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The Transformation of Proteins into Fats during the Ripening 
of Cheese. (Prelimanary Communication.) 
By M. NIERENSTEIN. 
(Communicated by Dr. Leonard Hill, F.R.S. Received November 8, 1910,—Read 
January 19, 1911.) 
(From the Chemical Department, University of Bristol.) 
It is generally accepted that the so-called ripening of cheese is accompanied 
by an increase in the amount of fat, and this statement is repeatedly brought 
forward as one of the evidences that proteins serve as a source for the 
formation of fat in the animal body. The production of fat during the 
ripening of cheese is traced to bacteria and other fungi, which break down the 
proteins present and set free fat, together with other degradation products.* 
During some previous investigation, jointly with Dr. Breinl,+ we had reason 
to doubt the accuracy of the view that proteins were the precursors of fat in 
the organism, and it appeared to me that, as the argument was partly based 
on a corresponding change during the ripening of cheese, this change was 
worth re-investigation. 
The older investigators dealt either with increase of fat and decrease of 
casein during the ripening process, or else with the increase of fat only. 
Blondeau,} in 1869, examined Roquefort cheese, and his striking results are 
as follows :— 
Fresh. 1 month. | 2 months. 1 year. 
| Per cent. Per cent. Per cent. Per cent. 
ASEM toads cctere ocdaees 85 °43 61 °33 43 °28 40 :23 
LINEN Bere PORES RCE Seen Hee | 1°85 16°12 18 °30 18 °33 
But these results have so far never been confirmed. 
Stohmann,§ who carefully repeated this work, and who is an authority on 
the chemistry of milk, concludes that “das Krasseste aber, was in diesen 
* See Leonard Hill, ‘Recent Advances in Physiology and Bio-chemistry’ (1908), 
p. 290; F. B. Leathes, ‘The Fats’ (1910), p. 106; and also E. Abderhalden, ‘ Physio- 
logische Chemie ’ (1909), p. 436. 
+ A. Breinl and M. Nierenstein, ‘Zeitschr. f. Immunitatsforschung,’ 1909, vol. 2 
p. 169. 
{ Blondeau, ‘ Ann. Chim. Physique’ (4), vol. 1, p. 208. 
§ Stohmann, ‘ Milch u. Molkereiprodukte ’ (1898), p. 842. 
