Page 286 - Algae Anatomy, Biochemistry, and Biotechnology

Algae and Men 269

naturally found in shallow sea water usually less than 1 m in depth, where it grows on rocks, coral,
mollusk shells, or other hard substrate, but also as an epiphyte on other sea macroalgae. It was used
as flavoring with other seaweed by Kashaya Pomo natives of northern California.
Caulerpa lentillifera (Figure 7.11) and Caulerpa racemosa are the two edible green algae used
in fresh salads and known as sea grapes or green caviar. As the common name suggests, their
appearance looks like bunches of green grapes. These algae often produce “runners” under the sub-
strate, which can produce several vertical branches that extend above the substrate. They naturally
grow on sandy or muddy bottom in shallow protected waters.
Caulerpa lentillifera has been very successfully cultivated in enclosures similar to prawn ponds
in the central Philippines, where about 400 ha of ponds are under cultivation, producing 12–15 tons
of fresh macroalgae per hectare per year. Water temperature can range between 25 and 308C. Pond
depth should be about 0.5 m and areas of about 0.5 ha are usual. Also some strains of C. racemosa
give good yields under pond cultivation conditions.
Planting is done by hand; about 100 g lots are pushed into the soft bottom at 0.5–1 m intervals.
Harvesting can commence about 2 months after the first planting; fronds are pulled out of the
muddy bottom, but about 25% of the plants are left as seed for the next harvest. Depending on
growth rates, harvesting can then be done every 2 weeks. The harvested plants are washed
thoroughly in seawater to remove all sand and mud, then sorted and placed in 100–200 g packages;
these will stay fresh for 7 days if chilled and kept moist.
Table 7.5 summarizes edible algae and the corresponding food item.

EXTRACTS
Agar, alginate (derivative of alginic acid), and carrageenan are three hydrocolloids that are
extracted from various red and brown macroalgae. A hydrocolloid is a non-crystalline substance
with very large molecules, which dissolves in water to give a thickened (viscous) solution. Agar,
alginate, and carrageenan are water-soluble carbohydrates used to thicken aqueous solutions, to
form gels (jellies) of varying degrees of firmness, to form water-soluble films, and to stabilize
certain products, such as ice-cream (they inhibit the formation of large ice crystals, allowing the
ice-cream to retain a smooth texture). The use of macroalgae as a source of these hydrocolloids

FIGURE 7.11 Frond of Caulerpa lentillifera.