Raw garlic (Allium sativum) is known to have antiplatelet activity (AA) that may reduce cardiovascular disease. Water extracts of raw garlic and onion have AA. This study was done to determine whether crushing and cooking garlic changed the AA.
A group of organosulfur compounds found in garlic and onions is responsible for their aroma and flavor. Thiosulfinates, including allicin and pyruvate, are the sulfur-containing compounds that are found when onion and garlic are cut. Thiosulfinates are good predictors of the AA content of raw garlic extracts. Allicin and pyruvate levels in garlic are also a good measure of AA.
Alliinase is the enzyme that produces allicin and pyruvate, and it is released by crushing and is heat sensitive. Allicin is more tolerant of heat than is alliinase. For garlic to have AA, the thiosulfinates must be produced before the alliinase is destroyed by heat, therefore garlic should be cut, sliced or crushed before cooking.
Testing was done on blood samples from humans who had eaten garlic samples cooked in various ways. Oven heating of garlic at 200 degrees C or boiling water for three minutes or less did not alter the AA of the garlic. Heating garlic in boiling water for six minutes completely blocked the AA in uncrushed samples. Previously crushed samples heated for six minutes had reduced AA. All garlic samples cooked over 10 minutes at more than 100 degrees C lost all AA and micro-waved, uncrushed garlic had very little AA. Garlic that was crushed and then micro-waved had AA similar to raw garlic.
Fertilization of garlic with sulfur while it is growing can increase the sulfur content and AA of the garlic.
CONCLUSION: Allicin and thiosulfinates increase AA, and crushing garlic prior to cooking preserves AA. “The partial loss of antithrombotic effect in crushed-cooked garlic may be compensated by increasing the amount consumed.” AA rapidly is lost at between three and six minutes of cooking. AA is restored by adding fresh garlic juice with alliinase.
NOTE: Read about the effect of processing and cooking on onions.
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