Refer to various literature concerning systematics, anatomy, history etc.!

Ingredients:

In intact cells the biggest fraction are various sugars (ca. 40%). The typical substance of garlic is found by 0,2 - 1,5%, it is called alliin. Chemically alliins are derivates of sulphur-containing animo acids (cystein-sulfoxides):



At different places within the same cell there are enzymes called alliinase (lyase) which catalyse a transformation to a substance called allicin. When garlic is ground the components come in contact so allicin-formation starts which is detected by the typical garlic smell:



Allicin undergoes further reactions expecially to form various aldylsulfides or - to a much smaller extent - a substance called ajoen.
Garlic extract reacts chemically as a reducing agent which can be seen by the following experiments:


Production of an aequous garlic extract

Peel 2 or 3 bulbils of garlic and cut them into small slices. Put them into a mortar and grind. Add ca. 10 [ml] of aqua dest. to the pulp, stir and filter through a cotton pad.
It yields a turbid liquid.


Production of an alcoholic garlic extract

Give the slices of 5 - 7 bulbils of garlic into a 100-ml-bottle and add ca. 30 [ml] ethanol. Allow to settle for at least one week.


Reduction experiments

Reduction of acidic permanganate-solution

Give ca. 10 [ml] of a very diluted potassium permanganate-solution into a small beaker, add a few drops of conc. sulphuric acid and finally 7 fresh slices of garlic.

Observations? - How is permanganate reduced under acidic conditions?


Reduction of dichromate-solution

Take a small test-tube with 3 [ml] diluted dichromate-solution and fill it with hot 2,5% agar-agar-solution. Give the mixture into a Petri dish and allow to cool.
Put on the agar some fresh slices of garlic and cover.
Observation? - Explanation?


Reduction of iodine

Ca. 4 [ml] of Lugol`s solution (alcoholic iodine solution) is put into a test-tube. Some fresh garlic-slices are added and carefully warmed.
Observation? - Explanation?


Reduction of Tillmann`s reagent (DCPIP = Dichlorophenolindophenol)

Prepare Tillmann`s reagent by dissolving 0,05 [g] DCPIP in 1000 [ml] of aqua dest.
Prepare an aequous pulp from one bulbil of garlic with less water. Add it to a test-tube containing 5 [ml] of Tillmann`s reagent and shake.
Observations?


Reduction of silver nitrate

4 [ml] of a given silver nitrate-solution is put into a test-tube. Then it is filled with hot 2,5% agar-solution and the mixture given into a Petri-dish where it is allowed to cool.
On the jelly surface fresh garlic-slices are given.
Variation:
Prepare two further Petri-dishes as above. To the first one some root-tips, to the second one some small parts of green leaves are given.
Compare the observations! - Conclusion?


Formation of a silver mirror

Into a new test-tube 3 [ml] of silver nitrate-solution are given. A few drops of KOH-solution are added so that a ppt. of silver hydroxide is formed. Then so many drops of conc. ammonia are added (in the fume chamber) that the ppt. just vanishes.
Finally some slices of garlic are added and carefully heated to boil in a water-bath.
If you`re lucky you`ll get a silver mirror!

All the experiments described above can be carried out by using garlic-extract too!