Trace Volatile Constituents of Beer Iv. Volatile Acids

Eighty-one volatile acids have been detected in the sodium bicarbonate solubles of an ethereal extract of beer, and they together account for 65% of the total ether-soluble acids. Acids positively identified are methanoic (formic), ethanoic (acetic), n-propanoic (propionic), n-butanoic (butyric), 3-methylpropanoic (isobutyric), n-pentanoic (n-valeric), 3-methylbutanoic (isovaleric), n-hexanoic (caproic), hex-2-enoic, hex-3-enoic, n-octanoic (caprylic), n- nonanoic (pelargonic), n-decanoic (capric), n-dodecanoic (lauric), n-tetradecanoic (myristic), n-hexadecanoic (palmitic), n-octadecanoic (stearic), n-octadec-9-enoic (oleic), n-octadec-9.12-dienoic (linoleic), n-octadec-9.12.15-trienoic (linolenic), n-docosanoic (behenic) and n-hexacosanoic (cerotic or cerotinic) acids. Crystalline ethane-1.2-dicarboxylic (succinic) acid was also isolated. Total ether-soluble acids isolated were found in beer at a concentration level of 125 p.p.m. compared with 67 p.p.m. for hopped wort and 61 p.p.m. for sweet wort. All volatile acids present in hopped wort were found to be present also In sweet wort, and in only slightly different proportions. Further, all volatile acids present in beer were found in hopped wort, though relative proportions differed.