Seaweeds: A Promising Source for Sustainable Development - Environmental Sustainability: Role of Green Technologies - page 69

most important criterion for the quality of agar.
High gel strength is a must for the bacteriological
grade of agar. Commercial agar obtained from
the Indian Gracilaria by acid treatment process
has got very low gel strength in the range of 200-
250 g/cm 2 . As the gel strength of agar produced is
very low, it fetches very low price.

sodium hydroxide solution before the hot
extraction (Bixler 1996 ).

5.1.3 Alginate
Alginate is a polysaccharide extracted from
brown seaweeds such as Sargassum , Turbinaria ,
Dictyota , and Padina generally growing in cold
water areas worldwide and also occurring in the
Indian waters. Alginate is used in the preparation
of various pharmaceutical food and rubber prod-
ucts, textile productions, and others. This can
readily form nontoxic gels (Chapman 1970 ).
Alginates fi nd their uses in varied industries, but
the most important consumers are textile (50 %)
and food (30 %) industries. As with other phyco-
colloids, various grades of alginate are available
for specifi c applications and associated prices,
e.g., sodium alginate in both pharmaceutical and
food grade (McHugh 1987 ).

5.1.2 Carrageenan
Carrageenans obtained from various red algae
like C hondrus , Gigartina , Eucheuma , and Hypnea
are employed in food industries. It is valuable in
the manufacture of “sausages,” meatballs, ham,
preparations of poultry and fi sh, chocolates, des-
ert gel, ice creams, juice, textiles, toothpastes, hair
shampoos, sanitary napkins, fungicides, etc.
There are three main types of carrageenan such as
lambda, kappa, and iota each having their own gel
characteristics. Previously, the use of carrageenan
was restricted because of the availability of natu-
ral resources of Chondrus crispus (common
name: Irish moss) from Canada, Ireland, Portugal,
Spain, and France and Gigartina / Iridaea from
South America and Southern Europe (Trono
1997 ). Chondrus contains a mixture of two types
(lambda and kappa) that could not be separated
during commercial extraction. Limited quantities
of wild Chondrus are still used; attempts to culti-
vate Chondrus in tanks have been biologically
successful but uneconomic as a raw material for
carrageenan (McHugh 2003 ). These sources now
only contribute 20 % of the total processed mate-
rial. Supplies for this phycocolloid are dominated
by Eucheuma which are cultivated in Indonesia
and the Philippines and recently very successfully
in India and Tanzania (Trono 1997 ).

6 Medicinal Uses of Algae

Seaweeds were considered to be of medicinal
value in the early as 3000 BC. Chinese and
Japanese used them in the treatment of goiter and
other diseases. Romans used the seaweeds for
healing wounds, burns, and rashes. Though the
importance of different seaweed products in
pharmacology is known, the development of anti-
bacterial, antifungal, and antiviral substances
from seaweeds is still in the growing stages of
research and development. Iodine is the most
important element to enable the thyroid glands to
secrete the thyroxin which contains 60 % iodine.
It controls the general development of the animal.
Seaweeds are the best source of iodine for human
beings. Several important seaweed medicinal
preparations are prepared in various countries,
i.e., Kelpeck is prepared from kelps in Chicago,
Burbank vegetable tablets are seaweed prepara-
tions from the USA, Kelpamalt is a seaweed
medicinal preparation from New York (USA),
Isokelp is prepared in California, and Parakelp
and Manamar are other medicinal seaweeds
(Chennubhotla et al. 2013 ).
Gelidium cartilagineum has been found to be
against infl uenza B and mumps viruses. Among

5.1.2.1 Production of Carrageenan
Washed sun-dried seaweed is boiled in a digester
by passing a team and treating with 10 % KOH
(caustic potash). The bleached seaweed is sun-
dried or dried indoor on sieve plates below which
hot air is passed. Then, the bleached and dried
seaweed is grinded in a pulverizer to make into
powder. Carrageenan is extracted from this
crude (semi-processed) carrageenan similar to
that of agar extraction by large-scale industry
method, except treating the seaweed with 5-10 %