You can use alcohol such as whiskey, to marinate meat. However, alcohol affects the meat's proteins. It causes proteins in the meat to contract and toughen. The net effect is a steak with an unpleasant brown color and a chewy surface. The best way to add whiskey's flavor to a marinade is by cooking the marinade down first. Simmer it in a pan until the alcohol has mostly evaporated, and the flavors of your whiskey are highly concentrated. This process will make your marinade tasty without the problems caused by alcohol.