FATS AND OILS
· Oils are liquid at room temperature but
solidify at - temperature. The commonly
used cooling oils are - oil , sesame oil , cotton sew oil, olive oil ,
peanut oil . corn oil
and sunflower oil.
Hydrogenation of oils:
Whale oil, cotton seed oil, soya been oil , peanut oil, etc are sold
as
shortening of varying consistencies .
The conversion of oil into fat is brought about by a process known as
the
hydrogenation .
Treating oil under presence of a catalyst, usually under these condition the unsaturated fatty
acids present in the oil combine with hydrogen. This chemical process beings
about a physical change, the liquid of become solid fat.
Fats are used in covering either as shortening agent or as frying
medium.
Fats are used in confection any to enrich the food and to import to
them short eating
qualities. Collectively they are referred to as shortening agent.
There effect is to be breakdown or destroy the toughness of gluten ,
so that instead of being long and sough to eat food containing fat brave of
short and really melt in the mouth.
As shortening agent Fat add up:
* Nutrition value.
* contributes for flavour and texture .
The type of fat and the way in which fat is incorporated affect the
texture as in short Crust pastry flaky pastry, puff pastry.
As the melt fat, cooling must be done at the correct temperature So
that the flour can absorb the fat as it melt .
Set the heat is insufficient the fat runs out of the mixture and is
wasted besides leaving the food fought and oily.
Fat as a frying medium function in 3 ways:
1. Transfer heat to the food to be fried.
2. It add nutritive value of the food.
3. It contributes to the flavour of the food.
Fat used for frying should have a high smoking point and low moisture content,
and high stability and a acceptable flavour.
Rendering of fats :
The process of melting to extract fat from fatty Tissues good soppy of
dripping
can be obtained by rendering down suet fat surrounding the kidney of
low or sheep and
pieces of fat and from meat.
Rancidity generally is the complete or
incomplete oxidation or hydrolysis of fats and oils when exposed to air, light,
or moisture or by bacterial action, resulting in unpleasant taste and odour.
Actions Of Heat On Fats
Fats are present in meats , poultry , fish , egg , milk products nuts
and grains and to a lesser
extent vegetables and fruits .
Fats are also important as cooling medium as for trying fats are
either solid or liquid at room
temperature . Liquid fats are called as oils .When solid fats vary. When
the fats are heated,
they begin to break down from solid to liquid . The melting point of
solids fats varies .when
the fats are heated , they begin to break down . When hot enough, they
deteriorate rapidly
and smoke the temperature at which this happens is called the smoke
point and it varies by
type of fat it stable fat one with a high smoke is an important
consideration in deep fat
frying .Continuous use of fat deteriorates because of excessive
temperature , moisture , air and the presence of carbonized crumbs and small pieces
of food to a point where it will just bubble in the pan , too where to perform
the action of frying . Fat begins to thicken, becoming gummy like substance. This
condition is known as BLYMENIZATION , and fat that has reached this stage is no
longer fit to use .