Determination of melting points of FATS

1. Fats and oils are important parts of human diet.
Fats and Oils are a rich source of dietary energy
and contain more than twice the caloric value of
equivalent amount of sugar. They contain certain
fatty acids which play an important role in
nutrition and are also carriers of fat soluble
vitamins.

2. Fats and Oils are chiefly mixture of
triglycerides. They do not exhibit either a
definite of sharp melting point. Therefore the
melting point does not imply the same
characteristics that it does with pure crystalline
substances. Fats pass through a stage of
gradual softening before they become
completely liquid. The melting point is
therefore defined by the specific conditions of
the method by which it is determined.

3. A) Lard
B) Olive oil
C) Safflower oil
D) Butter
These four
tubes have
been removed
from the
freezer (a bit
colder than 0'
C or 32' F, the
freezing point
of water.)

4. Notice that the lard (A),
and butter (D) are solid,
while both oils (B,C)
remain liquid despite
the freezing
temperature. As the
tubes warm up to room
temperature (about 21'
C, or 72' F), they remain
much the same. The lard
and butter stay solid,
and the oils stay liquid.
This shows that the
melting points of the oils
are lower than 0' C
(because even freezing
didn't make them solid),
and the melting points
for the lard and butter
are higher than room
temperature.

5. After being heated for a
few minutes at 37' C
(human body
temperature, or 98' F)
the butter (D) has
melted.
The lard (A) remains
solid, and the oils
remain liquid. This
demonstrates that the
melting point of
butter is higher than
room temperature but
lower than the
temperature of the
human body.

6. PRINCIPLE:
The temperature at which the oil or fat
softens or becomes sufficiently fluid to slip or
run as determined by the open-tube capillary-
slip method.
INTRODUCTION:
The slip melting point or “ SLIP POINT ”
is one conventional definition of the melting
point of a waxy solid. It is determined by
casting a 10 mm column of the solid in a glass
tube, then immersing it in a temperature
controlled water bath. The slip point is the
temperature at which the solid begins to rise in
the tube due to buoyancy and because the
outside surface of the solid is molten.

7. APPARATUS:
a) Melting point tubes -thin walled with uniform
bore capillary glass tubes open at both ends with
following dimensions:
Length 50 to 80 mm
Inside diameter 1.0mm
Outside diameter 2.0 mm
b) Thermometer with 0.2ºC sub-divisions and a
suitable range. The thermometer should be checked
against a standard thermometer which has been
calibrated and certified by National Physical Laboratory
New Delhi or any other laboratory approved for
calibration of instruments.
c) Beaker (1000ml) with a side tube heating
arrangement – Thiele melting point tube may be used.
d) Heat source: Gas burner or Spirit Lamp or electric
hot plate with rheostat control.

8. PROCEDURE:
 1cm length of fat or oil which has been melted into a
capillary tube was inserted using a piece of filter paper.
 The capillary tube was cooled at a temperature < 0
degree C for 2 hours.
 This tube was submerged in water so that the top end
of the fat or oils is 1 cm below the level of water.700 ml
water contained in a 1000 ml beaker.
 A thermometer was hung in the middle of the beaker.
The water was heated at the rate of 10 degree C per
minute.
 The temperature was recorded at which the fat starts to
slip out of the tube and also the final temperature
when all the fat has slipped out of the tube. This
temperature or range of temperature is referred to as
the slip point ( or melting point).

10. SOUNDARYA VIJAYAKUMAR