Crystal Control Ice cream Flashcards
What is the role of fat coalescence
it will prevent or slow down the ostwald ripening
What is the problem with low fat ice cream
you will have more ostwald ripening because less stability of the air bubbles
What can be added in the case of low fat ice cream to increase the air bubble stability
you can add calcite (caco3 and oleic acid)
what is the problem with low sugar ice cream ?
increased ice crystal size
what can be done to reduce the ice crystal size in the case of low sugar ice cream?
adding protein that will stabilize the ice crystal
how does calcite work to stabilize the air bubbles ?
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)
What does colligative Fp depression means
means that the freezing point depression depends on the quantity of molecules rather than on their chemical nature
T or F : the structure of AFP shows variability
true
what is non-colligative freezing point depression
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)
What is a special property of the non-colligative FPD
the melting point is not the same as the freezing point
At high AFP, the crystal will form a shape of ___
bipyramid
what can explain the thermal hysterisis curve
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
What are the three different ice planes ?
the oxygen atom is in white
how does the AFP binds to the crystal
they recognize the oxygen from the second layer and the threonine binds it
T or F : there are different specifificity of the AFP for the different ice crystal planes
true
T or F : the AFP from insects have more affinity to the ice crystals
true because they create a bigger thermal hysterisis effect
In a AFP, the higher the ____ and the higher is the thermal hysterisis
surface area binding the ice
The ice binding surface is rich in ___ (a.a) and ___ (a.a).
threonine and alanine
The biding the AFP to the ice crystal is due to the a.a. :
threonine
What are the two different hypothesis for the hydrogen binding between the theronine of the AFP and the ice surface
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
What are the advantages of using AFP (also called ice structuring proteins when used in foods)
- smaller particles, improved mouth feel
- more fruit can be incorporated in ice cream
- improved freeze-thaw stability
how does the AFP stabilise the structure of the ice crystals when melting?
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.
this graph is for the top-side of the protein, what could you conclude from this graph
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
this graph is from the bottom side of a AFP, what can you conclude about the affinity for ice crystals ?
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
what can you conclude on the efficacity of gelatin for the ice crystal size with this figure
gelatin is good for the freeze-thaw stability of the ice cream and could be an alternative to the use of AFP
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
that it is the smaller peptides (ellutes last) that creates the most homogenous ice cream (higher absorbance)
What is the sequence of a.a in gelatine that is responsible for the oxygen triad plane (ice binding properties)
Sequence : glycine-x-z
x-z position can be : alanine, serine, threonine, glycine, proline, hydroxyproline
