Friday, March 2, 2018

CINOGEL Gellan Gum:Hydrocolloid Formula-Agar

what is Agar?

Nameagar (E406)
Originpolysaccharide obtained from red algae
(several species)
Properties,
texture
thermoreversible, heat resistant, brittle gel;
high hysteresis
Clarityclear to semi-opaque
Dispersionin cold or hot water
Hydration
(dissolution)
> 90 °C; heating to boil necessary for gelling.
pH2.5-10
Setting35-45 °C, rapid (minutes)
Melting80-90 °C%
Promotersugar; sorbitol and glycerol improve
elasticity, stronger gel at higher pH
Inhibitortannic acid (counteracted by add. of
glycerol); prolonged heating at pH outside
the range 5.5-8
Toleratessalt, sugar, alcohol, acid, proteases
Viscosity of
solution
low
Typical
concentration

0.2% will set, 0.5% gives firm jelly, [0.07-
3%] *
Synergies
locust bean gum (only with certain agar
types)
Syneresis
yes (can be prevented by replacing 0.1-
0.2% agar with locust bean gum)

recommend tips for agar:

  • Addition of glycerol or sorbitol can prevent
    dehydration of the gel
     
  • When replacing gelatin or pectin for gels,
    use 2-3 and 10 times less agar
    respectively
      
  • For "raw" preparations dissolve agar in
    small quantity of water. Heat remaining
    solution to 35-45 °C and mix with agar
    solution
     
  • If left uncovered agar gels dry out, but if
    immersed in water or other liquid it swells
    and retains its original shape
  • A special property of agar is the large
    difference between the gelling temperature
    and the melting temperature. This is known
    as hysteresis
     
  • The minute amounts of agar needed can
    be difficult to measure. One trick is to make
    a 0.1x strength agar by mixing 10 g of agar
    with 90 g of sugar. For a recipe that calls
    for 0.5 g agar you then use 5 g of the 0.1x
    agar/sugar mixture. But keep in mind that
    you do add a small amount of sugar, so
    this is not suitable in every recipe 
  • Agar alone forms brittle gels, but in
    combination with locust bean gum elastic
    gels may be obtained.
      
Keywords:hydrocolloid,agar
Supported by: CINOGEL BIOTECH,available at: cinogel.com
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