MOLDINESS IN BUTTER 



By Charles Thom, Mycologist, and R. H. Shaw, Chemist, Dairy Division, 

 Bureau of Animal Industry 



INTRODUCTION 



References to mold in butter are not uncommon in dairy literature, 

 but specific information is lacking as to what forms of mold occur on 

 butter, the conditions which permit mold development, and the actual 

 changes produced in the butter. As met in the market, losses from 

 mold take two forms: (i) The growth of mold upon the tub, lining, 

 or wrapper injures the appearance and salability of the package with- 

 out seriously affecting the quality of its contents. (2) Mold develop- 

 ment upon the butter itself when continued for a considerable period 

 produces changes which can not be eliminated even by the renovation 

 process. Such butter becomes an actual loss. The work reported here 

 aims to cover the biological phases of this problem. The study of the 

 chemical changes produced in the butter will be reported later. 



ORIGIN OF BUTTER SAMPLES 



Characteristic samples representing the range of conditions and 

 appearances found in commercial butter were obtained through the 

 inspection service of the Dairy Division. These were examined in the 

 mycological laboratory. The number and variety of mold colonies 

 upon each sample were noted and cultures were made to obtain the 

 species represented. The samples were then taken to the chemical 

 laboratory for analysis. Consideration of the known factors influenc- 

 ing mold growth called for the determination of the quantities of water 

 and protein available, together with the percentage of salt as a possible 

 limiting factor. 



In Table I are given the analyses of samples of moldy butter from 

 several sources. 



Table I. — Analyses of samples of moldy butter 



Sample No. 



3529- 



3530- • 

 3554g 

 3554r. 



Sample No. 



3S54S. 

 3546a 

 3546b 

 3546c, 



Curd .a 



Per tcnt. 



o 57 

 .68 



•75 

 .6a 



" The term "curd," as used in this paper, means the amount of nitrogen multiplied by the factor 6.38. 



Journal of Agricultural Research, 

 Dept. of Agriculture, Washington, D. C. 



(301) 



Vol. Ill, No. 4 

 Jan. IS, 1915 



A— 12 



