peaking in late June. Ash does not vary in any fixed way, and changes over time are
not large. Stalks show lesser lipid, protein, and alginic acid content and greater ash
and fiber content than leaves, but seasonal changes do not necessary coincide with
those seen in the leaves.
6.8.2 Seaweed Polysaccharides
Polysaccharides represent the chief general components of seaweeds besides water.
Polysaccharides can be classified into three types according to their distribution
within the seaweed: cell wall polysaccharides, which form a small fibrous crystal
structure at the outermost layer; glycosaminoglycans, which form an amorphous gel
over them; and storage polysaccharides located within the cell.
Seaweeds inhabit waters with large salt concentrations and swift currents.
Polysaccharides play a major role in helping them adapt to this growth environment. For example, the seaweed’s cell wall, which is made of polysaccharides, is
thicker than that of a land plant, but also flexible and resilient. Additionally, seaweeds possess glycosaminoglycans between their cells that land plants do not have.
The constituent sugars of these polysaccharides include sugars with carboxyl
groups or sulfate groups. Their role is to select and absorb or exchange ions within
the seaweed to maintain water content at a fixed level.
Seaweeds thus possess glycosaminoglycans that land plants do not, as well as
storage polysaccharides that are unique to them. In addition to D-glucose,
D-galactose, D-xylose, L-rhamnose, L-arabinose, D-glucuronic acid,
Table 6.8 Seasonal changes in the general composition of sea mustard Undaria pinnatipida (%
of dry mass)
Harvesting date
Part
Proteins
Lipids
Carbohydrates
Ash
Alginic acid
Fiber
10-Apr
Leaf
21.6
1.7
–
1.6
36.5
Stalk
15.1
1.2
–
4.2
38.6
25-Apr
Leaf
21.1
1.6
24.4
1.2
34.1
Stalk
11.6
0.8
20.7
4.9
40.9
10-May
Leaf
29.6
1.9
24.7
–
40.0
Stalk
7.0
1.4
24.0
–
43.9
24-May
Leaf
11.3
2.3
27.9
2.4
36.2
Stalk
–
1.2
22.9
5.8
43.0
9-Jun
Leaf
11.8
2.5
30.7
3.6
32.5
Stalk
3.9
1.2
25.9
6.3
38.1
26-Jun
Leaf
10.9
2.1
26.9
3.0
36.6
Stalk
4.6
1.0
25.3
6.6
49
10-Jul
Leaf
8.4
1.1
28.9
3.3
34.6
Stalk
4.9
1.1
27.5
–
42.4
168
6 Seaweed Biotechnology
not large. Stalks show lesser lipid, protein, and alginic acid content and greater ash
and fiber content than leaves, but seasonal changes do not necessary coincide with
those seen in the leaves.
6.8.2 Seaweed Polysaccharides
Polysaccharides represent the chief general components of seaweeds besides water.
Polysaccharides can be classified into three types according to their distribution
within the seaweed: cell wall polysaccharides, which form a small fibrous crystal
structure at the outermost layer; glycosaminoglycans, which form an amorphous gel
over them; and storage polysaccharides located within the cell.
Seaweeds inhabit waters with large salt concentrations and swift currents.
Polysaccharides play a major role in helping them adapt to this growth environment. For example, the seaweed’s cell wall, which is made of polysaccharides, is
thicker than that of a land plant, but also flexible and resilient. Additionally, seaweeds possess glycosaminoglycans between their cells that land plants do not have.
The constituent sugars of these polysaccharides include sugars with carboxyl
groups or sulfate groups. Their role is to select and absorb or exchange ions within
the seaweed to maintain water content at a fixed level.
Seaweeds thus possess glycosaminoglycans that land plants do not, as well as
storage polysaccharides that are unique to them. In addition to D-glucose,
D-galactose, D-xylose, L-rhamnose, L-arabinose, D-glucuronic acid,
Table 6.8 Seasonal changes in the general composition of sea mustard Undaria pinnatipida (%
of dry mass)
Harvesting date
Part
Proteins
Lipids
Carbohydrates
Ash
Alginic acid
Fiber
10-Apr
Leaf
21.6
1.7
–
1.6
36.5
Stalk
15.1
1.2
–
4.2
38.6
25-Apr
Leaf
21.1
1.6
24.4
1.2
34.1
Stalk
11.6
0.8
20.7
4.9
40.9
10-May
Leaf
29.6
1.9
24.7
–
40.0
Stalk
7.0
1.4
24.0
–
43.9
24-May
Leaf
11.3
2.3
27.9
2.4
36.2
Stalk
–
1.2
22.9
5.8
43.0
9-Jun
Leaf
11.8
2.5
30.7
3.6
32.5
Stalk
3.9
1.2
25.9
6.3
38.1
26-Jun
Leaf
10.9
2.1
26.9
3.0
36.6
Stalk
4.6
1.0
25.3
6.6
49
10-Jul
Leaf
8.4
1.1
28.9
3.3
34.6
Stalk
4.9
1.1
27.5
–
42.4
168
6 Seaweed Biotechnology