Effect of Thermal Treatment on the Antiproliferative and Antioxidant Activities of Garlic.

Garlic is consumed chiefly for its pro-health properties, including the antiproliferative effect against cancer cells and the antioxidant action. Garlic is used as a raw vegetable but also after thermal treatment. Nonetheless, data concerning the effects of heating on the biological activities of garlic are scarce. The study aimed to examine the effect of heating at various temperatures of garlic homogenate and blanching, baking, and steaming of garlic cloves on the antiproliferative activity against human ovarian cancer cells and antioxidant activity of garlic. Heating of garlic homogenate (40°C-100°C for 10 min) did not decrease or even increase the content of phenolics and Total Antioxidant Activity (TAC) assayed by ABTS(•) decolorization, DPPH(•) decolorization, FRAC, and CUPRAC methods, but higher temperatures decreased the thiosulfinate content, inactivated alliinase, and decreased the cytotoxic activity. Baking and steaming of garlic cloves decreased TAC and phenolic content, inactivated alliinase, decreased thiosulfinate content, and compromised the cytotoxic activity of garlic. Blanching did not significantly affect TAC and phenolic content but caused small inactivation of alliinase and a slight decrease in thiosulfinate content. These results indicate that thermal treatment causes no or moderate decrease in TAC, but decreases the alliinase activity, thiosulfinate content, and the antiproliferative activity of garlic for ovarian cancer cells.