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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Watching paint dry: more exciting than it seems
Kooij, H.M. van der; Sprakel, J.H.B. - \ 2015
Soft Matter 11 (2015)32. - ISSN 1744-683X - p. 6353 - 6359.
latex film formation - thin liquid-films - colloidal dispersions - polymer diffusion - particle-size - cracking - coalescence - emulsion - water - deformation
With an ever-increasing demand for sustainable alternatives to solvent-borne coatings and paints, the pressure to develop aqueous alternatives that match or exceed the performance of their traditional counterparts rises. A crucial step in this sustainability challenge for the years to come is to arrive at a deep, and complete, understanding of how aqueous paints dry and form their final protective films. As it turns out, this is no minor challenge. Yet, understanding drying and film formation is a prototypical soft matter problem at heart, displaying a rich variety of complex non-equilibrium phenomena that are waiting to be understood. Watching paint dry is far from the boring activity the saying suggests.
Potential Health Impact of Environmentally Released Micro- and Nanoplastics in the Human Food Production Chain: Experiences from Nanotoxicology
Bouwmeester, H. ; Hollman, P.C.H. ; Peters, R.J.B. - \ 2015
Environmental Science and Technology 49 (2015). - ISSN 0013-936X - p. 8932 - 8947.
mytilus-edulis l. - persistent organic pollutants - field-flow fractionation - plastic marine debris - particle-size - hydrodynamic chromatography - drug-delivery - polystyrene nanoparticles - engineered nanomaterials - placopecten-magellanicus
High concentrations of plastic debris have been observed in the oceans. Much of the recent concern has focused on microplastics in the marine environment. Recent studies of the size distribution of the plastic debris suggested that continued fragmenting of microplastics into nanosized particles may occur. In this review we assess the current literature on the occurrence of environmentally released micro- and nanoplastics in the human food production chain and their potential health impact. The currently used analytical techniques introduce a great bias in the knowledge, since they are only able to detect plastic particles well above the nanorange. We discuss the potential use of the very sensitive analytical techniques that have been developed for the detection and quantification of engineered nanoparticles. We recognize three possible toxic effects of plastic particles: first due to the plastic particles themselves, second to the release of persistent organic pollutant adsorbed to the plastics, and third to the leaching of additives of the plastics. The limited data on microplastics in foods do not predict adverse effect of these pollutants or additives. Potential toxic effects of microplastic particles will be confined to the gut. The potential human toxicity of nanoplastics is poorly studied. Based on our experiences in nanotoxicology we prioritized future research questions.
Bioavailability and biodistribution of differently charged polystyrene nanoparticles upon oral exposure in rats
Walczak, A.P. ; Hendriksen, P.J.M. ; Woutersen, R.A. ; Zande, M. van der; Undas, A.K. ; Helsdingen, J.R. ; Berg, J.H.J. van den; Rietjens, I.M.C.M. ; Bouwmeester, H. - \ 2015
Journal of Nanoparticle Research : an Interdisciplinary Forum for Nanoscale Science and Technology 17 (2015). - ISSN 1388-0764 - 13 p.
zinc-oxide nanoparticles - titanium-dioxide nanoparticles - tissue distribution - silver nanoparticles - particle-size - absorption - food - translocation - microspheres - elimination
The likelihood of oral exposure to nanoparticles (NPs) is increasing, and it is necessary to evaluate the oral bioavailability of NPs. In vitro approaches could help reducing animal studies, but validation against in vivo studies is essential. Previously, we assessed the translocation of 50 nm polystyrene NPs of different charges (neutral, positive and negative) using a Caco-2/HT29-MTX in vitro intestinal translocation model. The NPs translocated in a surface charge-dependent manner. The present study aimed to validate this in vitro intestinal model by an in vivo study. For this, rats were orally exposed to a single dose of these polystyrene NPs and the uptake in organs was determined. A negatively charged NP was taken up more than other NPs, with the highest amounts in kidney (37.4 µg/g tissue), heart (52.8 µg/g tissue), stomach wall (98.3 µg/g tissue) and small intestinal wall (94.4 µg/g tissue). This partly confirms our in vitro findings, where the same NPs translocated to the highest extent. The estimated bioavailability of different types of NPs ranged from 0.2 to 1.7 % in vivo, which was much lower than in vitro (1.6–12.3 %). Therefore, the integrated in vitro model cannot be used for a direct prediction of the bioavailability of orally administered NPs. However, the model can be used for prioritizing NPs before further in vivo testing for risk assessment.
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 systematic review and meta-analysis examining the effect of eating rate on energy intake and hunger
Robinson, E. ; Almiron-Roig, E. ; Rutters, F. ; Graaf, C. de; Forde, C.G. ; Smith, C.T. ; Nolan, S.J. ; Jebb, S.A. - \ 2014
American Journal of Clinical Nutrition 100 (2014)1. - ISSN 0002-9165 - p. 123 - 151.
libitum food-intake - particle-size - gut hormones - obese - meal - women - appetite - men - weight - consumption
Background: Reductions in eating rate are recommended to prevent and treat obesity; yet, the relation between eating rate and energy intake has not been systematically reviewed, with studies producing mixed results. Objective: Our main objective was to examine how experimentally manipulated differences in eating rate influence concurrent energy intake and subjective hunger ratings. Design: We systematically reviewed studies that experimentally manipulated eating rate and measured concurrent food intake, self-reported hunger, or both. We combined effect estimates from studies by using inverse variance meta-analysis, calculating the standardized mean difference (SMD) in food intake between fast and slow eating rate conditions. Results: Twenty-two studies were eligible for inclusion. Evidence indicated that a slower eating rate was associated with lower energy intake in comparison to a faster eating rate (random-effects SMD: 0.45; 95% CI: 0.25, 0.65; P <0.0001). Subgroup analysis indicated that the effect was consistent regardless of the type of manipulation used to alter eating rate, although there was a large amount of heterogeneity between studies. There was no significant relation between eating rate and hunger at the end of the meal or up to 3.5 h later. Conclusions: Evidence to date supports the notion that eating rate affects energy intake. Research is needed to identify effective interventions to reduce eating rate that can be adopted in everyday life to help limit excess consumption.
State of the safety assessment and current use of nanomaterials in food and food production
Bouwmeester, H. ; Brandhoff, P.N. ; Marvin, H.J.P. ; Weigel, S. ; Peters, R.J.B. - \ 2014
Trends in Food Science and Technology 40 (2014)2. - ISSN 0924-2244 - p. 200 - 210.
environmental risk-assessment - silver nanoparticles - hydrodynamic chromatography - engineered nanomaterials - titanium-dioxide - mass-spectrometry - oral-exposure - particle-size - nanotechnology - toxicity
Nanomaterials are developed for and applied in food, food additives, supplements and food contact materials. In an inventory of internet databases 140 products in the food and food-related sectors were identified that claim to contain nanomaterials. A great diversity of nanomaterials is applied, ranging from inorganic metal and metal oxides to organic nanomaterials that carry bioactive ingredients. Here we present an overview of nanomaterial applications that are currently available, discuss state of the art analytical chemical characterization and toxicological assessment methods, as well as categorization methods to support the safety evaluation of the application of nanomaterials throughout food production.
Stable isotope labeled n-alkanes to assess digesta passage kinetics through the digestive tract of ruminants
Warner, D. ; Ferreira, L.M.M. ; Breuer, M.J.H. ; Dijkstra, J. ; Pellikaan, W.F. - \ 2013
PLoS One 8 (2013)10. - ISSN 1932-6203 - 9 p.
marker excretion patterns - carbon-isotope - dairy-cows - enrichments delta-c-13 - botanical composition - particle-size - in-vitro - rumen - herbivores - cattle
We describe the use of carbon stable isotope (13C) labeled n-alkanes as a potential internal tracer to assess passage kinetics of ingested nutrients in ruminants. Plant cuticular n-alkanes originating from intrinsically 13C labeled ryegrass plants were pulse dosed intraruminally in four rumen-cannulated lactating dairy cows receiving four contrasting ryegrass silage treatments that differed in nitrogen fertilization level (45 or 90 kg nitrogen ha-1) and maturity (early or late). Passage kinetics through the gastrointestinal tract were derived from the d13C (i.e. the ratio 13C:12C) in apparently undigested fecal material. Isotopic enrichment was observed in a wide range of long-chain n-alkanes (C27–C36) and passage kinetics were determined for the most abundant C29, C31 and C33 n-alkanes, for which a sufficiently high response signal was detected by combustion isotope ratio mass spectrometry. Basal diet treatment and carbon chain length of n-alkanes did not affect fractional passage rates from the rumen (K1) among individual n-alkanes (3.71–3.95%/h). Peak concentration time and transit time showed a quantitatively small, significant (p=0.002) increase with carbon chain length. K1 estimates were comparable to those of the 13C labeled digestible dry matter fraction (3.38%/h; r = 0.61 to 0.71; p=0.012). A literature review has shown that n-alkanes are not fermented by microorganisms in the rumen and affirms no preferential depletion of 13C versus 12C. Our results suggest that 13C labeled n-alkanes can be used as nutrient passage tracers and support the reliability of the d13C signature of digestible feed nutrients as a tool to measure nutrient-specific passage kinetics.
d13C as a marker to study digesta passage kinetics in ruminants: a combined in vivo and in vitro study
Pellikaan, W.F. ; Verstegen, M.W.A. ; Tamminga, S. ; Dijkstra, J. ; Hendriks, W.H. - \ 2013
Animal 7 (2013)5. - ISSN 1751-7311 - p. 754 - 767.
neutral detergent fiber - dairy-cows - internal markers - grass silages - particle-size - rumen - cattle - diets - digestibility - concentrate
The aim of the current study was to explore the use of the tracer 13C as an internal marker to assess feed fraction-specific digesta passage kinetics through the digestive tract of dairy cows. Knowledge on feed-specific fractional passage rates is essential to improve estimations on the extent of rumen degradation and microbial protein efficiency; however, this information is largely lacking. An in vivo and in vitro experiment was conducted with grass silages (Lolium perenne L.) that were enriched with 13C by growing the grass under elevated 13CO2 conditions. In a crossover design, two dairy cows received pulse doses of two 13C-enriched grass silages and chromium-mordanted neutral detergent fibre (Cr-NDF) into the rumen. The two 13C-enriched grass silages used differed in digestibility and were grown under identical field conditions as the bulk silages fed to the animals. Faecal excretion patterns of 13C-enriched dry matter (13C-DM), neutral detergent fibre (13C-NDF) and Cr-NDF were established, and a nonlinear multicompartmental model was used to determine their rumen passage kinetics. In addition, the 13C-enriched silages were incubated in rumen liquid in an in vitro batch culture system at different time intervals to determine the effect of fermentation on 13C-enrichment in the residue. The in vitro study showed that the 13C : 12C ratios in DM and NDF residues remained stable from 24 h of incubation onwards. In addition, in vitro fractional degradation rates for 12C in the DM and NDF did not differ from those of 13C, indicating that fermentative degradation does not affect the 13C : 12C ratio in the DM nor in the NDF fraction of the residue. Model fits to the faecal excretion curves showed a significant difference in fractional rumen passage rates between Cr-NDF, 13C-DM and 13C-NDF (P = 0.025). Silage type had no clear effect on rumen passage kinetics (P = 0.081). Moreover, it showed that peak enrichments for 13C-DM and 13C-NDF in faeces were reached at 30.7 and 41.7 h post dosing, respectively. This is well after the time (24 h) when the 13C : 12C ratios of the in vitro unfermented residues have reached stable enrichment level. Fractional rate constants for particle passage from the rumen are estimated from the descending slope of faecal excretion curves. The present study shows that the decline in 13C : 12C ratio after peak enrichment is not affected by fermentative degradation and therefore can be used to assess feed component-specific fractional passage rates.
An OxiTop (R) protocol for screening plant material for its biochemical methane potential (BMP)
Pabon Pereira, C.P. ; Castanares, G. ; Lier, J.B. van - \ 2012
Water Science and Technology 66 (2012)7. - ISSN 0273-1223 - p. 1416 - 1423.
anaerobic-digestion - particle-size - organic waste - biomass
A protocol was developed for determining the biochemical methane potential (BMP) of plant material using the OxiTop (R) system. NaOH pellets for CO2 absorption and different pretreatment methods were tested for their influence in the BMP test. The use of NaOH pellets in the headspace of the bottle negatively affected the stability of the test increasing the pH and inhibiting methanization. Sample comminution increased the biodegradability of plant samples. Our results clearly indicate the importance of test conditions during the assessment of anaerobic biodegradability of plant material, considering BMP differences as high as 44% were found. Guidelines and recommendations are given for screening plant material suitable for anaerobic digestion using the OxiTop (R) system.
Thermal Plasma Synthesis of Superparamagnetic Iron Oxide Nanoparticles
Lei, P.Y. ; Boies, A.M. ; Calder, S.A. ; Girshick, S.L. - \ 2012
Plasma Chemistry and Plasma Processing 32 (2012)3. - ISSN 0272-4324 - p. 519 - 531.
multifunctional magnetic nanoparticles - gamma-fe2o3 nanoparticles - biomedical applications - particle-size - flow reactor - rf plasma - flame - arc - pressure - functionalization
Superparamagnetic iron oxide nanoparticles were synthesized by injecting ferrocene vapor and oxygen into an argon/helium DC thermal plasma. Size distributions of particles in the reactor exhaust were measured online using an aerosol extraction probe interfaced to a scanning mobility particle sizer, and particles were collected on transmission electron microscopy (TEM) grids and glass fiber filters for off-line characterization. The morphology, chemical and phase composition of the nanoparticles were characterized using TEM and X-ray diffraction, and the magnetic properties of the particles were analyzed with a vibrating sample magnetometer and a magnetic property measurement system. Aerosol at the reactor exhaust consisted of both single nanocrystals and small agglomerates, with a modal mobility diameter of 8-9 nm. Powder synthesized with optimum oxygen flow rate consisted primarily of magnetite (Fe3O4), and had a room-temperature saturation magnetization of 40.15 emu/g, with a coercivity and remanence of 26 Oe and 1.5 emu/g, respectively
Approaches to the safety assessment of engineered nanomaterials (ENM) in food
Cockburn, A. ; Bradford, R. ; Buck, N. ; Kampers, F.W.H. - \ 2012
Food and Chemical Toxicology 50 (2012)6. - ISSN 0278-6915 - p. 2224 - 2242.
vitro digestion models - nanoparticle uptake - protein corona - polymeric nanoparticles - gastrointestinal-tract - silica nanoparticles - particle-size - in-vivo - toxicity - bioaccessibility
A systematic, tiered approach to assess the safety of engineered nanomaterials (ENMs) in foods is presented. The ENM is first compared to its non-nano form counterpart to determine if ENM-specific assessment is required. Of highest concern from a toxicological perspective are ENMs which have potential for systemic translocation, are insoluble or only partially soluble over time or are particulate and bio-persistent. Where ENM-specific assessment is triggered. Tier 1 screening considers the potential for translocation across biological barriers, cytotoxicity, generation of reactive oxygen species, inflammatory response, genotoxicity and general toxicity. In silica and in vitro studies, together with a sub-acute repeat-dose rodent study, could be considered for this phase. Tier 2 hazard characterisation is based on a sentinel 90-day rodent study with an extended range of endpoints, additional parameters being investigated case-by-case. Physicochemical characterisation should be performed in a range of food and biological matrices. A default assumption of 100% bioavailability of the ENM provides a 'worst case' exposure scenario, which could be refined as additional data become available. The safety testing strategy is considered applicable to variations in ENM size within the nanoscale and to new generations of ENM.
Presence of Nano-Sized Silica during In Vitro Digestion of Foods Containing Silica as a Food Additive
Peters, R.J.B. ; Kramer, E.H.M. ; Oomen, A.G. ; Rivera, Z.H. ; Oegema, G. ; Tromp, P.C. ; Fokkink, R.G. ; Rietveld, A. ; Marvin, H.J.P. ; Weigel, S. ; Peijnenburg, A.A.C.M. ; Bouwmeester, H. - \ 2012
ACS Nano 6 (2012)3. - ISSN 1936-0851 - p. 2441 - 2451.
gastrointestinal uptake - particle-size - bioaccessibility - model - contaminants - absorption - hazard
The presence, dissolution, agglomeration state, and release of materials in the nano-size range from food containing engineered nanoparticles during human digestion is a key question for the safety assessment of these materials. We used an in vitro model to mimic the human digestion. Food products subjected to in vitro digestion included (i) hot water, (ii) coffee with powdered creamer, (iii) instant soup, and (iv) pancake which either contained silica as the food additive E551, or to which a form of synthetic amorphous silica or 32 nm SiO2 particles were added. The results showed that, in the mouth stage of the digestion, nano-sized silica particles with a size range of 5–50 and 50–500 nm were present in food products containing E551 or added synthetic amorphous silica. However, during the successive gastric digestion stage, this nano-sized silica was no longer present for the food matrices coffee and instant soup, while low amounts were found for pancakes. Additional experiments showed that the absence of nano-sized silica in the gastric stage can be contributed to an effect of low pH combined with high electrolyte concentrations in the gastric digestion stage. Large silica agglomerates are formed under these conditions as determined by DLS and SEM experiments and explained theoretically by the extended DLVO theory. Importantly, in the subsequent intestinal digestion stage, the nano-sized silica particles reappeared again, even in amounts higher than in the saliva (mouth) digestion stage. These findings suggest that, upon consumption of foods containing E551, the gut epithelium is most likely exposed to nano-sized silica.
Improving digestive utilization of fiber-rich feedstuffs in pigs and poultry by processing and enzyme technologies: A review
Vries, S. de; Pustjens, A.M. ; Schols, H.A. ; Hendriks, W.H. ; Gerrits, W.J.J. - \ 2012
Animal Feed Science and Technology 178 (2012)3-4. - ISSN 0377-8401 - p. 123 - 138.
cereal nonstarch polysaccharides - early-weaned piglets - chain fatty-acids - plant-cell walls - broiler-chickens - dietary fiber - nutritive-value - particle-size - gastrointestinal-tract - extrusion-cooking
The effects of processing technologies, whether or not combined with cell wall degrading enzymes, on the physicochemical properties of non-starch polysaccharides (NSP) and the resulting effects on NSP degradation in both pigs and poultry were reviewed. Evaluation of the effects of processing technologies on digestion of NSP is hampered by the potential shift of polysaccharides recovered in the fiber fractions of common, gravimetric, fiber analysis methods. Results from in vivo studies describing effects of processing technologies or enzyme treatments on crude fiber, neutral detergent fiber, or acid detergent fiber digestibility, instead of NSP digestibility, should therefore, be interpreted with care. Detailed information on the composition of the NSP-fraction and digestibility of its components will help to identify and understand modifications that occur during processing. Processes based on mechanical modification of feedstuffs that are commonly used in the feed industry, such as hammer and roller milling increase solubility of the NSP-fraction resulting in a 6–7 percentage unit increase in coefficient of apparent total tract digestibility (CATTD) of the fiber fraction in both pigs and poultry. Dry thermal processes have a minor impact on physicochemical properties of feedstuffs and consequently, the effects on the coefficient of apparent ileal digestibility (CAID) and CATTD of the fiber fractions in pigs and poultry are limited. Hydrothermal processes that include high shear forces such as expander processing and extrusion cooking are more effective and increase solubility but also viscosity. The CATTD of fiber fractions in pigs can be increased on average 3 percentage units by hydrothermal processing of feeds and feed ingredients, although some studies have reported unchanged or even decreased digestibility values. In poultry, CATTD of fiber fractions can be increased 4–16 percentage units by hydrothermal processing. Increased digesta viscosity resulting from technological processing of feed and feed ingredients can be counteracted by the addition of specific enzymes. Enzyme addition to heat processed diets and diets containing heat processed ingredients results in a 3- to 4-fold reduction in viscosity compared with enzyme addition to unprocessed diets, or diets containing unprocessed ingredients. In addition, modifications in cell wall architecture obtained by processing technologies will improve the accessibility of NSP to enzymes. As a result, the effects of enzyme addition on digestibility of the fiber fraction are 1.5–6 times larger, when applied to heat processed diets compared with unprocessed diets.
Residual Carbohydrates from in Vitro Digested Processed Rapeseed (Brassica napus) Meal
Pustjens, A.M. ; Vries, S. de; Gerrits, W.J.J. ; Kabel, M.A. ; Schols, H.A. ; Gruppen, H. - \ 2012
Journal of Agricultural and Food Chemistry 60 (2012)34. - ISSN 0021-8561 - p. 8257 - 8263.
nutrient digestibility - growth-performance - pectic substances - dehulled rapeseed - feed ingredients - particle-size - dietary fiber - soybean-meal - pigs - polysaccharides
Rapeseed meal (RSM) was subjected to different physical or chemical pretreatments to decrease residual, hard to degrade carbohydrates and to improve fermentability of RSM polysaccharides. Next, these pretreated samples were in vitro digested and fermented, with or without the addition of commercial pectinolytic enzymes. Remaining carbohydrates were quantified, and two physical characteristics were analyzed: (1) water-binding capacity (WBC) of the insoluble residue and (2) viscosity of the soluble fraction. Mild acid pretreatment in combination with commercial pectinolytic enzyme mixtures showed best digestion of RSM carbohydrates; only 32% of the total carbohydrate content remained. For most pretreatments, addition of commercial pectinolytic enzymes had the strongest effect on lowering the WBC of the in vitro incubated RSM. In the cases that less carbohydrate remained after in vitro digestion, the WBC of the residue decreased, and less gas seems to be produced during fermentation.
Grinding performance of wheat, maize and soybeans in a multicracker system
Thomas, M. ; Vrij, M. ; Zandstra, T. ; Poel, A.F.B. van der - \ 2012
Animal Feed Science and Technology 175 (2012)3-4. - ISSN 0377-8401 - p. 182 - 192.
particle-size - barley - digestibility - diet - pigs
This manuscript presents the effects of a recent technology for particle size reduction using a new approach in which the cracking action of two rows of discs is used. Wheat, maize and full fat soybeans were ground by a multicracker system to study the effects of disc type (ceramic versus steel discs), disc speed in revolutions per minute (2650 versus 3800 rpm), throughput (3.43 versus 6.70 metric t/h) and the gap between the discs (0.11 versus 1.04 mm). Mean particle size, width of the particle size distribution curve and total and specific mechanical energy consumption were the dependent variables under investigation. Maize, soybeans and wheat had different grinding characteristics (P
Electrostatic powder coating of foods - State of the art and opportunities
Khan, M.K.I. ; Schutyser, M.A.I. ; Schroën, C.G.P.H. ; Boom, R.M. - \ 2012
Journal of Food Engineering 111 (2012)1. - ISSN 0260-8774 - p. 1 - 5.
transfer efficiency - particulate flows - particle-size - technology - surfaces - triboelectrification - electricity - transport - dustiness - ignition
Edible coatings and incorporation of active ingredients can improve food quality (appearance, taste, flavours, and increased shelf life). In this paper, specific emphasis is given to electrostatic application of powdercoatings that is known for high transfer efficiency and even coating. This application technique has the potential to reduce excessive use of coating material (up to 68%) and minimise dust release (up to 84%) to the environment. Different parameters (e.g. powder particle size) are discussed that influence powdercoating quality and efficiency for both non-electrostatic and electrostaticpowder application. Typical food processing systems are reviewed that can be combined with electrostaticpowdercoating. Finally, an overview of electrostatically coated food products and a short outlook of electrostaticpowdercoating of foods are given.
Impact of sound attenuation by suspended sediment on ADCP backscatter calibrations
Sassi, M.G. ; Hoitink, A.J.F. ; Vermeulen, B. - \ 2012
Water Resources Research 48 (2012)9. - ISSN 0043-1397 - 14 p.
doppler-current-profiler - particle-size - acoustic measurements - laboratory evaluation - particulate matter - settling velocity - beam attenuation - boundary-layer - transport - scattering
Although designed for velocity measurements, acoustic Doppler current profilers (ADCPs) are widely being used to monitor suspended particulate matter in rivers and in marine environments. To quantify mass concentrations of suspended matter, ADCP backscatter is generally calibrated with in situ measurements. ADCP backscatter calibrations are often highly site-specific and season dependent, which is typically attributed to the sensitivity of the acoustic response to the number of scatterers and their size. Besides being a joint function of the concentration and the size of the scatterers, the acoustic backscatter can be heavily affected by the attenuation due to suspended matter along the two-way path to the target volume. We aim to show that accounting for sound attenuation in ADCP backscatter calibrations may broaden the range of application of ADCPs in natural environments. The trade-off between the applicability and the accuracy of a certain calibration depends on the variation in size distribution and concentration along the sound path. We propose a simple approach to derive the attenuation constant per unit concentration or specific attenuation, based on two water samples collected along the sound path of the ADCP. A single calibration was successfully applied at five locations along the River Mahakam, located up to 200 km apart. ADCP-derived estimates of suspended mass concentration were shown to be unbiased, even far away from the transducer.
Nanocompounds of iron and zinc: their potential in nutrition
Zimmermann, M.B. ; Hilty, F.M. - \ 2011
Nanoscale 3 (2011)6. - ISSN 2040-3364 - p. 2390 - 2398.
particle-size - oxide nanoparticles - flame synthesis - oral delivery - phosphate nanoparticles - gastrointestinal-tract - ferric pyrophosphate - in-vivo - bioavailability - rats
Recent studies suggest nanostructured oxides and phosphates of Fe and atomically mixed Fe/Zn may be useful for nutritional applications. These compounds may have several advantages over existing fortificants, such as ferrous sulfate (FeSO(4)), NaFeEDTA and electrolytic iron. Because of their very low solubility and formation of soft agglomerates of micron size at neutral pH as well as their light native color, they tend to be less reactive in difficult-to-fortify foods and thus have superior sensory performance. At gastric pH the soft agglomerates break up and the Fe compounds rapidly and completely dissolve due to their very high surface area. This results in in vitro solubility and in vivo bioavailability comparable to FeSO(4). Doping with Mg and/or Ca may increase solubility and improve sensory characteristics by lightening color. Feeding the nanostructured compounds at 150-400 mu g Fe day(-1) for 15 days to weanling rats in two studies did not induce measurable histological or biochemical adverse effects. No significant Fe was detected in the submucosa of the gastrointestinal tract or lymphatic tissues, suggesting that the nanosized Fe is absorbed through usual non-heme Fe absorption pathways. Thus, these novel compounds show promise as food fortificants or supplements.
Modulation of rheological properties by heat-induced aggregation of whey protein solution
Purwanti, N. ; Smiddy, M. ; Goot, A.J. van der; Vries, R.J. de; Alting, A. ; Boom, R.M. - \ 2011
Food Hydrocolloids 25 (2011)6. - ISSN 0268-005X - p. 1482 - 1489.
beta-lactoglobulin - induced gelation - disulfide bonds - particle-size - isolate - ph - polymers - strength - gels
Heat-induced protein aggregation at low protein concentrations generally leads to higher viscosities. We here report that aggregated protein can yield weaker gels than those from native protein at the same concentration. Aggregated protein was produced by heating a solution of whey protein isolate (WPI) at 3% and 9% w/w. The higher protein concentration resulted in a larger aggregate size and a higher intrinsic viscosity. The protein fraction in native WPI had the smallest size and the lowest intrinsic viscosity. The same trend was observed for the shear viscosity after concentrating the suspensions containing aggregates to around 15% w/w. Suspensions containing aggregates that were produced from a higher concentration possessed a higher viscosity. After reheating the concentrated suspensions, the suspension from the 9% w/w aggregate system produced the weakest gel, followed by the one from 3% w/w, while the native WPI yielded the strongest gel. Reactivity of the aggregates was also an important factor that influenced the resulting gel properties. We conclude that aggregation of whey protein solution is a feasible route to manipulate the gel strength of concentrated protein systems, without having to alter the concentration of the protein.
Assaying total carotenoids in flours of corn and sweet potato flours by laser photoacoustic spectroscopy
Luterotti, S. ; Bicanic, D.D. ; Kijak, K. ; Grbesa, D. ; Martinez, E. ; Spruijt, R.B. - \ 2011
Food Biophysics 6 (2011)1. - ISSN 1557-1858 - p. 12 - 19.
thermal-diffusivity - particle-size - beta-carotene - stability - lycopene
This study describes the application of the laser photoacoustic spectroscopy (PAS) for quantification of total carotenoids (TC) in corn flours and sweetpotato flours. Overall, thirty-three different corn flours and nine sweetpotato flours were investigated. All PAS measurements were performed at room temperature using 488-nm argon laser radiation for excitation and mechanical modulation of 9 and 30 Hz. The measurements were repeated within a run and within several days or months. The UV–Vis spectrophotometry was used as the reference method. The concentration range that allows for the reliable analysis of TC spans a region from 1 to 40 mg kg-1 for corn flours and from 9 to 40 mg kg-1 for sweetpotato flours. In the case of sweetpotato flours, the quantification may extend even to 240 mg kg-1 TC. The estimated detection limit values for TC in corn and sweetpotato flours were 0.1 and 0.3 mg kg-1, respectively. The computed repeatability (n¿=¿3–12) and intermediate precision (n¿=¿6–28) RSD values at 9 and 30 Hz are comparable: 0.1–17.1% and 5.3–14.7% for corn flours as compared with 1.4–9.1% and 4.2–23.0% for sweetpotato flours. Our results show that PAS can be successfully used as a new analytical tool to simply and rapidly screen the flours for their nutritional potential based on the total carotenoid concentration
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