Interactive numerical educational resources for the analysis of complex media
Analysis of dietary fat
Welcome
In this part, we are presenting a note about the analysis of dietary fat
The aim is to help you to select the right fat
according to the application you want to perform
but also to give you some knowledge about the quality of dietary lipids
But first, I will remind you some properties of dietary lipids
They are defined by a common property
they are not soluble in water
but are partially or totally soluble in organic solvents
Therefore, there are a lot of different molecules in dietary lipids
There are mainly fatty acids
either free fatty acids
but most of the time, esterified fatty acids
e.g. triacylglycerols or phospholipids
In the dietary lipids, there are also a lot of micro-constituents
like sterols (phytosterols in vegetal oils or cholesterol in butter)
tocopherols
(as alpha-tocopherol which gets interesting vitamin E activity)
liposoluble pigments
(carotenoids)
but also all phenolic compounds
that can be found in some dietary oils
like olive oil
(tyrosol or hydroxytyrosol)
All these dietary lipids
get a lot of different functions in food
First of all, they get nutritional functions
Indeed, they take part into the energy supply provided by the food
they are a source of fatty acids
in particular essential fatty acids
as linoleic acid
(omega 6 precursor) or alpha-linolenic acid (omega 3 precursor)
Moreover, they bring and drive liposoluble vitamins
and other essential constituents as sterols
Lipids also take part to the organoleptic quality of the food
They are indeed responsible for the creamy texture
as well as the shiny aspect of food
Finally, they add a specific flavour
Last but not least
dietary lipids get technologic functions
They are used as heat transfer
for different cooking operations as the frying
They also can be used as coating agents
and they are able to bring some aromas or liposoluble compounds
These different functions are directly linked
to the chemical structure of these compounds
like the length of their carbon chain
or their number of unsaturations
But they are also linked to their physico-chemical properties
like the melting point
and to their chemical reactivity
which will be important during the production of food products
their use or their consumption
Why would you need to analyse dietary fats?
First, in order to know the composition
that means to know the quantity of each compound previously mentioned
e.g. fatty acids’ profile or content of vitamin E
These kind of information
will help you to know the properties of the fat
and also, to identify the possible applications
Moreover
these analyses could help you to assess the fat quality
Indeed, during the production and storage of food products
dietary fats are subjected to some reactions
For example, triacylglycerols or phospholipids
can be hydrolysed
Therefore, free fatty acids are released
which leads to a lower lipid quality
Also
unsaturated fatty acids can be subjected to isomerisation reactions
which will form trans fatty acids
Finally
oxidation reactions could occur
These complex reactions will produce a lot of different compounds
Among them, some volatile molecules
(as aldehydes, ketones or acids)
will be responsible for the rancidity of food products
So, in this note
you will find different analysis methods of dietary fats
For each method, we will remind you the theory
we will present you the procedure that you can perform
during your laboratory project
and finally, we will give you some information
to help you to understand your results
and to identify the interesting fats for your project
Analysis of dietary fat
Interactive numerical educational resources for the analysis of complex media