Septembee 12, 1913] 



SCIENCE 



377 



ferentiating the varieties having been placed on more uniform cheese during the siunmer months 

 cultural and biological characters. A summary of and will make it possible to produce good Swiss 

 these characters is given in the subjoined table. cheese during the entire year. 



The Cultural Clwiaoters of Whey Yeasts 

 -\- indicates positive results. Blanks indicate no action. 

 For convenience the organisms are designated by letters. 



All of the organisms made scanty growth in Cohn. 

 Yeasts -Dl, J2, PI, X2 made scanty growth in 

 Uschinsky; the others none. Organisms A2, Jl, 

 PI produced a marked pineapple flavor in wort 

 agar plates, and A5 and J2, marked strawberry 

 flavor in the same medium. Further work with 

 these organisms is planned. 



The Action of Bacillus Bulgaricus in Suppressing 



Gassy Fermentations in Cheese-making: 0. F. 



DOANE, Dairy Division, U. S. Department of 



Agriculture. 



It was found that pure cultures of iulgaricus 

 could be used with perfect results in suppressing 

 the undesirable fermentations, principally gas, 

 which have worried Swiss cheesemakers in the 

 past. There seems to be a difference in the eflS.- 

 eiency of different strains of bulgaricus for this 

 purpose without respect to their activity in form- 

 ing acid. One per cent, of a whey starter made 

 from one culture was sufficient, while it requires 

 three per cent, of another. The bulgaricus start- 

 ers could not be seen to have any effect on the 

 formation of the eyes or interfere with the flavor 

 or texture. It is believed that the proper use of 

 bulgaricus starters will go far towards making a 



^Does not ferment raffinose, glycerine, mannite, 

 inulin, starch. 



^Liquefaction was slow, in some cases occurring 

 only after a number of months. 



The Preparation of Dried Cultures: L. A. Rogers, 

 Dairy Division, U. S. Department of Agricul- 

 ture. 



The method of Shackell, consisting essentially 

 in holding the frozen material over sulphuric acid 

 in a high vacuum, is adapted for drying cultures 

 of the lactic acid bacteria, B. bulgaricus and other 

 organisms. A chamber was devised in which con- 

 siderable quantities of powder could be made. 

 The best results are obtained by drying cultures 

 grown on milk concentrated to one half its orig- 

 inal volume. Fresh lactic cultures dried by this 

 method curdle milk in twenty hours at 30° when 

 one part of powder is added to 1,000,000 parts of 

 milk. Dried cultures of B. bulgaricus curdle milk 

 in twenty hours at 37° when added to the milk in 

 the ratio of 1 : 100,000. The activity of a dried 

 culture diminishes more or less rapidly, depending 

 on the conditions under which it is held. The 

 deterioration is less rapid if the moisture content 

 is very low; it is less rapid as the temperature of 

 storage is diminished and is much more rapid in 

 air or oxygen than in an inert gas or in a vacuum. 



The Normal Bacteria of Swiss Cheese: E. E. 

 Eldeidqe and L. A. Rogers, Dairy Division, 

 XJ. S. Department of Agriculture. 

 Special media were devised which gave high 



