The production of citric acid from lactic acid and from alcohol.

IN the dairy industry moulds are often encountered on media containing lactic acid. According to the literature on the subject, the view appears to be justified that this acid is oxidized by the moulds into CO2 or transformed into oxalic acid. Wehmer [1929] reports that by the action of Aspergillus mutantus calcium lactate is transformed into carbonate and sodium lactate into oxalate. Similarly, Thies [1934] finds that A. fumigatus oxidizes calcium lactate to calcium carbonate, whilst its sodium, potassium and ammonium salts are changed into the oxalates of the respective cations. Acklin [1929] states that Penicillium glaucum oxidizeslactic acid towater and carbon dioxide viapyruvic acid and acetaldehyde, in agreement with Neuberg's theory. According to Walker & Coppock [1928] A. niger acting on calcium propionate first forms lactic acid which is then transformed into pyruvic acid; propionic acid therefore would appear before the lactic acid. These authors accept the view that acetic acid must also be formed as a transient product by dismutation of acetaldehyde, the presence of which was determined by them in these processes. Botrytis cinerea is a mould which relatively easily transforms acetic into citric acid [Chrzgszcz & Zakomorny, 1936]. If then acetic acid is formed during the decomposition of lactic acid, this would indicate that conditions exist for the relevant mould to form citric acid. The determination of this fact would afford further evidence in support of our hypothesis that citric acid is yielded by acetic acid [Chrzpszcz & Tiukow, 1930], whilst this would in addition throw rather a different light upon the problem of the decomposition of lactic acid by moulds. The following research was undertaken in order to elucidate this point.