The invention relates to a preparation method of
sodium alginate and belongs to the field of preparation methods for food additives. The preparation method comprises the following steps of cleaning,
drying and sectioning fresh
kelp, putting the fresh
kelp into a conversion tank, adding
formaldehyde with the weight being 10% of the weight of dried
kelp for soaking, adding an alkaline-containing solution into the conversion tank, stirring for reaction, so as to obtain pasty glue solution, adding water to dilute the pasty glue solution, foaming the diluted glue solution by a foaming
machine, flowing the diluted glue solution into a floating
sedimentation tank, collecting
clear liquid at the middle-lower part to enter a decalcifying tank, simultaneously adding a diluted
hydrochloric acid solution so that flocculent
calcium alginate becomes insoluble
alginic acid, crushing
alginic acid, adding a pure-alkaline solution into a neutralizing
machine with the alkaline-adding amount being 10-20% of the weight of
alginic acid, and stirring for reaction so as to obtain a
sodium alginate solution, and finally
drying the
sodium alginate solution in a
drying machine to obtain the
sodium alginate. The preparation method has the characteristics of simple process, strong
operability and the like, and is suitable for industrial production and high stability of products. The
viscosity of the prepared
sodium alginate reaches more than 1500cps, and is generally more than 1.5 times higher than the
viscosity 1000cps in the traditional preparation method.