SUMMARYUsing the interaction of carrageenan (Seakem type 5) with cetylpyridinium chloride as the type example, investigation was made of optimum conditions for the precipitation of carrageenan and its fractions by quaternary ammonium detergents. Found to be very critical factors for quantitative precipitation were the temperature and pH of the reaction medium. Comparatively, the amount of detergent cation bound by a particular sulfated hydrocolloid is indicative of its degree of sulfation.
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