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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    Mild disintegration of green microalgae and macroalgae
    Postma, Richard - \ 2016
    Wageningen University. Promotor(en): Michel Eppink; Rene Wijffels, co-promotor(en): Giuseppe Olivieri. - Wageningen : Wageningen University - ISBN 9789462579477 - 181
    algae - chlorella vulgaris - bioprocess engineering - biorefinery - proteins - milling - carbohydrates - biobased economy - disintegrators - technology - extraction - algen - chlorella vulgaris - bioproceskunde - bioraffinage - eiwitten - maling - koolhydraten - biobased economy - desintegrators - technologie - extractie

    An increased worldwide protein demand for food and feed and the necessity to release the water soluble proteins in the first stage of the cascade biorefinery require the development of mild protein extraction technologies. Cell disintegration is the first hurdle and is considered as one of the most energy consuming steps. Therefore, this thesis focused on the development of a mild, scalable and energy efficient disintegration technology for green microalgae and macroalgae (seaweed) aimed on extraction of water soluble components (like proteins and carbohydrates).

    For microalgae disintegration, two main technologies were investigated. First of all the conventional technology bead milling and second a novel approach using Pulsed Electric Field (PEF). In Chapter 2 a benchmark was set by means of bead milling for the release of water soluble protein from the green microalgae Chlorella vulgaris. Overall, protein yields between 32 and 42% were achieved, while the energy consumption was reduced with 85% by selective protein extraction to values as low as 0.81 kWh kgDW-1. Remarkably, the benchmark was much better than expected.

    In Chapter 3 the bead mill was further optimized by decreasing the applied bead size, furthermore the applicability of bead milling on two additional microalgae species (Neochloris oleoabundans, Tetraselmis suecica) was shown. In addition, to be able to better understand the disintegration mechanism, the so-called stress model was applied. This model describes the comminution process in a bead mill as function of the amount of bead contacts and the force of each impact. The release kinetics could be improved and thereby the specific energy consumption could be reduced to 0.45‒0.47 kWh kgDW-1 by using 0.3 mm beads for all algae.

    Chapter 4 describes a screening on the applicability of PEF, over a broad range of operating conditions, for the extraction of water soluble proteins from the microalgae C. vulgaris and N. oleoabundans. No substantial protein yields were observed under the investigated conditions. This led to the conclusion that PEF is not suitable to release water soluble proteins, not even at specific energy consumptions much higher than those for the benchmark, bead milling.

    In Chapter 5 it was attempted to improve the performance of PEF by investigating the synergistic effect with the processing temperature. The PEF experiments were performed using a pilot scale continuous flow electroporation unit in which the processing temperature was controlled between 25 – 65 °C. The results showed that under the tested conditions, the combined PEF-Temperature treatment did not cause substantial disintegration of the algal cells to effectively release water soluble proteins.

    In addition to the microalgae, macroalgae were subject of investigation in the search for new protein sources in Chapter 6. Four batch technologies were used to disintegrate the green macroalgae Ulva lactuca, being; osmotic shock, enzyme incubation, PEF and High Shear Homogenization (HSH). In descending order the highest protein yields per treatment; HSH (~40%) > enzyme degradation (~25%) > osmotic shock (~20%) > PEF (~15%).

    In the final chapter the main results and remaining bottlenecks are discussed and a future outlook on microalgae disintegration is presented. To date, bead milling is the only technology able to disintegrate fresh microalgae at specific energy consumptions below 10% of the total energy available from the algae and release substantial amounts of water soluble protein. The future outlook was based on a techno-economic evaluation, which showed that the cultivation costs are limiting the economic feasibility of microalgae biorefinery. Future focus should be on the cultivation.

    Ionic liquid pre-treatment of microalgae and extraction of biomolecules
    Desai, Rupali K. - \ 2016
    Wageningen University. Promotor(en): Michel Eppink; Rene Wijffels. - Wageningen : Wageningen University - ISBN 9789462579804 - 126
    salts - liquids - fractionation - extraction - hydrophobicity - algae - biomass production - zouten - vloeistoffen (liquids) - fractionering - extractie - hydrofobiciteit - algen - biomassa productie

    Liquid-liquid extraction (LLE) techniques are widely used in separation primarily due to ease of scale up. Conventional (LLE) systems based on organic solvents are not suitable for extraction of fragile molecules such as proteins as it would result in denaturation. On the other hand aqueous biphasic system though suitable for extraction of proteins they are restricted by limited polarity range. Ionic liquids are salts which are liquid at room temperature. Ionic liquids have gained interest in extraction over the past years due to its non-volatility and tunable property. In this thesis we explored the feasibility of using two ionic liquid based systems for extraction: 1) Ionic liquid based aqueous two phase system for extraction of microalgae proteins and 2) ionic liquid based emulsions for separation of hydrophilic (e.g. proteins) and hydrophobic (e.g. pigments) components from complex biomass such as microalgae. Additionally the influence of IL pre-treatment on microalgae cell walls and subsequent fractionation of its components (e.g. proteins, pigments, lipids) was also investigated.

    Toetsontwikkeling PSTVd in Dahlia
    Leeuwen, P.J. van; Trompert, J.P.T. ; Lemmers, M.E.C. ; Verbeek, M. ; Meekes, E.T. - \ 2016
    Lisse : Praktijkonderzoek Plant & Omgeving, onderdeel van Wageningen UR Business Unit Bloembollen, Boomkwekerij en Fruit - 23
    dahlia - plantenvirussen - aardappelspindelknolviroïde - detectie - extractie - experimenteel veldonderzoek - methodologie - diagnostische technieken - nederland - dahlia - plant viruses - potato spindle tuber viroid - detection - extraction - field experimentation - methodology - diagnostic techniques - netherlands
    Inhoudsstoffen - Verwerking van inhoudsstoffen : Kennisclip Bogo-project e-learning
    Baltissen, A.H.M.C. - \ 2016
    Groen Kennisnet
    plantensamenstelling - plantextracten - extractie - tuinbouw - biobased economy - innovaties - lesmaterialen - plant composition - plant extracts - extraction - horticulture - biobased economy - innovations - teaching materials
    Deze kennisclip maakt onderdeel uit van de lesmodule Biobased Economy van het CIV T&U.
    Micropolitics in Resistance: The Micropolitics of Large-Scale Natural Resource Extraction in South East Asia
    Rasch, E.D. ; Kohne, F.M. - \ 2016
    Society & Natural Resources 29 (2016)4. - ISSN 0894-1920 - p. 479 - 492.
    Micropolitics - resistance - natural resources - extraction - south east asia - society
    This article analyzes Southeast Asian local communities’ resistance against the globalizing large-scale exploitation of natural resources using a micropolitical ecology approach. It focuses on how communities struggle for livelihoods, both resisting and appropriating globalized practices and narratives. Our ethnographic material encompasses natural resource conflicts in two communities: one on Sumatra (Indonesia) and one on Palawan (the Philippines). In both communities foreign and national companies have laid claims on community lands, transforming local power relations and wealth distribution as well as the relations of the communities vis-à-vis globalized production and the state. Communities often split over such transformations; some members negotiate a share in the globalized markets, while others organize resistance against these developments. The article argues that the specifics of this resistance against globalization can only be explained by taking into account the “micropolitics” within which they are produced, which calls for an ethnographic research approach to globalization.
    Validation of ISO 17586 soil quality : extraction of trace elements using dilute nitric acid
    Vark, W. van; Harmsen, J. - \ 2016
    Alterra, Wageningen-UR (Alterra-rapport 2693) - 55
    soil - soil quality - trace elements - standards - bioavailability - iso - extraction - bodem - bodemkwaliteit - sporenelementen - normen - biologische beschikbaarheid - iso - extractie
    Characterisation of cell-wall polysaccharides from mandarin segment membranes
    Coll-Almela, L. ; Saura-Lopez, D. ; Laencina-Sanchez, J. ; Schols, H.A. ; Voragen, A.G.J. ; Ros-García, J.M. - \ 2015
    Food Chemistry 175 (2015). - ISSN 0308-8146 - p. 36 - 42.
    hairy ramified regions - cross-flow filtration - pectolytic enzyme - citrus-fruit - pectins - degradation - extraction - skin - rhamnogalacturonase - populations
    In an attempt to develop a process of enzymatic peeling of mandarin segments suitable for use on an industrial scale, the cell wall fraction of the segment membrane of Satsuma mandarin fruits was extracted to obtain a chelating agent-soluble pectin fraction (ChSS), a dilute sodium hydroxide-soluble pectin fraction (DASS), a 1 M sodium hydroxide-soluble hemicellulose fraction (1MASS), a 4 M sodium hydroxide-soluble hemicellulose fraction (4MASS) and a cellulose-rich residue (3.1, 0.9, 0.4, 0.7 and 1.6% w/w of fresh membrane, respectively). The ChSS pectin consisted mainly of galacturonic acid followed by arabinose and galactose. The DASS fraction contained less galacturonic acid and more neutral sugars than ChSS. Eighty-nine percent of the galacturonic acid present in the segment membranes was recovered in the above two pectin fractions. The two hemicellulosic fractions consisted of two different molecular weight populations, which also differed in their sugar composition. Arabinose, xylose, mannose, galactose and glucose were the main sugar constituents of these hemicellulose fractions. In addition to an (arabino)xylan and a xyloglucan, the presence of an arabinogalactan is suggested by the sugar composition of both hemicelluloses. The pectin fractions were also characterised by their degradability by the pectic enzymes polygalacturonase, pectinmethylesterase and rhamnogalacturonan hydrolase. However the degree of degradation of the pectin fractions by enzymes differed, and the amount of the polymeric materials resistant to further degradation and the oligomeric products also differed. Using pectic enzymes it is possible to obtain peeled mandarin segments ready to eat or for canning.
    Identification in residue analysis based on liquid chromatography with tandem mass spectrometry: Experimental evidence to update performance criteria
    Mol, J.G.J. ; Zomer, P. ; Garcia Lopez, M. ; Fussell, R.J. ; Scholten, J. ; dr. Kok, A. ; Wolheim, A. ; Anastassiades, M. ; Lozano, A. ; Fernandez Alba, A. - \ 2015
    Analytica Chimica Acta 873 (2015). - ISSN 0003-2670 - p. 1 - 13.
    mycotoxin analysis - veterinary drugs - food - confirmation - extraction - pesticides - matrices
    Liquid chromatography-tandem mass spectrometry (LC-MS/MS) is one of the most widely used techniques for identification (and quantification) of residues and contaminants across a number of different chemical domains. Although the same analytical technique is used, the parameters and criteria for identification vary depending on where in the world the analysis is performed and for what purpose (e.g. determination of pesticides, veterinary drugs, forensic toxicology, sports doping). The rationale for these differences is not clear and in most cases the criteria are essentially based on expert opinions rather than underpinned by experimental data. In the current study, the variability of the two key identification parameters, retention time and ion ratio, was assessed and compared against requirements set out in different legal and guidance documents. The study involved the analysis of 120 pesticides, representing various chemical classes, polarities, molecular weights, and detector response factors, in 21 different fruit and vegetable matrices of varying degrees of complexity. The samples were analysed non-fortified, and fortified at 10, 50 and 200µgkg(-1), in five laboratories using different LC-MS/MS instruments and conditions. In total, over 135,000 extracted-ion chromatograms were manually verified to provide an extensive data set for the assessment. The experimental data do not support relative tolerances for retention time, or different tolerances for ion ratios depending on relative abundance of the two product ions measured. Retention times in today's chromatographic systems are sufficiently stable to justify an absolute tolerance of ±0.1min. Ion ratios are stable as long as sufficient response is obtained for both product ions. Ion ratio deviations are typically within ±20% (relative), and within ±45% (relative) in case the response of product ions are close to the limit of detection. Ion ratio tolerances up to 50% did not result in false positives and reduced the false negative rate for pesticides with product ions in the low S/N range to
    Pre- and post-treatment enhance the protein enrichment from milling and air classification of legumes
    Pelgrom, P.J.M. ; Wang, J. ; Boom, R.M. ; Schutyser, M.A.I. - \ 2015
    Journal of Food Engineering 155 (2015). - ISSN 0260-8774 - p. 53 - 61.
    seed moisture-content - product characteristics - flour - pea - separation - fractions - starch - extraction - storage - lipids
    Air classification is a milder and more sustainable method to obtain protein-enriched fractions than commonly used wet fractionation. The protein content of air-classified fractions is generally lower than obtained with wet methods, therefore we applied pre- and post-treatments to increase the protein purity. A starch-rich legume, pea, and an oil-rich legume, lupine, were pre-treated by varying the moisture content, defatting, soaking or freezing cycles. Higher moisture contents and defatting of lupine increased the protein purity, but lower moisture contents increased the protein yield. Soaking and freezing cycles lowered the particle density, which impaired the separation. Electrostatic separation is based on electrostatic charging behaviour and was successfully applied to enrich air-classified fractions by separating protein and fibre into oppositely charged fractions. The results showed that pre- and post-treatments yielded protein fractions that are significantly purer than those obtained in single-step milling and air classification.
    Arabinoxylans concentrates from wheat bran by electrostatic separation
    Wang, J. ; Smits, E. ; Boom, R.M. ; Schutyser, M.A.I. - \ 2015
    Journal of Food Engineering 155 (2015). - ISSN 0260-8774 - p. 29 - 36.
    dietary fiber - phenolic-acid - particle-size - soft wheat - extraction - quality - (glucurono)arabinoxylans - carbohydrate - fractions - hydroxide
    Electrostatic separation has been recently proposed as a novel method to fractionate wheat bran into valuable ingredient fractions. However, systematic study into the influence of parameters on electrostatic separation was lacking. Therefore, this study aimed at a more detailed evaluation of electrostatic separation for enriching arabinoxylans (AX) from wheat bran. The influence of wheat bran particle size, carrier gas velocity and charging tube length were investigated with a lab-scale electrostatic separator. A combination of larger particle size (D[4,3] of 210 µm compared to 110 µm), higher gas velocity (>28 m/s) and shorter charging tube (125 mm compared to 225 mm) can sufficiently charge the particles, and at the mean time avoid agglomeration by oppositely charged particles. With the optimal settings, single step electrostatic separation of wheat bran could increase the AX content from 23% dm to 30% dm, which is similar as can be obtained by sieving. However, in comparison to sieving, the yield of the enriched fraction from electrostatic separation is lower due to the horizontal design of the setup. Improvement of the yield is expected when adjusting the system design from horizontal to vertical. A sieving step added after the electrostatic separation could effectively remove starch and protein and resulted in a fraction with an AX content of 43% dm, which is around the theoretical maximum value that can be reached by dry fractionation.
    A process synthesis approach for isolation of isoflavones from okara
    Jankowiak, L. ; Mendez Sevillano, D. ; Boom, R.M. ; Ottens, M. ; Zondervan, E. ; Goot, A.J. van der - \ 2015
    Industrial & Engineering Chemistry Research 54 (2015)2. - ISSN 0888-5885 - p. 691 - 699.
    driven process synthesis - antioxidant activity - food - adsorption - extraction - separation - products - recovery - integration - components
    Owing to the complexity of food matrices, process synthesis methodologies have not been as widely applied in the food industry as in the chemical industry. Here, we describe the application of a process synthesis methodology to design a system to separate valuable components from a byproduct of the soymilk production. The method yielded a number of potential processing pathways and relevant mechanistic questions, which required experimental input. The combination of considering the overall system on the level of general transformations, heuristics, and additional insights through experiments resulted in a simplified conceptual process design for the separation of isoflavones from okara with a globally more sustainable choice. The holistic approach within process design as an implication of the methodology is discussed.
    Long-lasting effects of Early-life Antibiotic Treatment and routine Animal Handling on Gut Microbiota Composition and Immune System in Pigs
    Schokker, D. ; Zhang, J. ; Vastenhouw, S.A. ; Heilig, G.H.J. ; Smidt, H. ; Rebel, J.M.J. ; Smits, M.A. - \ 2015
    PLoS ONE 10 (2015)2. - ISSN 1932-6203
    large gene lists - intestinal microbiota - bacterial - extraction - expression - disease - health - asthma - young - diet
    Background In intensive pig husbandry systems, antibiotics are frequently administrated during early life stages to prevent respiratory and gastro-intestinal tract infections, often in combination with stressful handlings. The immediate effects of these treatments on microbial colonization and immune development have been described recently. Here we studied whether the early life administration of antibiotics has long-lasting effects on the pig’s intestinal microbial community and on gut functionality. Methodology/Principal Findings To investigate the long-lasting effect of early-life treatment, piglets were divided into three different groups receiving the following treatments: 1) no antibiotics and no stress, 2) antibiotics and no stress, and 3) antibiotics and stress. All treatments were applied at day four after birth. Sampling of jejunal content for community scale microbiota analysis, and jejunal and ileal tissue for genome-wide transcription profiling, was performed at day 55 (~8 weeks) and day 176 (~25 weeks) after birth. Antibiotic treatment in combination with or without exposure to stress was found to have long-lasting effects on host intestinal gene expression involved in a multitude of processes, including immune related processes. Conclusions/Significance The results obtained in this study indicate that early life (day 4 after birth) perturbations have long-lasting effects on the gut system, both in gene expression (day 55) as well as on microbiota composition (day 176). At day 55 high variance was observed in the microbiota data, but no significant differences between treatment groups, which is most probably due to the newly acquired microbiota during and right after weaning (day 28). Based on the observed difference in gene expression at day 55, it is hypothesized that due to the difference in immune programming during early life, the systems respond differently to the post-weaning newly acquired microbiota. As a consequence, the gut systems of the treatment groups develop into different homeostasis.
    Quality of traditionally processed shea (Vitellaria paradoxa) kernels and shea butter
    Honfo, G.F. - \ 2015
    Wageningen University. Promotor(en): Tiny van Boekel; M.M. Soumanou, co-promotor(en): Anita Linnemann. - Wageningen : Wageningen University - ISBN 9789462572737 - 237
    sheaboter - voedselbereiding - plantaardige vetten - warmtebehandeling - extractie - inheemse kennis - kwaliteit - achteruitgang (deterioration) - benin - vitellaria paradoxa - shea butter - food preparation - plant fats - heat treatment - extraction - indigenous knowledge - quality - deterioration - benin - vitellaria paradoxa


    The shea tree is an endogenous and multipurpose tree from the Savanah zone of Africa, mostly used for its fruits and the fat extracted from its kernels, commonly known as shea butter. The butter is used for cooking and medicinal purposes by local populations, and in cosmetic products as well as a cocoa butter substitute in chocolate in others areas of Africa and at the international level. The butter is generally extracted by traditional methods, which vary throughout the production zones but involve some common processing operations viz. boiling of the fresh nuts, sun drying, shelling, crushing, roasting, milling, churning, and heating. This thesis investigated the influence of traditional processing of shea on quality attributes of shea kernels and butter.

    The results showed that 2 mains techniques (differing in the heat treatment applied to the fresh nuts) are used to process shea fruits after their collection: the boiling followed by sun drying technique and the smoking technique. Boiled and sundried kernels contained a higher fat content (48 % dw) and yielded more butter (30 % of kernel mass) than smoked kernels that had a fat content of 39 % dw. The butter extracted from the boiled kernels had a better quality than the butter from smoked kernels with respect to the unsaponifiable fraction (7 %), tocopherol compounds (125 mg/g), peroxide value (8 meq O2/kg), and FFA (2 %). Some processing operations, namely the storage of fresh nuts as related to their boiling time and the roasting of kernels, were optimized using the response surface method to design the experiments. The conditions to obtain an optimal quality of kernels are to store the nuts for 3 days and boil them for 28 ± 3 min. Subsequently, optimal roasting conditions for kernels were found to be 15 min at 171 ºC, which resulted in kernels with a fat content of 49 % dw, a butter yield of 32 %, and butter with a FFA of 1.2 %. The results also revealed that shea butter extracted from roasted kernels contained more volatile compounds (58) than that from unroasted kernels (27). Additionally, storage temperature and storage duration significantly affected some quality characteristics of shea butter, whereas the influence of local packaging materials was less pronounced

    Shea processors are advised to process shea fruits by integrating the optimal conditions of storage of fresh nuts, boiling and roasting found in this research, then pack the butter in clean and opaque plastic and store it in a relatively cool area to maintain the quality of the product during prolonged storage periods. Areas for future research were identified for further improvements of local shea processing.

    Label free targeted detection and quantification of celiac disease immunogenic epitopes by mass spectrometry
    Broeck, H.C. van den; Cordewener, J.H.G. ; Nessen, M.A. ; America, A.H.P. ; Meer, I.M. van der - \ 2015
    Journal of Chromatography. A, Including electrophoresis and other separation methods 1391 (2015). - ISSN 0021-9673 - p. 60 - 71.
    simulated gastrointestinal digestion - gliadin gene family - t-cell epitopes - wheat-varieties - gluten peptides - processed foods - next-generation - proteins - extraction - elisa
    Celiac disease (CD) is a food-related disease caused by certain gluten peptides containing T-cell stimulating epitopes from wheat, rye, and barley. CD-patients have to maintain a gluten-free diet and are therefore dependent on reliable testing and labeling of gluten-free products. So far, the R5-ELISA is the approved method to detect if food products can be labeled gluten-free. Because the R5-ELISA detects gluten in general, there is a demand for an improved detection method that quantifies specifically CD-epitopes. Therefore, we developed a new method for detection and quantification of CD-epitopes, based on liquid chromatography (LC) coupled to mass spectrometry (MS) in multiple reaction monitoring (MRM) mode. This method enables targeted label free comparative analysis of the gluten proteins present in different wheat varieties and species, and in wheat-based food products. We have tested our method by analyzing several wheat varieties that vary in CD-epitope content, as was shown before using immunoblotting and specific monoclonal antibodies. The results showed that a modern bread wheat variety Toronto contained the highest amounts of CD immunogenic peptides compared with the older bread wheat variety Minaret and the tetraploid wheat variety Dibillik Sinde. Our developed method can detect quantitatively and simultaneously multiple specific CD-epitopes in a high throughput manner.
    Valorization of jatropha fruit biomass for energy applications
    Marasabessy, A. - \ 2015
    Wageningen University. Promotor(en): Johan Sanders, co-promotor(en): Ruud Weusthuis; M. Moeis. - Wageningen : Wageningen University - ISBN 9789462572614 - 147
    landbouwbijproducten - jatropha curcas - bio-energie - bioraffinage - biobrandstoffen - economische aspecten - extractie - fractionering - hydrolyse - indonesië - agricultural byproducts - jatropha curcas - bioenergy - biorefinery - biofuels - economic aspects - extraction - fractionation - hydrolysis - indonesia

    Valorization of Jatropha fruit biomass for

    energy applications

    Ahmad Marasabessy

    Thesis Abstract

    Our research objectives were to develop sustainable technologies of Jatropha oil extraction and Jatropha biomass fractionation within a framework of bioconversions (enzymatic and microbial processings). Microbial extraction of oil from Jatropha kernels using whole cells of Bacillus pumilus yields 73% oil, and this is comparable to the known processes such as by using expeller or by enzymatic extraction. The bacterium facilitates oil liberation via degradation of hemicelluloses therefore the majority of Jatropha proteins were preserved in the solid phase of the extraction residues. In investigating the effect of dilute sulfuric acid pretreatment on the enzymatic digestibility of the lignocellulosic components of Jatropha fruit biomass, we found that the seed shell and the seed cake were more recalcitrant to dilute sulfuric acid pretreatments than the fruit hull. A pretreatment of the fruit hull at optimum conditions (10% solid loading, 0.9% sulfuric acid, 30 min, 178 oC) followed by neutralization and a 24-h enzymatic hydrolysis with cellulases (GC220) liberated 100% pentoses (71% yield and 29% degradation to furfural) and 83% hexoses (78% yield and 5% degradation to 5-hydroxymethylfurfural). The fruit hull hydrolyzate can be used as a substrate for Saccharomyces cerevisiae to produce ethanol in SSF process. Our economic analysis in the retrospectives showed that valorization of the fruit biomass into variuos products (oil, protein isolate, lignin, biogas, bio-oil, etc.) using the most known techniques (pretreatment, hydrolysis, fermentation, extraction, separation, anaerobic digestion, pyrolysis) could improve the economy value of this biofuel crop significantly.

    Use of methylene blue uptake for assessing cell viability of colony-forming microalgae
    Lemos Bicas, J. ; Kleinegris, D.M.M. ; Barbosa, M.J. - \ 2015
    Algal Research 8 (2015). - ISSN 2211-9264 - p. 174 - 180.
    botryococcus-braunii - yeast cells - race-b - biomass - hydrocarbons - extraction - chemicals - dyes
    During the past few years, interest in microalgae has grown, mainly because of their potential for biofuel production. Botryococcus braunii, a green microalga that can accumulate more than half of its dry weight as hydrocarbons, is one of the most important examples. This microorganism grows in colonies and there has been no reliable viability protocol reported for this species as yet. Knowing the number of dead cells in cultures is essential for the development of efficient bioprocesses such as non-destructive extraction procedures (“milking”) to obtain lipid soluble substances from microalgal biomass. Our study presents a simple colorimetric method to determine the proportion of living to dead cells in cultures, based on the uptake of methylene blue in solution by dead B. braunii cells. The main parameters influencing this process were investigated and used to develop a protocol. This technique was validated using flow cytometry and Neochloris oleoabundans, and appears not to be limited to use with B. braunii.
    A study on the potential of insect protein and lipid as a food source
    Yi, L. - \ 2015
    Wageningen University. Promotor(en): Tiny van Boekel; Arnold van Huis, co-promotor(en): Catriona Lakemond. - Wageningen : Wageningen University - ISBN 9789462572560 - 186
    eiwitbronnen - nieuwe voedingsmiddelen - insecten als voedsel - extractie - eiwitten - vleesvervangers - fysicochemische eigenschappen - protein sources - novel foods - insects as food - extraction - proteins - meat alternates - physicochemical properties


    Propositions belonging to the thesis, entitled:‘A study on the potential of insect protein and lipid as a food source’. Liya Yi

    Wageningen, 9 February 2015.High protein quality is, next to high protein content, a major argument to use insects as an alternative protein source. (this thesis)

    With respect to aqueous extraction, proteins from Tenebrio molitor behave similarly as proteins from meat and fish. (this thesis)

    In contrast to what Pascucci & Magistris (2013) claim, consumer information is not enough to achieve consumer acceptance of novel food.

    Pascucci, S., & Magistris, T. d. (2013). International Food and Agribusiness Management Review, 16, 1-16.

    Reducing environmental impact by changing human diet into a plant-based diet (Joyce, Dixon, Comfort, & Hallett, 2012) will not result in meeting the increasing global food demand.Joyce, A., Dixon, S., Comfort, J., & Hallett, J. (2012). Journal of Environmental and Public Health, 2012, 7.

    Scientific evidence and the availability of technology are not guarantees for a change in human behaviour.

    The statement of the Finnish writer Sebastyne Young “We all want to be extraordinary and we all just want to fit in. Unfortunately, extraordinary people rarely fit in.” applies to science where generation of extraordinary knowledge results in less fitting in.

    Soil biodiversity and DNA barcodes: opportunities and challenges
    Orgiazzi, A. ; Bonnet Dunbar, M. ; Panagos, P. ; Groot, G.A. de; Lemanceau, P. - \ 2015
    Soil Biology and Biochemistry 80 (2015)1. - ISSN 0038-0717 - p. 244 - 250.
    molecular microbial ecology - bacterial communities - ecosystem services - diversity - fungal - patterns - identification - assemblages - resilience - extraction
    Soils encompass a huge diversity of organisms which mostly remains to be characterized due to a number of methodological and logistical issues. Nonetheless, remarkable progress has been made in recent years toward developing strategies to characterize and describe soil biodiversity, especially thanks to the development of molecular approaches relying on direct DNA extraction from the soil matrix.Metabarcoding can be applied to DNA from any environment or organism, and is gaining increasing prominence in biodiversity studies. This approach is already commonly used to characterize soil microbial communities and its application is now being extended to other soil organisms, i.e. meso- and macro-fauna.These developments offer unprecedented scientific and operational opportunities in order to better understand soil biodiversity distribution and dynamics, and to propose tools and strategies for biodiversity diagnosis. However, these opportunities also come with challenges that the scientific community must face. Such challenges are related to i) clarification of terminology, (ii) standardisation of methods and further methodological development for additional taxonomic groups, (iii) development of a common database, and (iv) ways to avoid waste of information and data derived from metabarcoding. In order to facilitate common application of metabarcoding in soil biodiversity assessment, we discuss these opportunities and challenges and propose solutions towards a more homogeneous framework.
    Lignin solubilisation and gentle fractionation in liquid ammonia
    Strassberger, Z. ; Prinsen, P. ; Klis, F. van der; Es, D.S. van; Tanase, S. ; Rothenberg, G. - \ 2015
    Green Chemistry 17 (2015). - ISSN 1463-9262 - p. 325 - 334.
    technical lignins - renewable chemicals - catalysts - extraction - conversion - fuels - kraft - wood - purification - valorization
    We present a simple method for solubilising lignin using liquid ammonia. Unlike water, which requires harsh conditions, ammonia can solubilise technical lignins, in particular kraft lignin. A commercial pine wood Kraft lignin (Indulin AT) was solubilized instantaneously at room temperature and 7–11 bars autogeneous pressure, while a commercial mixed wheat straw/Sarkanda grass soda lignin (Protobind™ 1000) was solubilized within 3 h at ambient temperature, and 30 min at. 85 °C. Hydroxide salts were not required. Wheat straw, poplar and spruce organosolv lignins, as well as elephant grass native lignin (MWL) were also solubilized, albeit at lower values. Different sequences of solubilisation and extraction were tested on the Protobind™ 1000 lignin. The remaining lignin residues were characterized by FTIR, size exclusion chromatography (SEC), elemental analysis (ICP), 2D-NMR and 31P NMR. Liquid ammonia is not an innocent solvent, as some nitrogen was incorporated in the residual lignin which then rearranged to higher molecular weight fractions. Nevertheless, the mild solubilisation conditions make liquid ammonia an attractive candidate as a solvent for lignin in future biorefinery processes.
    Mild disintegration of the green microalgae Chlorella vulgaris using bead milling
    Postma, P.R. ; Miron, T.L. ; Olivieri, G. ; Barbosa, M.J. ; Wijffels, R.H. ; Eppink, M.H.M. - \ 2015
    Bioresource Technology 184 (2015). - ISSN 0960-8524 - p. 297 - 304.
    protein aggregation - cell disruption - microbial-cells - release - food - biomass - purification - extraction - economics - products
    In this work, the mild disintegration of the microalgae Chlorella vulgaris for the release of intracellular products has been studied. By means of bead milling the microalgae suspensions were successfully disintegrated at different biomass concentrations (25–145 gDW kg-1) over a range of agitator speeds (6–12 m s-1). In all cases over 97% of cell disintegration was achieved resulting in a release of water soluble proteins. A clear optimum rate of disintegration and protein release was observed at an agitator speed of 9–10 m s-1 regardless of the biomass concentration. Selective extraction of water soluble proteins was observed as proteins released sooner than cell disintegration took place. Proteins could be released at 85% lower energy input than for cell disintegration resulting in specific energy consumptions well below 2.5 kWh kgDW-1.
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