Carrageenan, an assortment of sulphated polyelectrolyte heteropolysaccharides
extracted from the red seaweed, has long been
used in food n (Fig. 1), has been employed
ubiquitously as a food additive because of its thickening and gelling
capabilities The
gelation of k-carrageenan, like other polysaccharides, has long been
known to be strongly affected by cosolvents, in particular such as
sugars and polyols; such cosolvents have therefore been exploited
widely to enhance k-carrageenan gelation and gel stability
What sugar/polyol cosolvents
do to the gelation of k-carrageenan is well known; however,
how these cosolvents actually enhance gelation, at a molecular level,
remains a mystery, and has been a subject of intense debate for
decades Hence the aim of
this paper is to provide a clear explanation, based upon a statistical
thermodynamic foundation, into how exactly sugar and polyol
cosolvents influence the gelation of biopolymers by examining the
gelation of k-carrageenan.
A number of hypotheses have been proposed regarding how
cosolvents affect the gelation of biopolymers; these hypotheses can
be classified into the following three categories: (i) cosolventinduced
changes in the water structure, and the consequent hydration
change of the biopolymer, induced by the cosolvent
(ii) preferential
exclusion of the cosolvent from the biopolymer surface
and (iii) direct binding of the
cosolvent to the biopolymer chain in the gel state