Class 12th Chemistry Projects for 2009 Exams
ANALYSIS OF VEGETABLES AND FRUIT JUICES
To analyse some fruits & vegetables juice for the contents present in
Fruits and vegetable are always a part of balanced diet. That means fruits
vegetables provide our body the essential nutrients, i.e. Carbohydrates,
proteins, vitamins and minerals. Again their presence in these is being
indicated by some of our general observations, like -freshly cut apples become
reddish black after some time. Explanation for it is that iron present in apple
gets oxidixed to iron oxide. So, we can conclude that fruits and vegetables
contain complex organic compounds, for e.g., anthocin, chlorophyll,
esters(flavouring compounds), carbohydrates, vitamins and can be tested in any
fruits or vegetable by extracting out its juice and then subtracting it to
various tests which are for detection of different classes of organic compounds.
Detection of minerals in vegetables or fruits means detection of elements other
than carbon, hydrogen and oxygen.
- Test Tubes
- Litmus paper
- Laboratory reagents
- Various fruits
- Vegetables juices
- pH indicator
- Iodine solution
- Fehling solution A and Fehling solution B
- Ammonium chloride solution
- Ammonium hvdroxide
- Ammonium oxalate
- Potassium sulphocynaide solution
The juices are made dilute by adding distilled water to it, in order to
remove colour and to make it colourless so that colour change can be easily
watched and noted down. Now test for food components are taken down with the
TEST, OBSERVATION & INFERENCE
|Test for acidity:
|Take 5ml of orange juice in a test tube and dip a pH paper
in it. If pH is less than 7 the juice is acidic else the juice is basic.
||The pH comes out to be 6.
||Orange juice is acidic.
|Test for Startch:
|Take 2 ml of juice in a test tube and add few drops of
iodine solution. It turns blue black in colour than the starch is
||Absence of blue black in colour.
||Orange juice is acidic.
|Test for Carbohydrates (FEHLING'S TEST):
|Take 2 ml of juice and 1 ml of fehling
solution A & B and boil it. Red precipitates indicates the presence
of producing sugar like maltose, glucose , fructose & Lactose.
||No red coloured precipitates obtained.
|Test for Iron:
|Take 2 ml of juice add drop of conc. Nitric
acid. Boil the solution cool and add 2-3 drops of potassium
sulphocyanide solution .Blood red colours shows the presence of iron.
||Absence of blood red colour.
||Iron is absent.
|Test for Calcium:
|Take 2 ml of juice add Ammonium chloride and
ammonium hydroxide solution. Filter the solution and to the filterate
add 2 ml of Ammonium Oxalate solution. white ppt or milkiness indicates
the presence of calcium.
||Yellow precipitate is obtained.
||Calcium is present.
From the table given behind it can be conducted that most of the fruits &
vegetable contain carbohydrate & vegetable contain carbohydrate to a small
extent. Proteins are present in small quantity. Therefore one must not only
depend on fruits and vegetables for a balance diet.