Alkali-modification of carrageenans: mechanism and kinetics in the kappa/iota-, mu/nu- and lambda-series

The cyclization reaction (formation of 3,6-anhydro-α-d-galactose units from α-d-galactose 6-sulfate) of carrageenans follows a pseudo first-order kinetics, being 20-60 times faster for carrageenans of the kappa-family than for those of the lambda-family. In lambda-carrageenans the clustering of the...

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Detalles Bibliográficos
Autores principales:	Ciancia, Marina, Noseda, Miguel D., Matulewicz, María Cristina, Cerezo, Alberto Saúl
Publicado:	1993
Materias:	Chemical modification Gelation Molecular structure Plants (botany) Reaction kinetics Synthesis (chemical) Alkali modification Anhydrogalactose Carrageenans Cyclization Cystocarpic plants Galactose sulfate Kappa series Lambda series Tetrasporic plants Sugars
Acceso en línea:	https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_01448617_v20_n2_p95_Ciancia http://hdl.handle.net/20.500.12110/paper_01448617_v20_n2_p95_Ciancia
Aporte de:	Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires

id	paper:paper_01448617_v20_n2_p95_Ciancia
record_format	dspace
spelling	paper:paper_01448617_v20_n2_p95_Ciancia2023-06-08T15:12:06Z Alkali-modification of carrageenans: mechanism and kinetics in the kappa/iota-, mu/nu- and lambda-series Ciancia, Marina Noseda, Miguel D. Matulewicz, María Cristina Cerezo, Alberto Saúl Chemical modification Gelation Molecular structure Plants (botany) Reaction kinetics Synthesis (chemical) Alkali modification Anhydrogalactose Carrageenans Cyclization Cystocarpic plants Galactose sulfate Kappa series Lambda series Tetrasporic plants Sugars The cyclization reaction (formation of 3,6-anhydro-α-d-galactose units from α-d-galactose 6-sulfate) of carrageenans follows a pseudo first-order kinetics, being 20-60 times faster for carrageenans of the kappa-family than for those of the lambda-family. In lambda-carrageenans the clustering of the sulfate groups around the hydroxyl on C-3 of the α-unit shields it from polarization or ionization, reducing the cyclization reaction rate. Furthermore, molecular models of lambda-carrageenans suggest an adequate geometry for the interaction between the hydroxyl group on C-3 of the α-unit and the sulfate group on C-2 of the β-unit. These observations also explain the lack of cyclized derivatives of lambda-carrageenans in nature. The ease with which the cyclization reaction occurs for carrageenans of the kappa-family indicates that the alkaline treatments used industrially could be carried out under milder conditions, giving products of high gel strength. © 1993. Fil:Ciancia, M. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Noseda, M.D. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Matulewicz, M.C. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Cerezo, A.S. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. 1993 https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_01448617_v20_n2_p95_Ciancia http://hdl.handle.net/20.500.12110/paper_01448617_v20_n2_p95_Ciancia
institution	Universidad de Buenos Aires
institution_str	I-28
repository_str	R-134
collection	Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA)
topic	Chemical modification Gelation Molecular structure Plants (botany) Reaction kinetics Synthesis (chemical) Alkali modification Anhydrogalactose Carrageenans Cyclization Cystocarpic plants Galactose sulfate Kappa series Lambda series Tetrasporic plants Sugars
spellingShingle	Chemical modification Gelation Molecular structure Plants (botany) Reaction kinetics Synthesis (chemical) Alkali modification Anhydrogalactose Carrageenans Cyclization Cystocarpic plants Galactose sulfate Kappa series Lambda series Tetrasporic plants Sugars Ciancia, Marina Noseda, Miguel D. Matulewicz, María Cristina Cerezo, Alberto Saúl Alkali-modification of carrageenans: mechanism and kinetics in the kappa/iota-, mu/nu- and lambda-series
topic_facet	Chemical modification Gelation Molecular structure Plants (botany) Reaction kinetics Synthesis (chemical) Alkali modification Anhydrogalactose Carrageenans Cyclization Cystocarpic plants Galactose sulfate Kappa series Lambda series Tetrasporic plants Sugars
description	The cyclization reaction (formation of 3,6-anhydro-α-d-galactose units from α-d-galactose 6-sulfate) of carrageenans follows a pseudo first-order kinetics, being 20-60 times faster for carrageenans of the kappa-family than for those of the lambda-family. In lambda-carrageenans the clustering of the sulfate groups around the hydroxyl on C-3 of the α-unit shields it from polarization or ionization, reducing the cyclization reaction rate. Furthermore, molecular models of lambda-carrageenans suggest an adequate geometry for the interaction between the hydroxyl group on C-3 of the α-unit and the sulfate group on C-2 of the β-unit. These observations also explain the lack of cyclized derivatives of lambda-carrageenans in nature. The ease with which the cyclization reaction occurs for carrageenans of the kappa-family indicates that the alkaline treatments used industrially could be carried out under milder conditions, giving products of high gel strength. © 1993.
author	Ciancia, Marina Noseda, Miguel D. Matulewicz, María Cristina Cerezo, Alberto Saúl
author_facet	Ciancia, Marina Noseda, Miguel D. Matulewicz, María Cristina Cerezo, Alberto Saúl
author_sort	Ciancia, Marina
title	Alkali-modification of carrageenans: mechanism and kinetics in the kappa/iota-, mu/nu- and lambda-series
title_short	Alkali-modification of carrageenans: mechanism and kinetics in the kappa/iota-, mu/nu- and lambda-series
title_full	Alkali-modification of carrageenans: mechanism and kinetics in the kappa/iota-, mu/nu- and lambda-series
title_fullStr	Alkali-modification of carrageenans: mechanism and kinetics in the kappa/iota-, mu/nu- and lambda-series
title_full_unstemmed	Alkali-modification of carrageenans: mechanism and kinetics in the kappa/iota-, mu/nu- and lambda-series
title_sort	alkali-modification of carrageenans: mechanism and kinetics in the kappa/iota-, mu/nu- and lambda-series
publishDate	1993
url	https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_01448617_v20_n2_p95_Ciancia http://hdl.handle.net/20.500.12110/paper_01448617_v20_n2_p95_Ciancia
work_keys_str_mv	AT cianciamarina alkalimodificationofcarrageenansmechanismandkineticsinthekappaiotamunuandlambdaseries AT nosedamigueld alkalimodificationofcarrageenansmechanismandkineticsinthekappaiotamunuandlambdaseries AT matulewiczmariacristina alkalimodificationofcarrageenansmechanismandkineticsinthekappaiotamunuandlambdaseries AT cerezoalbertosaul alkalimodificationofcarrageenansmechanismandkineticsinthekappaiotamunuandlambdaseries
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Alkali-modification of carrageenans: mechanism and kinetics in the kappa/iota-, mu/nu- and lambda-series

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