The invention discloses a preparation method of an instant
gracilaria agar with a low
freezing point. The preparation method comprises the following steps: taking
gracilaria as the
raw material, removing the salt and sand from
gracilaria by a roller,
processing gracilaria by alkali, acidifying and bleaching the gracilaria, cooking gracilaria to obtain gel, crudely filtering the gel, cooling to a temperature of 55 DEG C to obtain an
agar crudely-filtered solution; then
processing the solution by a compound
enzyme preparation, heating to inactivate the
enzyme, carrying out fine
filtration, condensing the solution under vacuum, adding
alcohol into the solution to trigger
flocculation, separating the
solid from the liquid,
drying the
solid in vacuum,
grinding the
solid, and sieving so as to obtain the instant gracilaria
agar with a low
freezing point. In the agar crude
filtration step, a compound
enzyme preparation is added to process the gel solution so as to maximally degrade the alga fibers, and thus the enzyme preparation can be completely inactivated more easily. The
alcohol is used to flocculate the gel solution, thus the safety and
hygiene of the gracilaria agar can be guaranteed, and at the same time the yield of agar is increased. The technologies of diaphragm press
filtration and
vacuum drying can guarantee that
alcohol is fully recycled and utilized. The
freezing point of the prepared agar is not higher than 30 DEG C, the agar can be completely dissolved in 10 minutes at a temperature of 80 DEG C, the extraction yield is not less than 15.5%, the lead (Pb) content is not more than 0.5 mg / kg, the
arsenic (As) content is not more than 0.3 mg / kg, and the total number of bacterium is not more than 1000 cfu / g.