Week 7

Question 1

Gel

Answer 1

A gel is a liquid suspended in a solid matrix. The solid matrix is a polysaccharide which can bind together in different ways and under different conditions. this matrix extends in three dimensions and traps large amounts of liquids, like a sponge.

Question 2

Mixed gel

Answer 2

.

Question 3

Junction zone

Answer 3

Junction zones are the main aspect that allows a polysaccharide to gel. The extent to which a chain will interact with another can determine how strong the gel is.

Question 4

Molecular irregularity

Answer 4

This describes the irregular nature of a molecule in regards to its charge and branches. These play important roles in how the chain will behave. For example, if a polysaccharide chain has irregularly spaced branches, it is more likely to interact with other chains and form and form junction zones. The length of these junction zones is also a function of how irregular the branches are.

Question 5

Kappa-carrageenan

Answer 5

This is the carrageenan with the least amount of charge, it is in a double helices form and forms a gel after heated and cooled in the presence of potassium ions. This gel is stiff and brittle. Strongest of the carrageenan gels.

Question 6

iota-carrageenan

Answer 6

Also has a double helix form and forms a gel upon heating and cooling. It gels in the presence of calcium and forms a soft and resilient gel. This type of carrageenan is more soluble in water and thus is more stable than the kappa form.

Question 7

Lamba-carrageenan

Answer 7

This type does not gel because all salts are soluble because of high charge density

Question 8

g-block

Answer 8

This is a portion of an algin that has only L-guluronopyranosyl units. These blocks have a pleated or corrugated confirmation. Gels made with higher proportions of g-blocks will be stronger.

Question 9

m-block

Answer 9

This is the portion of an algin that has only D-Mannuronopyranosyl units. This causes these blocks to have a flat, ribbon like conformation like cellulose because of the bonding pattern.

Question 10

Egg box model

Answer 10

The egg box model describes how alginates, carrageenan, and low methoxyl pectins are able to form gels. These molecules have high negative charge densities on the chain which means that they normally would not interact with one another. If you introduce cations into the mix they are able to bind with the negative charges of two different chains and pull them together. The cations become a bridge between the two chains and the resulting structure looks like an egg carton.

Question 11

High methoxyl pectin

Answer 11

High methoxyl pectin has more than 50% of its carbonyl groups are methyl esters or they have been oxidized and have a negative charge. In order for this substance to form a gel, the pH of the environment need to be low in order to get rid of some of the negative charges and reduce the hydration of the chain. This opens up sites on the HMP molecule to be able bind with other molecules. In addition to this, a large amount of sugar must be added to occupy some of the surrounding water molecules and prevent them from rebinding to the chain.

Question 12

Low methoxyl pectin

Answer 12

LMP can form a gel in less strict environments, only requiring calcium ions to bind. This creates a junction zone of the egg box model

Question 13

Soluble fiber

Answer 13

These are polysaccharide that are soluble in water and are able to be absorbed by the body

Question 14

Insoluble fiber

Answer 14

these are polysaccharides which are NOT soluble in water and act as ruff-age in the digestive system, pushing material through and cleaning it out.

Question 15

Resistant starch

Answer 15

These are starches that are resistant to digestion in the small intestine. They therefor act as a prebiotic for the microbes in your lower intestine.

Question 16

Prebiotic

Answer 16

A prebiotic is a food source for the bacteria in the gut. It is often fiber that is not absorbed by the body in the small intestine.