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Carbohydr Res. 2012 Feb 1;348:69-76. doi: 10.1016/j.carres.2011.11.011. Epub 2011 Nov 19.

Stiffness of Ca(2+)-pectin gels: combined effects of degree and pattern of methylesterification for various Ca(2+) concentrations.

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1
Laboratory of Food Technology, Leuven Food Science and Nutrition Research Centre, Department of Microbial and Molecular Systems (M(2)S), Katholieke Universiteit Leuven, Kasteelpark Arenberg 22, PO Box 2457, BE-3001 Leuven, Belgium.

Abstract

The influence of the degree and pattern of methylesterification (DM and PM, respectively) on the stiffness of Ca(2+)-pectin gels is extensively examined, at various Ca(2+) concentrations. Accordingly, a highly methyl-esterified pectin was selectively de-esterified using NaOH, plant or fungal pectin methylesterase in order to produce series of pectins with varied pattern and broad ranges of methylesterification. The PM was quantified as absolute degree of blockiness (DB(abs)). Ca(2+)-pectin gels were prepared at various Ca(2+) concentrations. Gel stiffness (G' at 1rad/s) was determined and mapped out as a function of DM, DB(abs) and Ca(2+) concentration. At low Ca(2+) concentrations, G' depends on polymer's DM and DB(abs). At high Ca(2+) concentrations, a master curve is obtained over a wide range of DM, irrespective of DB(abs). Depending on methylesterification pattern, increase of G' is related not only to an increase in the number of junction zones per pectin chain, but also to an increase in the size of junction zones and the number of dimerised chains occurring in the gels. These results provide a detailed insight into the occurrence of junction zones in Ca(2+)-pectin gels.

PMID:
22209690
DOI:
10.1016/j.carres.2011.11.011
[Indexed for MEDLINE]

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