Crush raw garlic and don't store it to maximize allicin

Physorg.com - Love that garlic? Fresh may be healthier than bottled
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Physorg.com - Recipe for healthy garlic: Crush before cooking

The ingredient allicin in garlic is believed to be help prevent blood clots, reduce cancer risk, and help fight off bacterial infection. Allicin breaks down rather easily; when stored in water, about half of the allicin in the garlic broke down in 6 days, in vegetable oil: 1 hour. Though allicin loses its bacteria-fighting benefit when broken down, the components are still believed to fight blood clots and cancer.

Allicin is produced by a catalyst enzyme alliinase, which becomes inactive when garlic is cooked-- effectively reducing allicin in cooked garlic. However the act of crushing or chopping the raw garlic prior to cooking activates alliinase, which catalyzes allicin. Researchers believe that chopping or crushing raw garlic 10 minutes prior to cooking will help retain some of the health benefits of allicin that are found in raw garlic.