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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    CVB Veevoedertabel 2016 : chemische samenstellingen en nutritionele waarden van voedermiddelen
    Blok, M.C. ; Spek, J.W. - \ 2016
    Netherlands : CVB - 629
    voedertabellen - voer - chemische samenstelling - voedingswaarde - diervoedering - diervoeding - feed composition tables - feeds - chemical composition - nutritive value - animal feeding - animal nutrition
    Water retention in mushroom during sustainable processing
    Paudel, E. - \ 2015
    Wageningen University. Promotor(en): Remko Boom, co-promotor(en): Ruud van der Sman. - Wageningen : Wageningen University - ISBN 9789462575967 - 148
    mushrooms - water holding capacity - physical properties - hydration - chemical composition - heat treatment - canning - process optimization - sustainability - paddestoelen - waterbergend vermogen - fysische eigenschappen - hydratatie - chemische samenstelling - warmtebehandeling - inblikken - procesoptimalisatie - duurzaamheid (sustainability)

    This thesis deals with the understanding of the water holding capacity of mushroom, in the context of a redesign of their industrial processing. For designing food process the retention of food quality is of the utmost importance. Water holding capacity is an important quality aspect of mushrooms. A convenient process design methodology which accounts also for product quality is Conceptual Process Design (CPD). An approach to follow CPD methodology is first to explore, the material properties of the products to find optimal processing conditions. In this stage the constraints of (existing) processing equipment are not considered. Later in the second stage, suboptimal processing conditions are determined considering the constrains of equipment.

    In mushroom canning, temperature induced loss of water holding capacity (WHC) of tissue manifests as a lower product yield. This loss of water is accompanied with the loss of nutrients, dissolved in the water. In addition to the loss of product quality like water holding capacity, mushroom canning (with alternating heating and cooling steps) also induces losses of useful resources as (potable) water. In terms of water use, water is added at several steps, and is discarded at other places. This shows that there is opportunity to improve the sustainability of the production system, but with the constraint that product quality is not impaired, or evenly improved.

    The WHC is an important property that determines several aspects of foods. For example, it determines the juiciness of fruits, vegetables and meat products; the freshness (firmness, or crispiness) of green-leafy vegetables; and the calorie intake per serving for high calorie containing foods such as cheese. Despite being a widely used term in food science, there is no clear definition of water holding capacity and its thermodynamic nature is not fully acknowledged. The understanding of the WHC is even poorer in structured cellular foods such as mushroom, where different water fractions are present in various compartments. In a cellular system water is present as 1) a solution in the vacuoles, 2) water osmotically bound to the cytoplasmic and the cell wall materials and 3) capillary water in pores, which might be filled during processing. Because they have a distinct capillary phase, the mushroom is a good system to study the contributions of various water fraction on the total water retention.

    The main aim of the current work is to provide insight for the development of canned mushroom processing where: 1) the resources of energy and water are efficiently used, and 2) the quality of mushroom is maintained. These two aims are related to the efficient use of raw materials and maintenance of full weight of mushroom during processing. The WHC is an important quality indicator of mushrooms. The analysis related to water retention of mushroom has been carried out at microscale where molecular and structural interactions in relation to water retention are studied. The micro scale analysis is discussed in chapter 2, chapter 3 and chapter 4. The sustainability analysis is carried out at mesoscale where analysis is carried out at the unit operation level which is described in chapter 5.

    In chapter 2, the heat-induced change in water holding capacity of particular the gel phase of the mushroom is interpreted with the Flory-Rehner theory, commonly applied to polymer gels. As done earlier for meat, we have first assumed that WHC loss in mushroom can also be attributed to the protein denaturation. This assumption is based on the experimental observation that, like meat, mushroom also follows a typical sigmoid relation with change in temperature. In the theory, we have regarded mushroom as a homogeneous biopolymer hydrogel, in which salt and sugar are dissolved. The water holding capacity is then understood as the swelling capacity of the biopolymer gel. The thermodynamic state of this simplified system is characterized by the so-called swelling pressure, which is decomposed into three independent contributions: 1) the mixing pressure induced by sugars and polymers, 2) the ionic pressure induced by the salt, and 3) the elastic pressure induced by the polymers. An assumption was made that the heat treatment denatures mushroom protein, which is reflected in the change of the Flory Huggins interaction for protein. It follows the same temperature dependency as the WHC loss by mushroom under zero mechanical load. The assumption of the temperature dependency of the interaction parameter is tested with an independent sorption measurement. With the assumption, the sorption curve for mushroom sample which were preheated previously at 30, 60 and 90 °C could accurately be predicted. Curve fitting of WHC under various mechanical loads has shown that model parameters that are associated with the elastic pressure, the crosslink density and fraction of the polymer in the relaxed state, are temperature dependant. The values of increased in contrast to the decrease of upon heating of mushroom tissue up to temperature of 70°C. The result indicates that heat treatment increases the polymer chain length between the cross links as original conformation of mushroom is lost. At the same time, more crosslinks are formed by a polymer because of aggregation of polymers. However, in our fitting procedure, we have excluded WHC data at low external pressure values, as water is present in both gel phase as in in the capillaries. This is done as the pores in this range are not fully collapsed and the Flory Rehner theory is valid only for the gel phase

    In chapter 2 mushroom is simplified in the sense that only compositional contribution is considered in WHC but not the structural contributions. In subsequent chapters we have acknowledged that mushroom has a cellular structure with a distinct pore phase. The pores are intentionally filled during processing via vacuum impregnation. The contribution of water present in the capillaries due to vacuum impregnation of mushroom has been discussed in chapter 3. Both the temperature of heat treatment and the initial porosity of mushroom contribute independently to water holding capacity of heat treated mushroom. The hydration of heat treated mushroom increases linearly with the initial porosity of mushroom for all the temperatures from 30 to 90 °C. The porosity of mushroom can also largely explain the increase in hydration of heat treated mushroom with storage as both porosity and the hydration increase simultaneously with the storage days. The fluid that filled in the capillaries acts against collapse of the hyphae which have inherent elastic force that works in the other direction. The initial porosity of mushroom is an important aspect that determines the hydration of the heat treated mushroom and therefore, cannot be ignored. In addition, the Flory-Rehner theory alone cannot capture the contribution of the capillary water. Hence an addition is needed in the theory to capture this effect.

    The cellular phase in mushroom tissue is even more complicated because water is present in this phase in two other forms, as gel water and the intracellular water. Chapter 4 takes into account the role of structure in the WHC. The role of cell membrane integrity and the cell-wall structural components is investigated for retention of the water fraction. The cell membrane integrity is calculated from the conductivity measurement of the fluid that leaches out from the vacuole that has salts in it. The loss of the cell membrane integrity largely explains the water loss from heat treated mushroom sample. The loss of cell membrane integrity is also related with the water loss from frozen mushroom, but additional losses occur during freezing due to novel crosslinks formed during the growth of ice crystals compressing the unfrozen cell wall material. The enzymatic hydrolysis of mushroom cellular components shows that chitin and mushroom protein both contribute to the water holding capacity either via osmotic binding or by their role to provide the mechanical strength to the mushroom hyphae. In addition, proteins have additional contributions to water retention by mushroom because of their electrostatic interaction as polyelectrolyte. This is evident as the hydration of the mushroom increases with pH of mushroom.

    In chapter 5, the efficiency of the use of the resources (raw materials, energy water) is investigated. The mass and exergy flow in the current production system is visualized with the Sankey diagrams. The sustainability of unit operations involved in the current production system of canned are analysed with the second law efficiency using exergy. Using ideas from Process Intensification three alternative routes are proposed for the production of canned mushrooms namely: 1). Slicing before vacuum hydration, and 2) Using hot water for vacuum hydration and 3) Using blanch water for vacuum hydration. Using hot water for vacuum hydration is not seen as a feasible option, since it consumed more resources. Slicing mushroom before their vacuum hydration and using blanch water for hydration of mushroom lowers the resources requirement for production. In addition, using blanch water for hydration also increases the final product yield.

    Finally, the main findings of this thesis are summarized in the general discussion in chapter 6. The findings from previous chapters are combined to an overall description of water loss from heat treated mushroom. The overall description of water holding capacity in mushrooms is given in terms of the thermodynamic conditions for equilibrium between the different compartments holding water. The two dimensions of the thesis, the higher water retention of processed mushroom and more sustainable operation are discussed in the light of conceptual process design, using a micro/mesoscale approach. At the microscale material properties of mushroom are discussed. The biggest effect comes from cell membrane integrity loss. The porosity of fresh mushroom and the ionic interactions of polymers are the other effects that influence the WHC. Mesoscale analysis shows that shifting the sequence of unit operations and reusing the blanch water that is discarded in the current production process can improve the sustainability. Finally based on outcome of current work, future perspective of current work is discussed briefly.

    Overall, this thesis demonstrated that there is substantial scope in improving the efficiency in the use of resources in producing preserved mushroom. Also scope in retention of water in the mushroom tissue is demonstrated. Thus this thesis shows that both aspects, product and process efficiency, can be improved at the same time.

    Correlating composition and functionality of soy protein hydrolysates used in animal cell cultures
    Gupta, A.J. - \ 2015
    Wageningen University. Promotor(en): Harry Gruppen, co-promotor(en): Peter Wierenga; J.W. Boots. - Wageningen : Wageningen University - ISBN 9789462573208 - 127
    sojaeiwit - eiwithydrolysaten - functionele eigenschappen - warmtebehandeling - celculturen - chemische samenstelling - metabolomica - soya protein - protein hydrolysates - functional properties - heat treatment - cell cultures - chemical composition - metabolomics


    Soy protein hydrolysates are often supplemented to chemically defined (CD) media in cell cultures, but there is little understanding of the effect of their composition on their functionality (viable cell density, total immunoglobulin (IgG), and specific IgG production). To identify the key parameters (e.g. compound classes) that determine their functionality, hydrolysates were prepared from different starting materials (meal, concentrates, and isolate) and from soybean meal that was heated for different time periods. The functionality of these hydrolysates were compared to those of industrial hydrolysates. From the comparison, it was shown that the variation in industrial and experimental processes of hydrolysate production induced larger variation in the functionality than the variation in starting materials. Moreover, it was observed that the correlations between the functionality and compositional parameters observed in one experiment were absent in the other experiments. During the study, it became apparent that the variations in other factors, like CD media and temperature during culturing also resulted in variation in functionality. The extent of variations in the functionality due to variation in CD media and temperature during culturing was equivalent to the variation caused by varying the hydrolysate composition. The functionality data of the different experiments were fitted with a model that described the relation between specific IgG production and viable cell density. Using the model, the maximum achievable total IgG production could be calculated for a culture condition. This information can provide directions for further optimization of hydrolysates to maximize total IgG production.

    New analytical approaches for faster or greener phytochemical analyses
    Shen, Y. - \ 2015
    Wageningen University. Promotor(en): Han Zuilhof; B. Chen, co-promotor(en): Teris van Beek. - Wageningen : Wageningen University - ISBN 9789462573307 - 206
    giftige planten - chemische samenstelling - massaspectrometrie - niet-destructief testen - bemonsteren - zuiveren - oplosmiddelen - illicium - poisonous plants - chemical composition - mass spectrometry - nondestructive testing - sampling - purification - solvents - illicium


    Chapter 1 provides a short introduction into the constraints of phytochemical analysis. In order to make them faster, less laborious and greener, there is a clear scope for miniaturized and simplified sample preparation, solvent-free extractions and the use of cleaner solvents in preparative HPLC. Possible modern techniques to achieve this, such as microfluidic chips, ambient mass spectrometry, selective magnetic nanoparticles, and use of less toxic but equally efficient solvents are discussed. Clear aims were formulated and research towards fulfilling these aims in the field of phytochemical analysis is carried out in this thesis.

    A first version of a 3-phase liquid-liquid extraction (LLE) chip for the miniaturized sample pretreatment of alkaloids was introduced by our group in 2009. In Chapter 2 more biodegradable and less-toxic solvents for the transport phase and a more suitable pH for the feed phase were evaluated. The extraction efficiency improved. On-line hyphenation of the 3-phase chip to nanoLC-UV/MS was also investigated. This combination saved a lot of time and solvent in comparison with traditional methods for the purification of alkaloids from plant materials.

    A novel Induced Phase Separation Extraction (IPSE) chip was introduced in Chapter 3 for efficient sample pretreatment. The acetonitrile – water (1:1) sample solutions were separated in organic and aqueous phases in this IPSE chip based on their affinity for both phases. In turn this could be correlated with the log D values of the analytes. Some optimization regarding design, operation, flows and solvents was carried out. Extraction efficiencies of several model compounds were determined. A real sample application with a plant used in Traditional Chinese Medicines (TCMs) was carried out to show the usefulness of the IPSE chip in dealing with complex matrixes.

    Chapter 4 presented an unambiguous distinction between toxic Japanese star anise and non-toxic Chinese star anise fruits within seconds without any sample pretreatment by DART-orbitrap MS technology. Both positive and negative mode gave the same result, although the latter mode is preferred because of its higher sensitivity and cleaner spectra. Not only raw plant materials but also a herbal tea containing both Chinese and Japanese star anise could be quickly and accurately distinguished by DART-HRMS.

    In Chapter 5, direct plant spray in combination with orbitrap HRMS allowed, like DART-HRMS, for an unambiguous distinction between toxic Japanese star anise and non-toxic Chinese star anise fruits within seconds without any sample pretreatment in both positive and negative mode. Direct plant spray ionization has the advantage of low cost, simplicity, room temperature and low standard deviations. Neither the DART nor the direct spray method is very suitable for quantitative measurements of solid samples like star anise fruits.

    Chapter 6 describes the purification of eight ginkgolic acids (GAs) from raw plant material (Ginkgo biloba) by using only three steps, namely (1) extraction; (2) selective purification by cheap Fe3O4 magnetic nanoparticles (MNPs); (3) preparative HPLC on a C8 column. The three main constituents occurring at concentrations of 0.15% - 0.60% were enriched to >95% absolute purity without using tedious (gravity) column chromatography with halogenated solvents.

    Preparative RP-HPLC is an efficient but not very green technique for the final purification of fine chemicals and natural products as large volumes of acetonitrile, methanol and tetrahydrofuran (THF) are consumed. In Chapter 7 it was investigated whether less toxic organic solvents could replace them. As a test case the preparative separation of Ginkgo terpene trilactones (TTLs) was selected. By a two-step chromatographic optimization procedure a 30 min gradient using only water, ethanol, acetone and ethyl acetate was developed, which gave a baseline separation of 480 mg of an injected TTLs mixture. All five individual TTLs were > 95% pure.

    Traditional Chinese Medicines (TCMs) are one of the oldest and most used traditional drugs in the world. Many plants are used for their preparation. An overview of HPLC-related methods such as: multicomponent quantitation, fingerprinting, bioaffinity chromatography and on-flow assays for screening and quality control of TCMs was presented and discussed in Chapter 8.

    The final Chapter 9 discusses the major findings of this work and gives further perspectives.

    Glucosinolates during preparation of Brassica vegetables in Indonesia
    Nugrahedi, P.Y. - \ 2015
    Wageningen University. Promotor(en): Tiny van Boekel, co-promotor(en): B. Widianarko; Matthijs Dekker; Ruud Verkerk. - Wageningen : Wageningen University - ISBN 9789462573048 - 155
    glucosinolaten - bladgroenten - thermische afbraak - chemische samenstelling - voedselbereiding - kookmethoden - fermentatie - indonesië - glucosinolates - leafy vegetables - thermal degradation - chemical composition - food preparation - cooking methods - fermentation - indonesia


    Glucosinolates during preparation of Brassica vegetables in Indonesia

    Dutch translation of title:

    Effecten van Indonesische bereidingsmethoden op gezondheidsbevorderende stoffen in groenten

    Title/description for non-professionals:

    Effects of Indonesian preparation methods on health promoting compounds in vegetables


    Stir-frying, one of the most popular method to prepare Brassica vegetables in Indonesia, can retain the content of the alleged health promoting glucosinolates. Meanwhile, long-term steaming and fermentation considerably reduce the glucosinolate content. By analysing the mechanisms underlying glucosinolate changes during preparation, alternative procedures or conditions to enhance the retention of glucosinolates were proposed. For fermentation, prior inactivation of myrosinase enzyme resulted in a higher retention of glucosinolate. For steaming, a reduction of the steaming time was shown beneficial to have a higher glucosinolate content. A mathematical modelling approach was successfully applied to describe the effects of variation in the conditions and processes on the glucosinolate content of products and to optimise them in order to get a more optimal glucosinolate content in the prepared products. Besides improvement of the content of vegetable products, the present study also yields important information to make a more accurate estimation of the dietary intake of glucosinolates in prepared dishes. Such estimation is important for establishing the relation between intake of phytochemicals and health effects like reducing the risk of certain diseases.

    Study of drimane sesquiterpenoids from the Persicaria genus and zigiberene from Callitropsis noorkatensis and their effect on the feeding behaviour of Myzus persicae and Bemisia tabaci
    Prota, N. - \ 2015
    Wageningen University. Promotor(en): Harro Bouwmeester, co-promotor(en): Maarten Jongsma. - Wageningen : Wageningen University - ISBN 9789462572133 - 191
    polygonum - xanthocyparis - sesquiterpenoïden - voedingsgedrag - myzus persicae - bemisia tabaci - vraatremmers - plantensamenstelling - pyrethrinen - chemische samenstelling - verdedigingsmechanismen - polygonum - xanthocyparis - sesquiterpenoids - feeding behaviour - myzus persicae - bemisia tabaci - antifeedants - plant composition - pyrethrins - chemical composition - defence mechanisms


    Whitefly is an insect pest that has systematically spread into colder latitudes for the past two decades and it poses a serious threat to crops, mainly due to the viruses for which it acts as a vector. As the application of synthetic pesticides is often less effective due to development of resistance or restricted by crop- and country-specific regulations, Integrated Pest Management (IPM) strategies to combat insect pests become attractive. In this thesis, I discuss the potential of the use of secondary metabolites, particularly sesquiterpenoids, of plant origin, both as sprayed repellents or antifeedants and as part of host plant resistance against whitefly.

    In Chapter 1, I give a detailed description of the silverleaf whitefly, Bemisia tabaci, its ecology and its effect on crop yield, taking both direct and indirect damage (caused by the viruses the insect transmits) into account. This chapter also provides a detailed account of pest management strategies, both traditional and emergent, with their advantages and disadvantages. The chapter introduces the reader to plant secondary metabolites, and specifically terpenes, discussing their role in plant ecology and their potential as pest management tools with a low environmental impact. Finally, a short overview of the following chapters is given.

    Chapter 2 focusses on the antifeedant activity of the drimane sesquiterpene polygodial. This dialdehyde had been described before as antifeedant to a number of insects, such as the Colorado potato beetle, Leptinotarsa decemlineata, the African cotton leafworm, Spodoptera littoralis, and the green peach aphid, Myzus persicae. In this chapter, the effect of polygodial on the feeding preference of whitefly is reported for the first time. The effect of polygodial was benchmarked against that of the more widely used natural pyrethrins, and both were also tested against M. persicae. From the results, we conclude that pyrethrins were effective against whiteflies at 18-fold lower concentrations than polygodial (ED50 of 1.4 and 25 μg gFW-1 respectively), while in the case of aphids this difference in efficacy was only two-fold (ED50 of 28 and 54 μg gFW-1, respectively).

    To adopt polygodial as a more persistent and easy to implement pest management strategy, we set out to isolate the genes responsible for its biosynthesis which could then be used to transform crops. As a basis for the selection of the right species and plant tissue to achieve this objective, Chapter 3 describes the chemical composition of one of the sources of polygodial – Persicaria hydropiper (water pepper), as well as of two other congeners (Persicaria minor and Persicaria maculosa). For all three species, GC-MS analysis of extracts of leaves and flowers was performed, which gave insight into the interspecific differences and similarities as well as into the differences between the two tissues. P. hydropiper was the species with the biggest variety and the greatest abundance of secondary metabolites, while P. maculosa had the fewest. The flowers of all species were richer in secondary metabolites compared with the leaves of the same species. Furthermore, the accumulation pattern of the identified compounds throughout the development of flowers and leaves is described. Finally, in this chapter, the possible ecological role of polygodial is also briefly addressed.

    Chapter 4 focuses on the discovery and characterization of genes involved in the biosynthesis of drimane sesquiterpenoids. Based on the findings of Chapter 3, we used 454 sequencing of a cDNA library constructed from young flowers of P. hydropiper and P. maculosa, for comparison, to identify a drimenol synthase (PhDS) and a drimenol oxidase (PhDOX1) which can convert farnesyl diphosphate (FPP) into drimenol and an array of other sesquiterpenoids when working in concert. Of the compounds produced in the heterologous systems used (Saccharomyces cerevisiae and Nicotiana benthamiana), two were identified as drimendiol and cinnamolide. The latter was purified and tested against whiteflies and aphids as described for polygodial in Chapter 2. Cinnamolide also displayed antifeedant activity against both insects, although with at slightly lower efficacy than polygodial. In the heterologous hosts used, no polygodial was detected amongst the products of the enzymatic activity of the two genes studied in this chapter. The potential reasons for this are explored in the discussion section of this chapter.

    Chapter 5 focuses on the volatile zingiberene, member of the bisabolane family of sesquiterpenes. This compound and its enantiomer, 7-epi-zingiberene have both been previously identified as repellent to whiteflies. In this chapter we used Alaska yellow cedar (Callitropsis nootkatensis) as a possible source of a zingiberene synthase, which we wanted to use a primary line of defence against whitefly next to polygodial, which would be a secondary line of defence. Alaska yellow cedar produces curcumene in some of its tissues, and this metabolite is known to be a dehydrogenation product of zingiberene. An EST from a C. nootkatensis cDNA library with homology to sesquiterpene synthases was cloned and expressed in E. coli. The resulting protein converted FPP to zingiberene as the sole product. This enzyme was therefore named zingiberene synthase (CnZIS). Although no strict correlation was found between the expression levels of CnZIS in Alaska yellow cedar tissues and the accumulation of curcumene in the same tissues, those with high CnZIS expression such as leaves also produced high amounts of curcumene, while heartwood neither expressed the gene nor had detectable levels of curcumene. Subsequently, we tested the effect of transiently expressed CnZIS in tobacco (Nicotiana tabacum) on whiteflies. Except for one time point, the effect of zingiberene on whitefly feeding was negligible, likely due to the fact that only trace amounts of zingiberene were emitted. When genes upstream of CnZIS in the biosynthetic pathway – 3-hydroxy-3-methyl-glutaryl-CoA reductase (HMGR) and farnesyl diphosphate synthase (FPS) – were co-expressed in tobacco, the antifeedant effect on whiteflies became very strong; however, there was still no detectable level of zingiberene emitted. Instead, the emission of the tobacco sesquiterpene, 5-epi-aristolochene, was almost 100-fold higher than in the control, not expressing HMGR and FPS. We discuss potential explanations of this phenomenon, as well as the uncommon outcome of having an endogenous sesquiterpene boosted by the co-expression and redirection to the mitochondria of the three genes of the zingiberene biosynthetic pathway.

    Chapter 6 brings all the findings together, discussing their place within a wider scientific perspective and their potential in the frame of IPM. Advantages as well as drawbacks of the use of GM crops are addressed. Finally, the emerging new agricultural paradigm, of a sustainable way of growing crops with less environmental impact compared with the current intensive industrial approach, is brought forth as a broad spectrum solution to most agricultural problems which arose in parallel to the intensification of agriculture that stemmed from the Green revolution.

    De in vitro verteerbaarheid van gedroogde algen
    Krimpen, M.M. van; Wikselaar, P.G. van; Bikker, P. - \ 2014
    Wageningen : Wageningen UR Livestock Research (Report / Wageningen UR Livestock Research 812) - 13
    voer - diervoeding - algen - drogen - voedingswaarde - in vitro verteerbaarheid - chemische samenstelling - bioraffinage - biobased economy - feeds - animal nutrition - algae - drying - nutritive value - in vitro digestibility - chemical composition - biorefinery - biobased economy
    In deze studie is de chemische samenstelling en de in vitro organische stof- en stikstofverteerbaarheid van gedroogde algen bepaald. Het betrof een drietal algenproducten, namelijk algen gedroogd bij 700C, algen samen met een hulpstof gedroogd met een innovatieve techniek en algen samen met rijst gedroogd bij 700C. Als referentiegrondstoffen zijn in deze studie een eiwitrijke (sojaschroot) en een vezelrijke grondstof (kuilgras) meegenomen. Op basis van de in vitro resultaten is tevens nagegaan wat de voederwaardeprijs is van de algenproducten.
    A taste of pepper: genetics, biochemistry and prediction of sweet pepper flavor
    Eggink, P.M. - \ 2013
    Wageningen University. Promotor(en): Richard Visser, co-promotor(en): Arnaud Bovy; Chris Maliepaard; J.P.W. Haanstra. - S.l. : s.n. - ISBN 9789461737243 - 159
    capsicum annuum - paprika's - wilde verwanten - genotypen - chemische samenstelling - smaak - geur en smaak - capsicum baccatum - introgressie - plantenveredeling - capsicum annuum - sweet peppers - wild relatives - genotypes - chemical composition - taste - flavour - capsicum baccatum - introgression - plant breeding

    This PhD project started with the composition of a diverse panel of genotypes that represented, (i) roughly the flavor variation in the commercial Capsicum annuum breeding program of Rijk Zwaan, (ii) parents of available mapping populations and (iii) some genotypes that were expected to have extraordinary flavors. The complete set consisted of 35 genotypes of which 24 genotypes were non-pungent. Volatile and non-volatile compounds as well as some breeding parameters were measured in mature fruits of all genotypes throughout the growing season. In addition, from three harvests the non-pungent genotypes were evaluated for taste by a trained descriptive sensory panel.

    The biochemical profiling with use of SPME-GC-MS allowed visualization of between- and within-species volatile compound variation. Principal components analysis (PCA) on the intensity patterns of 391 putative volatile compounds revealed individual grouping of C. chinense, C. baccatum var. pendulum and C. annuum, indicating potentially interesting volatile variation present in the former two groups. A large group of saturated and unsaturated esters were mainly responsible for the individual grouping of the C. chinense accessions. Due to the elevated acid concentrations and aberrant volatile profiles of the C. baccatum var. pendulum accessions PEN45 and PEN79, the two BIL populations derived from these accessions were identified as interesting candidates for further study. Compared to e.g. Mazurka the citrate concentration of the C. baccatum accessions was 2.5-3 times higher and the malate concentrations were even up to 12 times higher (Chapter 2).

    Based on the non-pungent genotypes, we found highly correlated clusters of volatiles and non-volatiles, which could be related to metabolic pathways and common biochemical precursors (Chapter 3). Contrasts between genotypes were caused by both qualitative and quantitative differences in these metabolic clusters, with the phenolic derivatives, higher alkanes, sesquiterpenes and lipid derived volatiles forming the major determinants. For the description of the non-pungent genotypes the panelists used fourteen attributes to describe the flavor sensation in the mouth/throat, which were the texture attributes crunchiness, stickiness of the skin, toughness and juiciness, the basic taste attributes sweetness and sourness and the retronasal flavor attributes aroma intensity, grassiness, green bean, carrot, fruity/apple, perfume, petrochemical and musty. The variation in flavor could be reduced into two major sensory contrasts, which were a texture related contrast and the basic sweet-sour contrast. The structure of the PCA plots resulting from the analysis with one harvest (Chapter 3) and the analysis with the combined three harvests (Chapter 4) remained almost identical, indicating the stability of these contrasts. To relate the sensory attributes to the metabolite data and to determine the importance of the individual compounds we used Random Forest regression on the individual harvests and on the three harvests together. Several predictors for the attributes aroma, fruity/apple, sourness and sweetness were found in common between harvests, which we proposed as key-metabolites involved in flavor determination of sweet pepper (Chapter 4). This list contains compounds with known relations to attributes, like sweetness and sugars, but also several compounds with new relations. In this respect we have demonstrated for the first time, that the metabolites p-menth-1-en-9-al, (E)-β-ocimene, (Z)-2-penten-1-ol, and 1-methyl-1,4-cyclohexadiene are related to fruity/apple taste and/or sweetness of pepper. For sourness the only compound with a consistent significant contribution was an unknown C6H8O2 compound. We postulated therefore the hypothesis that in pepper the effect of sourness related metabolites is masked by other volatile and non-volatile compounds or texture differences (Chapter 3). Subsequently in Chapter 4 we described a clear sweetness-sourness interaction and demonstrated that the masking effect of fructose and other sugars explained why we did not find organic acids contributing to the prediction of sourness. The major sensory attributes were also predicted between harvests. The Random Forest predictions of the texture related attributes (juiciness, toughness, crunchiness and stickiness of the skin) and sweetness were very good. The predictions of the attributes aroma intensity, sourness and fruity/apple were somewhat lower and more variable between harvests, especially in the second harvest. In general, we concluded that prediction of attributes with higher heritabilities works better and is more consistent over harvests (Chapter 4).

    Based on the results of the initial experiments (Chapter 2) the species C. baccatum was chosen for further study. To exploit the potential flavor wealth of C. baccatum PEN45 we combined interspecific crossing with embryo rescue, resulting in a multi-parent BC2S1 population, that was characterized for sensory and biochemical variation (Chapter 5). We developed a population specific genetic linkage map for QTL mapping of characterized traits. Because of the complex structure of our BC2S1 mapping population we encountered several limitations, such as accidental co-segregation, underrepresentation of color linked markers and pre-selection leading to skewness, which might have resulted in false positive or missed QTLs. Despite these limitations, we were still fairly well able to map several biochemical, physical and sensory traits, as demonstrated at first for the (monogenic) control traits red color and pungency in the BC2S1 mapping population and in second instance by validation of genetic effects via an experiment with near-isogenic lines (NILs).This two-step approach turned out to be very powerful, since it led to the identification of the main results from this thesis: (i) Asmall C. baccatum LG3 introgression causing an extraordinary effect on flavor, which resulted in significantly higher scores for the attributes aroma, flowers, spices, celery and chives. In an attempt to identify the responsible biochemical compounds few consistently up- and down-regulated metabolites were detected, including the well-known pepper compound 2-isobutyl-3-methoxypyrazine (down) and 6-methyl-4-oxo-5-heptenal (up); (ii) Two introgressions (LG10.1 and LG1) had major effects on terpenoid content of mature fruits, affecting at least fifteen different monoterpenes; (iii) A second LG3 fragment resulted in a strong increase in Brix (total soluble solids) without negative effects on fruit size (Chapter 5).

    In Chapter 6 some extra sensory results of the pungent genotypes are given and a comparison between the two C. baccatum pendulum BILs (PEN45 and PEN79 derived) is made in light of the overall results. Finally the perspectives for breeding are discussed and presented in the form of a flowchart for flavor improvement.

    Contaminanten in vis en schaaldieren uit de Noordzee
    Leeuwen, S.P.J. van; Roest, J.G. van der; Lee, M.K. van der; Hoogenboom, L.A.P. - \ 2013
    Wageningen : RIKILT Wageningen UR (Rapport / RIKILT 2013.011)
    vissen - ecotoxicologie - chemische samenstelling - chemische analyse - noordzee - visserij - fishes - ecotoxicology - chemical composition - chemical analysis - north sea - fisheries
    Het Productschap Vis verzorgt de hygiënecode voor de visafslagen. In deze code moeten mogelijke risico’s van chemische contaminanten in Noordzeevis opgenomen worden, en hoe deze gecontroleerd kunnen worden (HACCP plan). Als basis voor deze hygiënecode is in de huidige studie een evaluatie uitgevoerd van contaminanten in vis en garnalen uit de Noordzee om in kaart te brengen in hoeverre gehalten van contaminanten de van toepassing zijnde productnormen zullen overstijgen. Wanneer dit optreedt, dan mag het product niet verhandeld worden. Hiervoor zijn gehalten van contaminanten in Noordzeevis en garnalen geëvalueerd op basis van monitoringsgegevens uit de periode 2004-2011 die verkregen zijn uit een jaarlijks monitoringsprogramma uitgevoerd door RIKILT
    Rumen fermentation profile and intestinal digestibility of maize and grass silages
    Ali, M. - \ 2013
    Wageningen University. Promotor(en): Wouter Hendriks, co-promotor(en): John Cone; Gert van Duinkerken. - S.l. : s.n. - ISBN 9789461736581 - 157
    melkkoeien - maïskuilvoer - graskuilvoer - pensfermentatie - verteerbaarheid - darmfysiologie - chemische samenstelling - diervoeding - voedingsfysiologie - dairy cows - maize silage - grass silage - rumen fermentation - digestibility - intestinal physiology - chemical composition - animal nutrition - nutrition physiology

    Maize and grass silages are commonly used as major feed materials for dairy cows in Europe and are becoming common parts of dairy cow rations in other parts of the world. Thenutritive value of maize and grass silages varies greatly due to variation in chemical composition. A combination of different factors such as the use of various cultivars, fertilization practices, growing conditions, harvesting technology, maturity at harvest and ensiling conditions cause this variation in chemical composition. The first aim of this thesis was to investigate relationships between the chemical composition and the in situ rumen degradation characteristics and in situ mobile nylon bag digestibility of dietary nutrients of maize and grass silages. Maize and grass silages with a broad range in chemical composition and quality parameters were selected from different Dutch commercial farms. The broad range in the chemical composition of the maize and grass silages resulted in a large variation in rumen degradable fractions of dry matter (DM), organic matter (OM), crude protein (CP), neutral detergent fibre (NDF) and starch. The intestinal digestibility of CP, NDF and/or starch was affected by the concentration of these components in the maize and grass silages, by the rumen incubation time and the rumen escape content. Regression equations were developed describing relationships between the chemical composition and the in situ ruminal and postruminal degradation characteristics of dietary nutrients of maize and grass silages. A number of the developed regression equations presented in this thesis can be used for accurate and rapid estimation of the ruminal and postruminal degradation characteristics of dietary nutrients of maize and grass silages, without conducting time consuming and expensive in situ experiments. The second aim of this thesis was to determine whether three cows are sufficient to cover the variation between individual cows in in situ rumen degradation characteristics of dietary nutrients of maize and grass silages. Significant differences (P<0.05) were found between individual cows for a number of parameters of DM, OM and CP of maize silages, indicating that four or more cows should be used for nylon bag incubations of maize silages. For grass silages, no significant differences (P>0.05) between individual cows were found for all the parameters of DM, OM, CP and NDF. The results suggest that using three cows are sufficient for nylon bag incubations of grass silages and pooling of rumen incubated residues is allowed to obtain a representative sample. The third aim of this thesis was to compare two fractionation methods; the washing machine method and a modified method, for nitrogen (N) and starch fractions of maize silages and N fractions of grass silages. The N and/or starch fractions of maize and grass silages determined, using the washing machine method (washing with water for 40 min) and the modified method (shaking with buffer solution for 60 min) were compared. The different methodological approaches of both methods resulted in different values for the washout (W), the soluble (S) and the non-washout (D+U) fractions of N of maize and grass silages and for the W, the insoluble washout (W-S) and the D+U fractions of starch of maize silages. The loss of insoluble small particles of starch was less during shaking of nylon bags in buffer solution, compared to washing nylon bags in the washing machine. Therefore, large differences were found between the D+U fractions of starch determined by both methods compared to the D+U fractions of N of maize silages. The developed regression equations for W, S and D+U fractions of N in grass silages and for D+U fractions of starch in maize silages determined by both methods can be used for rapid estimation of these fractions from chemical characteristics of maize and grass silages. The information on nutrient bioavailability of maize and grass silages presented in this thesis can be used to more accurately formulate dairy ration in terms of maintenance, health and production of dairy cows.

    Monitoring perfluor- en organotinverbindingen in kabeljauw- en heeklever 2003 - 2010
    Hoek-van Nieuwenhuizen, M. van; Kwadijk, C.J.A.F. ; Lee, M.K. van der; Hoogenboom, L.A.P. - \ 2012
    IJmuiden : IMARES (Rapport / IMARES Wageningen UR nr.: C159/10) - 19
    ecotoxicologie - vissen - kabeljauw - gadidae - lever - chemische samenstelling - organische fluorverbindingen - organo-tinverbindingen - ecotoxicology - fishes - cod - gadidae - liver - chemical composition - organofluorine compounds - organotin compounds
    In 2010 heeft de werkgroep Kaderrichtlijn Mariene Strategie (KRMS) geadviseerd trends van perfluor- en organotinverbindingen te volgen in zeevis in afwachting van officiële normen. De gehalten aan PFOS in kabeljauwlevers, afkomstig uit de Noordzee, bevinden zich in de periode 2003-2009 boven de MKN voor PFOS in biota van 9.1 μg/kg nat gewicht. Bovendien is vanaf 2007 een stijgende lijn waarneembaar voor de gehalten PFOS in kabeljauwlever uit de Noordzee. De monitoring voortzetten voor deze component lijkt daarom zinvol. Voor heeklevers, afkomstig van Zuid-West Ierland, liggen de gehalten voor PFOS in de periode 2003-2010 tevens boven de MKN op één waarde, gemeten in 2008, na.
    Mineralenconcentraten uit dierlijke mest : monitoring in het kader van de pilot mineralenconcentraten = Mineral concentrates from animal slurry : monitoring of the pilot production plants
    Hoeksma, P. ; Buisonjé, F.E. de; Ehlert, P.A.I. ; Horrevorts, J.H. - \ 2011
    Lelystad : Wageningen UR Livestock Research (Rapport / Wageningen UR Livestock Research 481)
    mestverwerking - concentraten - mesttechnologie - kunstmeststoffen - chemische samenstelling - omgekeerde osmose - drijfmest - manure treatment - concentrates - fertilizer technology - fertilizers - chemical composition - reverse osmosis - slurries
    Processing of animal manure is considered as an opportunity to reduce the pressure on the manure market in the Netherlands. One of the options is to separate the slurry and to use the mineral concentrate, that is produced from the liquid phase by reverse osmosis, as a substitute for mineral fertilizer. Against this background the pilot mineral concentrates was started to study the agricultural, economic and environmental effects of the production and use of mineral concentrates. Within the framework of this pilot in 2009 and 2010 the participating manure processing plants were monitored.
    Duinzand verarmt relatief snel
    Leeuwen, P.J. van; Pronk, A.A. - \ 2010
    Vakblad voor de Bloemisterij 65 (2010)9. - ISSN 0042-2223 - p. 48 - 49.
    duinzand - duingronden - gronden van het duinlandschap - organische stof - chemische samenstelling - onderzoek - afbraak (plantenziektekundig) - organisch bodemmateriaal - humus - bloembollen - dune sand - dune soils - duneland soils - organic matter - chemical composition - research - breakdown - soil organic matter - ornamental bulbs
    PRI en PPO Bollen zijn twee jaar geleden onderzoek gestart naar de afbraaksnelheid van organische stof op duinzandgronden. Er zijn verschillen gevonden maar het is nog te vroeg voor conclusies
    Effects of chop length and ensiling period of forage maize on in vitro rumen fermentation characteristics
    Cone, J.W. ; Gelder, A.H. van; Schooten, H.A. van - \ 2008
    NJAS Wageningen Journal of Life Sciences 55 (2008)2. - ISSN 1573-5214 - p. 155 - 166.
    chemische samenstelling - verteerbaarheid - voederconversie - voederconversievermogen - spijsvertering - voedingswaarde - veevoeder - maïskuilvoer - maïs - chemical composition - digestibility - feed conversion - feed conversion efficiency - digestion - nutritive value - fodder - maize silage - maize - lactating dairy-cows - gas-production - corn-silage - kinetics - degradation - traits - yield - time
    The effect of chop length and ensiling period on in vitro rumen fermentation characteristics of forage maize was studied in two experiments. In the first experiment, maize plants of eight cultivars representing different combinations of Dry Down, Stay Green, early ripening, late ripening, starch and cell wall types were chopped at harvest into pieces of 6 or 15 mm and ensiled in small laboratory silos. After 8 weeks, silage samples were taken and freeze-dried (not ground) before in vitro rumen fermentation characteristics were determined using the gas production technique. Chop length appeared not to affect the in vitro fermentation characteristics. In the second experiment, plants of two of these maize cultivars were chopped into 6-mm pieces and ensiled for different periods in small laboratory silos and in large bunker silos as used in practice. After 0, 14, 42 and 180 days of ensiling, chemical composition and in vitro rumen fermentation characteristics were determined using the gas production technique. The in vitro fermentation characteristics were not influenced by the ensiling period up to 180 days. During the first two weeks of the ensiling period sugar content decreased and so did the gas production caused by fermentation of the soluble components.
    The lignan macromolecule from flaxseed : structure and bioconversion of lignans
    Struijs, K. - \ 2008
    Wageningen University. Promotor(en): Harry Gruppen, co-promotor(en): J.P. Vinken. - [S.l.] : S.n. - ISBN 9789085852476 - 179
    lignanen - lijnzaad - chemische samenstelling - fermentatie - sesamzaad - bioactieve verbindingen - lignans - linseed - chemical composition - fermentation - sesame seed - bioactive compounds
    Flaxseeds are known already for a long time for their positive health effects. The high content of dietary fiber, the advantageous fatty acid composition and the lignans are held responsible for this. Lignans are compounds, which have a similar structure as human estradiol. As a result of that, they are expected to influence hormone metabolism, and (beneficially) influence human health. However, the lignans from flaxseed are not bioactive themselves. They need to be bioactivated by the bacteria in the human intestinal tract. Firstly, it was investigated how lignans are present in flaxseed. Lignans were found to form oligomeric molecules together with other components. These oligomeric molecules are called the lignan macromolecule. Secondly, it was investigated, which microorganisms are involved in the bioconversion reaction and we isolated the formed bioactive lignans. Via this procedure bioactive lignans has been obtained, which can be used as a functional food ingredient.
    Indices to screen for grain yield and grain-zinc mass concentrations in aerobic rice at different soil-Zn levels
    Jiang, W. ; Struik, P.C. ; Zhao, M. ; Keulen, H. van; Fan, T.Q. ; Stomph, T.J. - \ 2008
    NJAS Wageningen Journal of Life Sciences 55 (2008)2. - ISSN 1573-5214 - p. 181 - 197.
    oryza sativa - gewasopbrengst - zink - chemische samenstelling - mineraalgehalte - chemische bodemeigenschappen - korrels (granen) - sporenelementen - bioconcentratie - oryza sativa - crop yield - zinc - chemical composition - mineral content - soil chemical properties - kernels - trace elements - bioconcentration - calcareous soil - field crops - in-field - efficiency - deficiency - wheat - genotypes - plants - tolerance - cultivars
    Zinc is an important micronutrient for both crop growth and human nutrition. In rice production, yields are often reduced and Zn mass concentrations in the grains are often low when Zn is in short supply to the crop. This may result in malnutrition of people dependent on a rice-based diet. Plant breeding to enhance low-Zn tolerance might result in higher yields and nutritional quality but requires effective selection criteria embedded in physiological insight into the Zn husbandry of the crop and applicable in field evaluation of advanced breeding material or in screening of existing varieties. Using existing and newly developed low-Zn tolerance indices, this study presents the results of screening experiments carried out in high- and low-Zn soils. Sixteen accessions of aerobic rice were grown under greenhouse conditions to conceptualize the indices and 14 under field conditions to validate the indices. As the differences in soil-Zn levels in these experiments did not result in differences in grain yield, literature data were used from experiments where the soil-Zn level did have an effect on grain yield, to further check the validity of the indices. Several indices were applied to evaluate the genotypic low-Zn tolerance performance in attaining (relatively) high grain yield, high grain-Zn mass concentration, or both. The results indicate that the grain-Zn mass concentration efficiency index is different from the grain yield efficiency index and that the low-Zn tolerance indices identified superior genotypes best. Amongst the indices tested, the low-Zn tolerance index for grain yield and the low-Zn tolerance index for grain-Zn mass concentration were closely correlated with grain yield and grain-Zn mass concentration, respectively. Therefore, the low-Zn tolerance index for grain yield was effective in screening for high stability and high potential of grain yield, and the low-Zn tolerance index for grain-Zn mass concentration was effective for grain-Zn mass concentration under low and high soil-Zn conditions. Genotypic differences in yield and grain-Zn mass concentration were shown to be unrelated and therefore deserve separate attention in breeding programmes. Combining the low-Zn tolerance index for grain yield and the low-Zn tolerance index for grain-Zn mass concentration in a single low-Zn tolerance index was considered but did not appear to be superior to using the two indices separately.
    Eiwitwaarde vers gras = Protein evaluation fresh gras
    Klop, A. ; Jonge, L.H. de; Brandsma, G.G. - \ 2008
    Wageningen : Animal Sciences Group (Rapport / Animal Sciences Group 124) - 11
    begrazing - graskuilvoer - graslanden, conditie - gewaskwaliteit - eiwitgehalte - chemische samenstelling - voedingswaarde - eiwitverteerbaarheid - grazing - grass silage - grassland condition - crop quality - protein content - chemical composition - nutritive value - protein digestibility
    Het CVB van het Productschap Diervoeder heeft het eiwitwaarderingsysteem uit 1991 in 2007 herzien. Daarvoor zijn van diverse voedermiddelen aanvullende analyses gedaan om tot betrouwbare rekenregels te komen. Voor vers gras is aanvullend onderzoek gedaan naar de oplosbare en uitwasbare fractie van ruw eiwit. In het DVE/OEB- 2007 systeem worden die gegevens gebruikt om te komen tot een betrouwbare schatting van de hoeveelheid darmverteerbaar bestendig eiwit en microbieel eiwit. Het CVB heeft de onderzoeksgegevens toegepast in de nieuwe rekenregels van het DVE/OEB-2007 systeem. Voor zowel de uitwasbare als de oplosbare eiwitfractie wordt een vaste waarde gehanteerd van 5,7%. Met het verbeterde systeem wordt de DVE waarde van vers gras gemiddeld 7% lager gewaardeerd dan voorheen. De OEB waarde stijgt met gemiddeld 7%. De verandering is niet alleen het gevolg van de uit dit onderzoek verkregen resultaten maar vooral ook met gewijzigde rekenregels voor Fermenteerbare Organische Stof en daarmee voor de hoeveelheid darmverteerbaar microbieel eiwit (DVME)
    Pathways for improving the nitrogen efficiency of grazing bovines
    Hoekstra, N.J. - \ 2007
    Wageningen University. Promotor(en): Paul Struik, co-promotor(en): Egbert Lantinga; R.P.O. Schulte. - [S.l.] : S.n. - ISBN 9789085047834 - 159
    bovidae - stikstof - begrazing - lolium perenne - diervoeding - koeien - grasbestand - graslandbeheer - plantensamenstelling - chemische samenstelling - gebruiksefficiëntie - bovidae - nitrogen - grazing - lolium perenne - animal nutrition - cows - herbage - grassland management - plant composition - chemical composition - use efficiency
    Livestock production has been identified as a major source of nitrogen (N) losses in agro-ecosystems. N excreted in dung and urine contributes to environmental N pollution either as ammonia and N oxides in air, or as nitrate in soil and ground water. Therefore, it is important to reduce N output through animal excretions by improving N utilisation by the animal. Bovine N utilisation can be increased substantially through changing the composition of the diet. In many parts of Europe, a large proportion of the bovine’s diet consists of grass taken up by grazing. Manipulating the nutritional composition of grazed grass poses a complex challenge, since it is hard to control the diet under grazing as this depends on grassland management and environmental factors. The objective of this research was to investigate the efficacy of grassland management tools for manipulating herbage quality and to assess the subsequent effect on the N efficiency of grazing cows. In the literature review, three pathways were identified through which more efficient N utilisation by grazing bovines can be achieved by manipulation of the chemical composition of the grass forage: 1) matching protein supply to animal requirements, 2) balancing and synchronising carbohydrate and N supply in the rumen, and 3) increasing the proportion of rumen undegradable protein (RUP). Under grazing conditions, grassland management tools, such as the length of the regrowth period, defoliation height, fertiliser N application rate, and growing high-sugar grass cultivars, are the main tools to manipulate herbage quality and subsequent bovine N efficiency. A field experiment was carried out to study the effect of those grassland management tools on the chemical composition of lamina and sheath material. These results were used to design a model for predicting the efficacy of herbage management tools for affecting the quality of herbage ingested by cattle under strip-grazing management. This model was validated and connected to the Cornell Net Carbohydrate and Protein System model in order to evaluate the effectiveness of a) the grassland management tools and b) the herbage quality pathways on the N utilisation of grazing dairy cows. Within the modelled scenario the concentration of crude protein (CP) in the ingested dry matter (DM) was the main factor affecting N utilisation. Model predictions indicated that herbage should be managed to achieve a CP concentration of 130−150 g / kg DM in order to maximise the efficiency of N utilisation for milk production and minimise the proportion of N excreted in urine. Both N application rate and rotation length were shown to be effective tools for affecting the CP concentration of the intake and subsequent cow N utilisation. However, there was no effect of the high-sugar cultivar and defoliation height on cow N utilisation. Assessment of the effectiveness of the three herbage quality pathways for improving bovine N utilisation resulted in the following conclusions: 1) N utilisation is strongly related to the daily N intake (g / day), however, this seems more connected to the N concentration of the ingested DM (g / kg DM), rather than the actual daily N intake. Therefore, the effect is more related to the balance between energy and N (pathway 2). 2) The balance between N and energy is the most important herbage quality factor for improving bovine N utilisation. In contrast, the synchronisation between the release of energy and N seems to have little effect. 3) The proportion of protein in the form of RUP is not much affected by the herbage management tools, and is therefore not an effective pathway for improving the N utilisation of grazing cows. It is recommended that the model will be extended to include a herbage yield and intake component. This would allow the model to be used to design herbage management systems to optimise N utilisation on a yearly basis.
    Measuring compounds in fruits using spectral image analysis
    Zedde, H.J. van de; Heijden, G.W.A.M. van der; Polder, G. - \ 2007
    rijp worden - rijpheid - multispectrale beelden - chemische samenstelling - vruchten - voedseltechnologie - chemische verbindingen - beeldvormende spectroscopie - ripening - maturity - multispectral imagery - chemical composition - fruits - food technology - chemical compounds - imaging spectroscopy
    In a greyvalue (black&white) image, a pixel contains a single value, representing light intensity. In an RGB color image, a pixel contains three values, corresponding with the light intensity at the red, green and blue band of the electromagnetic spectrum. In a spectral image, each pixel consists of an array of intensity values corresponding with small bands (
    Chemical composition of lamina and sheath of Lolium perenne as affected by herbage management
    Hoekstra, N.J. ; Struik, P.C. ; Lantinga, E.A. ; Schulte, R.P.O. - \ 2007
    NJAS Wageningen Journal of Life Sciences 55 (2007)1. - ISSN 1573-5214 - p. 55 - 73.
    afsnijhoogte - grasbestand - voedergewassen - lolium perenne - hergroei - rotaties - chemische samenstelling - graslandbeheer - voedingswaarde - lignine - totale hoeveelheid droge stof - koolhydraten - stikstof - vezelgehalte - bloeiwijzen - cutting height - herbage - fodder crops - lolium perenne - regrowth - rotations - chemical composition - grassland management - nutritive value - lignin - total solids - carbohydrates - nitrogen - fibre content - inflorescences - water-soluble carbohydrate - neutral detergent fiber - dairy-cows - nitrogen application - nutritive-value - ryegrass varieties - animal nutrition - milk-production - rumen function - l. cultivars
    The quality of grass in terms of form and relative amounts of energy and protein affects both animal production per unit of intake and nitrogen (N) utilization. Quality can be manipulated by herbage management and choice of cultivar. The effects of N application rate (0, 90 or 390 kg N ha¿1 year¿1), duration of regrowth period (2¿3, 4¿5, or 6¿7 weeks), and cutting height (8 or 12 cm) on the mass fractions of nitrogen (N), water-soluble carbohydrates (WSC), neutral detergent fibre (NDF), acid detergent fibre (ADF), lignin and ash in lamina and sheath material of a high-sugar (Aberdart) and a low-sugar (Respect) perennial ryegrass (Lolium perenne) cultivar, were studied in a factorial field experiment during four seasons in 2002 and 2003. Expressing NDF and ADF mass fractions in g per kg WSC-free dry matter (DM) increased the consistency of treatment effects. The high-sugar cultivar had generally higher WSC mass fractions than the low-sugar cultivar, especially during the late season. Moreover, the relative difference in WSC mass fraction between the two cultivars tended to be higher for the lamina material than for the sheath material, which suggests that the high-sugar trait may be more important under grazing conditions, when lamina forms the bulk of the intake, than under mowing regimes. Longer regrowth periods and lower N application rates increased WSC mass fractions and decreased N mass fractions; interactions between regrowth period and N application rate were highly significant. The mass fractions of NDF and ADF were much less influenced. The NDF mass fraction in terms of g per kg WSC-free DM tended to be higher at lower N application rates and at longer regrowth periods. The effect of cutting height on herbage chemical composition was unclear. In conclusion, high-sugar cultivars, N application rate and length of the regrowth period are important tools for manipulating herbage quality.
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