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Precipitation of Food Gums by Thiazine, Oxazine, Azine and Other Cationic Dyes: Specificity of the Methylene Blue Carrageenan Reaction
Author(s) -
GRAHAM HORACE D.,
THOMAS LINNIE B.
Publication year - 1961
Publication title -
journal of food science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.772
H-Index - 150
eISSN - 1750-3841
pISSN - 0022-1147
DOI - 10.1111/j.1365-2621.1961.tb00374.x
Subject(s) - azine , thiazine , chemistry , methylene blue , carrageenan , precipitation , cationic polymerization , moiety , nuclear chemistry , medicinal chemistry , organic chemistry , biochemistry , catalysis , physics , photocatalysis , meteorology
SUMMARY Several dyes of the thiazine, azine, azo and other classes were mixed with carrageenan, furcellaran, fucoidan and other hydrocolloids and the nature of the precipitates formed was carefully observed. The results obtained indicate that the antigen‐antibody‐like specificity ascribed to the methylene blue‐carrageenan reaction is much less rigid than previously thought. Dyes bearing the thiazine, phenazine, azine, oxazine or azo core structure will give the typical methylene blue‐carrageenan stringy precipitate when mixed with the hydrocolloids mentioned above. The sulfated polygalactose moiety is an essential for the formation of such a precipitate. Salts, at concentrations above certain threshold levels, inhibit formation of the stringy precipitate and, at low pH levels of the medium, the strings are considerably shortened. It is postulated that formation of the stringy precipitate results from the tendency of the linear macromolecules of carrageenan to agglomerate into fibers on precipitation from solutions.