934 



Journal of Agricultural Research 



Vol. VI, No. 24 



EFFECT OF CREAM ACIDITY UPON THE COMPOSITION OF THE AIR IN 

 BUTTER HELD IN STORAGE 



The samples, the gas-analysis data of which are given in Tables I, II, 

 and III, were prepared under conditions as nearly identical as possible, 

 the butter having been made at Troy, Pa. In each case the butter was 

 made from 60 pounds of cream taken from one lot, pasteurized at 140 F., 

 and cooled to 48 F. In all three cases the temperature of the butter- 

 milk was 58 F., the quantity of salt added to the butter each time was 

 12 ounces, and each working was carried to 15 revolutions. 



The cream of sample 1 was churned sweet. To the cream of sample 2 



was added 15 per cent of the starter, and the churning done at once. 



Before churning the cream of sample 3, sufficient lactic acid was added 



to it to make its acidity 0.71 per cent (calculated as lactic acid) by 



titration. 



Ta&LE I. — Analysis of air extracted from sweet-cream butter 



[Calculated to o° C and 760 mm. Acidity of cream as lactic acid, 0.11 per cent; salt, 1.21 per cent; 



curd, 0.5S per cent] 



Number of bacteria per gram. "• 



9,050,000. 



132,000. 



Time stored. 



At o° F. 



At 3 2°F. 



Days. 



81 

 81 

 no 

 no 

 150 

 180 



Days. 

 O 

 2* 



15 

 41 



57 

 o 



1 



13 

 o 



At 

 room tem- 

 perature. 



Hours. 



Oxygen. 



Per cent. 



6 25- iS 



22. 23 



15.96 



9.86 



5-49 

 25- 5 1 



22. 70 



20.45 

 20. 62 



23. 00 



24. 18 



25. 11 



Carbon 

 dioxid. 



Per cent. 

 b 2 . 



4-51 

 7-58 

 n. 91 

 15.24 

 1.49 

 2. 02 

 2.86 

 2.85 



2- 73 

 1. 62 



o-57 



a Thanks are due Mr. L,. A. Rogers, of the Dairy Division, for the bacteriological work in connection 

 with this investigation. 

 6 Analysis of gas extracted from butter as soon as tube was packed. 



Samples i and 2 were shipped on the afternoon of the same day, arriv- 

 ing in Washington, D. C, shortly before noon of the following day, when 

 the butter was immediately packed into sterilized special glass tubes and 

 small jars and then placed in storage at o° F. Sample 3 was finished late 

 in the afternoon of the same day on which the preceding samples were 

 made, and did not reach Washington until the second morning after, 

 when the butter was at once packed into tubes and jars and placed in 

 storage under the same conditions as above. 



From each of the three samples several tubes were taken and trans- 

 ferred to storage at 32 F. The remainder of the tubes were allowed to 

 continue at a storage temperature of o° F. From time to time tubes 

 were removed from both temperatures, the gas removed therefrom by 



