T-Carrageenan

Fig. 27.—C-l Portions of, 3C-N.m.r. Spectra of Agar (A 24 from Ahneltia plicata), K-Carrageenan (B 25, R = S03 Na+ from Eucheuma striatum), Partially Desulfated k-Carrageenan (C 25, R = S03 Na+ or H), and t-Carrageenan (D 26, R = R = S03 Na+ from Eucheuma spinosum). (Samples were examined as sodium salts in DzO at 90° chemical shifts, 8C, are values relative to external tetramethylsilane.)...

Abbasi, S., Dickinson, E. (2004). Gelation of t-carrageenan and micellar casein mixtures under high hydrostatic pressure. Journal of Agricultural and Food Chemistry, 52, 1705-1714. 

Model building in the computer is used to analyze the conformational effects of steric interactions between atoms of the polymer skeleton for x-carrageenan, t-carrageenan, A-carrageenan, agar, chondroltin, chondroitin sulfates, dermatan sulfate, keratan sulfate, hyaluronic acid, and related polysaccharides. Over 99% of the conformations are thus excluded and virtually all of the remainder for each polysaccharide lie close together. Predictions are also made from disaccharide crystal structures and checked against experimental results. 

FlG. 2.—Schematic Form of the Proposed Mechanism for Gelation of i- and K-Car-rageenan. [In t-carrageenan gels, aggregation of double-helix junction-zones does not occur.]... 

The osmotic coefficients of Na , K", and Ca counter-ions have been determined in aqueous solutions of K-, l- and X-carrageenans and the results were correlated with those calculated from the limiting law of Manning. An ordered secondary structure exists in k- and t-carrageenans, whose stability can be discussed as a function of temperature, ionic strength, and nature of the counterion. 

Fig. 24 Impedance spectra of solid-type (open circle, /t-carrageenan) and liquid-type cells (open triangle) (reprinted with permission from Elsevier [57])...

FIGURE 30.4. Primary structures of A,K,t-carrageenan and the typical normalized force curves obtained on (a) A-, (b) k-, and (c) t-carrageenan. 

The proportionality constant between theoretical helix content and optical rotation is found by fitting the data at the highest concentration of 5.66% measured. Then, theoretical results at other concentrations automatically fit the experimental data with high accuracy. It turned out that, for (n) = 50, the helix initiation parameter cf2 should be as small as 0.001 to obtain good fit. One of the main reasons why t-carrageenan does not form gels is the smallness of this helix initiation probability. The coil-helix transition temperature at dilute limit is fixed at To = 65°C. 

Hambleton, A., Voilley, A. Debeaufort, F. (2011). Transport parameters for aroma compounds through t-carrageenan and sodium alginate-based edible films. Food Hydrocolloids, Vol. 25, No. 5, pp. 1128-1133, ISSN 0268-005X. 

Table 1. Critical power-law parameters at the rheological gel point for incipient i-carrageenan and t-carrageenan /chitosan NPEC gels in 0.25 mol-L NaCl.

The name of the genus Rhabdonia is in fact a synonymous with the genus Agardhiella, well known in the family Solieriaceae and cultivated for the production of type t-carrageenan. Broadly speaking, few data have been published on the secondary metabolites of carrageenophytes. 

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