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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    Bier brouwen met enzymen spaart milieu
    Goot, Atze Jan van der; Donkelaar, Laura van - \ 2016
    The use of enzymes for beer brewing : Thermodynamic comparison on resource use
    Donkelaar, Laura H.G. van; Mostert, Joost ; Zisopoulos, Filippos K. ; Boom, Remko M. ; Goot, Atze Jan van der - \ 2016
    Energy 115 (2016)1. - ISSN 0360-5442 - p. 519 - 527.
    Biotechnology - Brewing - Enzymes - Exergy - Unmalted barley

    The exergetic performance of beer produced by the conventional malting and brewing process is compared with that of beer produced using an enzyme-assisted process. The aim is to estimate if the use of an exogenous enzyme formulation reduces the environmental impact of the overall brewing process. The exergy efficiency of malting was 77%. The main exergy losses stem from the use of natural gas for kilning and from starch loss during germination. The exergy efficiency of the enzyme production process ranges between 20% and 42% depending on if the by-product was considered useful. The main exergy loss was due to high power requirement for fermentation. The total exergy input in the enzyme production process was 30 times the standard chemical exergy of the enzyme, which makes it exergetically expensive. Nevertheless, the total exergy input for the production of 100 kg beer was larger for the conventional process (441 MJ) than for the enzyme-assisted process (354 MJ). Moreover, beer produced using enzymes reduced the use of water, raw materials and natural gas by 7%, 14% and 78% respectively. Consequently, the exergy loss in the enzyme production process is compensated by the prevention of exergy loss in the total beer brewing process.

    Brewing with fractionated barley
    Donkelaar, L.H.G. van - \ 2016
    Wageningen University. Promotor(en): Remko Boom; Atze Jan van der Goot. - Wageningen : Wageningen University - ISBN 9789462577343 - 152
    brewing - brewing quality - barley - fractionation - endosperm - beers - malt - filtration - industrial wastes - process optimization - food process engineering - bierbereiding - brouwkwaliteit - gerst - fractionering - endosperm - bieren - mout - filtratie - industrieel afval - procesoptimalisatie - levensmiddelenproceskunde

    Brewing with fractionated barley

    Beer is a globally consumed beverage, which is produced from malted barley, water, hops and yeast. In recent years, the use of unmalted barley and exogenous enzymes have become more popular because they enable simpler processing and reduced environmental impact. Raw barley, however, contains less endogenous enzymes and more undesired components for the use of beer brewing, compared to malted barley.

    The overall aim of this thesis is to investigate how barley can be fractionated to optimize the use of resources for the beer brewing process, while maintaining the quality of the brewed beer. A resource use efficiency analysis was performed to verify the presumed benefits on the environmental sustainability of the proposed process change. The work was based on the hypothesis that fractionation of the unprocessed barley will reduce the amount of undesired components, which leads to improvements in the brewing process based on partial or no malting. Fractionation can be performed by milling and separation, which requires physical disentanglement of the components. This fractionation can be influenced by properties of the components of the material, such as the glass transition temperature (Stuart et al.). Fractionation by abrasive milling, also known as pearling, is another possibility: here one makes use of the spatial distribution of components in the kernels. In case of barley for brewing this technique is especially promising as most of the undesired components are in the outer layer of the kernel. In addition, the removal of bran from the barley reduces the amount of water needed in the process. It will also reduce the volume of spent grains, hence reducing wastes and energy required for drying the spent grains. A disadvantage of pearling is however that it lowers the ability of the barley kernel to produce enzymes. This leads to the need of the addition of exogenous enzymes, as is the case when the malting step is omitted.

    Chapter 2 describes the glass-to-rubber transition of protein and starch isolated from the barley endosperm, for different moisture levels. The hypothesis for this chapter is that dry fractionation by milling is facilitated by milling conditions in which the protein is in a rubbery state and the starch in a glassy state. Two methods were used to measure the Tg; differential scanning calorimetry (DSC) and thermo-mechanical compression tests (TMCT). The methods gave different results due to the differences in moisture content range, and heating rates, which may lead to conformational changes of the protein. The value of the Tg of partially crystalline materials, such as starch in barley, was not unambiguous when using TMCT because the mechanical effect of expansion of these materials was smaller. For both results, the Tg lines were modelled using the Gordon-Taylor equation. Based on sorption isotherms, it was concluded that moisture does not distribute evenly over the protein and starch in the kernel. Starch absorbs more moisture than protein at given water activities. This required a correction of the Tg lines. After this correction, the glass transition lines of starch and protein were closer together. The expectation is therefore that achieving good separation between the components based on having one glassy component and one rubbery component is challenging.

    For this reason, another dry fractionation technique, pearling, was considered. Chapter 3 describes the chemical composition of the barley and of fractions removed by pearling. Pearling was shown to selectively remove insoluble fibre, ash, protein and polyphenols, while the β-amylase activity and starch content of the remaining kernel was hardly affected. For example, removing the outer 5% of the kernel reduced insoluble arabinoxylans (15%), insoluble fibres (23%), ash (19%), polyphenols (11%) and water holding capacity of the non-starch components (25%), while only lowering starch content by 0.20%. The water holding capacity of the barley fractions was strongly related to the fibre content. This indicates that when the fibre content in the mash was reduced by pearling, the spent grains will take up less water, leading to less wort and sugar losses in this waste stream, and hence better use of the raw materials and less wastes.

    Chapter 4 compares a traditional brewing process to an enzyme-assisted brewing process with respect to their resource use efficiency, which is one aspect of the sustainability of the processes. The use of exogenous enzymes is found to be more efficient than producing enzymes through the malting process. The exergetic efficiency of the conventional malting process was 77%. The main losses stem from the use of natural gas for removal of moisture from the barley in the kilning process, and from the loss of starch in the germination process. In case of the use of exogenous enzymes, it was concluded that the chemical exergy content of the enzymes was not a good measure for the exergy content of the enzymes. Instead, we proposed to use the cumulative exergetic consumption in the enzyme production rather than just the chemical exergy content of the enzymes. This cumulative exergetic consumption in the production of the enzymes was ± 30 times higher than their standard chemical exergy. This shows that the cumulative exergetic costs of minor components should be taken into account if a process uses them in significant quantities. This can be done by extending the system boundaries to include the production process of the purified components. The exergy efficiency of the enzyme formulation production process ranges between 20% and 42% depending on whether the by-product of the fermentation broth was considered as useful as the enzyme product. Even though the cumulative exergy consumption of the process was 30 times the standard chemical exergy of the dry enzyme, the total exergy input (i.e. both wasted and destroyed) for the production of 100 kg of beer was still larger for the conventional malting process (441 MJ) than for the enzyme-assisted process (354 MJ). In addition, beer produced using exogenous enzymes reduces the use of water by 7%, of raw materials by 14%, and of natural gas by 78%. Thus, the exergy loss of the enzyme production process is more than compensated by the prevention of exergy loss in the total beer brewing process.

    Chapter 5 describes brewing tests using malted, unmalted and pearled, unmalted barley kernels. Brewing with unmalted barley saves material, energy and water in the malting stage but may result in complications during processing. Pearling mitigates these problems. Exogenous enzymes were used to compensate for the low enzyme activity in unmalted barley. Lautertun filtration and mash filtration were considered as filtration methods. Principle component analysis was performed on the chemical composition of the wort and the various spent grains, to investigate the effect of the malt-to-barley ratio, the degree of pearling and the filter method. A mash filter is optimal for this type of process, and we identified a window of operation in which optimal use is made of the raw materials while maintaining the end product quality, judged on basis of 4 quality parameters.

    The concluding chapter 6 presents a general discussion of all results described in this thesis. In addition, the benefits of pearling over that of milling and fractionation, and the effect of pearling on milling properties were discussed. Furthermore, it explores the advantages in environmental sustainability that can be achieved by pearling. Pearling as a pre-treatment for malting reduces the enzyme activity of germinating barley, and therefore the mash quality.

    This thesis provides insights in how pre-treatment of barley can make beer brewing more efficient in the use of resources. It stresses the need to optimally use all material streams in a process, to be able to design an environmentally sustainable process, and it shows that efficient resource use is key for achieving this. Additionally the value of enzymes as processing aids was discussed. A clear result is that one needs to include the resource use in the production of enzymes or other processing aids, when analyzing the environmental sustainability of a process, since this can be significant in the overall process.

    Combining unmalted barley and pearling gives good quality brewing
    Donkelaar, Laura H.G. van; Hageman, Jos A. ; Oguz, Serhat ; Noordman, Tom R. ; Boom, Remko M. ; Goot, Atze Jan van der - \ 2016
    Journal of the Institute of Brewing 122 (2016)2. - ISSN 0046-9750 - p. 228 - 236.
    Brewing - Pearling - Unmalted barley

    Brewing with unmalted barley can reduce the use of raw materials, thereby increasing the efficiency of the brewing process. However, unmalted barley contains several undesired components for brewing and has a low enzymatic activity. Pearling, an abrasive milling method, has been proposed as a pre-treatment for barley to remove some of its undesired components, while maintaining its β-amylase activity. The potential of combining pearling with using barley/malt mixtures for brewing was studied. Filtration was performed either in a mash filter or in a lauter tun. The effects of the different barley/malt ratios, degree of pearling and two different filter types on compositional and quality parameters were assessed. It was concluded that a mash filter is optimal for this type of process, and a window of operation could be identified in which optimal use is made of the raw materials while maintaining the end product quality, judged on basis of four quality parameters.

    Glass transitions of barley starch and protein in the endosperm and isolated form
    Donkelaar, L.H.G. van; Martinez, J.T. ; Frijters, H. ; Noordman, T.R. ; Boom, R.M. ; Goot, A.J. van der - \ 2015
    Food Research International 72 (2015). - ISSN 0963-9969 - p. 241 - 246.
    air classification - temperature - enrichment - fractions - flours
    When studying the glass-to-rubber transition inside natural materials, it is important to take into account not only the moisture content but also the moisture distribution over the components in the material. We measured the Tg of protein and starch isolated from barley at different moisture contents using differential scanning calorimetry (DSC) (heating rate 10 °C/min) and by thermo mechanical compression tests (TMCT) (heating rate 2 °C/min). The measurement of the Tg of partially crystalline materials, such as barley starch, is more difficult using TMCT because the mechanical effect of expansion of these materials is smaller. For both measurement sets the glass transition lines were modeled using the Gordon–Taylor equation. The lines were adapted for the differences in moisture content over the endosperm by using the sorption isotherms of isolated barley starch and protein and whole barley endosperm. The glass transition lines measured by TMCT were closer together than the ones measured by DSC
    Pearling barley to alter the composition of the raw material before brewing
    Donkelaar, L.H.G. van; Noordman, T.R. ; Boom, R.M. ; Goot, A.J. van der - \ 2015
    Journal of Food Engineering 150 (2015). - ISSN 0260-8774 - p. 44 - 49.
    hull-less barley - liquid-chromatography - phenolic-compounds - hordeum-vulgare - rich fractions - alpha-amylase - malt extracts - dietary fiber - quality - components
    Partly replacing malt with unmalted barley is a trend in brewing. The use of unmalted barley, however, leads to issues such as haze and high mash viscosity, due to its higher content of undesired components. Pearling, an abrasive method to remove the outer layers of the barley kernels has been shown to reduce the content of insoluble fibre, ash, protein and polyphenols; the ß-amylase activity and starch content of the remaining kernel were hardly affected. Removing the outer 5% of the kernel, for example, results in a 15% reduction of insoluble arabinoxylans, 23% of the insoluble fibre content and 25% of the water holding capacity of the non-starch components. It also reduces the ash content by 19% and the polyphenol content by 11%, but only 0.20% of the starch is pearled off. A relation was found between the insoluble fibre content and the water holding capacity of a fraction. Lower fibre content reduces the water holding capacity and thus the volume of the spent grains, which implies that less wort and sugar are lost during filtration. In addition, that the bran fraction remains dry, implies a reduction in energy required to dry the spent grains.
    Glass transitions to facilitate dry fractionation in food processing
    Donkelaar, Laura van - \ 2014
    Constraints on ship NOx emissions in Europe using GEOS-Chem and OMI satellite NO2 observations
    Vinken, G.C.M. ; Boersma, K.F. ; Donkelaar, A. van; Zhang, W. - \ 2014
    Atmospheric Chemistry and Physics 14 (2014). - ISSN 1680-7316 - p. 1353 - 1369.
    ozone monitoring instrument - nitrogen-oxide emissions - marine boundary-layer - tropospheric no2 - interannual variability - power-plants - global-model - inventories - retrieval - columns
    We present a top-down ship NOx emission inventory for the Baltic Sea, the North Sea, the Bay of Biscay and the Mediterranean Sea based on satellite-observed tropospheric NO2 columns of the Ozone Monitoring Instrument (OMI) for 2005–2006. We improved the representation of ship emissions in the GEOS-Chem chemistry transport model, and compared simulated NO2 columns to consistent satellite observations. Relative differences between simulated and observed NO2 columns have been used to constrain ship emissions in four European seas (the Baltic Sea, the North Sea, the Bay of Biscay and the Mediterranean Sea) using a mass-balance approach, and accounting for nonlinear sensitivities to changing emissions in both model and satellite retrieval. These constraints are applied to 39% of total top-down European ship NOx emissions, which amount to 0.96 TgN for 2005, and 1.0 TgN for 2006 (11–15% lower than the bottom-up EMEP ship emission inventory). Our results indicate that EMEP emissions in the Mediterranean Sea are too high (by 60 %) and misplaced by up to 150 km, which can have important consequences for local air quality simulations. In the North Sea ship track, our top-down emissions amount to 0.05 TgN for 2005 (35% lower than EMEP). Increased top-down emissions were found for the Baltic Sea and the Bay of Biscay ship tracks, with totals in these tracks of 0.05 TgN (131% higher than EMEP) and 0.08 TgN for 2005 (128% higher than EMEP), respectively. Our study explicitly accounts for the (non-linear) sensitivity of satellite retrievals to changes in the a priori NO2 profiles, as satellite observations are never fully independent of model information (i.e. assumptions on vertical NO2 profiles). Our study provides for the first time a space-based, top-down ship NOx emission inventory, and can serve as a framework for future studies to constrain ship emissions using satellite NO2 observations in other seas.
    Does acute tryptophan depletion affect peripheral serotonin metabolism in the intestine?
    Keszthelyi, D. ; Troost, F.J. ; Jonkers, D.M. ; Donkelaar, E.L. van; Dekker, J. ; Buurman, W.A. ; Masclee, A.A. - \ 2012
    American Journal of Clinical Nutrition 95 (2012)3. - ISSN 0002-9165 - p. 603 - 608.
    5-hydroxyindoleacetic acid - gastrointestinal-tract - cerebrospinal-fluid - brain - permeability - depression - cortisol - reuptake - humans - lumbar
    Background: Serotonin (5-hydroxytryptamine; 5-HT), a tryptophan metabolite, plays an important regulatory role in the human central nervous system and in the gastrointestinal tract. Acute tryptophan depletion (ATD) is currently the most widely established method to investigate 5-HT metabolism. Objective: The aim of this study was to assess the effect of an acute decrease in the systemic availability of tryptophan on intestinal 5-HT metabolism and permeability. Design: Thirty-three healthy volunteers (17 with ATD, 3 of whom dropped out; 16 placebo) participated in this randomized placebo-controlled study. Plasma and duodenal mucosal concentrations of 5-HT, 5-hydroxyindoleacetic acid (5-HIAA), and kynurenic acid (KA) were measured by HPLC-mass spectrometry. Intestinal barrier function was assessed with a multisugar plasma test, and analysis of tight junction transcription was performed in duodenal biopsy samples obtained by gastroduodenoscopy. Results: Mucosal 5-HT, 5-HIAA, and KA concentrations remained unaltered by ATD. In contrast, ATD significantly decreased plasma 5-HT (P <0.05) and 5-HIAA (P <0.0001) concentrations. After endoscopy, a significant increase in plasma 5-HT concentrations was observed in the placebo group (P = 0.029) compared with the ATD group. Moreover, a significant increase in plasma KA concentrations over time was found in the placebo group (P <0.05). No changes in intestinal barrier function were observed. Conclusions: An acute decrease in precursor availability does not affect mucosal concentrations of serotonergic metabolites, in contrast with systemic concentrations. ATD alters biochemical responses to acute stress from the endoscopic examination reflected by lower 5-HT concentrations. Changes in 5-HT concentrations were paralleled by alterations in KA concentrations, which suggest competition between the 2 metabolic pathways for the mutual precursor. This trial was registered at clinicaltrials.gov as NCT00731003. Am J Clin Nutr 2012;95:603-8.
    Sources, distribution, and acidity of sulfate–ammonium aerosol in the Arctic in winter–spring
    Fisher, J.A. ; Jacob, D.J. ; Wang, Q. ; Bahreini, R. ; Carouge, C.C. ; Cubison, M.J. ; Dibb, J.E. ; Diehl, T. ; Jiminez, J.L. ; Leibensperger, E.M. ; Lu, Z. ; Meinders, M.B.J. ; Pye, H.O.T. ; Quinn, P.K. ; Sharma, S. ; Streets, D.G. ; Donkelaar, A. van; Yantosca, R.M. - \ 2011
    Atmospheric Environment 45 (2011)39. - ISSN 1352-2310 - p. 7301 - 7318.
    circulation model assessment - cloud resolving simulations - dry deposition - chemical-composition - asian pollution - ice nucleation - air-pollution - intex-b - atmospheric transport - ozone depletion
    We use GEOS-Chem chemical transport model simulations of sulfate–ammonium aerosol data from the NASA ARCTAS and NOAA ARCPAC aircraft campaigns in the North American Arctic in April 2008, together with longer-term data from surface sites, to better understand aerosol sources in the Arctic in winter–spring and the implications for aerosol acidity. Arctic pollution is dominated by transport from mid-latitudes, and we test the relevant ammonia and sulfur dioxide emission inventories in the model by comparison with wet deposition flux data over the source continents. We find that a complicated mix of natural and anthropogenic sources with different vertical signatures is responsible for sulfate concentrations in the Arctic. East Asian pollution influence is weak in winter but becomes important in spring through transport in the free troposphere. European influence is important at all altitudes but never dominant. West Asia (non-Arctic Russia and Kazakhstan) is the largest contributor to Arctic sulfate in surface air in winter, reflecting a southward extension of the Arctic front over that region. Ammonium in Arctic spring mostly originates from anthropogenic sources in East Asia and Europe, with added contribution from boreal fires, resulting in a more neutralized aerosol in the free troposphere than at the surface. The ARCTAS and ARCPAC data indicate a median aerosol neutralization fraction [NH4+]/(2[SO42-] + [NO3-]) of 0.5 mol mol-1 below 2 km and 0.7 mol mol-1 above. We find that East Asian and European aerosol transported to the Arctic is mostly neutralized, whereas West Asian and North American aerosol is highly acidic. Growth of sulfur emissions in West Asia may be responsible for the observed increase in aerosol acidity at Barrow over the past decade. As global sulfur emissions decline over the next decades, increasing aerosol neutralization in the Arctic is expected, potentially accelerating Arctic warming through indirect radiative forcing and feedbacks.
    Effect van moulded fibre trays op de kwaliteitsontwikkeling van enkele kaassoorten
    Kreft, F.I.N.G. ; Thoden van Velzen, E.U. ; Weert, C.L.M. van; Polderdijk, J.J. ; Donkelaar, J.R. ten; Zegveld, A.Z. - \ 2004
    Wageningen : ATO B.V. Agrotechnologisch Onderzoeksinstituut - 14
    Beperking zilverschurft bij tafelaardappelen : rapportage 3e en afsluitende jaar
    Hoof, Michiel van; Thoden van Velzen, Ulphard ; Donkelaar, Janneke ten; Hermans, J. - \ 2001
    Wageningen : ATO Agrotechnologisch Onderzoekinstituut - 44
    Performance of egg trays during transport and storage
    Boogaard, G.J.P.M. van den; Donkelaar, J.R. ten - \ 2001
    Wageningen : Agrotechnologisch Onderzoeksinstituut (ATO) (Report / Agrotechnological Research Institute (ATO) B530) - 14
    Witlof, aardbeien en golfkarton op de pijnbank : transportsimulatorexperimenten onder in de keten realistische omstandigheden
    Weert, K. van; Donkelaar, J. ten; Boogaard, G. van den - \ 2001
    Voedingsmiddelentechnologie 34 (2001)8. - ISSN 0042-7934 - p. 50 - 51.
    verpakkingsmaterialen - materialen - karton - papier - verse producten - fruit - groenten - vervoerskwaliteit - mechanische schade - verbetering - simulatie - packaging materials - materials - paperboard - paper - fresh products - vegetables - transporting quality - mechanical damage - improvement - simulation
    Het voorkomen van transportschade aan producten en verpakkingen door verbetering van verpakkingen en verpakkingsmaterialen
    Notes on the taxonomy and ecology of the genus Hoya (Asclepiadaceae) in central Sulawesi
    Kleijn, D. ; Donkelaar, R. van - \ 2001
    Blumea 46 (2001). - ISSN 0006-5196 - p. 457 - 483.
    Toepassingen van Paragon® films als levensmiddelenverpakking
    Jaeger, C.R. ; Schennink, G.G.J. ; Kreft, F.I.N.G. ; Polderdijk, J.J. ; Donkelaar, J.R. ten; Zegveld, A.Z. ; Beukelaar, H.J. de - \ 2000
    Wageningen : ATO B.V. Agrotechnologisch Onderzoekinstituut (Rapport / ATO B.V. Agrotechnologisch Onderzoekinstituut B453) - 52
    Integrale aanpak voor ontwikkeling verpakkingen : innovatieve verpakking voor aardbeien als voorbeeld
    Jaeger, R. ; Donkelaar, J. ten; Boerrigter, H. ; Boogaard, G. van den; Leeuw, P. de; Moezelaar, R. - \ 2000
    Voedingsmiddelentechnologie 33 (2000)20. - ISSN 0042-7934 - p. 47 - 48.
    voedselindustrie - voedingsmiddelen - verpakking - voedselverpakking - voedseltechnologie - verpakkingsmaterialen - bederfelijke producten - houdbaarheid (kwaliteit) - bewaartijd - gemodificeerde atmosfeer opslag - gasbewaring - aardbeien - food industry - foods - packaging - food packaging - food technology - packaging materials - perishable products - keeping quality - storage life - modified atmosphere storage - controlled atmosphere storage - strawberries
    Uit onderzoek door ATO is een nieuw verpakkingsconcept ontstaan dat de houdbaarheid van aardbeien kan verlengen. Rekening moet gehouden worden met de prestatie van de verpakking; de eigenschappen van het product; de eisen van de logistieke keten en de acceptatie door de consument
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