When slow-cooking food in beer, the temperature is kept at a low simmer and cooking is usually done for several hours, meaning that most of the alcohol will evaporate away. The boiling point of alcohol is 173 degrees Fahrenheit, which is lower than that of water, 212 F. What this means is that the alcohol in your slow-cooked meal will burn off even though there is still some liquid in the slow cooker, which is the remaining water. According to the United States Department of Agriculture, simmering beer alone for 2.5 hours will remove 95 percent of the alcohol it contains, leaving 5 percent of the original alcohol content behind.

While heating alcohol will remove much of its alcohol content, there are several factors that can affect how much will actually remain. Although simmering beer uncovered for 2.5 hours will remove most of the alcohol in it, if you add in fatty meats and other ingredients, they can retain a small amount of the alcohol, meaning that more than 5 percent may remain. Covering the food as it cooks, which is vital to the slow-cooking process, also means that the alcohol may not evaporate away and can instead be deposited back into the food, according to the Pittsburgh Post-Gazette.

Most beers have an alcohol content of anywhere between 4 and 6 percent, averaging around 5 percent. This means that if you slow-cook your dish for at least 2.5 hours, only around 5 percent of this alcohol content, or possibly just a bit more based on your ingredients, will remain. Based on the data from the US Department of Agricutlure, a minimum of about 0.0025 percent alcohol content would then be left in your stew. Of course, this number is doubled if you cook the stew for only two hours and quadrupled if you cook the stew for only 1.5 hours. Even still, the amount of alcohol remaining will be relatively small.

Whether you want to use beer in your dish is completely up to you, but be aware that there will likely always be a small amount of alcohol remaining in a dish slow-cooked in beer. To further minimize this, you could use non-alcoholic beers in your cooking, which by law contain less than 0.5 percent alcohol before cooking, making any alcohol remaining marginal, while still giving you the flavor in your dish. Check with your dinner guests ahead of time, regardless, to see if they are averse to drinking or ingesting any alcohol for religious or health reasons; if so, you may want to skip the beer in your stews and soups.