Molecular properties and structure of lipids Flashcards
viscosity and consistency
The thickness or resistance to flow that an a liquid expereinces whereas consistency is the resistence to flow a semi solid experiences. The longer the chain the greater the viscsoity and consistency due to a greater experience in molecular drag.
phospholipids
Due to their ampiphilic nature they have a strong polar binding capacity which makes their viscosity very strong.
double bonds and single bonds
the greater the number of double bonds in a molecule the less ability it has to align with other chains causing a decrease in viscosity due to a decrease in the number of intermolecular associations between each other.
trans vs. cis
Trans double bonds contain pi orbitals aligned with one another which prevents bending of the chain from occuring enabling alignment but disables alignment due to election-electron repulsion caused by the pi orbitals resulting in a moderate decrease in viscosity and melting point»> weaker and lesser intermolecular interactions between chains. Cis double bonds causes bends in fatty acid chains which prevent alignment decreasing melting point and viscosity to the maximum level.
melting points
Refers to the amount of energy needed to seperate chains from one another in solid or semi solid fats.
Factors that affect melting point:
Double bonds-decrease melting point
shorter chains-decrease melting point
crystal structure and polymorphism of fats and oils
alpha crystals-when a fat is heated and cooled down to produce tag’s far apart from one another. This is a meta stable and intermediate stage used for rarely soft food products.
B prime crystals-organized in parrellel and anti parrelell orders of tag’s. The space between these rows allows for air to be captured resulting in areation of food products liked baked goods.
Beta products: tag’s are packed very tightly to produce hard crystalized solid fats used for hard bread and chocolate.
plasticity of fat
fats often contain a wide range of fatty acids which various parts of them to solidify and melt at a variety of temperatures giving them different levels of solidity and crystalinity. They melt at a slower temperature and are able to hold their structure across a wide temperature range.
Conjugated double bonds
when double bonds are only seperated by one methyl group the electrons from each pi orbital are evenly distributed amongst one another making the p orbitals more closely aligned with another decreasing bending, the melting point and viscosity.
hydrolyis of fatty acids:
Many times h bonded dimers form when fats are placed in water resulting in difficulty seperating them through heat. This can be fixed by exterfying fatty acids to prevent h bonding reducing melting point and viscsity.
