References of "Janas, Sébastien"
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See detailContribution à la modélisation du séchage du maïs en lit-fixe
Janas, Sébastien ULg

Doctoral thesis (2012)

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See detailInfluence of drying and hydrothermal treatment of corn on the denaturation of salt-soluble proteins and color parameters
Odjo, Sylvanus; Malumba Kamba, Paul ULg; Dossou, Joseph et al

in Journal of Food Engineering (2012), 109(3), 561-570

The effect of heat treatments (drying and hydrothermal treatment) on the extractability of salt-soluble protein (SSP) was assessed using Promatest methodology for corn kernels heated between 60 C and 120 ... [more ▼]

The effect of heat treatments (drying and hydrothermal treatment) on the extractability of salt-soluble protein (SSP) was assessed using Promatest methodology for corn kernels heated between 60 C and 120 C. During drying, the evolution of the grain moisture content is fitted using the analytical solution of Fick equation developed by Crank (1979) for spherical material. The decrease of extractible salt-soluble protein during heating is forecasted using a first and a second order ordinary differential equation. It was found that temperature; moisture content and time of processing greatly influence the kinetic denaturation of SSP of corn kernels. The evolution of extractible SSP content of corn kernels during drying at high temperature is more correctly described with second order kinetic than with the first order kinetic reaction. The Hunterlab color parameters of corn also vary during drying. Lightness and color intensity decrease while yellowness, redness, chroma and hue angle increase through drying time. Most of these Hunterlab color parameters are highly correlated with the salt-soluble proteins content and therefore could be used as indicators of excessive heat treatment and denaturation of salt-soluble proteins in corn kernels [less ▲]

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See detailInfluence des traitements de steam explosion sur la dégradation thermique des fibres de cellulose
Jacquet, Nicolas ULg; Quievy; Vanderghem, Caroline ULg et al

Poster (2011, December)

La présente étude a pour but d’identifier l’impact de différents traitements de steam explosion sur les propriétés de dégradation thermique des fibres de cellulose. Dans un premier temps, les intensités ... [more ▼]

La présente étude a pour but d’identifier l’impact de différents traitements de steam explosion sur les propriétés de dégradation thermique des fibres de cellulose. Dans un premier temps, les intensités des traitements appliqués ont été définies sur base d’un facteur de sévérité (SF), établi par une corrélation entre le temps de séjour et la température du process. Les résultats obtenus montrent que la dégradation thermique des fibres de cellulose reste limitée lorsque la valeur du facteur de sévérité est inférieure à 4.0. Aux intensités supérieures, le dosage des produits de dégradation montre une croissante importante des concentrations en hydroxyméthylfurfurals (5-HMF) dans les phases liquides issues des différents traitements. Lorsque la valeur du facteur de sévérité dépasse 5.2, les analyses TGA indiquent que l’augmentation des produits de dégradation est couplée à une croissance importante du taux de résidus carbonés, indiquant une forte dégradation thermique de la cellulose [less ▲]

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See detailInfluence des traitements de steam explosion sur la dégradation thermique des fibres de cellulose
Jacquet, Nicolas ULg; Quievy, Nicolas; Vanderghem, Caroline ULg et al

in Récents Progrès en Génie des Procédés (2011), 101

The aim of this study is to identify the impact of different steam explosion treatments on the thermal degradation of cellulose fibers. The intensities of the treatments were defined by a severity factor ... [more ▼]

The aim of this study is to identify the impact of different steam explosion treatments on the thermal degradation of cellulose fibers. The intensities of the treatments were defined by a severity factor (SF), based on the residence time and the process temperature. The results obtained show that thermal degradation of cellulose fibers is limited when the severity factor value is below 4.0. At higher intensities, determination of thermal degradation products shows a significant increase of the hydroxymethylfurfural (5-HMF) amount when increasing the intensity of the treatment. When the severity factor reached 5.2, TGA analysis shows that the increase of degradation products is coupled to an increase of the char level meaning a strong degradation of the cellulose. [less ▲]

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See detailInfluence of steam explosion on the thermal stability of cellulose fibres
Jacquet, Nicolas ULg; Quievy, Nicolas; Vanderghem, Caroline ULg et al

in Polymer Degradation & Stability (2011), 96

The aim of the present study was to compare the effect of different steam explosion treatments on the thermal degradation of a bleached cellulose. The intensity of a steam explosion treatment, which ... [more ▼]

The aim of the present study was to compare the effect of different steam explosion treatments on the thermal degradation of a bleached cellulose. The intensity of a steam explosion treatment, which allows breakdown of the structural lignocellulosic material was determined by a correlation between time and temperature of the process. Results of this study showed that thermal degradation of cellulose fibres was limited when the severity factor applied was below 4.0. For higher intensities, determination of the degradation products in the water-soluble extract showed an important increase of the 5-hydroxymethyl-furfural concentration with the temperature. When the severity factor reached 5.2., TGA analysis showed that the increase of degradation products was coupled to an increase of the char level meaning a strong degradation of the cellulose. dTGA behaviour also showed that thermal stability of the steam explosion samples decreased with the intensity of the treatment. To conclude, a theoretical diagram predicting the degradation of the cellulose during the steam explosion treatment was established. [less ▲]

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See detailStructure de l’amidon de maïs et principaux phénomènes impliqués dans sa modification thermique
Malumba Kamba, Paul ULg; Janas, Sébastien ULg; Deroanne, Claude et al

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment [=BASE] (2011), 15(2), 315-326

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See detailApplication de la méthode des éléments finis au pricing d'options
Janas, Sébastien ULg

Master's dissertation (2011)

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See detailModelling dehydration and quality degradation of maize during fluidized-bed drying
Janas, Sébastien ULg; Boutry, Sébastien; Malumba Kamba, Paul ULg et al

in Journal of Food Engineering (2010), 100(3), 527-534

At harvest time, maize (Zea mays L.) has a moisture content too high to be stored, and has to be dried. To control the previous termdryingnext term impact on maize characteristics, it is necessary to ... [more ▼]

At harvest time, maize (Zea mays L.) has a moisture content too high to be stored, and has to be dried. To control the previous termdryingnext term impact on maize characteristics, it is necessary to accurately know the spatial distribution of temperature and moisture content in the kernel, and the kinetics of quality loss in relation to these two factors. To this end, a physical model of heat and mass transfer in a maize kernel was designed. The Fick and Fourier equations were solved by the finite element method (FEM). The real 3D geometry of maize was obtained by NMR imaging and then used to build the mesh needed for the FEM computations. The model correctly describes the evolutions of maize moisture and salt-soluble protein content during fluidized-bed previous termdryingnext term with a constant previous termdryingnext term air temperature between 50 °C and 100 °C. [less ▲]

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See detailComparaison d’un modèle empirique et d’un modèle physique de séchage de grains de maïs en lit fluidisé
Janas, Sébastien ULg; Malumba Kamba, Paul ULg; Deroanne, Claude et al

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment [=BASE] (2010), 14(3), 389-398

Dans cet article, deux modèles prévisionnels de la température et de la teneur en eau de grains de maïs durant leur séchage en lit fluidisé sont comparés. Le premier modèle est un modèle empirique, où les ... [more ▼]

Dans cet article, deux modèles prévisionnels de la température et de la teneur en eau de grains de maïs durant leur séchage en lit fluidisé sont comparés. Le premier modèle est un modèle empirique, où les phénomènes physiques impliqués dans le processus ne sont pas décrits. Ses équations peuvent être résolues à l’aide de logiciels gratuits disponibles sur Internet. Le second est un modèle plus complexe, basé sur les lois physiques régissant les transferts de chaleur et de masse au sein du produit. Sa résolution nécessite l’utilisation de logiciels commerciaux de calcul par éléments finis. Les deux modèles sont paramétrés sur des séchages à température constante, puis validés sur des séchages à température variable et un séchage discontinu. Les deux modèles permettent de décrire avec une précision acceptable les évolutions de teneurs en eau au cours des séchages continus et de prévoir les évolutions de teneurs en eau lors des séchages à température variable et du séchage discontinu. Le modèle empirique ne permet pas de décrire l’évolution de la température des grains lors de séchages à température variable avec une précision meilleure qu’1 °C. Si cette précision est suffisante, l’exploitation du modèle empirique permettra de réduire considérablement les couts en temps et en licence de logiciels pour la modélisation du séchage du maïs en lit fluidisé. [less ▲]

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See detailComparative study of the effect of drying temperatures and heat-moisture treatment on the physicochemical and functional properties of corn starch
Malumba Kamba, Paul ULg; Janas, Sébastien ULg; Roiseux, Olivier et al

in Carbohydrate Polymers (2010), 79(3), 633-641

This manuscript compares the modifications induced by the heat-moisture treatment of native starch (HMT) and by the hot-air drying of corn on wet-milled starch granules. High temperatures applied during ... [more ▼]

This manuscript compares the modifications induced by the heat-moisture treatment of native starch (HMT) and by the hot-air drying of corn on wet-milled starch granules. High temperatures applied during both corn drying and HMT reduced the swelling capacity of granules, increased the starch gelatinization temperatures and decreased their residual enthalpy. Pasting behaviour of pre-treated starch showed a decrease of peak and breakdown viscosity when corn drying and HMT temperatures increased. Microscopic analysis showed that after hydrothermal treatment, starch granules extracted from corn dried at lower temperature swell more significantly than those extracted from corn dried at higher temperature. All these changes suggest the occurring of structural modifications within starch granules during high-temperature pre-treatments. At similar temperatures and initial moisture contents, HMT affected the physicochemical and functional properties of cornstarch more dramatically than hot-air drying. Differences induced by these two treatments were attributed to the availability of water around granules during these two pre-treatment procedures. [less ▲]

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See detailMaillage 3D par imagerie RMN d’un grain de maïs et modélisation des transferts de chaleur et de masse durant son séchage
Janas, Sébastien ULg; Boutry, Sébastien; Vander Elst, Luce et al

Poster (2010)

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See detailSensitivity analysis of a 3D diffusive drying model
Janas, Sébastien ULg; Deroanne Claude; Bera, François ULg

Poster (2009)

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See detailInfluence of drying temperature on the wet-milling performance and the proteins solubility indexes of corn kernels
Malumba Kamba, Paul ULg; Janas, Sébastien ULg; Masimango, Thaddée et al

in Journal of Food Engineering (2009), 95

The effects of air drying temperature on the wet-milling performance and the proteins solubility indexes were investigated for corn kernels dried between 54°C and 130°C. It was observed that when the ... [more ▼]

The effects of air drying temperature on the wet-milling performance and the proteins solubility indexes were investigated for corn kernels dried between 54°C and 130°C. It was observed that when the drying temperature increases, the starch yield drops significantly. The gluten recovered increased abruptly for drying temperatures up to 80 C. The albumin, globulin and zein solubility indexes decreased continuously when corn drying temperatures increased. According to the temperatures used, the starch yield, the gluten recovered and the salt-soluble proteins solubility indexes were adjusted satisfactorily by using a two asymptotic logistic model. This model has the advantage of supplying information on the dynamic of the variation of described parameters. The solubility index of total salt-soluble proteins was shown to be a suitable indicator of the severity of the drying treatment in regard to the corn wet-milling performance. [less ▲]

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