Various Food Gums

Question 1

Food gums for specific applications

Answer 1

1. Xyloglucan: storage polysaccharide (tamarin seeds)
2. Gum arabic: tree exudate
3. Cellulose: plant material

Question 2

Food applications of tamarind xyloglucan:

Answer 2

• Seed from tamarind tree
• Highly stable to heat, pH, shear
• Close to Newtonian flow behaviour (viscosity depends on the concentration).
  Applications:
• Thickener for sauce, ice cream, dressing, fruit beverages
• Jellies
• Noodles (preventing starch aging)

Question 3

Structure of the xyloglucan:

Answer 3

Repeating units. It is a beta1,4-linked glucose, where you have every four glucose, you have a substitution by 3-alpha-1,6-linked xylose residues. On this xylose you may or not have a galactose as a further substitution.
E.g: XXXG repeating unit.

Question 4

Food applications of gum Arabic

Answer 4

• Exudate of e.g. Acacia senegal
• Contains 3% hydrophobic polypeptide with a bulk of arabinogalactan (70-80% galactose + arabinose, and some rhamnose and glucuronic acid)
  Applications:
• Confectionery (winegums, marshmallows, toffees)
• Stabiliser of e.g. citrus and cola flavour concentrates
• Flavour encapsulation

Question 5

Structure of gum arabic:

Answer 5

• Polypeptide chain with the carbohydrate blocks (mol mass 200.000).
• Water blossom model.
• 1,3 linked galactan backbone substituted at O6 and the side chains of galactose and rhamnose, arabinose and glucuronic acid.

Question 6

How can gum arabic stabilize oil droplets?

Answer 6

In fact the molecule shape reshuffles when you have a water and oil mixture, and the protein part is in the oil phase and the hydrophilic carbohydrates parts are in the water phase and you have strong emulsifying properties.

Question 7

Food applications of cellulose

Answer 7

• Cellulose as bulking agent as is highly insoluble: filling agent and as a dietary fiber.
• Cellulose derivatives having tailored functionalities by changing solubility, hydrophobicity, hydrophilicity, charge.
• Physically modified cellulose:
• Microfibrillated– holds water, pseudoplastic.
• Microcrystalline– pseudoplastic.
  Applications:
• Sauces, baked goods, whipped toppings, reduced-fat foods.

Question 8

How can we make the microcrystalline cellulose ?

Answer 8

Beta glucan chains in cellulose fiber are organized rather in a crystalline manner or amorphous. If you then add acids, with higher temperature you only hydrolyze the amorphous parts, the crystalline parts are resistant to the hydrolysis, you end up with microstructures in a very fine powder.

Question 9

Two different types of MCC:

Answer 9

1. If you freeze dry this powder you will end up with very porous aggregates. Can be use for flavour carrier and anticaking agent.
2. If you separate those particles after hydrolysis, by high shear , high energy, you end up with extremely small particles of the same size, uniform particles and you have a very nice stabilization of foam and emulsions, especially in high T-processing.

Question 10

Can you explain why gum Arabic is highly soluble and a

good emulsifier?

Answer 10

The high level of branching of gum Arabic explains the high solubility (flexible O1,3, galactan chain with many branches and the charges in the side chain ) while only 3% of the protein explains the emulsifying properties originate from the polypeptides present within the gum Arabic structure