There is disclosed a method for preparing allicin which comprises the following steps: (a) mechanically treating a natural source of alliinase to release alliinase therefrom; (b) contacting the mechanically treated alliinase source with an aqueous solution of allicin containing alliin at a concentration greater than that found in raw garlic, whereby the alliin is enzymatically converted to allicin by the alliinase released from the alliinase source; and optionally (c) extracting the resultant allicin into a low boiling point non-polar organic solvent.