Antibiotic effect of garlic on cooking

Chemistry is a fascinating subject. It is our life! We eat chemistry, breathe chemistry and in short live with chemistry! This article elucidates the chemistry involved while cooking garlic and its impact on its medicinal properties.

Cooking involves interesting chemistry and knowing the reactions would benefit us to utilize the nutrients and prevent nutrient loss. We all know the health benefits of garlic. It helps in preventing accumulation of cholesterol in the body. It is known for its antibiotic properties. Two recent studies on the antibiotic potency of garlic have proved that garlic was effective against pathogens that were resistant to even drugs. Garlic juice is even reported to be effective against ciprofloaxacin resistant staphylococci.

The smell of garlic is due to the compound diallyl sulphide present in it.

 CH₂=CH-CH₂-S-S-CH₂-CH=CH₂

( C Stands for carbon; H for hydrogen and S for sulphur)

The molecule alliin present in garlic has no antibiotic properties.  This molecule affects immune responses in blood.

When garlic is crushed, as we do for making rasam, allinase an enzyme comes out and this breaks down alliin and removes one half of the molecule.

 The one half left combines with another similar half and a water molecule is eliminated forming allicin.

-water

         +       

Half of allin                             Half of allin                                      Allicin

Allicin is a colourless liquid having pungent smell and has antibacterial and           antifungal properties.

This allicin is highly antibiotic and is the compound responsible for  the antibiotic properties of garlic.

Thus crushed garlic in food will kill the bacteria in food. When food is cooked allicin breaks down to diallyl disulphide and hence is no longer antibiotic. Garlic in cooked foods is healthy but it may not have antibiotic effect. Therefore in conditions of fever, when we give rasam, we should have in mind that cooking spoils the antibiotic effect of garlic and hence garlic should be crushed and added at the end of preparation.