Food chem lecture 5 recall part 2

Question 1

Hydrocolloids

Answer 1

Hydrocolloids are carbohydrates that crosslink with one another to form gels by creating juctions through crosslinking and increase the viscosities of a solution and to stabalize emulsions. Choosing a hydrocolloid depends on a variety of conditions such as the type and degree of impact you want to have on a solution.

Question 2

Xanthan gum

Answer 2

Long cellulose chain with trisaccaride side chains which make it stiff, give it a large hydrodynamic volume and cause it to have a large viscosity. It starts out with a large viscosity but quickly declines once you apply shear stress to it and can interact with locus bean gum to produce a gel and increase viscosity with guar gum.

Question 3

Gum Acacia

Answer 3

Made up of glycoproteins and carbohydrates which give it emulsifying abilities. The glycoproteins act as the hydrophobic body while carbohydrates act as hydrophilic steric repellants to other particles suspended by guma acacia. The viscosity is low even for high concentrations and it can form a stable and strong gel.

Question 4

Red Seaweed:

Answer 4

These are polymers with alpha 1,4 and beta 1,4 links which connect galactose units to one another. There exist in many forms such as agar

Question 5

Agar

Answer 5

This is made from agarose a dissaccaride that is very flexible and produces solutions of low viscosity because it is so. It also produces gels by binding to locus bean gum.

Question 6

Carrageenan

Answer 6

Consists of three forms kappa, lambda and iota. Kappa carrageenan and iota produce gells when in double helix form and/or in the presence of locus bean gum or ca2+ ions while lambda only increases viscosity

Question 7

alginate

Answer 7

Contains exclusivly mannose units, galactose units and a mixture of them. The galactose units that the chain makes up binds to ca2+ ions and to form a gell based junction while the mannose units do not and ca2+ can be added after alginate is added to produce an outer gel skin or before such that it is slowly added at a time»>emulsion droplet releases.

Question 8

Propylene glycol alginate

Answer 8

Alginate with propylene glycol group that prevents it from binding to ca2+ and forming gels. It is instead used to stabalize foam and emulsions.

Question 9

Pectin

Answer 9

Made up of galacuronic units that either exist as low methoxy pectin or high methoxy pectin and either form gels through ca2+ ions or interaction between galacturonic groups. It can be used to produce fruit jellies and jams.

Question 10

Gellan gum

Answer 10

Used to produce fluid gels and create emulsions without increasing viscosity by much and consist of low acyl chains and high acyl chains (low produces hard gels and high which produces soft gels).