especially at high concentrations, known to cause severe fouling in regular membrane filtration, these effects were occurring as a result of shear-induced diffusion of the droplets. If only small particles are targeted, the module can be operated at fluxes of 40L/(m2/h); if fractionation is targeted the fluxes can be considerably higher. These fluxes are comparable to current operational fluxes, but here cross-flow velocity and trans-membrane pressure are much lower (corresponding to fluxes of 1-4m3/(m2/h/bar)) with stable retention and flux as function of time. © 2013 Elsevier B.V.


PubMed | Agrotechnology and Food science Group
Type: | Journal: Advances in colloid and interface science | Year: 2012

Microfluidic devices are an emerging technology for processing suspensions in e.g. medical applications, pharmaceutics and food. Compared to larger scales, particles will be more influenced by migration in microfluidic devices, and this may even be used to facilitate segregation and separation. In order to get most out of these completely new technologies, methods to experimentally measure (or compute) particle migration are needed to gain sufficient insights for rational design. However, the currently available methods only allow limited access to particle behaviour. In this review we compare experimental methods to investigate migration phenomena that can occur in microfluidic systems when operated with natural suspensions, having typical particle diameters of 0.1 to 10 m. The methods are used to monitor concentration and velocity profiles of bidisperse and polydisperse suspensions, which are notoriously difficult to measure due to the small dimensions of channels and particles. Various methods have been proposed in literature: tomography, ultrasound, and optical analysis, and here we review and evaluate them on general dimensionless numbers related to process conditions and channel dimensions. Besides, eleven practical criteria chosen such that they can also be used for various applications, are used to evaluate the performance of the methods. We found that NMR and CSLM, although expensive, are the most promising techniques to investigate flowing suspensions in microfluidic devices, where one may be preferred over the other depending on the size, concentration and nature of the suspension, the dimensions of the channel, and the information that has to be obtained. The paper concludes with an outlook on future developments of measurement techniques.

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