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.
5.9 Uses of Agar in Various Sectors
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 |
5.9.1 Applications of Agar in Food Industry
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 |
|