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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Autores principales: Ciancia, M., Noseda, M.D., Matulewicz, M.C., Cerezo, A.S.
Formato: JOUR
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:http://hdl.handle.net/20.500.12110/paper_01448617_v20_n2_p95_Ciancia
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Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires
id todo:paper_01448617_v20_n2_p95_Ciancia
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spelling todo:paper_01448617_v20_n2_p95_Ciancia2023-10-03T14:59:41Z Alkali-modification of carrageenans: mechanism and kinetics in the kappa/iota-, mu/nu- and lambda-series Ciancia, M. Noseda, M.D. Matulewicz, M.C. Cerezo, A.S. 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. JOUR info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by/2.5/ar 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, M.
Noseda, M.D.
Matulewicz, M.C.
Cerezo, A.S.
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.
format JOUR
author Ciancia, M.
Noseda, M.D.
Matulewicz, M.C.
Cerezo, A.S.
author_facet Ciancia, M.
Noseda, M.D.
Matulewicz, M.C.
Cerezo, A.S.
author_sort Ciancia, M.
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
url http://hdl.handle.net/20.500.12110/paper_01448617_v20_n2_p95_Ciancia
work_keys_str_mv AT cianciam alkalimodificationofcarrageenansmechanismandkineticsinthekappaiotamunuandlambdaseries
AT nosedamd alkalimodificationofcarrageenansmechanismandkineticsinthekappaiotamunuandlambdaseries
AT matulewiczmc alkalimodificationofcarrageenansmechanismandkineticsinthekappaiotamunuandlambdaseries
AT cerezoas alkalimodificationofcarrageenansmechanismandkineticsinthekappaiotamunuandlambdaseries
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