Lipids Flashcards
What is a lipid?
It is a substance that is soluble in non-polar solvents.
What are some naturally occurring lipids?
Waxes, Fats, Sterols and some Vitamins (A, B, E and K)
What are the two general categories of lipids in food?
Oils, being liquid lipids
Fats, being solid Lipids
What qualities of food do lipids effect?
Texture, Flavour, Stability, Nutrition and Available Energy.
What is the major component of lipids?
Lipids are typically consist of fatty acids, which are long carbon chains consisting between 14 - 24 carbon count (14 - 24, always even). Fatty acids have a carboxylic group on the end of the chain.
What is the difference between a saturated and unsaturated fat?
A saturated fat consists of no double/triple bonds as it has bonded with hydrogen as much as feasibly possible.
An unsaturated fat consists of at least one double, and is therefor possible to undergo hydrogenation.
In terms of fatty acid structure forming, what effect does a double carbon bond cause?
A naturally occurring formation of a carbon bond causes an interruption of bond rotation, as there is a preference to form the bond on the ‘same side.’ This would be known as a -cis structure.
What is a -trans structure?
If in a carbon chain a double bond forms whilst maintaining the bond rotation a -trans structure is formed. This formation is typically unfavourable and generally unnatural.
In consumption, what is the difference between a cis-fat and a trans-fat?
The human body is capable of metabolising cis-fats, however ill-suited to metabolise trans-fats. The consumption of trans-fats can cause a build in systems such as the eyes.
How does a cis-bond react to temperature and density?
A cis-bond causes a lower melting point, such as in margarine. In some products a cis-bond will be hydrogenised in order to raise the melting point of a product.
A cis-bond will also decrease density.
How do we name a fatty acid?
The prefix- is the IUPAC name for the carbon count
The -body- is defined by amount of double bonds (0 = an , 1 = en, 2 = dien)
the -Suffix is ‘oic’ acid as fatty acids contain a carboxylic functional group.
There are two ways to number count carbons in a chain, what are they?
You have the delta method, which counts from the carboxylic group.
There is a omega method which counts from the methyl group on the other end.
What is cyto-toxicity
it is a substance that is toxic to cells.
How are fatty acids typically found in animals?
As free fatty acids are typically cytotoxic, the are esterified with glycerol to decrease toxicity and create a unit for energy storage.
What is triacylglycerol?
It is a glycerol unit that has esterified with with three free fatty acids (same or different) to create a stable energy unit.
How does the climate effect the production of Fatty Acids?
A colder climate will allow for more unsaturated fats to be produced, as there is no need for the higher melting point you would get from saturated fats.
A warmer climate will produce more saturated fats to prevent the liquification of fatty acids in the body.
What is the smoke point?
The smoke point is the temperature that fats start to decompose. This gives of volatile products that have been broken down.
What is a volatile?
It is a product that readily evaporates under normal conditions.
What is a flash point and a fire point?
The flash point is where enough volatiles from the decomposition are produced from heat that it causes an unsustainable combustion.
The fire point is where the volatiles produced can create a sustained combustion
