152
7 Agar
3.88 million tonnes in 2015 and 4.15 million tonnes in 2016 (weight of the live plant)
(FAO 2018).
The yield of algae toward production of agar can be improved by modifying the
growth conditions and growth methods. The algae can grow at rates between 0.5 and
1.3% per day on the low side (Rejeki et al. 2018) depending on the types of seeds
and the growth conditions. The Gracilaria red algae can contain around 9.6% agar
per weight. This particular strain of red algae contributes significantly to the export
commodity of producing countries such as Indonesia where annual export is valued
at an estimated 280 thousand USD annually from an export of 20 thousand tonnes of
Gracilaria red algae (Rejeki et al. 2018). The red algae from which agar is sourced
can be grown using the off-bottom, longline or broadcast method. Method of algae
cultivation is discussed in the chapter dedicated to aquatic environment.
As of 2010, escalation in the price of seaweed was reported. This escalation in
price was attributed to the emerging markets entering the seaweed market at a larger
scale and increase in demand for seaweed products which makes their cost as raw
materials for production of phycocolloids such as agar much higher. The value of
seaweed in its whole form was competitive enough for producers to want to focus on
a product requiring less energy and production cost, hence focusing on cultivation
and quality such as nutrient value and appearance.
For many years, Gracilaria has been the main source of agar produced globally.
The Gracilaria species are endemic to a few parts of the world, and this often results
in companies either having to outsource production or move factories to locations
nearer to the resource at some additional cost compared to if factory was located
in home country. This therefore makes a compelling case to explore alternative red
algae species to serve as sources of commercial production of agar. To this end,
research efforts have been directed at seeking alternative sources of agar with yield
and properties comparable to the agar from Gracilaria species. Pyropia yezoensis, for
example, yields agar which forms gels which are suitable for bacterial culture media
and DNA electrophoresis, two common applications of commercial agar (Sasuga
et al. 2017). Having a more diverse range of red algae species which can serve as
reliable sources of agar can improve the availability of raw material in more regions
of the world and limiting the chances or resource scarcity.
7.5 Extraction of Agar from Red Seaweed
Agar can be extracted from red seaweed using aqueous extraction which generally
involves heat treatment at boiling point temperature in water. The variable conditions
of extractions include the pH and pressure. Here we look first at the conventional
and then the more contemporary extraction methods.
7 Agar
3.88 million tonnes in 2015 and 4.15 million tonnes in 2016 (weight of the live plant)
(FAO 2018).
The yield of algae toward production of agar can be improved by modifying the
growth conditions and growth methods. The algae can grow at rates between 0.5 and
1.3% per day on the low side (Rejeki et al. 2018) depending on the types of seeds
and the growth conditions. The Gracilaria red algae can contain around 9.6% agar
per weight. This particular strain of red algae contributes significantly to the export
commodity of producing countries such as Indonesia where annual export is valued
at an estimated 280 thousand USD annually from an export of 20 thousand tonnes of
Gracilaria red algae (Rejeki et al. 2018). The red algae from which agar is sourced
can be grown using the off-bottom, longline or broadcast method. Method of algae
cultivation is discussed in the chapter dedicated to aquatic environment.
As of 2010, escalation in the price of seaweed was reported. This escalation in
price was attributed to the emerging markets entering the seaweed market at a larger
scale and increase in demand for seaweed products which makes their cost as raw
materials for production of phycocolloids such as agar much higher. The value of
seaweed in its whole form was competitive enough for producers to want to focus on
a product requiring less energy and production cost, hence focusing on cultivation
and quality such as nutrient value and appearance.
For many years, Gracilaria has been the main source of agar produced globally.
The Gracilaria species are endemic to a few parts of the world, and this often results
in companies either having to outsource production or move factories to locations
nearer to the resource at some additional cost compared to if factory was located
in home country. This therefore makes a compelling case to explore alternative red
algae species to serve as sources of commercial production of agar. To this end,
research efforts have been directed at seeking alternative sources of agar with yield
and properties comparable to the agar from Gracilaria species. Pyropia yezoensis, for
example, yields agar which forms gels which are suitable for bacterial culture media
and DNA electrophoresis, two common applications of commercial agar (Sasuga
et al. 2017). Having a more diverse range of red algae species which can serve as
reliable sources of agar can improve the availability of raw material in more regions
of the world and limiting the chances or resource scarcity.
7.5 Extraction of Agar from Red Seaweed
Agar can be extracted from red seaweed using aqueous extraction which generally
involves heat treatment at boiling point temperature in water. The variable conditions
of extractions include the pH and pressure. Here we look first at the conventional
and then the more contemporary extraction methods.