Carrageenan, methylation

Etherification. Carbohydrates are involved in ether formation, both intramoleculady and intermoleculady (1,13). The cycHc ether, 1,4-sorbitan, an 1,4-anhydroalditol, has already been mentioned. 3,6-Anhydro-a-D-galactopyranosyl units are principal monomer units of the carrageenans. Methyl, ethyl, carboxymethyl, hydroxyethyl, and hydroxypropyl ethers of cellulose (qv) are all commercial materials. The principal starch ethers are the hydroxyethyl and hydroxypropylethers (see Cellulose ethers Starch). 

The GBR resin works well for nonionic and certain ionic polymers such as various native and derivatized starches, including sodium carboxymethylcel-lulose, methylcellulose, dextrans, carrageenans, hydroxypropyl methylcellu-lose, cellulose sulfate, and pullulans. GBR columns can be used in virtually any solvent or mixture of solvents from hexane to 1 M NaOH as long as they are miscible. Using sulfonated PDVB gels, mixtures of methanol and 0.1 M Na acetate will run many polar ionic-type polymers such as poly-2-acrylamido-2-methyl-l-propanesulfonic acid, polystyrene sulfonic acids, and poly aniline/ polystyrene sulfonic acid. Sulfonated columns can also be used with water glacial acetic acid mixtures, typically 90/10 (v/v). Polyacrylic acids run well on sulfonated gels in 0.2 M NaAc, pH 7.75. 

Polymer Media Alginate (Sodium) Cellulose Sulfate Carboxy- methyl Cellulose Xanthan Carrageenan (A) Gellan Gum Poly Glutamic Acid... 

Cation-exchange columns have been used effectively by some investigators for the fractionation of casein (Annan and Manson 1969 Kim et al 1969 Kopfler et al. 1969 Snoeren et al. 1977 Saito et al 1979). Sulfoethyl-Sephadex was used by Annan and Manson (1969) with formate buffer to fractionate the as-casein complex. Cellulose phosphate, carboxyl-methyl-cellulose (CMC), potassium-K-carrageenan, and sodium Amberlite CG50 columns have also been used to fractionate the caseins (Kim et al. 1969 Kopfler et al. 1969 Snoeren et al 1977). A batch method for the preparation of para-K-casein from rennin-treated whole casein has been developed with CMC Sephadex (Saito et al. 1979). 

Carrageenans, alginates, polysaccharides, carboxy methyl cellulose etc. Provide mouthfeel, shelf-life stability, viscosity... 

In addition to their role in primary stabilization related to viscosity increase, some hydrocolloids (particularly carrageenan) are traditionally used as secondary stabilizers. Many of the primary stabilizing hydrocolloids, including locust bean gum and carboxy methyl cellulose induce precipitation of the milk proteins in the mix. This phenomenon in ice cream mix is known as wheying-off, and may be due to direct protein-polysaccharide binding and/or protein-polysaccharide incompatibility in the water phase40. The latter phenomenon may be due to decreased solvent quality due to the competition between protein and polysaccharide for solubilisation. 

In the field of natural red algal galactans, MS was used for the first time in the structural analysis of odonthalan.353 Galactose and 6-O-methylgalactose, the hydrolysis products of the polysaccharide, were separated by column chromatography and identified by MS in the form of their di-O-isopropylidene derivatives. Cyclic derivatives of this type had been shown previously to be especially suitable for mass-spectrometric characterization of the structure and (in certain instances) stereochemistry of monosaccharides.349,354 A combination of GLC and MS was also used for identification of methyl 4.6-O-0 -methoxycarbonylethylidene)-D-galactosides (as their trifluoroacetates) in the methanolysis products of Ji-carrageenan from Petrocelis middendorfii,355... 

C. A. Stortz and A. S. Cerezo, The systems of carrageenans from cystocarpic and tetrasporic stages from Iridaea undulosa Fractionation with potassium chloride and methylation analysis of the fractions, Carbohydr. Res., 242 (1993) 217-227. 

A. Chiovitti, M.-L. Liao, G. T. Kraft, S. L. A. Munro, D. J. Craik, and A. Bacic, Cell wall polysaccharides from Australian red algae of the family Solieriaceae (Gigartinales, Rhodophyta) Highly methylated carrageenans from the genus Rhabdonia, Bot. Mar., 39 (1996) 47-59. 

M. C. Matulewicz, M. Ciancia, M. D. Noseda, and A. S. Cerezo, Methylation analysis of carrageenans from tetrasporic and cystocarpic stages of Gigartina scottsbergii, Phytochemistry, 29 (1990) 3407-3410. 

A. S. Cerezo, The carrageenan system of Gigartina scottsbergii S. et G. Part IV. Methylation analysis of a partly desulphated derivative, Carbohydr. Res., 36 (1974) 201-204. 

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