Titre :
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Shear-induced structuring of particulate whey protein gels
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Auteurs :
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P. Walkenstrom ;
E. Windhab ;
A. Hermansson
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Type de document :
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article/chapitre/communication
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Année de publication :
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1998
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Format :
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p. 459-468
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Langues:
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= Anglais
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Catégories :
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INDUSTRIE AGRO-ALIMENTAIRE
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Mots-clés:
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CISAILLEMENT
;
PROTEINE
;
LACTOSERUM
;
RHEOLOGIE
;
PH
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Résumé :
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The effects of steady shear on particulate whey protein isolate (WPI) gels, at pH 5.4, have been investigated by light microscopy (LM) and dynamic oscillatory measurements. The steady shear was performed on suspensions at constant rates between 0.5 and 126/s. The gel point under static conditions (T-g) was around 78 °C and the shearing was performed during heating from 20 to 76 or to 82 °C. The gel point was postponed by the shear up to 82 °C. Steady shear up to 76 °C, at rates less than similar to 6/s) resulted in a weaker storage modulus (G'), less frequency dependence and a higher stress at fracture compared to the unsheared gel. Steady shear up to 82 degrees C, at rates below similar to 6/s) resulted in the formation of two different types of network structure. One structure was similar in appearance to the unsheared network, showing pores in the range of 50 mu m. The other structure was dense, composed of smaller particles than the unsheared network and with pores in the range of 10 mu m. The gels composed of two structures showed a lower G' and stress at fracture compared to the unsheared gel. A shear rate above 24/s up to 76 °C resulted in irregular networks, which were composed of two different types of structures.
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Source :
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Food Hydrocolloids, vol.12, n°4
|