198
9 Laminarins
9.5.2 Calcium Chloride Extraction
In an another approach to the extraction of laminarin from brown algae, the alginate
can first be extracted and precipitated out followed by the extraction of laminarin. This
method as applied to the extraction of laminarin from the brown algae A. nodosum
is as follows (Yvin et al. 1993): The fresh algae biomass was ground using mill to
smaller particle size <1 mm. This gave a suspension with a 10–12% solid content.
The groundmass is then added to 2% aqueous solution of calcium chloride. For this,
300 g of the ground algae biomass (10–12% solid content) was added to 900 ml of
the calcium chloride solution. This addition of calcium chloride allowed the alginate
to precipitate. It is then required to separate the laminarin from the solid mass. This is
achieved by extraction in hot water at 60 °C since the laminarin is soluble in hot water.
The extraction is allowed a duration of 7 h under continuous stirring. After this period,
the laminarin is dissolved in the hot water, and this can then be separated by filtration.
Further, purification is achieved using ultrafiltration and dialysis. The residue from
the first extraction can then be taken through another extraction process to remove
residual laminarin. This repeated extraction is necessary since the solvent overtime
becomes saturated; a fresh solvent is then required to increase the concentration
gradient for further extraction.
9.5.3 Enzyme Extraction
Laminarin can also be extracted from brown algae through the use of enzymes.
These enzymes can either be enzymes which digest the non-polysaccharide components of the brown algae biomass leaving behind laminarin in a mixture with
other polysaccharides. This mixture of polysaccharides can then be separated by
hydrothermal treatment, precipitation and/or molecular separation methods. Another
approach involves the partial degradation of the laminarin into even shorter-chain
laminarin oligosaccharides using laminarin degrading enzymes (Ojima et al. 2018).
This form of extraction is desirable where laminarin oligosaccharides are desired
for their bioactive properties. For example, laminarin oligosaccharides extracted
from the brown algae E. bicyclis showed immunomodulatory effects by promoting
the immune response of monocytes (Ojima et al. 2018). There is the β-1,3 glucanase which degrades glucans by breaking some specific forms of β-1,3-linkages.
The form of glucanase enzymes which are specific to laminarins is generally called
laminarinase. The different glucanases differ in their mode of actions and are bondspecific. The endo-1,3;1,4-β-glucanase cleaves the β-1,3-glycosidic bond as well as
the β-1,4-linkage while another type of glucanase the lichenase splits only specific
terminal β-1,4-linkage and glucan endo-1,3-β-d-glucosidase would break the β-1,3linkage but only when at least two adjacent β-1,3-linkages are present (Ojima et al.
2018). These enzymes can be obtained from sources such as barley and baker’s yeast
(Hrmova and Fincher 2009).
9 Laminarins
9.5.2 Calcium Chloride Extraction
In an another approach to the extraction of laminarin from brown algae, the alginate
can first be extracted and precipitated out followed by the extraction of laminarin. This
method as applied to the extraction of laminarin from the brown algae A. nodosum
is as follows (Yvin et al. 1993): The fresh algae biomass was ground using mill to
smaller particle size <1 mm. This gave a suspension with a 10–12% solid content.
The groundmass is then added to 2% aqueous solution of calcium chloride. For this,
300 g of the ground algae biomass (10–12% solid content) was added to 900 ml of
the calcium chloride solution. This addition of calcium chloride allowed the alginate
to precipitate. It is then required to separate the laminarin from the solid mass. This is
achieved by extraction in hot water at 60 °C since the laminarin is soluble in hot water.
The extraction is allowed a duration of 7 h under continuous stirring. After this period,
the laminarin is dissolved in the hot water, and this can then be separated by filtration.
Further, purification is achieved using ultrafiltration and dialysis. The residue from
the first extraction can then be taken through another extraction process to remove
residual laminarin. This repeated extraction is necessary since the solvent overtime
becomes saturated; a fresh solvent is then required to increase the concentration
gradient for further extraction.
9.5.3 Enzyme Extraction
Laminarin can also be extracted from brown algae through the use of enzymes.
These enzymes can either be enzymes which digest the non-polysaccharide components of the brown algae biomass leaving behind laminarin in a mixture with
other polysaccharides. This mixture of polysaccharides can then be separated by
hydrothermal treatment, precipitation and/or molecular separation methods. Another
approach involves the partial degradation of the laminarin into even shorter-chain
laminarin oligosaccharides using laminarin degrading enzymes (Ojima et al. 2018).
This form of extraction is desirable where laminarin oligosaccharides are desired
for their bioactive properties. For example, laminarin oligosaccharides extracted
from the brown algae E. bicyclis showed immunomodulatory effects by promoting
the immune response of monocytes (Ojima et al. 2018). There is the β-1,3 glucanase which degrades glucans by breaking some specific forms of β-1,3-linkages.
The form of glucanase enzymes which are specific to laminarins is generally called
laminarinase. The different glucanases differ in their mode of actions and are bondspecific. The endo-1,3;1,4-β-glucanase cleaves the β-1,3-glycosidic bond as well as
the β-1,4-linkage while another type of glucanase the lichenase splits only specific
terminal β-1,4-linkage and glucan endo-1,3-β-d-glucosidase would break the β-1,3linkage but only when at least two adjacent β-1,3-linkages are present (Ojima et al.
2018). These enzymes can be obtained from sources such as barley and baker’s yeast
(Hrmova and Fincher 2009).