Agar

Agar, also known as Agar-Agar, is a gelling polysaccharide that is obtained from the cell walls of certain red marine algae (mostly of the genera Gelidium and Gracilaria). In Japan, Agar, also known as, Kanten, has been used for centuries both in traditional cuisine and for health purposes. Agar was originally discovered by chance in the 17th century, when a Japanese monk realized that dried algae release a gelling substance when they are boiled in water and cooled. Today, Agar is used primarily in the food industry, microbiology, and biochemistry. Due to its plant origin, Agar is a popular alternative to gelatin and is often used in vegetarian and vegan products.

What health aspects is Agar associated with? Agar is largely indigestible and acts as dietary fiber in the digestive tract. As a result, it can promote digestion and contribute to improved intestinal function. Agar is also used in dietetics, as it has a satiating effect and contains hardly any calories. However, it is important to mention here that there is hardly any study data on the health benefits. The following list of benefits therefore refers to areas of application of Agar within traditional medicine, not to well-founded statements from studies:

  • Diet and weight management: In Japan, Agar is often used as a natural aid for weight reduction. Due to its ability to swell in the digestive tract and create a feeling of satiety, it is used in diets to control hunger without adding many calories. Agar absorbs water and expands in the stomach, which reduces the feeling of hunger and can lead to lower food intake.
  • Promotion of digestion: Agar is a soluble dietary fiber that is not digested in the stomach and intestines. For this reason, Agar is regarded as an effective aid for promoting gut health. It is said to support digestion by acting as a mild laxative and regulating bowel movements. In Japan, Agar is traditionally used for digestive complaints such as constipation.
  • Blood sugar regulation: Agar is said to be able to help regulate blood sugar levels. It slows the absorption of sugar in the digestive tract, which leads to a more stable glucose uptake. This property makes Agar particularly popular in Japan among people who want to better control their blood sugar, including those with diabetes or an increased risk of it.
  • Detoxification: In Japanese health culture, Agar is regarded as a mild aid for detoxifying the body. It is believed that the fiber in Agar helps to bind toxins in the gut and excrete them, which can improve overall gut health.

Origin and extraction Agar is extracted by boiling red algae and is then purified and dried. The resulting product is a white to slightly yellowish powder. It is soluble in hot water but forms a firm gel when cooled, which is particularly valued in food production.

What are the main components of Agar? Agar consists mainly of two polysaccharides:

Agarose: This part of Agar is responsible for gel formation. It is a linear polysaccharide consisting of D-galactose and 3,6-anhydro-L-galactose.

Agaropectin: Another polysaccharide that occurs alongside agarose but does not play a significant role in gel formation. It contains sulfate-containing and other substituted sugars.

Use in the food industry In the food industry, Agar is used as a thickening and gelling agent. It is taste-neutral and is used in a wide variety of products:

  • Jellies and puddings: Agar can be used to make vegan or vegetarian jellies, as it has a similar consistency to gelatin but is of plant origin.
  • Sweets: In Asian sweets, especially in Japan and China, Agar is a popular gelling agent.
  • Baked goods and jams: Agar is also used to improve the consistency of jams and jellies.

A key advantage of Agar is that it melts at higher temperatures (around 85-90 °C) and gels at lower temperatures (around 35-40 °C), which makes it more heat-resistant than gelatin.

Agar in Japanese cuisine Common uses of Agar include:

Kanten teas: A traditional application in Japan is the preparation of Kanten teas or Agar teas. Here, Agar is dissolved in hot water and consumed as a drink to promote metabolism, support digestion, and enable gentle detoxification. These teas are especially popular in the winter months.

Yōkan: A jelly dessert made from Agar, often combined with red bean paste and other healthy ingredients.

Mizuyōkan: A lighter version of Yōkan that contains more water and also uses Agar as its base. It is often served as a refreshing dessert in hot summer months.

Use in science and microbiology In microbiology, Agar is used as a nutrient medium for the growth of microorganisms. It is ideal for culturing bacteria and fungi, as it remains solid at body temperature. Special Agar media enriched with nutrients serve as the basis for the cultivation and analysis of microbes.

Safety and side effects Agar is considered safe for human consumption and is approved as a food additive in many countries. However, in large amounts it can have a laxative effect, as it binds water in the digestive tract and can thus lead to faster bowel movements. It is recommended to consume Agar in moderate amounts to avoid unwanted side effects.

Conclusion Agar is a versatile and valuable polysaccharide that is used both in the food industry and in scientific research. Its plant origin and its excellent gelling abilities make it an ideal alternative to animal-based gelling agents. In addition, it offers health benefits through its fiber-rich properties, which can support digestion.

Sources:

  1. Chen, X., Fu, X., Huang, L., Xu, J., & Gao, X. (2021). Agar oligosaccharides: A review of preparation, structures, bioactivities and application. Carbohydrate polymers, 265, 118076. https://doi.org/10.1016/j.carbpol.2021.118076
  2. Leung AY, Foster S. Encyclopedia of Common Natural Ingredients Used in Food, Drugs and Cosmetics. 3rd ed. New York, NY: John Wiley & Sons, 2010.
  3. Armisen, R., Hispanagar, F. G., S.A., CHAPTER 1 - PRODUCTION, PROPERTIES AND USES OF AGAR, Burgos, https://www.fao.org/4/x5822e/x5822e03.htm#TopOfPage
  4. Pandya, Yash & Bakshi, Manish & Sharma, Anushka. (2022). Agar-agar extraction, structural properties and applications: A review. 11. 1151-1157.
  5. Yun, E. J., Yu, S., & Kim, K. H. (2017). Current knowledge on agarolytic enzymes and the industrial potential of agar-derived sugars. Applied microbiology and biotechnology, 101(14), 5581–5589. https://doi.org/10.1007/s00253-017-8383-5
  6. Yun, E. J., Yu, S., Kim, Y. A., Liu, J. J., Kang, N. J., Jin, Y. S., & Kim, K. H. (2021). In Vitro Prebiotic and Anti-Colon Cancer Activities of Agar-Derived Sugars from Red Seaweeds. Marine drugs, 19(4), 213. https://doi.org/10.3390/md19040213