Polysaccharides - Группа авторов

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Synergies

      It has been observed that agar–locust bean gum or LBG-synergies are only feasible in the agars of Gelidium and Pterocladia agarophytes. LBG-synergies increases the gel strength, transforms the gel texture in such a way that gel stiffness drops off and gel flexibility is elevated, making the gel less fragile. On the other hand, agars extracted from Gracilaria algae do not illustrate such synergies. In their case, gel rigidity drops with the decrease in gel concentration. The synergies between agar and locust bean gum occur due to agaropectin of Gelidium and Pterocladia, but agaropectin of Gracilaria doesn’t show such connections.

      Applications of agar are primarily based on its gel structure, flexibility, high hysteresis, ideal reversibility and their gel strength. More than 80% of agar produced, is consumed by the food industries. The rest is utilizes mainly in biotechnology applications and other scientific applications. In 1995 Armisen, described both, the natural as well as industrial agar sources and their applications. It is mentioned below in Table 5.2.

      Table 5.2 Types of different agars, their applications and their respective agarophytes [9].

Agar name Type of agar and their application/purpose Type of agarophyte
Natural agar Square shaped Gelidium
Stripe shape Predominantly used in asian kitchens
Industrial agar Food quality agar Primarily used in food industry Geludium, Gracilaria, Gracilariopsis, Pterocladia, Ahnfetia, Gelidiella
Pharmacological agar Gelidium
Cloning plants production quality agar Gelidium or Pterocladia
Bacteriological grade agar Used for bacterial culture Gelidium or Pterocladia
Finely purified agar Utilizes in biochemistry and microbiology specific bacteria Gelidium

      The FDA (Food and Drug Administration) declared agar as GRAS (Generally Recognized as Safe) in USA. Globally agar is used in a lot of food stuff. It is considered as E406 food additive in Europe. Agar can be found as 9002-18-0 compound in chemical abstracts. It is important to take care of different synergies when dealing with the agar gel. The synergy between agar and locust bean gum in Pterocladia and Gelidium improves the inflexibility and texture, making it additionally palatable due to the elasticity conferred. This synergy also helps in removing the brittleness as well as making the gel less hydrophobic during managing, shipping and storage of the gel. On the other hand synergies of Gracilaria agars with sugars, increases their gelling strength. This occurs only when sugar level is more than 60%, like in jams and jellies.

      Gel drying due air exposure, can be restricted with the use of glycerol or sorbitol in aqueous phase of agar gel preparation. The ambient temperature of agar changes during its life and affects the gel behavior. Agar is tasteless and it is hard to taste it in food stuffs with subtle flavour. However the food stuffs which require cation (like calcium, carragenate, potassium, alginate, etc.) to gel, should be adjoined with strong flavor. Because these cations have stronger taste compared to the agar, and has to be cover up with strong flavors.

      Table 5.3 Region-wise global agar applications [31].

Application/ product Geographical areas
US/Europe Latin America Asia
Jams and jellies Present Present Present
Processed cheese Present Information not available Absent
Farm and dairy products Present Present Present
Wine clarification Present Present Information not available
Gelled meats Present Information not available Present
Dulce de batata Absent Present Absent
Mitsumame Absent Absent Present
Red bean jelly Absent Absent Present
Agar jelly beverages Present Present Present
Ice cream Present Present Present
Milk shakes Present Present Present
Sherbet Present Present Present
Custard pudding Present Present Present
Cakes Present Present

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