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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Strain diversity and phage resistance in complex dairy starter cultures
Spus, M. ; Alexeeva, S.V. ; Wolkers-Rooijackers, J.C.M. ; Zwietering, M.H. ; Abee, T. ; Smid, E.J. - \ 2015
Journal of Dairy Science 98 (2015)8. - ISSN 0022-0302 - p. 5173 - 5182.
streptococcus-cremoris - lactic streptococci - lactococcus-lactis - food fermentations - bacteriophages - competition - products - genomics - bacteria - plasmid
The compositional stability of the complex Gouda cheese starter culture Ur is thought to be influenced by diversity in phage resistance of highly related strains that co-exist together with bacteriophages. To analyze the role of bacteriophages in maintaining culture diversity at the level of genetic lineages, simple blends of Lactococcus lactis strains were made and subsequently propagated for 152 generations in the absence and presence of selected bacteriophages. We first screened 102 single-colony isolates (strains) from the complex cheese starter for resistance to bacteriophages isolated from this starter. The collection of isolates represents all lactococcal genetic lineages present in the culture. Large differences were found in bacteriophage resistance among strains belonging to the same genetic lineage and among strains from different lineages. The blends of strains were designed such that 3 genetic lineages were represented by strains with different levels of phage resistance. The relative abundance of the lineages in blends with phages was not stable throughout propagation, leading to continuous changes in composition up to 152 generations. The individual resistance of strains to phage predation was confirmed as one of the factors influencing starter culture diversity. Furthermore, loss of proteolytic activity of initially proteolytic strains was found. Reconstituted blends with only 4 strains with a variable degree of phage resistance showed complex behavior during prolonged propagation. Key words: starter culture; bacteriophage; diversity; proteolytic activity
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.
Social sustainability of cod and haddock fisheries in the northeast Atlantic: what issues are important?
Veldhuizen, L.J.L. ; Berentsen, P. ; Bokkers, E.A.M. ; Boer, I.J.M. de - \ 2015
Journal of Cleaner Production 94 (2015). - ISSN 0959-6526 - p. 76 - 85.
life-cycle assessment - environmental impacts - production systems - fish - categories - indicators - products - welfare - stress - salmon
Research on the sustainability of capture fisheries has focused more on environmental and economic sustainability than on social sustainability. To assess social sustainability, first relevant and important social sustainability issues need to be identified. The objective of this study was to identify relevant social sustainability issues for cod and haddock fisheries in the northeast Atlantic and to determine the importance of these issues based on stakeholder input. A heterogeneous group of stakeholders was invited to take part in two consecutive surveys on social sustainability issues. The first survey (n=41) resulted in a long list of 27 relevant social sustainability issues, including six issues that were not identified in previous studies and that address aspects of fish welfare, employees' training and education opportunities, and employees' time off from work. The second survey (n=51) resulted in a ranking of the social sustainability issues in order of importance. The most important issues are worker safety, product freshness and companies' salary levels. In general, social sustainability issues concerning working conditions, employees' job fulfilment and fish welfare are seen as more important than other social sustainability issues. A main discussion point concerns the relation between the importance of a social sustainability issue on the one hand and the type of need that the issue relates to and the state of the issue on the other hand. From the study it can be concluded that the relative importance of social sustainability issues differs per stakeholder group depending on the relation between the stakeholder group and each particular issue. This demonstrates the importance of consulting different stakeholder groups in future studies on social sustainability in order to get a balanced view on the importance of social sustainability issues. Results on the relevance and importance of social sustainability issues for cod and haddock fisheries in the northeast Atlantic enable the fishing industry and policy-makers to direct improvement efforts towards the more important issues. ©
Establishing Guidelines to Retain Viability of Probiotics during Spray Drying
Perdana, J.A. ; Fox, M.B. ; Boom, R.M. ; Schutyser, M.A.I. - \ 2015
Drying Technology 33 (2015)13. - ISSN 0737-3937 - p. 1560 - 1569.
lactobacillus-plantarum wcfs1 - inactivation - integration - isotherms - products - sorption - storage - trends - foods - model
We present the application of a model-based approach to map processing conditions suitable to spray dry probiotics with minimal viability loss. The approach combines the drying history and bacterial inactivation kinetics to predict the retention of viability after drying. The approach was used to systematically assess the influence of operational co-current spray drying conditions on residual viability. Moreover, two promising alternative drying strategies for probiotics were evaluated involving encapsulation in a hollow particle and using an ‘ideal-mixed’ dryer system. Finally, a graph was constructed with the model to provide visual guidelines to optimize spray dying for probiotics in terms of viability and drying efficiency.
Evaluation of Satellite Rainfall Estimates for Drought and Flood Monitoring in Mozambique
Tote, C. ; Patricio, D. ; Boogaard, H.L. ; Wijngaart, R. van der; Tarnavsky, E. ; Funk, C. - \ 2015
Remote Sensing 7 (2015)2. - ISSN 2072-4292 - p. 1758 - 1776.
west-africa - precipitation - validation - products - microwave - climate - dataset - gages - sahel - trmm
Satellite derived rainfall products are useful for drought and flood early warning and overcome the problem of sparse, unevenly distributed and erratic rain gauge observations, provided their accuracy is well known. Mozambique is highly vulnerable to extreme weather events such as major droughts and floods and thus, an understanding of the strengths and weaknesses of different rainfall products is valuable. Three dekadal (10-day) gridded satellite rainfall products (TAMSAT African Rainfall Climatology And Time-series (TARCAT) v2.0, Famine Early Warning System NETwork (FEWS NET) Rainfall Estimate (RFE) v2.0, and Climate Hazards Group InfraRed Precipitation with Stations (CHIRPS)) are compared to independent gauge data (2001–2012). This is done using pairwise comparison statistics to evaluate the performance in estimating rainfall amounts and categorical statistics to assess rain-detection capabilities. The analysis was performed for different rainfall categories, over the seasonal cycle and for regions dominated by different weather systems. Overall, satellite products overestimate low and underestimate high dekadal rainfall values. The RFE and CHIRPS products perform as good, generally outperforming TARCAT on the majority of statistical measures of skill. TARCAT detects best the relative frequency of rainfall events, while RFE underestimates and CHIRPS overestimates the rainfall events frequency. Differences in products performance disappear with higher rainfall and all products achieve better results during the wet season. During the cyclone season, CHIRPS shows the best results, while RFE outperforms the other products for lower dekadal rainfall. Products blending thermal infrared and passive microwave imagery perform better than infrared only products and particularly when meteorological patterns are more complex, such as over the coastal, central and south regions of Mozambique, where precipitation is influenced by frontal systems.
Evaluation of research methods to study domestic food preparation
Bongoni, R. ; Verkerk, R. ; Dekker, M. ; Steenbekkers, B. - \ 2015
British Food Journal 117 (2015)1. - ISSN 0007-070X - p. 7 - 21.
brassica vegetables - handling behaviors - cooking methods - health - questionnaire - reliability - attributes - products
Purpose – Domestic preparation practices influence the sensory properties and nutritional composition of food products. Information on the variability in actual domestic preparation practices is needed to assess the influence of applied conditions on the sensory and nutritional quality of food. The collection of such information requires a reliable, valid and practical research method. The paper aims to discuss these issues. Design/methodology/approach – Direct in-home observations, observations in a model-kitchen using cameras, and a self-reporting questionnaire were evaluated for reliability and validity, to study domestic food preparation practices by consumers. Broccoli preparation practices by Dutch consumers were checked by these three methods in this research paper. Findings – All three research methods were found to be test-retest, inter-observer, parallel-form reliable; and face, content and concurrent valid. However, the self-reporting questionnaire is the most practical research method that can be administered on a large number of respondents in a short time to capture the wide variations in preparation practices. Originality/value – Consumers can be assisted on domestic food preparation practices that reach their sensory preferences (e.g. texture, colour) as well as have health benefits on consumption. Keywords Reliability, Validity, Consistency in behaviour, Food preparation, Observation (through cameras), Self-reporting questionnaire Paper type Research paper
A straightforward method to determine flavouring substances in food by GC-MS
Lopez Sanchez, P. ; Sisseren, M. van; Marco, S. De; Jekel, A.A. ; Nijs, W.C.M. de; Mol, J.G.J. - \ 2015
Food Chemistry 174 (2015). - ISSN 0308-8146 - p. 407 - 416.
solid-phase extraction - essential oils - cinnamaldehyde - beverages - coumarin - cinnamon - products - pulegone - absinthe - thujone
A straightforward GC–MS method was developed to determine the occurrence of fourteen flavouring compounds in food. It was successfully validated for four generic types of food (liquids, semi-solids, dry solids and fatty solids) in terms of limit of quantification, linearity, selectivity, matrix effects, recovery (53–120%) and repeatability (3–22%). The method was applied to a survey of 61 Dutch food products. The survey was designed to cover all the food commodities for which the EU Regulation 1334/2008 set maximum permitted levels. All samples were compliant with EU legislation. However, the levels of coumarin (0.6–63 mg/kg) may result in an exposure that, in case of children, would exceed the tolerable daily intake (TDI) of 0.1 mg/kg bw/day. In addition to coumarin, estragole, methyl-eugenol, (R)-(+)-pulegone and thujone were EU-regulated substances detected in thirty-one of the products. The non-EU regulated alkenylbenzenes, trans-anethole and myristicin, were commonly present in beverages and in herbs-containing products.
Assessing global land cover reference datasets for different user communities
Tsendbazar, N.E. ; Bruin, S. de; Herold, M. - \ 2015
ISPRS Journal of Photogrammetry and Remote Sensing 103 (2015). - ISSN 0924-2716 - p. 93 - 114.
classification accuracy assessment - thematic map accuracy - validation data set - igbp discover - design - products - modis - challenges - imagery - area
Global land cover (GLC) maps and assessments of their accuracy provide important information for different user communities. To date, there are several GLC reference datasets which are used for assessing the accuracy of specific maps. Despite significant efforts put into generating them, their availability and role in applications outside their intended use have been very limited. This study analyses metadata information from 12 existing and forthcoming GLC reference datasets and assesses their characteristics and potential uses in the context of 4 GLC user groups, i.e., climate modellers requiring data on Essential Climate Variables (ECV), global forest change analysts, the GEO Community of Practice for Global Agricultural Monitoring and GLC map producers. We assessed user requirements with respect to the sampling scheme, thematic coverage, spatial and temporal detail and quality control of the GLC reference datasets. Suitability of the datasets is highly dependent upon specific applications by the user communities considered. The LC-CCI, GOFC-GOLD, FAO-FRA and Geo-Wiki datasets had the broadest applicability for multiple uses. The re-usability of the GLC reference datasets would be greatly enhanced by making them publicly available in an expert framework that guides users on how to use them for specific applications.
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.
Photopyroelectric assessment of the thermal effusivity of fresh hen egg and of rehydrated egg powders
Szafner, G. ; Nemeth, C. ; Bicanic, D.D. ; Doka, O. - \ 2015
Journal of Thermal Analysis and Calorimetry 120 (2015)1. - ISSN 1388-6150 - p. 363 - 368.
conductivity - diffusivity - parameters - products - heat - spectroscopy - temperature - milk
The availability of thermo-physical data of foods and their constituents is of general importance to food industry. The thermal effusivity e is one among the relevant thermodynamical quantities. The latter is normally calculated from the relationship e = (¿¿c)½, where c is specific heat, ¿ is the density, and ¿ is the thermal conductivity. The necessity for performing the time consuming independent measurements of these three quantities is the major reason that the existing database with effusivity of foods is not very wide. This paper describes the application of the inverse photopyroelectric (IPPE) technique that allows the determination of effusivity from a single measurement. This approach was used to directly measure thermal effusivity of fresh egg yolk, egg white, and white/yolk blends. In addition, thermal effusivity of rehydrated egg powders (white, yolk, and the whole egg powder) has been measured and compared to that of the fresh hen egg. In case of the egg white, effusivity of rehydrated egg powders was practically the same as that of the fresh egg. However, the difference in effusivity between fresh egg yolk and rehydrated egg yolk, and between the blend of fresh egg and the rehydrated whole egg power was significant. Finally, thermal effusivity of rehydrated egg yolk, egg white, and the whole egg powder was determined as a function of dilution factor.
Managing Perishables with Time and temperature History
Ketzenberg, M. ; Bloemhof, J.M. ; Gaukler, G. - \ 2015
Production and Operations Management 24 (2015)1. - ISSN 1059-1478 - p. 54 - 70.
shelf-life prediction - supply chain - deteriorating inventory - ordering policies - information - products - replenishment - management - storage - demand
We address the use and value of time and temperature information to manage perishables in the contextof a retailer that sells a random lifetime product subject to stochastic demand and lost sales. The product’s lifetime is largely determined by the temperature history and the flow time through the supply chain. We compare the case in which information on flow time and temperature history is available and used for inventory management to a base case in which such information is not available. We formulate the two cases as Markov Decision Processes and evaluate the value of information through an extensive simulation using representative, real world supply chain parameters.
Improved Surface Reflectance from Remote Sensing Data with Sub-Pixel Topographic Information
Roupioz, L.F.S. ; Nerry, F. ; Jia, L. ; Menenti, M. - \ 2014
Remote Sensing 6 (2014)11. - ISSN 2072-4292 - p. 10356 - 10374.
landsat-tm data - satellite imagery - rugged terrain - atmospheric correction - spatial-resolution - illumination - products - albedo - china - model
Several methods currently exist to efficiently correct topographic effects on the radiance measured by satellites. Most of those methods use topographic information and satellite data at the same spatial resolution. In this study, the 30 m spatial resolution data of the Digital Elevation Model (DEM) from ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer) are used to account for those topographic effects when retrieving land surface reflectance from satellite data at lower spatial resolution (e.g., 1 km). The methodology integrates the effects of sub-pixel topography on the estimation of the total irradiance received at the surface considering direct, diffuse and terrain irradiance. The corrected total irradiance is then used to compute the topographically corrected surface reflectance. The proposed method has been developed to be applied on various kilometric pixel size satellite data. In this study, it was tested and validated with synthetic Landsat data aggregated at 1 km. The results obtained after a sub-pixel topographic correction are compared with the ones obtained after a pixel level topographic correction and show that in rough terrain, the sub-pixel topography correction method provides better results even if it tends to slightly overestimate the retrieved land surface reflectance in some cases.
Contagious animal diseases: The science behind trade policies and standards (Personal View)
Boqvist, S. ; Dekker, A. ; Depner, K. ; Grace, D. ; Hueston, W. ; Stark, K.D.C. ; Sternberg Lewerin, S. - \ 2014
The Veterinary Journal 202 (2014)1. - ISSN 1090-0233 - p. 7 - 10.
pcr detection methods - swine-fever virus - mouth-disease - ring test - vaccination - transmission - products - drivers - impacts - trends
Mobilization of biomass for energy from boreal forests in Finland & Russia under present sustainable forest management certification and new sustainability requirements for solid biofuels
Sikkema, R. ; Faaij, A.P.C. ; Ranta, T. ; Heinimö, J. ; Gerasimov, Y.Y. ; Karjalainen, T. ; Nabuurs, G.J. - \ 2014
Biomass and Bioenergy 71 (2014). - ISSN 0961-9534 - p. 23 - 36.
environmental impacts - wood - bioenergy - resources - fuel - alternatives - procurement - potentials - countries - products
Forest biomass is one of the main contributors to the EU's renewable energy target of 20% gross final energy consumption in 2020 (Renewable Energy Directive). Following the RED, new sustainability principles are launched by the European energy sector, such as the Initiative Wood Pellet Buyers (IWPB or SBP). The aim of our study is the investigation of the quantitative impacts from IWPB's principles for forest biomass for energy only. We deploy a bottom up method that quantifies the supplies and the costs from log harvest until forest chip delivery at a domestic consumer. We have a reference situation with existing national (forest) legislation and voluntary certification schemes (scenario 1) and a future situation with additional criteria based on the IWPB principles (scenario 2). Two country studies were selected for our (2008) survey: one in Finland with nearly 100% certification and one in Leningrad province with a minor areal share of certification in scenario 1. The sustainable potential of forest resources for energy is about 54 Mm3 (385 PJ) in Finland and about 13.5 Mm3 (95 PJ) in Leningrad in scenario 1 without extra criteria. The potential volumes reduce considerably by maximum 43% respectively 39% after new criteria from the IWPB, like a minimum use of sawlogs, stumps and slash for energy, and by an increased area of protected forests (scenario 2A Maximum extra restrictions). In case sawlogs can be used, but instead ash recycling is applied after a maximum stump and slash recovery (scenario 2B Minimum extra restrictions), the potential supply is less reduced: 5% in Finland and 22% in Leningrad region. The estimated reference costs for forest chips are between €18 and €45 solid m-3 in Finland and between €7 and €33 solid m-3 in the Leningrad region. In scenario 2A, the costs will mainly increase by €7 m-3 for delimbing full trees (Finland), and maximum €0.3 m-3 for suggested improved forest management (Leningrad region). In scenario 2B, when ash recycling is applied, costs increase by about €0.3 to €1.6 m-3, depending on the rate of soil contamination. This is an increase of 2%, on top of the costs in scenario 2A.
Status quo and future research challenges on organic food quality determination with focus on laboratory methods
Kahl, J. ; Bodroza-Solarov, M. ; Busscher, N. ; Hajslova, J. ; Kneifel, W. ; Kokornaczyk, M.O. ; Ruth, S.M. van; Schulzova, V. ; Stolz, P. - \ 2014
Journal of the Science of Food and Agriculture 94 (2014)13. - ISSN 0022-5142 - p. 2595 - 2599.
wheat-grain leakages - grown winter-wheat - nutritional quality - crystallization patterns - samples - standardization - authentication - definition - validation - products
Organic food quality determination needs multi-dimensional evaluation tools. The main focus is on the authentication as an analytical verification of the certification process. New fingerprinting approaches such as ultra-performance liquid chromatography–mass spectrometry, gas chromatography–mass spectrometry, direct analysis in real time–high-resolution mass spectrometry as well as crystallization with and without the presence of additives seem to be promising methods in terms of time of analysis and detecting organic system-related parameters. For further methodological development, a system approach is recommended, which also takes into account food structure aspects. Furthermore, the authentication of processed organic samples needs more consciousness, hence most of organic food is complex and processed.
To pool or not to pool? Impact of the use of individual and pooled fecal samples for in vitro fermentation studies
Aguirre, M. ; Ramiro Garcia, J. ; Koenen, M.E. ; Venema, K. - \ 2014
Journal of Microbiological Methods 107 (2014). - ISSN 0167-7012 - p. 1 - 7.
human large-intestine - gut microbiota - model - bacteria - oligosaccharides - metabolism - products - patterns - starch - core
This study investigated the stability and the activity of the microbiota from a single and a pool of donors in the TNO in vitro model of the colon (TIM-2 system). Our findings demonstrate the suitability of the preparation of a pool of fecal sample to be used for fermentation experiments.
Analysis of Palmitoyl Apo-astaxanthinals, Apo-astaxanthinones, and their Epoxides by UHPLC-PDA-ESI-MS
Weesepoel, Y.J.A. ; Gruppen, H. ; Bruijn, W.J.C. de; Vincken, J.P. - \ 2014
Journal of Agricultural and Food Chemistry 62 (2014)42. - ISSN 0021-8561 - p. 10254 - 10263.
beta-carotene degradation - mass-spectrometry - hypochlorous acid - haematococcus-pluvialis - products - myeloperoxidase - autoxidation - stability - oxidation - esters
Food products enriched with fatty acid-esterified xanthophylls may result in deviating dietary apo-carotenoids. Therefore, free astaxanthin and its mono- and dipalmitate esters were subjected to two degradation processes in a methanolic model system: light-accelerated autoxidation and hypochlorous acid/hypochlorite (HOCl/OCl–) bleaching. Reversed phase ultrahigh-performance liquid chromatography photodiode array with in-line electrospray ionization mass spectrometry (RP-UHPLC-PDA-ESI-MS) was used for assessment of degradation products. Apo-astaxanthinals and -astaxanthinones containing 3 (apo-9) to 10 (apo-8') conjugated double bonds were found upon autoxidation for all three types of astaxanthin (except free apo-8'-astaxanthinal). Fragmentation of [M + H]+ and [M + Na]+ parent masses of apo-astaxanthins from dipalmitate astaxanthin indicated palmitate esterification. Astaxanthin monopalmitate degradation resulted in a mixture of free and palmitate apo-astaxanthins. HOCl/OCl– rapidly converted the astaxanthins into a mixture of epoxy-apo-9- and epoxy-apo-13-astaxanthinones. The palmitate ester bond was hardly affected by autoxidation, whereas for HOCl/OCl– the ester bond of the apo-astaxanthin palmitoyl esters was degraded.
Biorefinery methods for separation of protein and oil fractions from rubber seed kernel
Widyarani, R. ; Ratnaningsih, E. ; Sanders, J.P.M. ; Bruins, M.E. - \ 2014
Industrial Crops and Products 62 (2014). - ISSN 0926-6690 - p. 323 - 332.
aqueous enzymatic extraction - supercritical carbon-dioxide - hevea-brasiliensis seeds - biodiesel production - functional-properties - alpha-lactalbumin - nutritive-value - amino-acids - products - recovery
Biorefinery of rubber seeds can generate additional income for farmers, who already grow rubber trees for latex production. The aim of this study was to find the best method for protein and oil production from rubber seed kernel, with focus on protein recovery. Different pre-treatments and oil separation methods were tested, and alkaline conditions were used to extract protein. Next to processes with subsequent oil and protein recovery, a one-step combined oil and protein extraction was tested. Our study showed that oil separation is not necessary to obtain high protein recovery, however most of the extracted oil is present as an emulsion. The origin of the seeds and their treatment on the plantation before processing were most important for high oil and protein recoveries, and in all cases tested had more influence on recoveries than its subsequent method of processing. Pressing the rubber seed kernel to separate the oil fraction followed by protein extraction from the press cake gives the highest protein recovery with satisfactory recovery for oil.
Solid phase microextraction speciation analysis of triclosan in aqueous mediacontaining sorbing nanoparticles
Zielinska, K. - \ 2014
Environmental Chemistry 11 (2014)1. - ISSN 1448-2517 - p. 72 - 76.
nd-spme - samples - water - adsorption - products - binding - surface
Solid phase microextraction (SPME) is applied in the speciation analysis of the hydrophobic compound triclosan in an aqueous medium containing sorbing SiO2 nanoparticles (NPs). It is found that these NPs, as well as their complexes with triclosan, partition between the bulk medium and the solid phase poly(dimethylsiloxane) (PDMS). Furthermore, they appear to aggregate at the PDMS–water interface. The total triclosan concentration in the solid phase thus includes both the free and the NP-bound forms. Proper computation of the analyte concentration in the sample medium requires (i) consideration of the speciation of triclosan inside the solid phase and (ii) elimination of the effects of aggregation of NP complexes at the solid phase–bulk medium interface. Possible solutions include application of a protective membrane with pore size smaller than the NP diameter. This allows measurement of the free triclosan concentration, albeit at the cost of longer accumulation times and loss of kinetic information on the triclosan–NP complex.
Lupine and rapeseed protein concentrate in fish feed: a comparative assessment of the techno-functional properties using a shear cell device and an extruder
Draganovic, V. ; Boom, R.M. ; Jonkers, J. ; Goot, A.J. van der - \ 2014
Journal of Food Engineering 126 (2014). - ISSN 0260-8774 - p. 178 - 189.
trout oncorhynchus-mykiss - rainbow-trout - wheat gluten - glass-transition - kernel meal - starch - extrusion - products - moisture - quality
The techno-functional properties of soy, lupine and rapeseed protein concentrates (SPC, LPC and RPC, respectively) in fish feed were evaluated relative to fish meal (FM). The effects were studied using a shear cell device and an extruder with emphasis on the added moisture content. Six diets were formulated: an SPC-based diet with 300 g SPC kg-1, diets containing 100 and 200 g LPC kg-1 or 100 and 200 g RPC kg-1 and an FM-based diet with 450 g FM kg-1. Each diet was extruded with an added moisture content of 29%, 25% and 22% of the mash feed rate. It was found that the technological properties of LPC closely resemble FM, being high solubility, low water-holding capacity (WHC) and low paste viscosity. The LPC 100 and 200 g kg-1 diets could be extruded at 22% moisture, which gives an extrudate with reduced drying requirements. In addition, less specific mechanical energy was needed for extrusion. In contrast, both SPC and RPC have high WHC and paste viscosity. This explains the higher feed moisture required during extrusion. The properties of the feeds containing RPC could be well within the ranges acceptable for commercial fish feed use at even higher moisture content compared with SPC. The results of the extrusion trials confirmed the observations made from the shear cell device. Thus, the shear cell device can be used to study processing conditions that are close to extrusion conditions.
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