276 EXPERIMENT STATION EECORD. [V<rf.35 



The composition of the milk of Egjrptian animals, A. Pappel and G. Hogan 

 (Cairo: Dept. Pub. Health, 1914, PP- 12). — An analysis of Egyptian buffalo milk 

 is given. 



Effect of pasteurization on mold spores, C. Thom and S. H. Ayebs (Z7. S. 

 Dept. Agr., Jour. Agr. Research, 6 {1916), No. 4, pp. 15S-166, figs. S).— Studies 

 were made with spores from pure cultures of a series of molds including several 

 species of Penicillium, of Aspergillus, and of the mucors, with, in some experi- 

 ments, the addition of Oidium (Oospora) lactis and one strain of Fusarium. 

 These sets of experiments were made to test the temperatures used in pasteuri- 

 zation by the holder process, those used in the flash process, and the effects of 

 dry heat. 



In the holder process of pasteurization, in which milk was heated to from 120° 

 to 150° F. and maintained at these temperatures for 30 minutes, the Mucor 

 racemosus group and RMzopus nigricans, which are found more frequently than 

 all others of the mucor group combined, were destroyed at 130°. The common 

 green species of Penicillium are mostly dead at 130° ; a few stand 135°, but two, 

 one of them an undescribed soil organism, survived 140° for 30 minutes. Among 

 species of Aspergillus, however, the strains of A. flavus, A. f^imigatus, and 

 A. repens all survived 145° for 30 minutes, and A. repens and A. fumigatus both 

 survived 150°. These three species are always found in forage and feeding 

 stuffs ; hence, milk is more or less subject to contamination with them. A. 

 repens grows very poorly in milk, however, and the examination of a great many 

 cultures of milk and its products has shown that the actual development of 

 A. flavus and A. fumigatus is comparatively rare. Pasteurization of milk at 

 145° may therefore be regarded as destroying mold spores completely enough 

 to render them a negligible factor in the further changes found in the milk. 



In the flash process of pasteurization, where milk was heated to from 145° 

 to 175° for a period of 30 seconds, the spores of all the molds tested were de- 

 stroyed with the exception of many spores of one form and occasional spores of 

 three more forms. At 175° only occasional spores of two forms developed. 



When the heating process was performed in dry air for a period of 30 seconds 

 at 200°, 31 out of 42 forms of Penicillium and 7 out of 24 forms of Aspergillus 

 were destroyed, but none of the cultures of the mucors. A temperature of 250° 

 over a period of 30 minutes killed all the forms of Penicillium spp. tried, but 

 left an occasional living spore in one species of Aspergillus and 3 out of 6 mucors. 



Careful study of the cultures showed that the first effect of heating was to 

 delay germination. At times heating to a degree just under the death point 

 delayed germination almost the full length of the usual growing period of the 

 species. There is frequently a survival of a few spores where a majority of the 

 spores die. There may be, therefore, a difference of as much as 20° between the 

 temperature at which an occasional culture is completely killed and that at which 

 cultures of that species are uniformly killed. These results resemble those 

 obtained in determining the thermal death point of bacteria. 



Metallic flavor in dairy products, E. S. Guthrie (New York Cornell Sta. 

 Bui. 573 (1916), pp. 609-64S) .—The results of these studies seemed to indicate 

 that there may be a cause of metallic flavor other than direct contact of the 

 dairy product with metal. In several instances it seemed to increase when the 

 product was not in contact with metal. 



Buttermilk in sterilized glass bottles developed the flavor in many cases. Of 

 241 samples of cream in sterilized glass bottles metallic flavor was produced in 

 79 by inoculation with metallic-flavored buttermilk; and of 157 samples of 

 cream in sterilized glass bottles which were inoculated with individual bacteria 

 52 showed metallic flavor. It is concluded that the organism that causes metallic 



