Lipids Flashcards
How many possible FA variations are there?
27
What factors affect melting points of FA?
chain length
degree of unsaturation
What is tempering?
Controlled crystallisation
- liquid is cooled then reheated to 32 degrees, stirred to form small beta crystals and then solidified
Identify the sources of TGs
Ruminant milk fat
- branched, short chain trans FAs
Vegetable oil/ fat
- seeds and oils have a low concentration of FAs
- vegetable oil has a high unsat: sat ratio
Animal fat
- fully saturated, solid at room temperature
Marine oils
- low in sat FAs, liquid at room temperature due to long chain PUFAs
What are two examples of plastic fats?
Butter
Margarine
Which kind of butter gives chocolate its unique properties?
Cocoa butter
What happens to allow FA to melt
the intermolecular bonds are broken by heat
What happens to allow FAs to melt
the intermolecular bonds are broken by heat
How does chain length affect MP
longer the chain, more bonds, more heat required to break bonds and melt FA
How does the degree of unsaturation affect MP
The more saturated a fatty acid, the higher the melting point.
The more unsaturated, the lower the melting point- there are more double bonds, this reduces the packing of chains and therefore there are less van de Waals interactions hence the lower melting point as less energy is required to break the bonds
This phenomenon deals with intermolecular interactions of fatty acids.
TG are polymorphic and so can exist in more than one crystalline form- what are they?
Alpha, beta prime, beta
What does the final form of a TG structure depend on?
The cooling technique
Which polymorphic state is formed by rapid cooling?
Alpha
Which polymorphic state is formed by moderate cooling?
Beta prime
Which polymorphic state is formed by slow cooling?
Beta
