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Titolo:
Emulsification properties of hydrocolloids
Autore:
Garti, N; Leser, ME;
Indirizzi:
Hebrew Univ Jerusalem, Sch Appl Sci & Technol, Casali Inst Appl Chem, IL-91904 Jerusalem, Israel Hebrew Univ Jerusalem Jerusalem Israel IL-91904 -91904 Jerusalem, Israel Nestec Ltd, Nestle Res Ctr, CH-1000 Lausanne 26, Switzerland Nestec Ltd Lausanne Switzerland 26 Ctr, CH-1000 Lausanne 26, Switzerland
Titolo Testata:
POLYMERS FOR ADVANCED TECHNOLOGIES
fascicolo: 1-2, volume: 12, anno: 2001,
pagine: 123 - 135
SICI:
1042-7147(200101/02)12:1-2<123:EPOH>2.0.ZU;2-8
Fonte:
ISI
Lingua:
ENG
Soggetto:
GUM; GALACTOMANNANS; SURFACE;
Keywords:
hydrocolloids; gums; water-soluble polysaccharides; biopolymers; amphiphiles; macromolecules; emulsifiers; emulsions surface activity; guar; galactomannans; pectin; tragacanth; xanthan; Portulaca Oleracea;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
48
Recensione:
Indirizzi per estratti:
Indirizzo: Garti, N Hebrew Univ Jerusalem, Sch Appl Sci & Technol, Casali Inst Appl Chem, IL-91904 Jerusalem, Israel Hebrew Univ Jerusalem Jerusalem Israel IL-91904 rusalem, Israel
Citazione:
N. Garti e M.E. Leser, "Emulsification properties of hydrocolloids", POLYM ADV T, 12(1-2), 2001, pp. 123-135

Abstract

Water soluble/dispersible polysaccharides, termed hydrocolloids or gums, are known as viscosity builders and/or gelling agents in aqueous systems. Technologists call them stabilizers, since they can improve long-term stability in systems consisting of water and oil. Many scientists claim that hydrocolloids are not true emulsifiers, since they do not actively adsorb onto liquid interfaces and the stability that they impart is mainly via increasing viscosity and decreasing mobility. Only certain hydrocolloids, such as gum arabic, were known to exhibit emulsification properties. The surface activity was proved to be derived from the anchoring ability of the hydrophobic proteineous moieties (attached to the polysaccharide backbone) onto the oil phase. The aim of this review is to demonstrate that certain hydrophilic (anionicor non-ionic) polysaccharides purified to a level of being almost protein-free can exhibit surface and emulsification properties inspite of their rigid and hydrophilic nature. The adsorption isotherms of the surface-active biopolymers ave similar to other macromolecular amphiphiles. The main gums to be discussed are those of the galactomannan family [locust bean gum (LBG), guar and fenugreek]. Other gums from less known sources (Portulaca Oleracea and Opuntia Ficus) also exhibit surface properties. It appears that the statements made by several authors claiming that hydrocolloids cannot be considered as emulsifiers, were inaccurate. It seems that the requirements for built-in hydrophobic moieties on the hydrocolloids' backbone internal structure, are not obligatory for active adsorption. Adsorption can be induced by a salting-out effect, resulting in semi-solid interfacial layers. Hydrocolloids can form thick birefringent gel-like mechanical barriers at the oil-water interface of emulsion oil droplets. This new category of natural-occurring hydrocolloid-emulsifiers should be reconsidered by food technologists and by other emulsion technologists for other industrial applications. Copyright (C) 2001 John Wiley & Sons, Ltd.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 01/12/20 alle ore 13:17:54