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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    Cursus dierenwelzijn
    Ruis, M.A.W. ; Luyten, I. ; Hilverda, H. ; Smeets, M. ; Jessen, E. van; Jong-Timmerman, M. de; Bolderman, K. ; Heemink, G. - \ 2019
    Wageningen : Dierenwelzijnsweb
    dierhouderij - dierenwelzijn - diergezondheid - diergedrag - diervoeding - huisvesting, dieren - dierethiek - dierverzorging - lesmaterialen - animal husbandry - animal welfare - animal health - animal behaviour - animal nutrition - animal housing - animal ethics - care of animals - teaching materials
    Deze cursus helpt je te begrijpen wat dierenwelzijn precies inhoudt. De cursus behandelt de onderwerpen gedrag en gezondheid, informatiebronnen voor dierenwelzijn, huisvesting en voeding, omgevingsfactoren die een belangrijke invloed hebben op dierenwelzijn. Daarnaast helpt de cursus je te begrijpen wat dierethiek is en leer je zelf een afweging te maken over hoe jij vindt dat wij met dieren om moeten gaan. Aan de hand van praktische voorbeelden, dilemma's en casussen leer je na te denken over dierenwelzijn. De voorbeelden betreffen o.a. gezelschapsdieren, landbouwhuisdieren, proefdieren en in het wild levende dieren. Aan het eind van elk blok vind je een toets, waarmee je je kennis over dat onderwerp kunt testen.
    Unravelling of the water-binding capacity of cold-gelated whey protein microparticles
    Peters, Jorien P.C.M. ; Vergeldt, Frank J. ; As, Henk Van; Luyten, Hannemieke ; Boom, Remko M. ; Goot, Atze Jan van der - \ 2017
    Food Hydrocolloids 63 (2017). - ISSN 0268-005X - p. 533 - 544.
    Cold gelation - Particle–particle interactions - Protein microparticles - Time domain nuclear magnetic resonance - Water-binding capacity

    Whey protein microparticles (CG MPs) were made with a cold gelation method. Without shearing or mixing during gelation spherical CG MPs were formed, while shearing or mixing resulted in smaller irregularly shaped CG MPs. The water-binding capacity of pellets (WBC-P) that were obtained after centrifuging CG MP dispersions was remarkably large (11–18 g water/g dry matter), though this value decreased at larger centrifugation speeds. Microscopy images hinted at the presence of two water domains in the CG MP pellets: water within and between the CG MPs. The images also imply that the amount of water within the CG MPs was determined by the centrifugation speed. The amount of water between CG MPs seemed to be defined by the amount of particle-particle interactions that were present, as suggested by the effects of the particles' size and the inhibition of the disulphide bridge formation on the WBC-P. Although microscopy images showed two water domains, only one main peak was found with time domain nuclear magnetic resonance. This was explained by water diffusion from one water domain to the other within the measuring time. This fast diffusion implies that the CG MPs had a relatively open structure. Overall, it was concluded that water-binding by CG MPs was affected by various factors and that a good understanding of the water-binding requires the use of a range of measurements.

    Time domain nuclear magnetic resonance as a method to determine and characterize the water-binding capacity of whey protein microparticles
    Peters, J.P.C.M. ; Vergeldt, F.J. ; As, H. Van; Luyten, H. ; Boom, R.M. ; Goot, A.J. van der - \ 2016
    Food Hydrocolloids 54 (2016). - ISSN 0268-005X - p. 170 - 178.
    Centrifugation - Microstructure - Nuclear magnetic resonance - Whey proteins - Swelling - Water-binding capacity

    Water-binding capacity (WBC) is commonly measured with a centrifugation method in which a sample is hydrated in excess water and the pellet weight after centrifugation defines the WBC. When a dispersion is being analyzed, here containing whey protein microparticles (MPs), the pellet consists of swollen particles and water between the particles. These two water domains in MP pellets were distinguished using time domain nuclear magnetic resonance (TD NMR). This distinction showed that an increase in WBC from 2 to 5.5 g water/g dry matter was mainly due to an increase in water between the MPs. Besides, it was found that TD NMR-measurements could be used to provide accurate values of the amount of water in both water domains in MP pellets. This makes TD NMR therefore a more accurate method to determine the WBC of the whole pellet than weighing the pellet after centrifugation.

    Hard and semi-hard cheese comprising water retaining particles, a method for preparing such hard or semi-hard cheese, and the use of such particles in the preparation of cheese
    Luyten, J.M.J.G. ; Koning, A. ; Faber, T.J. ; Peters, J.P.C.M. ; Paques, J.P. - \ 2015
    Octrooinummer: WO2015060715, gepubliceerd: 2015-04-30.
    The present invention relates to a method for the preparation of hard or semi-hard type cheese, wherein use is made of water retaining particles, which particles comprise at least seventy-five percent by weight of water. The present invention further relates to a hard or semi- hard cheese comprising said water retaining particles and to the use of such particles in the preparation of cheese.
    Effect of crosslink density on the water-binding capacity of whey protein microparticles
    Peters, J.P.C.M. ; Luyten, H. ; Alting, A.C. ; Boom, R.M. ; Goot, A.J. van der - \ 2015
    Food Hydrocolloids 44 (2015). - ISSN 0268-005X - p. 277 - 284.
    microbial transglutaminase - statistical-mechanics - beta-lactoglobulin - moisture transport - gels - particles - genipin - isolate - meat - disulfide
    The ability of whey protein microparticles (MPs) to bind water and consequently to swell is, amongst others, determined by the crosslink density of the MPs. The Flory-Rehner model states that a decrease in crosslink density should lead to an increased swelling of the MPs. Decreasing the crosslink density of MPs with dithiothreitol (DTT) decreased the amount of disulphide bridges and increased the water-binding capacity (WBC) from 6 to 9 g water/g protein. Increasing the crosslink density with transglutaminase or genipin resulted in a decreased number of primary amino groups, although the WBC did not change significantly. The WBC of the MPs was determined using a centrifugation method that resulted in the formation of a pellet, so water inside and between the MPs was measured simultaneously. Therefore, additional microscopy and swelling tests were performed, which suggested that an increased WBC of the pellet of MPs was not only related to an increased swelling of the MPs, but also to an increased amount of water between the MPs.
    An improved instrumental characterization of mechanical and acoustic properties of crispy cellular solid foods
    Castro-Prada, E.M. ; Luyten, J.M.J.G. ; Lichtendonk, W.J. ; Hamer, R.J. ; Vliet, T. van - \ 2007
    Journal of Texture Studies 38 (2007)6. - ISSN 0022-4901 - p. 698 - 724.
    sounds - emission - crunchy - texture - products - biscuits - behavior - evaluate - cereals - model
    A detailed study was performed to simultaneously measure the mechanical and acoustic properties of crispy cellular solid foods. Different critical aspects are discussed in order to assess optimal test conditions. These are primarily data sampling rate, microphone positioning, frequency spectrum of interest, sound/noise ratio and selection of measuring probe. A data sampling rate of more than 50 kHz was shown to be sufficient to register fracture event and acoustic event, and the frequencies audible by human ear (at least 40 kHz needed). The optimum positioning of the microphone with respect to the test piece should be a compromise between a distance that the microphone registers a good sound over the whole human audible frequency spectrum and a good sound/noise ratio. It is shown that test method selection has to depend on whether the goal is determining material fracture behavior or correlation of data to consumer perception. The best method from a fracture mechanics point of view does not have to be the best choice for a combined fracture and acoustic measurement.
    On the mechanism by which oil uptake decreases crispy/crunchy behaviour of fried products
    Vliet, T. van; Visser, J.E. ; Luyten, J.M.J.G. - \ 2007
    Food Research International 40 (2007)9. - ISSN 0963-9969 - p. 1122 - 1128.
    food-products - crispness - crunchy
    A large problem for fried snack products with a crispy crust and a soft moist interior is that the crust often loses its crispy character fast, in the order of 3¿20 min. As known during cooling of these snacks adherent oil will be sucked into the crust. The presence of oil in a cellular solid crispy material was found to affect the sound emitted on fracture dramatically, while it did not affect mechanical characteristics at least for shorter ageing times. Both the number of sound events and the acoustic energy released during fracture decreased. This could be explained by reflection of emitted sound at the oil¿air interface. Both the smaller number of acoustic events and the lower loudness will cause a decrease in crispy perception of the crust and in that way oil uptake during cooling of fried snacks can explain their fast decrease in crispness after frying.
    Individual fracture events in cellular solid foods
    Luyten, J.M.J.G. ; Castro Prada, E.M. ; Timmerman, E. ; Lichtendonk, W.J. ; Vliet, T. van - \ 2007
    In: Fracture of nano and engineering materials and structures : proceedings of the 16th European conference of fracture, Alexandroupolis, Greece, July 3-7, 2006 / Gdoutos, E.E., Berlin : Springer - ISBN 9781402049712 - p. 439 - 440.
    Mechanisms Determining Crispness and Its Retention in Foods with a Dry Crust
    Vliet, T. van; Visser, J.E. ; Lichtendonk, W.J. ; Luyten, J.M.J.G. - \ 2007
    In: Food Colloids. Self-Assembly and Material Science, Cambridge, UK, 24 - 26 April, 2006. - Cambridge UK : Royal Society of Chemistry - ISBN 9780854042715 - p. 485 - 501.
    In vitro evaluation of genistein bioaccessibility from enriched custards
    Sanz, T. ; Luyten, J.M.J.G. - \ 2007
    Food Hydrocolloids 21 (2007)2. - ISSN 0268-005X - p. 203 - 211.
    green leafy vegetables - beta-carotene - aroma compounds - water emulsions - bioavailability - release - humans - digestion - isoflavones - retention
    The suitability of custards with genistein incorporated in the fat phase of the milk to become a new `functional food¿ with good bioaccessibility was evaluated. Intestine bioaccessibility was mainly attributed to the incorporation of genistein into micelles and did depend on fat concentration. In terms of bioaccessibility, a milk fat content of 3% was found to be the optimum. Saliva and pepsin significantly affected the bioaccessibility of genistein in the mouth and the stomach but they did not have an effect on intestine bioaccessibility. The use of carboxymethylcellulose instead of starch as thickening agent significantly reduced bioaccessibility. Similar bioaccessibilities and structure breakdown properties were found among the waxy maize and the tapioca pregelatinized starches, which convert the latest in a good alternative when a cold custard preparation is required. Values of bioaccessibility up to 92% were obtained, so it is concluded that custards are a useful carrier for genistein.
    A new sensory vocabulary for crisp and crunchy dry model foods
    Dijksterhuis, G.B. ; Luyten, J.M.J.G. ; Wijk, R.A. de; Mojet, J. - \ 2007
    Food Quality and Preference 18 (2007)1. - ISSN 0950-3293 - p. 37 - 50.
    The creation of a sensory descriptive panel for dry crusted, `crispy¿ and `crunchy¿ food products is presented. A sensory vocabulary comprising appearance, odour, taste, texture and sound is developed and the panel is trained to use these attributes. Model deep-fried battered snack and baked bread food products are used in the experiments with this panel. Special attention is given to ageing of the model products, and the effects this has on the sensory perception. The separation of the sensory assessment in a `first bite¿ and a `during chewing¿ phase turns out to be useful for this type of products, as does the inclusion of sound attributes. The vocabulary allowed both the effect of ageing and the differences between model products to be investigated in considerable detail.
    Fracture events in rusk roll and the effect of changing water activity
    Castro Prada, E.M. ; Luyten, J.M.J.G. ; Vliet, T. van - \ 2006
    In: Proceedings 4th International Symposium on Food Rheology and structure, Zurich, Switzerland, February 20-23, 2006 Zurich : ETH - p. 389 - 393.
    Crispness is a desired sensorial property of many foods, like bread. Both fracture properties and sound emission play an important role in crispness. With aging, bread crusts become less crispy. This is often ascribed to an increase in water activity of the crusts altering the mobility of the different molecules. However, it is difficult to relate the change in molecular properties directly to changes in crust behavior. One of the reasons is bread crust morphology, which is a heterogeneous cellular solid. A method was developed allowing to determine the fracture properties and accompanying acoustic emission of the individual fracture events. As a model for crispy products rusk rolls were selected. The amount of fracture events could be directly related to the morphology of the product, more precisely to the amount of beams and struts in the cellular solid. The method thus allows studying the solid material behaviour of the bread crusts independently from its morphology. This enables studying the relation between changes in the molecular behaviour and the fracture behaviour of the solid material. As an example, we showed the effect of water activity on the individual fracture events and accompanying acoustic emission.
    Exploring cracks, of breads and snacks
    Dijksterhuis, G.B. ; Luyten, J.M.J.G. ; Nijenhuis-de Vries, M.A. - \ 2006
    Acoustic emission, fracture behavior and morphology of dry crispy foods : a discussion article
    Luyten, J.M.J.G. ; Vliet, T. van - \ 2006
    Journal of Texture Studies 37 (2006)3. - ISSN 0022-4901 - p. 221 - 240.
    crushing sounds - chewing sounds - time - composites - texture - crunchy
    This article describes sound properties that are special for crispy foods and relates them to general knowledge on the acoustic emission and mechanical properties of fracturing materials. From properties like the occurrence of sound, the sound energy, the duration of single sound waves, the time interval between the sound pulses and from the force drops involved, it was possible to calculate the morphological constraints for dry, crispy cellular foods. We present data for the minimum and maximum sizes of the pores and of the sizes of the solid material element surrounding them. The loss of crispness in foods caused by aging under deteriorating circumstances was found not to be caused by changes in the type of elements that fracture.
    Release, partitioning and stability of isoflavones from enriched custards during mouth, stomach and intestine in vitro simulations
    Sanz, T. ; Luyten, J.M.J.G. - \ 2006
    Food Hydrocolloids 20 (2006)6. - ISSN 0268-005X - p. 892 - 900.
    beta-glucosidase activity - carotenoid bioavailability - soy foods - humans - metabolism - flavonoids - glycosides - aglycones - transport - digestion
    Custard desserts were enriched with a soy germ extract as source of isoflavones and the influence of the thickening agent (starch or carboxymethylcellulose (CMC)) and the presence of fat on the release, partitioning and stability of the isoflavones after mouth, stomach and small intestine in vitro incubations were studied. A suspension in water of the soy germ extract was first analyzed. Mouth incubation did not affect the amount and partitioning of isoflavones. A lower recovery and different partitioning were found after the stomach incubation, which was associated to the low pH. After the intestine incubation, a higher recovery and an effect in the partitioning were found. Regarding the effect of the custard matrix, the starch custards were able to release a significantly higher amount of isoflavones than the CMC ones, due to the higher general enzymatic resistance of the latter one's. The presence of fat significantly increased the bioaccessibility of the aglycone forms, especially of genistein
    Effect of thickening agent in the in vitro mouth, stomach and intestine release of tyrosol from enriched custards
    Sanz, T. ; Luyten, J.M.J.G. - \ 2006
    Food Hydrocolloids 20 (2006)5. - ISSN 0268-005X - p. 703 - 711.
    carotenoid bioavailability - perception - sweetness - isoflavones - digestion - texture - model
    Custards prepared with four thickeners (two modified starches: waxy maize and tapioca, and two derives of cellulose: CMC and HPMC) and at two levels of consistency were enriched with a water-soluble functional ingredient (tyrosol) and its release evaluated after in vitro mouth, stomach and small intestine incubations. Tyrosol release was related to structure breakdown and water release properties of the custards. After mouth incubation, the ¿-amylase sensibility of the starch custards determined their higher release. Although less evident, the difference still remains after the stomach and intestine incubations. The intestine produced a complete release in the starch custards. In comparison to HPMC, CMC showed higher structural resistance, with lower values of release. The increase in consistency decreased the release after mouth and stomach incubations, but did not have an effect after the intestine incubation. The differences found will allow a control in the release of water-soluble ingredients.
    Acoustic Emission from Crispy/Crunchy Foods to Link Mechanical Properties and Sensory Perception
    Luyten, J.M.J.G. ; Lichtendonk, W.J. ; Castro Prada, E.M. ; Visser, J.E. ; Vliet, T. van - \ 2005
    In: Food Colloids. Interactions, Microstructure and Processing. - Cambridge : Royal Society of Chemistry - ISBN 9780854046386 - p. 380 - 392.
    Simoultaneous mechanical and acoustic emission measurement
    Castro Prada, E.M. ; Luyten, H. ; Vliet, T. van - \ 2004
    Crispy/crunchy crusts of cellular solid foods: a literature review with discussion
    Luyten, J.M.J.G. ; Plijter, J.J. ; Vliet, T. van - \ 2004
    Journal of Texture Studies 35 (2004)5. - ISSN 0022-4901 - p. 445 - 492.
    scanning-electron-microscope - nuclear-magnetic-resonance - post-frying period - mechanical-properties - acoustic-emission - fracture-behavior - glass-transition - chewing sounds - sensory perception - moisture sorption
    Literature on the crispy / crunchy behaviour of cellular solid foods with a crust is discussed. The emphasis is on products with a dry crispy or crunchy crust as bread and various snacks and especially on mesoscopic and macroscopic aspects. Successively, the sensory sensation involved, the relation to fracture behaviour, morphological aspects, and the relation between crispy and crunchy behaviour and mobility of the macromolecules and plasticizer (primarily water) involved, are discussed. Finally we will discuss some ideas for an integrated approach of crispy / crunchy behaviour of cellular solid foods with a dry crust.
    Using proteins as additives in foods : an introduction
    Luyten, J.M.J.G. ; Vereijken, J.M. ; Buecking, M. - \ 2004
    In: Proteins in food processing / Yada, R.Y., Cambridge : Woodhead - ISBN 9781855737235 - p. 421 - 441.
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