To the consumer the appearance of beer is one of its most important qualities, which is largely determined by the foam. Foam stability depends on the foam stabilizing and deteriorating compounds. Major differences in foam behavior are thought to be caused by the interaction of proteins with other beer compounds like iso-alpha-acids, metals and lipids. Lipids are considered to be the principal head destabilizing compounds, however, some fatty acids have beneficial effects on the yeast metabolism, facilitating rapid fermentation under anaerobic conditions. The brewer's objectives are to take full advantage of the beneficial effects of fatty acids in brewing, while at the same time, controlling and minimizing the negative effects on beer foam, that is, the foam-damaging effects. Therefore, the purpose of this study is to introduce a method for evaluating the foam-damaging effects of fatty acids which are based on their adsorption properties on the foam surface. We found that it is adequate to use the adsorption amount (surface excess) of the foam destabilizing compounds such as the fatty acids dissolved in beer as their adsorption properties. The foam-damaging effect value of the fatty acids was determined according to the following three steps: First, the adsorption amount (surface excess) of the various fatty acids per its unit concentration was measured. Second, the concentration(C) of the fatty acids in the beer was determined using GC-MS. Finally, the total adsorption amount of the fatty acids was determined by multiplying A and C. The foam-damaging effect (FDE) value of the fatty acids showed a negative correlation with the foam stability within the series of beers. The FDE value showed that the di- and trihydroxyoctadecenoic acids derived from the linoleic acids were than 50% of the portion of all the FDE values from the long-chain fatty acids (C(10)-C(18)), which suggested that the hydroxy fatty acids were the major foam-damaging compounds in beer. These hydroxy acids were mainly produced during the wort production and about 80% of them were transferred into the finished beer. The addition of di- and trihydoxyoctadecenoic acids to a beer caused a decrease in both the foam stability and foam clinging. The study about the behavior of di- and trihydroxyoctadecenoic acids during laboratory-scale mashing showed that starting the mashing at a higher temperature, lowering the pH of the mash, and preventing oxygen uptake into mash are effective in reducing the amounts of these hydroxy acids produced during mashing. Based on the results presented so far, the foam-damaging effect value of the lipids will be useful for controlling the foam behavior and improving the quality of the beer foam.