Difference Between agar and agarose

Main Difference – Agar vs Agarose

Red algae or seaweeds are mainly used to produce different types of polysaccaradises such as agar and agarose. This seaweed is commonly cultivated in some parts of Asia and the United states. Agar and agarose are used in different applications such as culturing micro-organisms and as a culinary ingredient. The terms agar and agarose are frequently used interchangeably since they are closely interconnected. However, there is a difference; Agarose is derived by purifying agar. In contrast, agar is directly derived from red algae. This is the main difference between agar and agarose. Agar is also cheaper than agarose. Due to gel-like characteristics, both of these materials are used in the field of microbiological analysis and deliver nutrients to microorganisms. Furthermore, agar is commonly used in the food industry as a food ingredient whereas agarose is ordinarily used in gel electrophoresis. In this article, let’s look at the difference between agar and agarose in terms of their physical, chemical characteristics and intended uses.

Difference Between Agar and Agarose -infographic

What is Agar

Agar is also known as agar-agar, and is manufactured from different types of red algae including Gracilaria and Gelidium. Due to its gelatinous properties, it is used as a component in the preparation of growth media for culturing of bacteria and fungi, mainly for scientific and medicinal research. Agar polymer is based on galactose, which is derived from the polysaccharide agarose, and it is also used in gelatine-like food which vegans can substitute for meat. It was first found in the late 1650s by Mino Tarōzaemon in Japan. Agar is found in the supporting structure of the cell walls of certain species of algae, and it can be released after boiling. The term “agar” comes from the Malay/Indonesian name for red algae, from which the jelly is produced. It is also a food ingredient mainly used in traditional Malay and Japanese desserts. Other terms for agar are Kanten, Japanese isinglass, Ceylon moss or Jaffna moss. Agal-agal or Ceylon agar is mainly derived from Gracilaria lichenoides.

Difference Between agar and agarose

Agar gel in bacterial culture

What is Agarose

Agarose is a result of purification of polysaccharide agar. In other words, agar is purified from agar by removing agaropectin in agar. Agarose is very beneficial to bacteria culture since it does not contain protein, food of the bacteria. An agarose is generally extracted from seaweed of agar. Biochemically, it is a linear polymer synthesized by the repeating unit of agarobiose. Agarobiose is a disaccharide consisting of D-galactose and 3,6-anhydro-L-galactopyranose. One of the other main applications of agarose is its use in electrophoresis, a process that is used to separate proteins and studying DNA.

Main Difference - Agar vs Agarose

Agarose gel in electrophoresis

Difference Between Agar and Agarose

Agar and agarose may have some different chemical effects and some functional properties. These differences may include,

Origin

Agar is derived from red algae and seaweed such as Gracilaria and Gelidium.

Agarose is a purified form of agar and the predominant component of agar

Chemical Nature

Agar is a mixture of two components including the linear polysaccharide agarose and a heterogeneous mixture of smaller molecules known as agaro-pectin.

Agarose is a linear polysaccharide.

Price

Agar is cheaper than agarose.

Agarose is more expensive than agar.

Production

Agar is extracted from the cell walls of some species of red algae, mainly from the genera Gelidium and Gracilaria. For commercial purposes, agar is mainly obtained from Gelidium amansii.

Agarose is purified to obtain high-quality agarose, and the production process of agarose is expensive, more time-consuming and complex compared to agar production.

Uses

Agar is mainly used in the following applications;

  • Used in microbiological studies for culturing bacteria
  • Used in the food industry for making jellies, ice cream, puddings, and custards as well as other culinary dishes
  • Used as a laxative, an appetite suppressant
  • Used as the vegetarian substitute for gelatin
  • Used as a thickener for soups

Agarose is mainly used in the following applications;

  • Used in electrophoresis in molecular biology for the separation of large molecules such as DNA
  • Used in immune diffusion and immune electrophoresis
  • Used in bacteria culture

In conclusion, agar and agarose are both very useful in different fields and industries, ranging from the food industry, home science, to the chemistry and medical labs. Agar and agarose have been used broadly due to the development of microbiology.

References:

Williams, Peter W.; Phillips, Glyn O. (2000). Chapter 2: Agar. Handbook of hydrocolloids. Cambridge: Woodhead. p. 28. ISBN 1-85573-501-6.

Maeda H, Yamamoto R, Hirao K, Tochikubo O (2005). Effects of agar (kanten) diet on obese patients with impaired glucose tolerance and type 2 diabetes. Diabetes, Obesity, and Metabolism 7 (1): 40–6.

Philip Serwer (1983). Agarose gels: Properties and use for electrophoresis. Electrophoresis 4 (6): 375–382.

Alistair M. Stephen, Glyn O. Phillips, ed. (2006). Food Polysaccharides and Their Applications. CRC Press. p. 226. ISBN 978-0824759223.

Image Courtesy:

“Agar” by Y tambe – Y tambe’s file, (CC BY-SA 3.0) via Commons Wikimedia 

“Agarose gel” by School of Natural Resources from Ann Arbor – DNA lab, (CC BY 2.0) via Commons Wikimedia 

About the Author: Geesha

Geesha has a BSc (Hons) degree in Food Science and Technology and Master's degree in Food and Nutrition. She is currently reading for her PhD in Food science and technology. Sharing what she learned is a passion of hers and enjoys writing.