Titre :
|
Glass transition-related or crystalline forms in the structural properties of gelatin/oxidised starch/glucose syrup mixtures
|
Auteurs :
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M. Ong ;
A. Whitehouse ;
R. Abeysekera ;
AL Et
|
Type de document :
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article/chapitre/communication
|
Année de publication :
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1998
|
Format :
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p. 273-281
|
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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AMIDON
;
MELANGE
;
TEMPERATURE
;
GLUCIDE
;
VISCOELASTICITE
|
Résumé :
|
The structural properties of acid pigskin gelatin/oxidised waxy maize starch/glucose syrup mixtures at a 70% total level of solids were investigated. Depending on polymer composition and pH, mixtures form phase-separated gels with a gelatin or an oxidised starch continuous matrix. It was found that the continuous phase determined the mechanical behaviour of a mixture. Thus gelatin/glucose syrup systems or gelatin continuous mixtures show a three-fold transformation in viscoelasticity, namely: from solutions at high temperature (>35 °C) and rubbery solids at ambient temperature to high modulus viscoelastic liquids at subzero temperatures (e.g, > 10(6) Pa at 10 Hz and -20° C). In the language of polymer physics a transition was observed from rubber-like to glass-like consistency. By contrast, oxidised starch/glucose syrup systems and oxidised starch continuous mixtures show a transformation from liquid-like to solid-like behaviour at subzero temperatures due to water crystallisation. Concentrated oxidised starch (approximate to 31%) with glucose syrup (approximate to 39%) systems are capable of forming intermolecular amylose-like structures at high temperatures (e.g. 80 °C), which remain solid-like throughout the cooling run (down to -20 °C). Therefore the development of crystallinity (water/polymeric aggregates) in starch-dominated systems prevents them from exhibiting glass-related viscoelasticity.
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Source :
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Food hydrocolloids, vol.12
|