Crystal Control Ice cream

Question 1

What is the role of fat coalescence

Answer 1

it will prevent or slow down the ostwald ripening

Question 2

What is the problem with low fat ice cream

Answer 2

you will have more ostwald ripening because less stability of the air bubbles

Question 3

What can be added in the case of low fat ice cream to increase the air bubble stability

Answer 3

you can add calcite (caco3 and oleic acid)

Question 4

what is the problem with low sugar ice cream ?

Answer 4

increased ice crystal size

Question 5

what can be done to reduce the ice crystal size in the case of low sugar ice cream?

Answer 5

adding protein that will stabilize the ice crystal

Question 6

how does calcite work to stabilize the air bubbles ?

Answer 6

CaCO3 has an hydrophilic nature and then oleic acid is hydrophobic and so it gives stabilisation of the air bubbles by pickering interactions (solid at the interphase)

Question 7

What does colligative Fp depression means

Answer 7

means that the freezing point depression depends on the quantity of molecules rather than on their chemical nature

Question 8

T or F : the structure of AFP shows variability

Answer 8

true

Question 9

what is non-colligative freezing point depression

Answer 9

a freezing point depression that depends on the chemical nature of the molecule and not on the concentration of the molecule (this is colligative FPD)

Question 10

What is a special property of the non-colligative FPD

Answer 10

the melting point is not the same as the freezing point

Question 11

At high AFP, the crystal will form a shape of ___

Answer 11

bipyramid

Question 12

what can explain the thermal hysterisis curve

Answer 12

the AFP will bind the surface of the crystal and create a curvature that prevent the water molecules to be added to the surface of the crystals

Question 13

What are the three different ice planes ?

Answer 13

the oxygen atom is in white

Question 14

how does the AFP binds to the crystal

Answer 14

they recognize the oxygen from the second layer and the threonine binds it

Question 15

T or F : there are different specifificity of the AFP for the different ice crystal planes

Answer 15

true

Question 16

T or F : the AFP from insects have more affinity to the ice crystals

Answer 16

true because they create a bigger thermal hysterisis effect

Question 17

In a AFP, the higher the ____ and the higher is the thermal hysterisis

Answer 17

surface area binding the ice

Question 18

The ice binding surface is rich in ___ (a.a) and ___ (a.a).

Answer 18

threonine and alanine

Question 19

The biding the AFP to the ice crystal is due to the a.a. :

Answer 19

threonine

Question 20

What are the two different hypothesis for the hydrogen binding between the theronine of the AFP and the ice surface

Answer 20

hypothesis 1 : the binding of threonine is between the oxygen of water from the first layer and the hydrogen from threonine
hypothesis 2 : the binding happens between the oxygen from threonine and the hydrogen from water from the second layer

Question 21

What are the advantages of using AFP (also called ice structuring proteins when used in foods)

Answer 21

1. smaller particles, improved mouth feel
2. more fruit can be incorporated in ice cream
3. improved freeze-thaw stability

Question 22

how does the AFP stabilise the structure of the ice crystals when melting?

Answer 22

When melting the nice hexagonal structure of the ice is usually lost. when AFP are present, they set the ice crystal in a certain way.

Question 23

this graph is for the top-side of the protein, what could you conclude from this graph

Answer 23

that the bidning of the AFP to the ice crystal is due to the top-side of the proteins since the thermal hystersis is loss when changing the TH for tyrosine

Question 24

this graph is from the bottom side of a AFP, what can you conclude about the affinity for ice crystals ?

Answer 24

that there is not much change in the termal hysterisis (affinity of the protein for the ice crystal) when the threonin from the bottom side are replaced for tyrosine.
Bottom side is not involved in ice crystal binding

Question 25

what can you conclude on the efficacity of gelatin for the ice crystal size with this figure

Answer 25

gelatin is good for the freeze-thaw stability of the ice cream and could be an alternative to the use of AFP

Question 26

Whart can you conclude from this figure of the separation of gelatin upon size exclusion chromatography and the measurment of the absorbance of the ice cream

Answer 26

that it is the smaller peptides (ellutes last) that creates the most homogenous ice cream (higher absorbance)

Question 27

What is the sequence of a.a in gelatine that is responsible for the oxygen triad plane (ice binding properties)

Answer 27

Sequence : glycine-x-z
x-z position can be : alanine, serine, threonine, glycine, proline, hydroxyproline