The invention discloses a method for extracting
carrageenan, which comprises the following steps: washing a
raw material with water, performing combined alkali treatment on the
raw material, wherein the concentration of alkali is decreased gradually, washing the
raw material to enable the pH to be 7-8; carrying out composite
enzyme treatment, removing
heavy metals by using a
metal chelating agent, boiling
carrageenan, filtering coarsely, filtering finely, reducing temperature, gelling,
dewatering,
cutting into strips,
drying, crushing and screening so as to obtain the
carrageenan. According to the invention, a
mixed solution of NaOH, KOH and LCI with gradually
decreased concentration in three grades is adopted in an alkali treatment process, the loss of carrageenan is reduced effectively while the alkali
treatment time is reduced;
cellulase and
protease combined treatment is adopted, and the yield of the carrageenan is improved while the high
gel strength of the carrageenan is ensured;
ethylene diamine tetraacetic acid and nopotassium
phosphate are adopted for further treatment for the raw material, and the
heavy metals in the raw materials are removed effectively. The
gel strength of the carrageenan prepared by the method is greater than or equal to 2139.2 g / cm<2>, the extraction rate is greater than or equal to 23.9 percent, Pb is less than or equal to 2.5 mg / kg, As is less than or equal to 1.0 mg / kg, Hg is less than or equal to 0.5 mg / kg, and the Cd is less than or equal to 1.0 mg / kg.