Cooking with beer: How much alcohol is left?

When cooking with beer and other alcoholic beverages the loss of ethanol relative to loss of water determines the final concentration of ethanol in the food, but predicting the rate of loss is not simple. Since many people for various reasons (drivers, pregnant women etc.) may strictly want to limit their ethanol intake, it is important to obtain knowledge on this topic. Knowing the final ethanol concentration in prepared foods is also crucial for precisely calculating the energy content of a food. In the current study ethanol was quantified using gas chromatography in ten foods prepared with beer: vinaigrette, pancake, carrot soup, rye bread porridge, steamed fish, spareribs, braised beef, rye bread and wheat bread before, during and after preparation. The estimated amount of ethanol per serving was calculated accordingly. The final concentrations in the foods were in the range from 2.62% (v/v) and 2.48% (w/w) to below detection limit. The highest estimated amount of ethanol per serving was accordingly 1.28 g which would be of little concern to most people. Theoretical concentration values calculated from the recipe were in most cases higher than the measured ones, since these values do not reflect the loss during preparation. Nor do the theoretical concentration values reflect the production of ethanol in yeast fermented foods as demonstrated by the rye bread in which case the measured ethanol concentration was higher than the theoretical. The heat-treated foods generally decreased in ethanol concentration during preparation, implying that a higher proportion of the initial amount of ethanol has been lost than of water. The decrease in ethanol concentration observed during cooking further implies that the cook can control the final ethanol content of a food by adjusting cooking time. The other parameter in control of the cook is the initial concentration as prescribed by the recipe.