Chapter 7
Agar
Abstract Agar is obtained from red algae. It occurs as a mixture of agarose and
agaropectin with agarose having the more desirable properties. Its applications are
mainly attributed to its rheological properties. Such applications extend to the food,
biotechnology and pharmaceutical industries where it is used as a thermoreversible
gelling agent, stabilizer, texture modifier and thickener. The ability to serve as a substitute additive for the animal-sourced gelatin also contributes to its economic value.
In this chapter, the extraction, chemistry, occurrence in nature and applications are
discussed. In the process, the economic and environmental impact of agar production
is evaluated.
Keywords Agar · Agarose · Agaropectin · Polymers · Gels
7.1 Introduction
A range of polysaccharides can be sourced from the aquatic environment, and some
of these polysaccharides have well-established process technology and market presence. Agar is one of such well-explored polysaccharides. It is present exclusively
in red algae; there are yet to be other non-aquatic sources of agar to date. The most
common form of agar is agarose which is familiar with almost every biology student and researcher. This partially sulfated polysaccharide of the red algae is most
valuable in its gel form for its rheological properties, which has earned it a potential
global annual market valued at around 172.8 million USD (Bixler and Porse 2011).
It can therefore be considered a highly valuable aquatic-derived resource.
Agar is one of the three main phycocolloids obtained from the aquatic environment, the other two being carrageenan and alginate. Agar is comprised of agarose
and agaropectin, where the composition of each within the organism and this in turn
affects the properties and applications of the agar (Armisen and Gaiatas 2009). Agar
finds applications in food, biotechnology and pharmaceutical industries where it is
used as a thermoreversible gelling agent, stabilizer, texture modifier and thickener.
It is often used as a substitute additive for the animal-sourced gelatin (Marcus 2014)
for reasons of ethical, health or dietary preferences where animal-derived gelling
agents are not desirable.
© Springer International Publishing 2020
O. Olatunji, Aquatic Biopolymers, Springer Series on Polymer and Composite Materials,
https://doi.org/10.1007/978-3-030-34709-3_7
145
Agar
Abstract Agar is obtained from red algae. It occurs as a mixture of agarose and
agaropectin with agarose having the more desirable properties. Its applications are
mainly attributed to its rheological properties. Such applications extend to the food,
biotechnology and pharmaceutical industries where it is used as a thermoreversible
gelling agent, stabilizer, texture modifier and thickener. The ability to serve as a substitute additive for the animal-sourced gelatin also contributes to its economic value.
In this chapter, the extraction, chemistry, occurrence in nature and applications are
discussed. In the process, the economic and environmental impact of agar production
is evaluated.
Keywords Agar · Agarose · Agaropectin · Polymers · Gels
7.1 Introduction
A range of polysaccharides can be sourced from the aquatic environment, and some
of these polysaccharides have well-established process technology and market presence. Agar is one of such well-explored polysaccharides. It is present exclusively
in red algae; there are yet to be other non-aquatic sources of agar to date. The most
common form of agar is agarose which is familiar with almost every biology student and researcher. This partially sulfated polysaccharide of the red algae is most
valuable in its gel form for its rheological properties, which has earned it a potential
global annual market valued at around 172.8 million USD (Bixler and Porse 2011).
It can therefore be considered a highly valuable aquatic-derived resource.
Agar is one of the three main phycocolloids obtained from the aquatic environment, the other two being carrageenan and alginate. Agar is comprised of agarose
and agaropectin, where the composition of each within the organism and this in turn
affects the properties and applications of the agar (Armisen and Gaiatas 2009). Agar
finds applications in food, biotechnology and pharmaceutical industries where it is
used as a thermoreversible gelling agent, stabilizer, texture modifier and thickener.
It is often used as a substitute additive for the animal-sourced gelatin (Marcus 2014)
for reasons of ethical, health or dietary preferences where animal-derived gelling
agents are not desirable.
© Springer International Publishing 2020
O. Olatunji, Aquatic Biopolymers, Springer Series on Polymer and Composite Materials,
https://doi.org/10.1007/978-3-030-34709-3_7
145