Selection of polysaccharides

Question 1

Desired functionality in gelling behaviour:

Answer 1

1. Firm, brittle: LA (low acetyl) gellan gum, agar, K-carrageenan
2. Middle
3. Soft, flexible: Xanthan/LBG, HA(high acetyl) gellan gum, gelatin.

Question 2

Stability under product and process conditions: carrageenan.

Answer 2

Carrageenan is sensitive to hydrolysis of anhydro-galactose unit at lower pH. So it cannot be used in all different applications. If you heat up at a lower pH the anhydrogalactose residue will be degraded and the polymer will be degraded in smaller molecules affecting the gel strength, lowering.

Question 3

Stability under product and process conditions: HM pectin.

Answer 3

High methyl pectin is sensitive for β-elimination at higher pH values and higher temperature next to methylester you will have a splitting of the backbone ending up with a unsaturated galacturonic acid residue, ending up with small molecules.

• HM pectin: beta elimination consequently a very low gel strength.
• LM pectin: much less methylester, will end up to be more stable, when heated at higher pH´s.

Question 4

Stability under process and product conditions

Answer 4

• Esters as present in e.g. pectin, xanthan, gellan, might be removed at higher pH’s
• Alginate and low methyl pectin might be over reactive towards high levels of calcium present giving strong gels. This is not the case for dairy products, you have a higher level of calcium, but most of the calcium is bound by the protein.

Question 5

Why are not all ice cream manufacturers using one single ideal recipe for producing the ultimate quality ice cream?

Answer 5

There is no ideal recipe for ice cream nor for ice cream stabilisation!
The selection of a specific hydrocolloid may depend on precise recipe, process, and availability/price of hydrocolloid.