2. Title of experiment:
Title of experiment:
Determinatiom of acid value
Determinatiom of acid value
Objective:
Objective:
To determine the acid value of sample of
To determine the acid value of sample of
fat and oil.
fat and oil.
Introduction and principle:
Introduction and principle:
The major constituents of fats and oil are
The major constituents of fats and oil are TAG
TAG.
.
Although some free f.as are also usually present
Although some free f.as are also usually present
and contribute to the acidity of the fat or oil.
and contribute to the acidity of the fat or oil.
These free f.as and any other acids which may be
These free f.as and any other acids which may be
present, may be neutralized with
present, may be neutralized with KOH
KOH in the
in the
determination of the acid value,
determination of the acid value,
3. Acid value is defined
Acid value is defined as the no. of mg
as the no. of mg
of KOH required to neutralize the
of KOH required to neutralize the
free f.as in one gm of fats or oil
free f.as in one gm of fats or oil
.
.
The saudi
The saudi STD
STD for edible fats and oils
for edible fats and oils
indicate that the acid value must
indicate that the acid value must
not exceed
not exceed 0.6 mg KOH/1gm
0.6 mg KOH/1gm
.
.
4. Method
Method
:
:
1
1
-
-
weight 5 gm of sample
weight 5 gm of sample
.
.
2
2
-
-
dissolve the sample in 50 ml ethanol
dissolve the sample in 50 ml ethanol
3
3
-
-
titrate the mixture using 0.1M NaOH
titrate the mixture using 0.1M NaOH
solution with
solution with ph.ph
ph.ph as indicator
as indicator
4
4
-
-
acid value
acid value =
= 0.561
0.561*
* titre
titre /
/ weight of
weight of
sample
sample
.
.
5. Determination of S.G of fat and oil
Determination of S.G of fat and oil
.
.
Objectives
Objectives
:
:
To determine the S.G of samples of fat
To determine the S.G of samples of fat
and oil
and oil
.
.
Introduction and principle
Introduction and principle
:
:
The S.G of fat or oil is one of it’s
The S.G of fat or oil is one of it’s
characteristic physical properties
characteristic physical properties
.
.
All fat and oil have S.G of
All fat and oil have S.G of less than 1
less than 1
Where S.G defined as
Where S.G defined as
:
:
6. The density of the sample relative to
The density of the sample relative to
density of water at the same temp
density of water at the same temp
.
.
Since, S.G is the
Since, S.G is the temp.-dependant
temp.-dependant, it’s
, it’s
determination should be carried out at
determination should be carried out at
a specified constant temp. each time
a specified constant temp. each time
.
.
This is usually
This is usually 40C
40C for afat and
for afat and 20C
20C an oil
an oil
.
.
7. Method
Method
:
:
1
1
-
-
clean S.g bottle by shaking with acetone then
clean S.g bottle by shaking with acetone then
ether
ether
.
.
2
2
-
-
weight empty S.G bottle
weight empty S.G bottle
.
.
3
3
-
-
fill the S.G bottle with the sample and cover it
fill the S.G bottle with the sample and cover it
.
.
4
4
-
-
weight the fill S.G bottle
weight the fill S.G bottle
.
.
5
5
-
-
repat using Dis.water in place of the sample
repat using Dis.water in place of the sample
.
.
6
6
-
-
calculate
calculate
:
:
S.G
S.G = weight of the sample in S.G bottle
= weight of the sample in S.G bottle /
/ weight
weight
of water in S.G bottle
of water in S.G bottle
.
.
8. 3
3
-
-
Determination of saponification value
Determination of saponification value
.
.
Introduction and principle
Introduction and principle
:
:
The saponification value
The saponification value is
is the no. of the
the no. of the
mg of KOH required to saponify one gm
mg of KOH required to saponify one gm
of an oil or fat
of an oil or fat
.
.
The vast majority of f.as in neutral fat and
The vast majority of f.as in neutral fat and
oil are in ester linkage with glycerol in
oil are in ester linkage with glycerol in
the form of TAG and may be liberated
the form of TAG and may be liberated
by hydrolysis at either acidic or alkali is
by hydrolysis at either acidic or alkali is
termed (
termed ( saponification
saponification )
)
.
.
10. On the other hand, vegetable oil and fat
On the other hand, vegetable oil and fat
will
will
tend to have relatively
tend to have relatively low
low saponification
saponification
values, since the constituent TAG are
values, since the constituent TAG are
relatively rich in long chain f.as giving
relatively rich in long chain f.as giving
fewer mol. Per one gm of sample
fewer mol. Per one gm of sample
.
.
11. Method
Method
:
:
Weight
Weight 2 gm
2 gm of oil into glass flask
of oil into glass flask
.
.
2
2
-
-
add
add 25
25 ml of alcoholic KOH sol. And boil
ml of alcoholic KOH sol. And boil
for
for 1 hour
1 hour under a condenser, shaking the
under a condenser, shaking the
content of the flask at frequent intervals
content of the flask at frequent intervals
.
.
3
3
-
-
determine the
determine the excess
excess of alkali by titration
of alkali by titration
with HCL using
with HCL using 0.5
0.5 ml of the indicator
ml of the indicator
4
4
-
-
set a blank test upon the same quantity
set a blank test upon the same quantity
of KOH at the same time and under the
of KOH at the same time and under the
same conditions
same conditions
.
.
13. 5
5
-
-
calculate
calculate
:
:
Saponification value = 28.05 ( T1
Saponification value = 28.05 ( T1-
-T2 )
T2 )/
/W
W
Where
Where
:
:
T1
T1= vol. in ml of HCL required for testing the
= vol. in ml of HCL required for testing the
blank
blank
.
.
T2
T2 = vol. in ml of HCL required for testing the
= vol. in ml of HCL required for testing the
sample
sample
.
.
W
W = weight of sample
= weight of sample
Where W is the
Where W is the weight of the sample in gm
weight of the sample in gm and
and
28.05
28.05
is half of the m.w of KOH ( 56.05 ), since
is half of the m.w of KOH ( 56.05 ), since
0.5N acid was used in both titrations
0.5N acid was used in both titrations
.
.
