Galactomannans Flashcards
Galactommanans in food applications ?
-To control the viscosity (alone).
-To control gel texture (with other food gum)
- Emulsifier
- Properties like viscosity and gelling power strongly depend on type of GM.
- Frequently used in combination with other gums like carrageenans, xanthan, starches:
● increase in gel strength
● different gel structure
● Lower dosages
Processing of galactomannans:
From seed pods of trees/plants–>dehulling–>milling seeds–>galactomannan
Galactomannans structure:
There are a storage polysaccharide present in many seeds
- Backbone of ß-1,4-linked mannose residues
- Substitution at O-6 with single unit side chains of α-linked galactose
All types of galactomannans:
- Gal:Man ratio differs
- casia gum G:M = 1:8
- locust bean gum G:M = 1:4
- tara gum G:M = 1:3
- guar gum G:M = 1:2
- fenugreek gum G:M = 1:1
What is the main difference between galactomannans and cellulose?
Is the position of the hydroxyl group at O2. The galactose substitution prevents those aggregation and you may even high solubility. Solubility depends on level and distribution of galactose.
Having less substitution in the molecule means that you have a stronger gel, in combination for example with xanthan. TRUE OR FALSE?
TRUE
Interaction between galactomannan and xanthan: And what effect has on the hardness of the gel obtained?
- Helix form of xanthan together with locust bean gum or galactomannan.
- Between 30% xanthan in locust bean gum till 70% you can really manipulate the hardness, the flexibility of your gel.
How to explain the great solubility of guar gum, as well as its poor gelling behaviour in an interaction gel with xanthan?
*Due to 1:2 substitution with galactose, guar gum is highly soluble. However, not enough neighbouring unsubstituted mannose residues are present in the backbone to form a junction zone with xanthan.
