The structure of high-methoxyl sugar acid gels of citrus pectin as determined by AFM

Images of native high-methoxyl sugar acid gels (HMSAGs) were obtained by atomic force microscopy (AFM) in the Tapping Mode ™. Electronic thinning of the pectin strands to one-pixel wide allowed the pectin network to be viewed in the absence of variable strand widths related to preferentially solvate...

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Bibliographic Details
Published in:Carbohydrate research 2009-09, Vol.344 (14), p.1792-1797
Main Authors: Fishman, Marshall L., Cooke, Peter H.
Format: Article
Language:English
Subjects:
AFM, structure
Citrus - chemistry
citrus fruits
crosslinking
electron microscopy
Gel strength
gelling properties
gels
Gels - chemistry
image analysis
limes
Microscopy, Atomic Force - methods
Molecular Structure
Networks
oranges
Pectin
pectins
Pectins - chemistry
Pectins - ultrastructure
seedless varieties
Sugar acid gels
sugar acids
Sugar Acids - chemistry
thickeners
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Summary:Images of native high-methoxyl sugar acid gels (HMSAGs) were obtained by atomic force microscopy (AFM) in the Tapping Mode ™. Electronic thinning of the pectin strands to one-pixel wide allowed the pectin network to be viewed in the absence of variable strand widths related to preferentially solvated sugar. Thinned images revealed that HMSAGs of pectin comprise a partially cross-linked network, in that many of the cross-linking moieties are attached at only one end. Based on their structural similarities, aggregated pectin in water appears to be a fluid precursor of a HMSAG of pectin. Furthermore, examination of AFM images revealed that gels with ‘uniform’ distribution of strands and pores between strands had higher gel strengths than gels in which strands were non-uniformly distributed and were separated by large and small spaces.
ISSN:0008-6215
1873-426X
1873-426X
DOI:10.1016/j.carres.2008.09.031