Low Molecular Non-Volatile Organic Acids in Wort and Beer

Low molecular nonvolatile acids in wort and in bottom-fermented and top-fermented beer have been estimated quantitatively on a silica column and the results further substantiated by means of paper chromatography. In wort as well as in the two types of beer the following acids were found: citric, fumaric, lactic, malic, pyruvic and succinic, together with an unidentified acid (II) and a non-separated mixture of levulinic and mesaconic acid. The wort also contained oxalic acid. α-Ketoglutaric acid was found in wort and bottom-fermented beer, but only a trace of this was present in top-fermented beer. In both types of beer another unidentified acid (I) was found. Bottom-fermented beer alone also contained glycollic acid and top-fermented beer glutaric acid and a third unidentified acid (III). The total amount of non-volatile acids was larger in beer than in wort, chiefly depending on the content of succinic and lactic acid. Total acidity in top-fermented beer was also higher than in bottom-fermented beer for the same reason. Of the non-volatile acids considered here, those originating from hops were insignificant in amount.