C. U. C. p. ALUMNI JOURNAL 



231 



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Conducted by Prof. George C. Diekman. 



Fermentation Process for Citric Acid. 



J. A. Martin, in Amer. J. of Pliarm., 

 1916, gives the results of experiments 

 made by him in this direction. The 

 mould used was probably the Citromyces 

 tollensianus, as this particular mould 

 has been found capable of converting 

 larger quantities of dextrose than other 

 similar ones studied until now. The 

 author inoculated a 10 per cent, dex- 

 trose solution containing the proper 

 nutrient salts with spores of the mould. 

 The mixture was kept at a temperature 

 of 20° C. in presence of air. Results 

 were noted after four days, a growth 

 becoming visible and the liquid becom- 

 ing covered with a thin, soft green layer. 

 The formation of citric acid began after 

 five days had elapsed and the maximum 

 amount was reached after tweny-four 

 days, totaling then about 20 per cent, of 

 the weight of dextrose employed. The 

 experiments were conducted in shallow 

 vessels, as it was found that the citric 

 acid remained in the upper layers and 

 this procedure also facilitated free ac- 

 cess of air. The acid was neutralized 

 from time to time by addition of calcium 

 carbonate, and in this way it was foun'l 

 possible in one experiment to increase 

 the quantity of acid to 43 per cent, ot 

 the weight of sugar employed, after 60 

 days had elapsed. The best results were 

 obtained in solutions of sugar contain- 



ing not more than 10 per cent, of this 

 substance. The medium should be 

 either neutral or slightly acid, and suit- 

 able nutrient salts must be present. 

 Light has no influence on the produc- 

 tion ; the temperature must, however, be 

 carefully regulated, and as the process 

 is one of oxidation, free access of air 

 must be insured. The author is of the 

 opinion that the process may be made of 

 commercial value after more study. 



Rancid Fats. 



G. Issoglio, Atti. R. Accad. Sci. 

 Torino, 51, 582-605. Through Journ. 

 Cheni. Soc, 1916, no, 401-402, proposes 

 a new method for the analysis of rancid 

 fats. He uses the term "oxidisability 

 number," by which he refers to the num- 

 ber of milligrammes of oxygen required 

 to oxidise the organic compounds re- 

 moved by the distillation of 100 grammes 

 of a fat or oil in a current of steam. For 

 fat and oils which are to be used as 

 foods, this number was found to range 

 between 3 and 10. Fats which had 

 undergone decomposition yielded num- 

 bers which were much higher. The au- 

 thor states that in his opinion a number 

 exceeding 15 would justify the rejection 

 of the sam.ple as a food. The "oxidis- 

 ability number" is ascertained as follows : 

 20 to 25 grammes of the fat or oil to be 



