The USDA's Nutrient Data Laboratory studied how much alcohol is retained in foods after various cooking methods and times. Their data show that even after 2.5 hours of simmering or baking, approximately 5% of the original alcohol content remains in the dish.
This finding is supported by peer-reviewed research and is frequently cited by medical and food science organizations. Shorter cooking times and methods like flambéing retain much higher percentages of alcohol—up to 75% in some cases.
Complete evaporation of alcohol from food does not occur, even with prolonged cooking. These figures are especially important for individuals who wish to avoid alcohol for medical, religious, or personal reasons.