Analysis of fruit juices_2
Determination of saccharin
Objective:
To determine the amount of saccharine which may
be added to fruit juice
Introduction & principle
Saccharin (o-benzoic acid sulphamide),
MW=183.19, is weakly acidic & is artificial
sweating agent and can be used as
preserevative
It has the following structure
_It is used as a sucrose substitute because of its
sweetness & may be present in fruit juices as an
adulterant.
_At neutral PH, saccharin is neutral & quite soluble
in diethyl ether. The method used here for its
determination involves extraction into diethyl
ether, followed by titration with 0.05M NaOH,
using Bromothymol blue as indicator
. The latter is yellow in acid solution & blue in
alkaline solution.
Method
1. Extract 50g of the sample three times with 12.5 ml
diethyl ether in a separatory funnel
2. Remove the lower layer & label it as (washing 1)
3. In the separatory funnel wash the diethyl ether extract
with three 2.5ml portions of distilled water
4. Remove the lower layer & label it as (washing 2), &
transfer the upper layer to a beaker & will be your main
extract
5. Shake the combined washing with 5ml diethyl ether &
the upper layer to your main extract
6. Evaporate the ether on warm water bath, dissolve the
residue in 5ml acetone & evaporate to dryness, add 4ml
d H2O
7. Titrate with 0.05M NaOH using
Bromothymol blue indicator
8. Calculate the saccharine present :
1 ml of NaOH = 0.00916 g saccharine
Wt of saccharine (g)= ml * 0.00916
% of saccharine= wt of saccharine/ wt of
sample *100
Normal range 5%
Determination of ethanol in
soft drink
Objective
To determine the presence of ethanol
Introduction & principle
Soft drink are commonly available in markets, these drinks
must be completely free from any amount of ethanol.
The presence of ethanol lowers the specific gravity.
If water is added to the sample, mixed & distilled, water
evaporates together with the volatile materials, ethanol.
So the determination of specific gravity of the distillate
can detect the presence of ethanol especially if it is
lower than one .
Method
1. Weight 100ml of sample & add to it 50ml
distilled water
2. Distil & collect 100ml of solution
3. Measure the specific gravity of the
solution using S.G bottle
4. Alcohol is present if the S.G was lower
than one.