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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    Deep frying : from mechanisms to product quality
    Koerten, K.N. van - \ 2016
    Wageningen University. Promotor(en): Maarten Schutyser, co-promotor(en): Remko Boom. - Wageningen : Wageningen University - ISBN 9789462576476 - 119
    deep fat frying - quality - chips (french fries) - evaporation - crusts - moisture meters - fried foods - crisps - frituren - kwaliteit - patates frites - evaporatie - korsten - vochtmeters - gebakken voedsel - aardappelchips

    Deep frying is one of the most used methods in the food processing industry. Though practically any food can be fried, French fries are probably the most well-known deep fried products. The popularity of French fries stems from their unique taste and texture, a crispy outside with a mealy soft interior, but also because of the ease and speed of preparation. However, despite being a practical and easy method, the fundamental phenomena that occur during frying are very complex. This thesis aimed at gaining a deeper understanding of the frying of French fries. This was done at the product level, with regards to heat transfer, moisture loss, oil uptake and crust formation, and at the process level, which encompasses the oil movement in a frying unit and the consequent oil-fry interactions.

    Firstly a numerical model was developed to describe the water evaporation during frying (Chapter 2). Though various models exist for describing moisture loss, they all use constant values for the heat transfer coefficient. However, the heat transfer coefficient actually varies greatly due to the varying degrees of turbulence, induced by the vapour bubbles escaping from the fry surface. Therefore, the model in this thesis incorporated an evaporation rate dependent heat transfer coefficient. Other than the varying heat transfer coefficient, the model was heat transfer dependent, with a sharp moving evaporation boundary and Darcy flow describing the flow of water vapour through the crust. The model was successfully validated against experimental results for moisture loss and temperature profiles in the fry.

    For oil uptake during frying, a pore inactivation model from membrane technology was adopted (Chapter 3). In membranes, pores will inactivate when the transmembrane pressure becomes too low. In fries, this can be translated as pores in the crust inactivating when the evaporation rate becomes too low. As pores stop expelling water vapour, oil can migrate into the fry. The model also took into account the lengthening of the pores with increasing crust thickness, allowing for more oil uptake in inactivated pores. The model fitted well with experimental data for oil uptake during frying. Also, the pore inactivation model better described oil uptake during the initial stages of frying, where the evaporation rate is still relatively high, compared to the linear relation between oil uptake and moisture content, which is usually assumed in literature.

    Both the influences of frying temperature and moisture content on crust structure and consequent textural properties were studied (Chapter 4). The crust structure was visualized and quantified using X-ray tomography (XRT), which uses multiple 2D X-ray pictures of a rotated sample to reconstruct a 3D density map. Textural properties, like hardness and crispness, were quantified using force deformation curves from a texture analyser. Moisture loss was shown to greatly increase porosity and pore size in fries. More crispy behaviour was also shown for higher moisture loss, though not significantly at moisture contents close to the initial moisture content. Though increased frying temperatures also showed an increased porosity and pore size, there was no significantly observed increase in crispness. This is most likely because the texture analysis was not sensitive enough to discern any increased crispness for porosities below a certain degree. Strikingly, for frying temperature around 195 °C, a decrease in crispness was observed. These samples visually also showed more plastic behavior. The most likely cause for this is degradation of sucrose, which happens around 186 °C, and consequent caramelization of glucose, thus increasing the glass transition temperature.

    At the process level, oil flow and fry quality distribution were investigated using a pilot scale cross-flow fryer (Chapter 5). Oil circulation velocities were varied to observe the initial fluidization behavior of the fry bed through an observation window. This fluidization behavior was well described by the Ergun equation, modified for non-spherical particles. The distribution in moisture content of the fries was used as an indicator for quality distribution. Though increased oil circulation initially increased the homogeneity of the moisture content, upon fluidization the homogeneity actually decreased. Image analysis of fries before and after frying showed local packing of fries around their fluidization point. This was due to the non-spherical shape of the fries, making them more sensitive to channelling.

    The results obtained in this thesis were finally discussed, together with the possibility to also model the process scale of the frying process (Chapter 6). The possibility of modelling the oil flow through a packed bed of fries, and the free-convective heat transfer during frying, using a CFD software package (STARCCM+) was shown. Additionally, the possibility of linking oil flows computed using CFD to the general models developed in this thesis was discussed. Modelling the momentum transfer of the expelled vapour bubbles to the oil, but also the movement of the fries themselves is still a faraway goal. However, a multiphase model that can describe both the entire frying setup as the consequent individual fry parameters would be invaluable.

    Bioboer wil ook frietaardappel
    Hutten, R.C.B. - \ 2012
    Kennis Online 9 (2012)mei. - p. 11 - 11.
    plantenveredeling - biologische plantenveredeling - aardappelen - consumptieaardappelen - aardappelchips - patates frites - biologische landbouw - plant breeding - organic plant breeding - potatoes - table potatoes - crisps - chips (french fries) - organic farming
    Biologische aardappeltelers hebben nog nauwelijks goede rassen voor chips en friet. In het project BioImpuls wordt gezocht naar een oplossing.
    Geschiktheid biologische aardappelrassen voor biofrites en biochips : verkenning naar eisen en de mogelijkheden van de huidige biologische aardappelrassen voor biofrites en biochips
    Wijk, C.A.P. van; Bus, C.B. - \ 2011
    Lelystad : Praktijkonderzoek Plant & Omgeving, Business Unit Akkerbouw, Groene Ruimte en Vollegrondsgroenten - 37
    consumptieaardappelen - aardappelen - rassen (planten) - bakkwaliteit - kwaliteit voor industriële verwerking - biologische landbouw - biologische voedingsmiddelen - akkerbouw - patates frites - aardappelchips - table potatoes - potatoes - varieties - baking quality - industrial processing quality - organic farming - organic foods - arable farming - chips (french fries) - crisps
    Uit bakproeven met biologische aardappelrassen blijkt dat een aantal rassen met een hoog niveau van Phytophthora-resistentie, perspectief biedt voor goede frites- en chipbereiding. Hoewel de bakkwaliteit van deze rassen standaard minder optimaal was dan van het ras Phytophthora-gevoelige hoofdras Agria, kan, door ‘reconditioneren’ en ‘blancheren’, met deze rassen toch een acceptabele frites- en chipskwaliteit verkregen worden. Gebruik van deze rassen als Bionica, Biogold en Sarpo Mira in de biologische teelt voor verwerking geeft extra productie voor de teler en meer leveringszekerheid voor de industrie in jaren met een vroege Phytophthora-aantasting.
    Aardappel wint sterk aan populariteit in de gordel van smaragd
    Haverkort, A.J. - \ 2011
    Aardappelwereld 65 (2011)1. - ISSN 0169-653X - p. 24 - 29.
    aardappelen - groenteteelt - akkerbouw - consumptie-overschot - aardappelchips - marketing - teelt - java - potatoes - vegetable growing - arable farming - consumer surplus - crisps - marketing - cultivation - java
    Aardappelonderzoeker Anton Haverkort van Plant Research International (PRI) uit Wageningen trok onlangs ruim een week door West en Centraal Java. Dit deed hij in het kader van een project voor het opwaarderen van de aardappelteelt in Indonesië. De aanvraag hiervoor kwam van landbouwraad Hans van der Zijl uit Jakarta. Aan Haverkort en zijn reisgenoten van PRI, Joost van der Burg en Thomas Been, was het de taak te kijken hoe de teelt hier duurzamer te maken is en goodwill te kweken bij de bevolking voor de Nederlandse aardappelnijverheid. In vogelvlucht beschrijft hij waarom van de groeiende belangstelling voor het gewas in deze gordel van smaragd.
    Filippino's op zoek naar rassen voor eigen teelt van chipsaardappelen
    Anonymous, - \ 2010
    Aardappelwereld 64 (2010)2. - ISSN 0169-653X - p. 26 - 29.
    aardappelen - aardappelchips - zetmeelgewassen - kwaliteit voor industriële verwerking - rassen (planten) - industriële gewassen - verwerkingskwaliteit - filippijnen - ontwikkelingslanden - zuidoost-azië - eilanden - potatoes - crisps - starch crops - industrial processing quality - varieties - industrial crops - processing quality - philippines - developing countries - south east asia - islands
    De LNV-raad namens Nederland voor de Filippijnen is drs. Adriede Roo. Nog niet zo lang geleden overlegde hij met de minister van landbouw van de Filippijnen over mogelijkheden om op de eilanden aardappelen te telen die geschikt zijn voor verwerking.Dit om deviezen te sparen en om lokaal meerwaarde aan de aardappelketen te geven. Ook is gesproken over een mogelijke rol voor het Nederlandse bedrijfsleven in dit voorstel. Aan onderzoekers van Wageningen UR, Anton Haverkort en Romke Wustman, is gevraagd om de haalbaarheid hiervan uit te zoeken.
    Kinetic modeling of acrylamide formation in aqueous reaction systems and potato crisps : Text & Figures
    Knol, J.J. - \ 2008
    Wageningen University. Promotor(en): Tiny van Boekel, co-promotor(en): Jozef Linssen. - [S.l.] : S.n. - ISBN 9789085852018 - 171
    acrylamiden - aardappelchips - maillard-reactie - maillard-reactieproducten - gezondheidsgevaren - wiskundige modellen - kinetica - warmtebehandeling - verwarming - reactiemechanisme - acrylamides - crisps - maillard reaction - maillard reaction products - health hazards - mathematical models - kinetics - heat treatment - heating - reaction mechanism
    Acrylamide can be formed in foods that have undergone a high temperature treatment (>120 °C) such as French fries, crisps, coffee and bread, due to the Maillard reaction. The evidence of acrylamide in foods posing a risk for different types of cancer has been strengthened. Mitigation of acrylamide formation in foods is, therefore, of great importance. The aim of this PhD study was to derive mathematical models that describe the formation of acrylamide as a function of product and processing parameters. The technique of multiresponse modeling was used to unravel the reaction networks of the formation of acrylamide in the Maillard reaction using aqueous reaction systems. Furthermore, the use of empirical models was studied to describe and predict the formation of acrylamide in potato crisps. With that, the work described in this thesis contributes to the development of strategies to lower acrylamide formation in food.
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