156
7 Agar
Other extraction methods which have been explored include extraction by photobleaching process (Li et al. 2008). Photobleaching extracts of agar from Gracilaria
asiatica and Gracilaria lemaneiformis showed good gel strength of 1913 g cm
−2
which is higher than that obtained from using the conventional methods. For example using microwave-assisted method, a gel strength of 1331 g/cm
2 was obtained
(Sousa et al. 2010). A yield of 14.4%, sulfate content of 1.73% and 3.6-anhydrol-galactose content of 39.4% are achievable using the microwave-assisted method
from Gracilaria vermiculophylla (Sous et al. 2010).
7.6 Environmental Implications
Although agar is a biodegradable and biocompatible polymer, the process of extraction of agar requires energy and materials consumption, and the release of substances
into the environment in the process. This therefore needs to be weighed against its
advantages to the environment and commercial value. Agar degradation goes through
two stages of degradation before finally degrading into its monomer which can then
be broken down by microbes for use as energy or as carbon source. The product itself
is therefore not toxic or a nuisance to the environment unlike the non-biodegradable
petrochemical-derived plastics which over time have accumulated in the oceans. An
estimated 10–20 million tonnes of plastics accumulate in the ocean (Ubanek et al.
2018) annually to the point that these form what is now known as plastic islands
(Lebreton et al. 2018). In developing solutions and alternatives to the plastic management problem, it is important to evaluate the environmental implications of the
process involved in the production of these biopolymers and identify areas where
improvements are required to make these biopolymers as environmentally benign as
possible.
7.6.1 Cultivation of Red Algae
Red algae are a renewable natural resource as they grow freely in the wild, and
when harvested, they are replenished naturally within a number of days. Unlike fossil fuels which are formed over billions of years and are therefore constantly being
depleted, demand for fossil products increases with increasing population. The growing demand for algae as food and as a feedstock for the production of phycocolloids
can potentially reduce overfishing of some aquatic species being experienced in some
parts of the world. By serving as an alternative source of income, it reduces the pressure on the fish resource as people in the fishing industry diversify their commercial
interests.
Naturally, algae are able to extract nutrients from the environment for their growth
and metabolism. This is advantageous where they can be used to clean polluted
waters. While uncontrolled algae growth can have adverse impacts such as harmful
7 Agar
Other extraction methods which have been explored include extraction by photobleaching process (Li et al. 2008). Photobleaching extracts of agar from Gracilaria
asiatica and Gracilaria lemaneiformis showed good gel strength of 1913 g cm
−2
which is higher than that obtained from using the conventional methods. For example using microwave-assisted method, a gel strength of 1331 g/cm
2 was obtained
(Sousa et al. 2010). A yield of 14.4%, sulfate content of 1.73% and 3.6-anhydrol-galactose content of 39.4% are achievable using the microwave-assisted method
from Gracilaria vermiculophylla (Sous et al. 2010).
7.6 Environmental Implications
Although agar is a biodegradable and biocompatible polymer, the process of extraction of agar requires energy and materials consumption, and the release of substances
into the environment in the process. This therefore needs to be weighed against its
advantages to the environment and commercial value. Agar degradation goes through
two stages of degradation before finally degrading into its monomer which can then
be broken down by microbes for use as energy or as carbon source. The product itself
is therefore not toxic or a nuisance to the environment unlike the non-biodegradable
petrochemical-derived plastics which over time have accumulated in the oceans. An
estimated 10–20 million tonnes of plastics accumulate in the ocean (Ubanek et al.
2018) annually to the point that these form what is now known as plastic islands
(Lebreton et al. 2018). In developing solutions and alternatives to the plastic management problem, it is important to evaluate the environmental implications of the
process involved in the production of these biopolymers and identify areas where
improvements are required to make these biopolymers as environmentally benign as
possible.
7.6.1 Cultivation of Red Algae
Red algae are a renewable natural resource as they grow freely in the wild, and
when harvested, they are replenished naturally within a number of days. Unlike fossil fuels which are formed over billions of years and are therefore constantly being
depleted, demand for fossil products increases with increasing population. The growing demand for algae as food and as a feedstock for the production of phycocolloids
can potentially reduce overfishing of some aquatic species being experienced in some
parts of the world. By serving as an alternative source of income, it reduces the pressure on the fish resource as people in the fishing industry diversify their commercial
interests.
Naturally, algae are able to extract nutrients from the environment for their growth
and metabolism. This is advantageous where they can be used to clean polluted
waters. While uncontrolled algae growth can have adverse impacts such as harmful